Thesis (Ph. D.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2005. Directed by Ching-Hua Huang. / Wine, Paul, Committee Member ; Pavlostathis, Spyros, Committee Member ; Mulholland, James, Committee Member ; Yiacoumi, Sotira, Committee Member ; Huang, Ching-Hua, Committee Chair. Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (MSc.(Pharmacology)--Faculty of Health Sciences)-University of Pretoria, 2002.

Resumo: O objetivo deste estudo foi avaliar a atividade antibacteriana das soluções Tetraclean®, MTAD® e modificações desta formulação sobre uma cepa de Enterococcus faecalis pelo teste de contato direto e frente ao biofilme. Na metodologia de contato direto, uma suspensão de E. faecalis foi exposta às soluções irrigadoras, por períodos de 30 s, 1, 3 e 10 min, e um agente neutralizante foi utilizado. As colônias viáveis foram quantificadas após diluições seriadas e cultura em placas de ágar. Para determinação do número inicial de UFC, água esterilizada foi usada como controle. Para o crescimento do biofilme, amostras de biofilme dentário foram suspensas em BHI (Brain Heart Infusion), e incubadas por 14 dias em anaerobiose, tendo como substrato, discos de hidroxiapatita. Após o período de incubação, os biofilmes foram expostos às soluções irrigadoras por períodos de 30 s, 1 e 3 min. Os biofilmes corados com o Live/Dead Baclight stain (Molecular Probes, Europe BV), que diferencia células viáveis (verde) e células não-viáveis (vermelho) foram observados na microscopia confocal. As imagens do biofilme obtidas pelo software EZ-C1 for Nikon foram transferidas para análise quantitativa da proporção de células viