Orientador: Ismael Antonio Bonassi / Banca: Maura Seiko T. Esperancini / Banca: Regina de Oliveira Moraes Arruda / Resumo: No presente trabalho estudou-se o comportamento das hortaliças couve-flor e feijão-vagem, submetidas ao processo de fermentação lática controlada sob temperatura de 20 C (variação de 0,5 C). O experimento constituiu-se de três ensaios de fermentação para cada uma das hortaliças: Tratamento Controle (Testemunha), Tratamento com Adição de Inóculo Comercial e Tratamento com Adição de Inóculo Comercial + Adição de Acido Lático. O monitoramento das fermentações foi realizado por meio de análises químicas, físicas, físico-químicas e microbiológicas, no decorrer e no final do processo fermentativo. Para a avaliação sensorial foram elaborados picles em vinagre de vinho branco condimentado, utilizando-se dos produtos fermentados e a matéria-prima "in natura'. A pesquisa foi complementada com o estudo do gasto de energia elétrica e do custo de elaboração dos produtos fermentados, considerando-se o processamento em laboratório; e foi determinado o consumo de energia e sua racionalização, comparando-se com o armazenamento refrigerado (processamento mínimo) das diferentes hortaliças em estudo. Os resultados obtidos através das análises químicas, físico-químicas e microbiológicas, permitiram verificar que as fermentações transcorreram normalmente, obtendo-se produtos com características desejáveis, ou seja, de alimento fermentado e produzidos com as condições tecnológicas para se apresentaram seguros, em relação aos aspectos de conservação e de saúde pública. Para ambas as hortaliças estudadas (couve-flor e feijão-vagem), os tratamentos em que houve Adição de Inóculo Comercial, resultaram em produtos com níveis mais elevados de acidez. Para couve-flor a maior acidez foi desenvolvida no tratamento com Adição de Inóculo Comercial;...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the present work it was studied the behavior of the vegetables cauliflower and snap-bean, submitted to the process of controlled lactic acid fermentation under temperature of 20 °C (variation of l 0,5 °C). The experiment was constituted for three trials of fermentation process for each one of the vegetables: Control Treatment (test) with Addition of Starter (Lactobacillus plantarum) and with Addition of Starter (L. plantarum) + Lactic Acid. The monitoring of the fermentations was accomplished through chemical, physical, physical-chemical and microbiological analyses, during and at the end of the fermentation process. Using the fermented products and raw vegetable, pickles were elaborated in spiced white vinegar for the purpose of sensorial evaluation. Parallelly, the research was complemented with the study of the expense of electric energy and the elaboration cost of the fermented products, being considered the processing in laboratory; and also, it was verified of the consumption of energy and its rationalization, being compared with the refrigerated storage (minimum processing) of the different vegetables in study. The obtained results through the chemical, physical-chemical and microbiological analyses, allowed to verify that the fermentations usually elapsed, being obtained products with desirable characteristics, that is to say, of fermented food and produced with the technological conditions for they came safe, in relation to the conservation aspects and of public health. For both studied vegetables (cauliflower and snap-bean), the treatments in that there were Addition of Starter, they resulted in products with a higher acidity levels. For cauliflower the greatest acidity was developed in the treatment with Addition of Starter;...(Complete abstract click electronic access below) / Mestre

Pour limiter la production de déchets, la voie de polymères biodégradables est largement explorée. La biodégradation en compost est un phénomène complexe qui dépend de la température, de l’humidité, du soleil et du polymère lui-même. Dans un premier temps, les effets de ces différents paramètres sur la biodégradation de l’acide polylactique (PLA) sont étudiés à l’aide de la viscoélasticité à l’état fondu. Il en résulte que l’échantillon lui-même n’a que peu d’influence sur sa dégradation, mais les conditions de dégradation influencent d’avantage les phénomènes mis en jeu. Dans un deuxième temps, le PLA est associé au poly(butylène succinate) (PBS), un polymère plus favorable à la biodégradation afin d’améliorer la dégradation du PLA. Après s’être intéressée à la biodégradation de polymères « compostables », cette étude se tourne vers la biodégradation d’un polymère non-biodégradable : le polypropylène (PP). Afin d’initier un processus de bio assimilation, des charges sont ajoutées au PP pour dégrader préalablement le polymère et ainsi favoriser l’action des micro-organismes sur les chaines plus courtes. Les hydroxydes doubles lamellaires induisent bien une dégradation mais ce n’est pas assez pour permettre l’assimilation du polymère. Finalement, ce travail aborde la biodégradation de différents polymères dans le but de comprendre ce phénomène et d’améliorer la biodégradation des polymères étudiés. / Nowadays, to minimize our waste production, many studies are focused on environmentally friendly polymers. Degradation in compost is a complex phenomenon with unclear mechanism depending on temperature, micro-organism population, humidity and polymer it-self. In a first hand, these different parameter effects on poly(lactic acid)(PLA) biodegradation are studied with melt viscoelasticity to assess the molecular evolution of the materials during biodegradation. In a second hand, PLA is mixed with a polymer more biodegradable, poly(butylene succinate), to improve PLA biodegradation. After the biodegradation of a compostable polymer, a non biodegradable polymer is studied: polypropylene(PP). To achieve the initiation of its bio-assimilation, fillers are added to promote its degradation and therefore improve its assimilation by micro-organisms. Layered double hydroxides induce degradation but not enough to observe polymer biodegradation.

L’utilisation de bactéries lactiques (BL), telle que Lactococcus lactis (LL), comme vecteur de transfert d’ADN, constitue une stratégie prometteuse dans la mesure où elles sont considérées sans risque pour la santé. Des souches sauvages (wt) ou recombinantes de LL ont été décrites comme capables de transférer un plasmide dans des cellules épithéliales in vitro et in vivo. Cependant, les mécanismes d'action grâce auxquels certaines souches de LL ont la capacité de transférer de l’ADN plasmidique sont toujours inconnus. C’est pourquoi, nous avons décidé de construire une nouvelle souche recombinante de LL exprimant l’internaline mutée (mlnlA,) à partir de la souche pathogène Listeria monocytogenes, de manière à comprendre par quel procédé l’ADN est transféré à des cellules eucaryotes. Nous avons détecté l’expression de mInIA par FACS et montré que la souche LLmInIA était plus invasive que la souche sauvage wt après co-incubation avec des cellules épithéliales intestinales (IECs) non confluentes ou polarisées. La microscopie confocale confirme ces propriétés d’invasivité de la souche LL-mLnLA capable de transférer plus efficacement le vecteur d’expression eucaryote codant pour l’allergène de la β-lactoglobuline, pValac :BLG, in vitro dans des IECs et dans des cellules dendritiques (DCs). La souche LL-mInIA a aussi la capacité de transférer le vecteur pValac:BLG à des DCs à travers une monocouche de IECs différenciées. Des essais in vivo montrent que des bactéries invasives du genre Lactococcus ont tendance à augmenter l’expression de BLG chez la souris. De plus, il est montré qu’une souche non invasive de LL, ou la souche invasive LL-mInIA, stimulent la sécrétion de la cytokine pro-inflammatoire IL-12 dans des DCs, et que, in vivo, après des essais d’immunisation oraux ou intra nasaux, la souche LL non invasive oriente la réponse immunitaire plutôt vers le type 1, alors que la souche LL invasive génère une réponse de type 2 chez des animaux immunisés. Tous ces résultats apportent un nouvel éclairage sur le mécanisme d’assimilation des lactocoques en tant que vecteurs de transfert de molécules actives. / The use of Lactic Acid Bacteria (LAB), such as Lactococcus lactis (LL), as DNA delivery vehicles represents an interesting strategy as they are regarded as safe. Wild type (wt) LL or recombinant invasive LL, were able to trigger DNA expression by epithelial cells both in vitro and in vivo. However, important information about how LL can transfer DNA plasmids is still missing. Therefore, we decided to construct a new recombinant invasive LL strain expressing mutated Internalin A (mInlA) from the pathogen Listeria monocytogenes to understand the manner by which the DNA is transferred to mammalian cells. mInlA expression was detected by FACS analysis and LL-mInlA strain showed to be more invasive than the wt strain after co-incubation assays with non-confluent or polarized intestinal epithelial cells (IECs). Confocal microscopy confirmed the invasive status of LL-mInlA which demonstrated to deliver more efficiently the eukaryotic expression vector coding the allergen β-lactoglobulin, pValac:BLG, in vitro to IECs and to dendritic cells (DCs). LL-mInlA was also capable to transfer pValac:BLG to DCs across a monolayer of differentiated IECs. In vivo, invasive lactococci tended to increase the number of mice expressing BLG. Moreover, noninvasive or invasive LL-mInlA stimulated the secretion of the pro-inflammatory cytokine IL-12 in DCs and, in vivo, after oral or intranasal immunization trials, non-invasive LL polarized the immune response more in the type 1 direction while invasive LL generated a Th2-type response in immunized animals. All these data gives new insights on the mechanism of lactococci uptake for delivery of therapeutics.

Bacteriocins are peptides produced by various species of bacteria, especially lactic acid bacteria (LABs), which exhibit a large spectrum of action against spoilage bacteria and foodborne pathogens. However, when this bacteriocin has not been completely characterized regarding its amino acid and the nucleotide sequences of the corresponding gene, the qualified term bacteriocin-like inhibitory substance (BLIS) is recommended. In order to increase the antimicrobial activity of bacteriocins, the ability of probiotics LABs, such as Pediococcus pentosaceus, to ferment different carbon and nitrogen sources has been studied. For the development of an improved culture medium, carbon and nitrogen sources must be considered as nutrients responsible for cell growth and bacteriocin production. The best condition, after 48 h of cultivation, for growth (3.420 g/L) and for BLIS production by Pediococcus pentosaceus ATCC 43200 was in Man, Rogosa and Sharp (MRS) culture medium supplemented with 1.5% peptone, initial pH 6.0 and under the following culture conditions: anaerobiosis, 30oC and agitation of 200 rpm. Compared with control (MRS without supplement), the growth of Pediococcus was significantly lower (1.995 g/L) as well as it reduced significantly its generation time from 2.05 h (control) to 1.28 h (MRS supplemented), a reduction of approximately 62.5%. Moreover, addiction of peptone to MRS medium promoted reduction of 4 h to the Pediococcus exponential phase onset. Regarding BLIS antimicrobial activity, addition of nitrogen source to MRS medium was also quite significant. Through the agar diffusion method, BLIS showed inhibition halos between 12.50 and 19.50 mm against LABs strains (Lactobacillus sakei ATCC 15521, Lactobacillus plantarum CECT 221 and Carnobacterium piscicola CECT 4020). Against Listeria strains (Listeria innocua NCTC 111288 and Listeria seeligeri NCTC 11289), their antimicrobial activity was better detected in liquid medium assay, evaluating the minimal inhibitory concentration of 50%. BLIS was able to inhibit 60 and 100% of L. seeligeri and L. innocua, respectively, as well as, diluted 1x (v/v) in water was able to inhibit 100% growth of both Listeria. BLIS 17 showed also good results as food preservative when applied in ready-to-eat pork ham artificially contaminated with L. seeligeri in vacuum-package at 4oC during shelf life of 10 days. BLIS was able to maintain low Listeria multiplication, lower samples weight loss, low lipid peroxidation and good color parameters during samples storage. Results demonstrated the importance of optimizing the culture medium to increase microbial mass, to produce and to improve the activity of this antimicrobial molecule. Moreover, results also suggest the possible application of BLIS as a natural food preservative. / Bacteriocinas são peptídeos produzidos por várias espécies de bactérias, especialmente bactérias ácido-láticas (BALs) e apresentam um amplo espectro de ação contra bactérias deteriorantes e patógenos de origem alimentar. Entretanto, quando estas bacteriocinas não foram completamente caracterizadas quanto a sequência de seus nucleotídeos e do seu gene correspondente, é recomendada a denominação de substância semelhante a bacteriocina (BLIS). Para aumentar a atividade antimicrobiana de bacteriocinas, a habilidade de BALs probióticas, como Pediococcus pentosaceus, em fermentar diferentes fontes de carbono e nitrogênio tem sido estudado. Para o desenvolvimento de um meio de cultura melhorado, fontes de carbono e nitrogênio devem ser consideradas como nutrientes responsáveis pelo crescimento celular e pela produção de bacteriocina. A melhor condição, após 48 h de cultivo, para o crescimento (3,420 g/L) e para a produção de BLIS por P. pentosaceus ATCC 43200 foi em meio de cultivo Man, Rogosa e Sharp (MRS) suplementado com 1,5% de peptona, pH inicial 6,0 e sob as seguintes condições de cultivo: anaerobiose, 30oC e agitação de 200 rpm. Comparado ao controle (MRS sem suplementação), o crescimento de Pediococcus foi significativamente menor (1,995 g/L) assim, como também, reduziu significativamente o tempo de geração de 2,05 h (controle) para 1,28 h (MRS suplementado), uma redução de aproximadamente 62,5%. Além disso, a adição de peptona ao meio MRS promoveu redução de 4 h para o início da fase exponencial de Pediococcus. Quanto a atividade antimicrobiana de BLIS, a adição de fonte de nitrogênio ao meio MRS também foi bastante significativa. Através do método ágar difusão, BLIS apresentou halos de inibição entre 12,50 a 19,50 mm contra cepas de BALs (Lactobacillus sakei ATCC 15521, Lactobacillus plantarum CECT 221 e Carnobacterium piscicola CECT 4020). Contra cepas de Listeria (Listeria innocua NCTC 11288 e Listeria seeligeri NCTC 11289), a sua atividade inibitória foi melhor detectada em meio líquido, através da determinação da concentração mínima inibitória de 50%. BLIS sem diluição foi capaz de inibir 60 e 100% de L. seeligeri e L. innocua, 15 respectivamente, assim como, diluído 1x (v/v) em água foi capaz de inibir 100% o crescimento de ambas Listeria. BLIS também apresentou bons resultados como conservante de alimento quando aplicado em presunto contaminado artificialmente com L. seeligeri e armazenado a 4oC a vácuo por 10 dias. BLIS foi capaz de manter baixa a multiplicação de Listeria, menor perda de peso das amostras, baixa peroxidação lipídica e bons parâmetros de cor durante o armazenamento das amostras. Os resultados demonstraram a importância de se otimizar meio de cultivo tanto para o aumento da massa microbiana como para a produção e melhoramento da atividade desta molécula antimicrobiana. Além disso, os resultados também sugerem a possível aplicação de BLIS como conservante natural de alimentos.

As bacteriocinas são peptídeos antimicrobianos produzidos por algumas bactérias, que atuam como bio-conservantes e têm grande potencial de aplicação em produtos cárneos. Estudos mostram que as bacteriocinas de bactérias lácticas (BAL) a serem utilizadas em um determinado alimento são mais eficientes quando produzidas por bactérias lácticas isoladas do mesmo tipo de alimento. Este estudo objetivou obter novas BAL produtoras de bacteriocinas a partir de mortadela fatiada, caracterizar as bacteriocinas produzidas, obter a bacteriocina semi-purificada e verificar seu potencial de aplicação in vitro e in situ no controle de Listeria monocytogenes e na vida de prateleira (VDP) de mortadela fatiada. Foram obtidos 19 isolados de BAL comprovadamente produtoras de bacteriocinas, que foram avaliadas quanto ao espectro de ação frente a uma grande variedade de bactérias Gram positivas e Gram negativas, e estabilidade em diferentes pH. As que apresentaram melhor estabilidade e inibiram maior número de bactérias foram avaliadas quanto a estabilidade térmica e resistência a diferentes agentes químicos e concentrações de NaCl. As que apresentaram maior resistência foram submetidas a testes de otimização da produção da bacteriocina em diferentes combinações de tempo/temperatura. Com base nestes resultados, selecionou-se um isolado que identificado como Lactobacillus curvatus pelo sequenciamento do gene 16S e confirmado por reações de PCR com primers específicos. A bacteriocina produzida por este isolado foi submetida a uma purificação por extração ácida e aplicada em fatias de mortadela experimentalmente contaminadas com um pool de cepas de Listeria monocytogenes, observando-se as contagens deste patógeno durante o armazenamento em refrigeração (7°C) por 40 dias em embalagem à vácuo. Paralelamente, foi realizada contagem de bactérias láticas para avaliar o efeito da bacteriocina nesta população, responsável pela VDP deste produto. A bacteriocina parcialmente purificada foi capaz de reduzir em 1 ciclo logarítmico a população inicial de Listeria monocytogenes na mortadela fatiada, que foi mantida durante os 40 dias de análise. Durante toda a VDP, a contagem de L. monocytogenes permaneceu constante, sem multiplicação nas condições de armazenamento do produto tanto nas amostras testes quanto controle. A bacteriocina semi-purificada não teve ação inibitória contra as bactérias lácticas presentes no produto e portanto não teve impacto na VDP do produto. Os resultados indicaram que a bacteriocina produzida pelo isolado L. curvatus RJC 1 apresenta potencial de aplicação em produtos cárneos fatiados como bioconservante. / Bacteriocins are peptides with antimicrobial properties produced by some bacteria, that act as bio-preservatives with great potential of application in meat products. Several studies show that bacteriocins from lactic acid bacteria (LAB) to be used in a specific food product have a better performance when produced by LAB isolated from the same kind of product. This study aimed to obtain new bacteriocinogenic LAB from sliced Bologna, to characterize the bacteriocins produced, to obtain a semi-purified bacteriocin, and to verify its potential of application in vitro and in situ in the control of Listeria monocytogenes and in the shelf-life of sliced bologna. 19 bacteriocin producer LAB, were evaluated as to spectrum of action against a great variety of Gram positives and Gram negatives bacteria and pH stability. The ones with better stability and that inhibited a larger number of bacteria were evaluated according to its thermal stability and resistance against different chemical agents and NaCl concentrations. The ones that showed better resistance were submitted to tests to optimize the bacteriocin production in different combinations of time and temperature. Based on these results, one was selected, identified as Lactobacillus curvatus by gene 16S sequencing and confirmed by PCR reactions with specific primers. The bacteriocin produced by this strain was submitted to partial purification by acid extraction and was applied in mortadella slices experimentally contaminated with a pool of L. monocytogenes strains, observing the counts of this pathogen along refrigerated (7ºC) storage fo r 40 days in vacuum package. Parallel, it was done LAB counts to evaluate the effect of the bacteriocin on this population, responsible for limiting the shelf life of this product. The semi-purified bacteriocin was able to reduce 1 log cicle of the initial population of L. monocytogenes in the sliced mortadella, which was maintained during the 40 days of analysis. Along the whole shelf-life, the counts of L. monocytogenes remained constant, without multiplication in the storage conditions in the test samples as well as in the control samples. The semi-purified bacteriocin did not act against de LAB naturally present at the product, having no impact in the shelf life of the product. The results indicated that the bacteriocin produced by the isolated L. curvatus RJC 1 presents potential of application in sliced deli products as a bio-preservative.

A microbiota vaginal saudável é constituída, majoritariamente, por espécies de lactobacilos que representam uma barreira natural contra microrganismos causadores de doenças como a candidíase vulvovaginal (CVV), vaginose bacteriana (VB) e infecções do trato urinário (ITU), que juntas acometem cerca de um bilhão de mulheres no mundo anualmente. Um melhor entendimento da ecologia microbiana vaginal pode ser útil na otimização de tratamentos existentes para as infecções urogenitais, os quais podem destruir parcialmente a microbiota autóctone, predispor a novas infecções, contribuir para a seleção de microrganismos resistentes e causar efeitos colaterais indesejáveis. A utilização de microrganismos certificadamente probióticos, Lactobacillus rhamnosus GR-1 e Lactobacillus reuteri RC-14, representa uma alternativa terapêutica promissora na abordagem de VB e CVV, uma vez que são capazes de colonizar o trato vaginal, apresentam atividade inibitória frente a diversos patógenos do trato urogenital, exibem risco mínimo para a seleção de microrganismos resistentes e podem auxiliar na restauração da microbiota vaginal. Os objetivos deste trabalho foram: (i) avaliar a prevalência de espécies de lactobacilos na microbiota vaginal de mulheres saudáveis e diagnosticadas com infecções vaginais (CVV e VB) da cidade de Ribeirão Preto (São Paulo, Brasil), (ii) avaliar a capacidade de isolados de lactobacilos produzirem peróxido de hidrogênio (H2O2) e (iii) determinar a eficácia da utilização de L. rhamnosus GR-1 e L. reuteri RC-14 no tratamento de CVV e VB, quando co-administrados com medicamentos antimicrobianos tradicionais. Participaram deste estudo, 196 pacientes voluntárias, atendidas por médicos ginecologistas de centros de saúde ligados à Universidade de São Paulo, campus de Ribeirão Preto (64 saudáveis, 68 diagnosticadas com CVV e 64 diagnosticadas com VB) e duas amostras vaginais de cada paciente foram coletadas com o auxílio de zaragatoas esterilizadas. Uma zaragatoa foi utilizada para semeadura em ágar MRS (de Man, Rogosa & Sharpe), os isolados de bactérias láticas obtidos foram analisados através da técnica de PCR-ARDRA (Reação em cadeia da polimerase Análise de restrição do DNA ribossomal amplificado) e a habilidade de Lactobacillus spp. produzir H2O2 foi determinada semi-quantitativamente. A outra zaragatoa foi utilizada para a análise das espécies de lactobacilos da microbiota vaginal pela técnica independente de cultivo PCR-DGGE (Reação em cadeia da polimerase Eletroforese em gel de gradiente de desnaturação). As leveduras do gênero Candida foram obtidas através da semeadura das amostras vaginais provenientes de pacientes saudáveis e com CVV no meio Chromagar® Candida e identificadas através de provas bioquímicas de referência. As pacientes diagnosticadas com CVV participaram de um estudo randomizado, duplo-cego, placebo-controlado e foram tratadas com dose única de fluconazol (150mg) e suplementação diária durante 28 dias com (i) duas cápsulas contendo os microrganismos probióticos L. rhamnosus GR-1 e L. reuteri RC-14 (Urex-Cap-5®) ou (ii) duas cápsulas de placebo. As pacientes com VB também participaram de um estudo randomizado, duplo-cego, placebo-controlado e foram tratadas com dose única de tinidazol (2g) e suplementação diária com cápsulas do probiótico (Urex-Cap-5®) ou placebo, conforme descrito acima. Todas as pacientes foram reavaliadas ao final do tratamento, no 28º dia. Foram realizados experimentos para averiguar o possível efeito de L. rhamnosus GR-1 e L. reuteri RC-14 na modulação in vitro da infecção por Candida albicans em culturas de células epiteliais vaginais humanas (VK2/E6E7) Os resultados mostraram que, pela técnica de PCR-ADRA, L. crispatus foi a espécie mais prevalente nos grupos de pacientes saudáveis (37,0%) e com CVV (35,9%), enquanto que L. gasseri foi predominante no grupo de pacientes com VB (34,6%). De acordo com o método de PCR-DGGE, L. iners foi o microrganismo mais prevalente nos três grupos de pacientes avaliados: saudáveis, com CVV e VB (48,7%, 44,7% e 65,0%, respectivamente). A maioria dos isolados de Lactobacillus spp. obtidos nos grupos de pacientes saudáveis (98,6%) e diagnosticadas com CVV (97,4%) foram capazes de produzir H2O2 (1 a 100mg/L), em comparação a apenas 68,2%, determinado no grupo de pacientes com VB (p<0,05). L. crispatus e L. johnsonii produziram as maiores quantidades médias de H2O2 (30mg/L). A taxa de colonização por leveduras do gênero Candida foi de 26,6% no grupo de pacientes saudáveis (C. albicans correspondeu a 52,4% de todos os isolados), enquanto que no grupo de pacientes com CVV, 89,2% dos isolados leveduriformes foram identificados como C. albicans. Para as análises estatísticas dos dados obtidos com os testes clínicos, foram consideradas 55 pacientes diagnosticadas com CVV (pela presença de sinais e sintomas da infecção e cultura positiva para Candida sp.) e foi observado que a utilização de dose única de fluconazol e suplementação diária com o probiótico, resultou em taxa de cura mais elevada para a infecção (89,7%) em comparação com aquela verificada no grupo placebo (65,4%) (p<0,05). A utilização de tinidazol em associação com a ingestão diária de Urex-Cap-5® no tratamento de pacientes com VB também resultou em taxa de cura mais elevada para a condição (87,5%), em comparação àquela observada no grupo placebo (50,0%) (p<0,05). A atividade anti-Candida de L. rhamnosus GR-1 e L. reuteri RC-14 foi observada através do modelo in vitro para infecção vaginal. Em conclusão, quando as técnicas de PCR-ARDRA e PCR-DGGE foram comparadas entre si, foi observado que ambas apresentaram limitações, evidenciando a importância do emprego de diferentes metodologias para avaliação adequada das espécies de lactobacilos presentes na microbiota vaginal. As espécies de lactobacilos vaginais determinadas nas mulheres saudáveis do presente trabalho foram semelhantes àquelas verificadas em estudos prévios descritos na literatura com pacientes com dieta e localização geográfica notadamente distintas. Os dados do presente trabalho sugerem que a presença de lactobacilos produtores de H2O2, isoladamente, não confere proteção contra CVV, enquanto que a ausência desses microrganismos pode ser um fator contribuinte para VB. Além disso, foi demonstrado que a utilização de medicamentos antimicrobianos tradicionais e suplementação com os microrganismos probióticos L. rhamnosus GR-1 e L. reuteri RC-14 foi mais eficiente no tratamento de CVV e VB em comparação com medicamentos clássicos e placebo. Estes resultados podem contribuir para prolongar a vida útil de medicamentos cuja eficácia pode ser comprometida devido à seleção de microrganismos resistentes e também reduzir o tempo de tratamento para pacientes que necessitam de terapias clássicas por períodos prolongados. / The vaginal microbiota is mainly constituted by lactobacilli species, which represent a natural barrier against microorganisms that cause vulvovaginal candidiasis (VVC), bacterial vaginosis (BV), and urinary tract infections (UTI). Together, these conditions afflict each year an estimated one billion women worldwide. A better understanding of the vaginal microbial ecology may be useful to improve the current available treatments for urogenital infections, which can partially destroy the autochthonous microbiota, predispose to other infections, contribute for the selection of resistant microorganisms and cause undesirable collateral effects. The use of microorganisms with demonstrated probiotic properties, Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14, represents a promising therapeutic alternative for BV and VVC, since they are able to colonize the vaginal tract, present inhibitory against several urogenital pathogens, pose minimal risk for the selection of resistant microorganisms and can help to restore the vaginal microbiota. The objectives of this work were: (i) to evaluate the prevalence of lactobacilli species in the vaginal microbiota of healthy women and those diagnosed with vaginal infections (VVC and BV) in the city of Ribeirão Preto (São Paulo, Brazil), (ii) to evaluate the ability of the lactobacilli isolates to produce hydrogen peroxide (H2O2) and (iii) to determine the efficacy of the use of L. rhamnosus GR-1 and L. reuteri RC-14 in the treatment of VVC and BV, in co-administration with traditional antimicrobials. 196 voluntary subjects were examined by the gynecologists team from health centers affiliated with Universidade de São Paulo, campus at Ribeirão Preto (64 healthy, 68 diagnosed with VVC and 64 diagnosed with BV) and two vaginal samples from each patient were collected by the use of two sterile swabs. One swab was cultured in MRS (de Man, Rogosa & Sharpe) agar, the isolates of lactic acid bacteria obtained were analyzed by PCR-ARDRA (Polymerase chain reaction - Amplified ribosomal DNA restriction analysis) and the ability of Lactobacillus spp. to produce hydrogen peroxide was determined semi-quantitatively. The other swab was used for the analysis of lactobacilli species from the vaginal microbiota using the culture-independent PCR-DGGE (Polymerase chain reaction Denaturating gradient gel electrophoresis). The yeasts belonging to Candida genus were obtained also by culturing the vaginal material from healthy and VVC patients in Chromagar® Candida and were identified by standard biochemical tests. VVC patients were enrolled in a randomized, double-blind, placebo-controlled trial and treated with a single dose fluconazole (150mg) and daily supplementation for 28 days with (i) two capsules containing the probiotic microorganisms L. rhamnosus GR-1 and L. reuteri RC-14 (Urex-Cap-5®) or (ii) two placebo capsules. BV patients were also enrolled in a randomized, double-blind, placebo controlled trial and treated with a single dose of tinidazole (2g) and supplementation with probiotic capsules (Urex-Cap-5®) or placebo, as described above. All patients were re-evaluated at the end of treatment, on the 28th day. Experiments were also conducted to assess the possible effect of L. rhamnosus GR-1 and L. reuteri RC-14 in the in vitro modulation of vaginal infection by Candida albicans on cultures of human vaginal epithelial cells (VK2/E6E7). The results revealed that according to PCR-ADRA, L.crispatus was the most prevalent species in the groups of healthy women (37.0%) and those with VVC (35.9%), while L. gasseri was dominant in BV patients (34.6%). By PCR-DGGE method, L. iners was the most prevalent Lactobacillus species in all the three groups evaluated: healthy, VVC and BV (48.7%, 44.7% and 65.0%, respectively). The majority of the isolates of Lactobacillus spp. from healthy women (98.6%) and those with VVC (97.4%) were able to produce H2O2 (1 to 100mg/L) in comparison with only 68.2% assessed for the BV group (p<0.05). L. crispatus and L. johnsonii produced the highest average levels of H2O2 (30mg/L). Colonization rate by yeasts belonging to Candida genus was 26.6% in the group of healthy patients (C. albicans represented 52.4% of all isolates), whereas in the VVC group, 89.2% of yeast isolates were identified as C. albicans. For the performance of statistical analysis of the results obtained with the clinical trials, 55 patients diagnosed with VVC (by the presence of symptoms and signals of the infection and positive culture for Candida sp.) were taken into consideration and it was observed that the use of a single dose of fluconazole and daily supplementation with probiotics, yielded a higher cure rate (89.7%), in comparison with the placebo group (65.4%) (p<0.05). The use of tinidazole plus probiotic also resulted in higher cure rate of the infection (87.5%), compared to placebo group (50.0%) (p<0.05). An anti-Candida activity of L. rhamnosus GR-1 and L. reuteri RC-14 was observed in the in vitro model of vaginal infection. In conclusion, when PCR-ARDRA and PCR-DGGE were compared, it was verified that both presented limitations, which evidences the need of using different techniques for a better knowledge of lactobacilli species present in the vaginal microbiota. The lactobacilli species found in healthy women in this work were similar to those reported in previous studies described in the literature for patients with distinctly different diet and geographic localization. The data of the present work indicate that solely the presence of H2O2-producing isolates does not render protection against VVC, whereas the absence of those microorganisms may be a contributing factor for BV. Moreover, it was demonstrated that the use of classical medicines supplemented with the probiotics L. rhamnosus GR-1 and L. reuteri RC-14 was more efficient to treat VVC and BV in comparison with classical medicines plus placebo. These results may contribute to extend the longevity of drugs whose efficacy is compromised due to the selection of resistant microorganisms and also to shorten the length of treatment courses for patients that require long regimens with standard therapy.

A formação de biofilmes é um fator preocupante para indústria de alimentos, pois pode comprometer a sanitização de superfícies de contato e aumentar o risco de contaminação por patógeno em alimentos processados. L. monocytogenes é uma bactéria de ampla distribuição no ambiente e com capacidade de formar biofilmes e sobreviver por longos períodos em condições adversas. Esta bactéria pode causar doenças em pessoas imunocomprometidas e mulheres grávidas manifestando-se por infecções do sistema nervoso central, abortos e nascimentos prematuros. Vários estudos têm demonstrado que algumas bactérias podem sofrer transição para o estado viável mas não cultivável em resposta ao estresse. Considerando-se a importância da garantia da segurança e qualidade dos alimentos, há necessidade de desenvolvimento e de padronização de técnicas rápidas para a quantificação de células viáveis de L. monocytogenes em alimentos e biofilmes. Neste estudo foi avaliada a formação de biofilmes e viabilidade celular de Listeria monocytogenes em condições de estresse. Foram utilizadas técnicas de semeadura em placa e quantificação direta por microscopia de fluorescência com os corantes cloreto de 5-ciano-2,3-di-(p-tolil) tetrazólio (CTC) e 4,6-diamino-2- fenilindol (DAPI). Foram também realizados ensaios preliminares para padronização da Reação da Polimerase em Cadeia em tempo real (PCR em tempo real) com amostras previamente tratadas com brometo de etídio monoazídico (EMA). Os resultados obtidos demonstraram que o método de semeadura em placa foi adequado somente para a enumeração de células viáveis de L. monocytogenes em biofilmes enquanto que o método de enumeração por microscopia de fluorescência com CTC-DAPI permitiu quantificar bactérias no estado viável e viável mas não cultivável. Também foi observado que a presença de bacteriocinas de L. sakei 1 e L. mensenteroides 11 causou a diminuição na viabilidade e formação de biofilmes por L. monocytogenes. Os resultados preliminares utilizando culturas puras de L. monocytogenes demonstraram que o tratamento com brometo de etídio monoazídico (EMA) antes da análise por PCR em tempo real reduziu a amplificação do DNA de células mortas em 1 log de UFC por mL. No entanto dependendo da concentração utilizada, pode ocorrer também a inibição da amplificação de células viáveis de L. monocytogenes. Os resultados do presente trabalho indicaram que a microscopia de fluorescência é comparável à placa para análise de células de L. monocytogenes não estressadas. Entretanto, para a quantificação de L. monocytogenes submetida a estresse, é desejável a utilização de corantes de viabilidade celular. O método de PCR em tempo real com pré-tratamento com EMA é promissor mas, ainda necessita de maior padronização para avaliação de sua aplicabilidade na determinação seletiva de células viáveis de L. monocytogenes. / Biofilm formation is of great concern for food industry because it may compromise sanitization of surfaces and increase contamination risk of processed foods by bacterial pathogens. L. monocytogenes is an ubiquitous bacterium which is able to form biofilms and to survive for long periods under adverse conditions. L. monocytogenes may cause disease in immunocomprommised people and pregnant women, manifesting as central nervous system infections, abortion and premature birth. Some bacteria can undergo transition to viable but non-cultivable state in response to stress and it is important to study techniques for rapid quantification of viable cells of L. monocytogenes in foods. In this study biofilm formation and cell viability of Listeria monocytogenes were studied in stress conditions by plate counting, direct quantification by fluorescence microscopy with double staining dyes 5-cyano-2,3-ditolyl tetrazolium chloride (CTC)/4\'-6 diamino-2 phenylindole (DAPI). Preliminary experiments with real time polymerase chain reaction and treatment with ethidium bromide monoazide (EMA) were also performed. The results showed that plate count method was suitable for enumeration only of viable cells of L. monocytogenes in biofilms since, fluorescence microscopy with CTC-DAPI yielded higher counts, probably due to the presence of viable but nonculturable cells. It was also observed that the presence of bacteriocins of L. sakei 1 and L. mensenteroides 11 decreased viability and formation of biofilm by L. monocytogenes. Results obtained with pure cultures of L. monocytogenes showed that the treatment with ethidium bromide monoazide (EMA) before real time PCR detection, reduced DNA amplification of dead cells in 1 log CFU per mL, but depending on the concentration used, EMA also inhibited amplification of viable cells of L. monocytogenes. The results indicated that plate counting and fluorescence microscopy are equivalent for enumeration of non-stressed L. monocytogenes cells. However, the use of double staining with fluorescence microscopy is a more suitable method if stressed cells are present. The EMA-real time PCR is a promissing tool for rapid evaluation of viable L. monocytogenes, but it needs further standartization.

Les ferments lactiques, d’une importance industrielle considérable, sont très largement commercialisés sous forme concentrée, congelée ou lyophilisée en vue de leur utilisation ultérieure dans les procédés industriels tels que les procédés de production de fromage. Cependant, les procédés de stabilisation (congélation et lyophilisation) engendrent différents stress qui peuvent conduire à de faibles taux de survie et des pertes de fonctionnalités des microorganismes. Dans ce contexte, ce travail de thèse vise à mieux comprendre l’incidence de l’état physiologique des cellules de L. lactis TOMSC161 au moment de la récolte sur leur tolérance à la lyophilisation et au stockage, et de développer des outils simples mais efficaces d’évaluation de l’état physiologique des cellules au cours de la fermentation pour les industriels. Dans une première partie, l’influence de différents paramètres de fermentation (température, pH et phase de croissance) sur la croissance et la résistance de L. lactis TOMSC161 à chaque étape du procédé de lyophilisation et au stockage a été étudiée. Alors que les performances de la souche ne sont pas dégradées après congélation, L. lactis s’est avéré sensible au séchage et au stockage à température ambiante. De plus, la température de fermentation et l’instant de récolte influencent la résistance au séchage de cette bactérie. Ainsi, les cellules de L. lactis TOMSC161 cultivées à 32 °C, pH 6,2 et récoltées tardivement (en phase stationnaire avancée) présentent une croissance optimale et la meilleure résistance à la lyophilisation et au stockage à 4 °C. Dans une seconde partie, une caractérisation approfondie de la membrane de L. lactis TOMSC161 aux niveaux biochimique et biophysique a été réalisée au cours de fermentations à différentes températures (22 et 30 °C) et a été mise en lien avec la résistance des ferments à la lyophilisation et au stockage. La cyclopropanation des acides gras insaturés de L. lactis TOMSC161 au cours de la fermentation est reliée à une rigidification de la membrane et permet d’améliorer la tolérance des cellules à la lyophilisation et au stockage. A l’inverse, la culture des cellules à une température inférieure à la température optimale de croissance induit une adaptation homéovisqueuse de la membrane, mise en évidence par la température de transition lipidique, mais n’a pas induite une amélioration de la résistance à ce procédé de préservation. Dans une troisième partie, la caractérisation de l’état physiologique des cellules de L. lactis TOMSC161 a été complétée au niveau du transcriptome, du protéome et de l’état d’oxydation cellulaire. Le procédé de lyophilisation provoque la formation d’espèces réactives de l’oxygène (ROS) intracellulaires qui dégradent la performance des ferments au cours du stockage. Par ailleurs, l’état d’oxydation des cellules diminue au cours de la fermentation et est expliqué, en phase stationnaire, par un ralentissement du métabolisme énergétique aérobie et une induction des réponses au stress oxydatif. Cette « pré-adaptation » initiale des cellules de L. lactis TOMSC161 au cours de la fermentation permet, là encore, une amélioration de leur tolérance à la lyophilisation et au stockage par une limitation de l’accumulation de ROS lors de ce procédé de préservation. Ce travail se conclut par une vérification des fonctionnalités du ferment lyophilisé, dans les conditions de production optimisées lors de cette thèse, en fabrication fromagère. Malgré l’étape de lyophilisation, les propriétés technologiques de L. lactis TOMSC161 sont conservées, validant ainsi le travail d’optimisation réalisé. / Lactic acid bacteria, which have a significant industrial importance, are widely distributed in frozen or freeze-dried state for further use in industrial processes such as cheesemaking. However, stabilization processes (freezing or freeze-drying) causes different stresses which can lead to low survival rates and functionality losses of microorganisms. In this context, this thesis aimed at better understanding the impact of the physiological state of L. lactis TOMSC161 cells during fermentation on their freeze-drying and storage resistance, and at developing simple but efficient tools to evaluate the cells physiological state during fermentation for industrials.In the first part of this work, the influence of fermentation parameters (temperature, pH and harvesting time) on the growth and resistance of L. lactis TOMSC161 to each step of the freeze-drying process and storage has been investigated While the strain performance was not deteriorated after freezing, L. lactis was sensitive to the drying step and to ambient temperature storage. Moreover, the fermentation temperature and the harvesting time influenced the drying resistance of this bacterium. L. lactis TOMSC161 cells grown at 32 °C, pH 6.2 and harvested late (at late stationary phase) exhibited therefore both an optimal growth and the highest resistance to freeze-drying and storage at 4 °C. In the second part, a deep characterization of the L. lactis TOMSC161 membrane at a biochemical and biophysical level was analyzed during fermentation at different temperatures and was linked to the freeze-drying and storage resistance of starters. The cyclopropanation of unsaturated fatty acids of L. lactis TOMSC161 during fermentation was correlated with a membrane rigidification and allowed an improvement of the cell tolerance to freeze-drying and storage. Conversely, cultivating cells at lower fermentation temperature than the optimum growth temperature induced as expected a homeoviscous adaptation as evidenced by lowered lipid phase transition temperature but did not induce any improvement of resistance to this preservation process.In the third part, the physiological state characterization of L. lactis TOMSC161 cells was completed by investigating at the transcriptomic and proteomic levels as well as the cellular oxidation state. The results proved that the freeze-drying process caused intracellular reactive oxygen species (ROS) formation, responsible of degradation of the starter performance during storage at 25 °C. Furthermore, the cellular oxidation state decreased during fermentation and was explained, in the stationary phase, by a slowdown of the aerobic energy metabolism and the induction of oxidative stress responses. This initial “pre-adaptation” of L. lactis TOMSC161 during fermentation allowed improving their tolerance to freeze-drying and storage by a limitation of ROS accumulation through the whole preservation process.Finally, this work has been concluded by verifying the functionalities of starter freeze-dried in the optimized production conditions defined in this thesis during cheesemaking. Despite the freezedrying step, the technological properties of L. lactis TOMSC161 were preserved, thus validating the performed optimization.

L’objectif de ce travail est de préparer des polymères composites antimicrobiens, utilisant de l’acide polylactique (PLA) et/ou du caoutchouc naturel époxydé et incluant des particules d’argent insérées dans des matrices zéolites (AgZ), agissant en tant que composé actif. Un des verrous contrôlant l’activité antibactérienne des matériaux synthétisés est relié à l’étude de l’absorption de l’eau. En effet la mise en œuvre de composites PLA antibactériens rencontre le problème du caractère faiblement hydrophile de PLA, induisant une faible efficacité antimicrobienne. Ainsi afin d’amplifier l’activité antibactérienne des composites AgZ/PLA, une solution prometteuse consiste à introduire un second polymère hautement polaire et flexible. Le caoutchouc naturel époxydé a été ainsi sélectionné pour être associé au composite AgZ/PLA et le taux d’absorption d’eau mesuré témoigne d’un accroissement notable. La morphologie et la distribution des particules AgZ a été étudiée. L’accroissement remarquable du caractère antibactérien des composites ENR/AgZ/PLA a été démontré ; ainsi des tests menés sur S. aureus montrent que la croissance bactérienne a été inhibée à hauteur de 98-99%. L’étude a aussi été menée en fonction de la proportion de caoutchouc et des particules AgZ. De plus les composites ENR/AgZ/PLA possèdent une plus haute résistance à l’impact comparés à l’emploi de PLA pur, suggérant ainsi que ces nouveaux composites pourront constituer des matériaux de choix pour des applications à la fois antibactériennes et nécessitant une résistance à l’impact forte. / The aim of this work is to prepare antibacterial polymers composites, involving especially poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) in the presence of silver-substituted zeolites (AgZ) as an active ingredient. Herein, the key to control the antibacterial activity of the composites which is the water absorption characteristic was thoroughly studied. In general, the fabrication of antibacterial PLA composites encounters with the problem relating to the poor hydrophilicity of PLA which is the cause of antibacterial ineffectiveness. To enhance the antibacterial activity of the composites, blending with the second polymer having high polarity and flexibility is a promising way to produce the antibacterial AgZ/PLA composite. Herein, epoxidized natural rubber (ENR) was selected to blend with AgZ/PLA composites and the increase in the water absorption percentage could be observed. The morphology as well as the AgZ distribution in the composites were also investigated. The remarkable enhancement of antibacterial activity of ENR/AgZ/PLA composites was observed because more than 98-99% inhibition of S. aureus growth was found. Furthermore, the effects of rubber content and amount of AgZ on the antibacterial activity of the composites were investigated. Moreover, the ENR/AgZ/PLA composites possessed the higher impact resistance compared to neat PLA, suggesting that the improved composites might be a choice in applications at which both antibacterial activity and impact resistance property are of great importance.

Les produits laitiers fermentés tels que les yaourts, les laits fermentés et les fromages frais, occupent une place importante dans l’économie française. La stabilité de ces produits et leurs chances d’exportation sont cependant limitées par de fréquentes altérations fongiques. De plus, l’augmentation des résistances de certains champignons aux conservateurs chimiques ainsi que la forte demande des consommateurs pour des produits dépourvus d’additifs poussent les industriels à en réduire l’ajout. Dans ce contexte, il est nécessaire de développer des alternatives innovantes, telle que la bio-conservation. Les bactéries lactiques, utilisées depuis des millénaires dans la fermentation de nombreux aliments, et généralement reconnues comme inoffensives pour la santé, sont potentiellement de bonnes candidates pour la bio-conservation. Dans le but d’obtenir une ou deux souches de bactéries lactiques antifongiques, capables d’être compétitives au sein de produits laitiers fermentés tels que le yaourt, une collection de bactéries lactiques antifongiques a d’abord été constituée. Pour cela, un criblage de colonies isolées de laits crus de vache, de chèvre et de brebis a été effectué sur une période d’une année. Ce criblage, ciblé contre 4 champignons communément retrouvés dans les produits laitiers contaminés, a abouti à l’isolement de 1235 colonies de bactéries lactiques antifongiques. Ceci a permis d’évaluer la biodiversité des bactéries lactiques antifongiques d’une part, et celle des champignons, d’autre part, dans ces échantillons de lait, afin d’observer une éventuelle corrélation entre la présence de champignons et l’expression des activités antifongiques. L’influence de l’origine du lait, de la période d’échantillonnage, du milieu d’isolement et du champignon ciblé, sur le pourcentage de colonies actives isolées a été mise en évidence. Parmi les champignons ciblés, Pénicillium expansum était le plus facilement inhibé, et la majorité des colonies ont été isolées durant la troisième période d’échantillonnage, majoritairement sur les milieux à base de MRS. Les laits de vache et de chèvre se sont révélés être des réservoirs de bactéries lactiques antifongiques, contrairement aux laits de brebis. La majorité des bactéries lactiques antifongiques isolées et identifiées appartenait au genre Lactobacillus, majoritairement du groupe Lb. casei. Onze isolats, dont 10 appartenant au groupe Lb. casei, ont été sélectionnés selon l’intensité de leur activité antifongique et leur spectre d’action sur milieu MRS. Certaines de leurs propriétés technologiques ont été caractérisées, en vue de leur utilisation comme cultures protectrices dans des produits laitiers fermentés. Leur activité antifongique a également été testée dans le lait et dans le yaourt, contre 6 contaminants fongiques communément responsables d’altérations dans les yaourts. Une souche, Lb. harbinensis K.V9.3.1Np, a révélé de fortes activités antifongiques dans le yaourt contre 6 cibles fongiques. Les études complémentaires effectuées ont permis de montrer que la variation de certains paramètres technologiques (présence ou absence de saccharose, temps de fermentation) n’avait pas d’influence sur l’activité antifongique de cette souche. La découverte du potentiel antifongique de Lb. harbinensis K.V9.3.1Np est innovante. Cette espèce, isolée pour la première fois en 2005 d’un produit fermenté végétal, n’avait encore jamais été décrite comme présentant des activités antimicrobiennes. Sa forte activité antifongique dans le yaourt fait de Lb. harbinensis K.V9.3.1Np un bon candidat pour la bioconservation de produit(s) laitier(s) fermenté(s). / Fermented dairy products such as yogurt, fermented milks and fresh cheeses are of great importance in the French economy. The stability of these products and export opportunities are however limited by frequent fungal spoilages. In addition, the increase of fungal resistances to Chemical preservatives and the strong consumer demand for products deprived of Chemical additives are pushing manufacturers to reduce the quantities of added Chemical preservatives in these products. In this context, it is necessary to develop alternatives to classical food preservation methods, such as biopreservation. Lactic acid bacteria (LAB), used for millennia for diverse food fermentations, and generally recognized as safe for human health, can potentially be used for biopreservation. In order to select 1 or 2 LAB strains with antifungal activity capable to compete in fermented dairy products such as yogurt, a collection of antifungal LAB was first created. This was done by screening colonies isolated from cow, goat and ewe raw milk samples over a one-year period. This screening step, targeted against 4 fungi found in contaminated dairy products, resulted in the isolation of 1235 antifungal colonies. The biodiversity of the isolated antifungal LAB was then determined along with that of the fungi found in the different raw milks, in order to observe a possible correlation between the presence of fungi and the expression of antifungal activities. The influence of milk origin, sampling period, isolation medium and targeted fungus on the percentage of isolated active colonies was highlighted and clearly showed that both cow and goat milks were reservoirs of antifungal LAB. Among the targeted fungi, P. expansum was more easily inhibited, and the majority of colonies were isolated during the third sampling period, mainly on MRS-based media. The majority of identified antifungal LAB belonged to the genus Lactobacillus, mainly to the Lb. casei group. Eleven isolates, including 10 belonging to the Lb. casei group, were selected from these lactobacilli, according to their activity level and action spectrum in MRS medium. Some of their technological properties were characterized for their potential use as protective cultures in fermented dairy products and their antifungal activity was tested in milk and yogurt. To do this, 6 fungal contaminants commonly encountered in yogurt spoilage were used. A particular strain, Lb. harbinensis K.V9.3.1Np, showed a strong antifungal activity in yogurt. Additional experiments showed that the variation of technological parameters (presence or absence of sugar, fermentation time) had no influence on the antifungal activity of this strain. This is the first time that an antifungal potential has been observed for Lb. harbinensis, a species isolated for the first time in 2005 from a fermented vegetable product. Because of its effectiveness in yogurt, Lb. harbinensis K.V9.3.1Np is a promising strain for biopreservation of fermented dairy product(s).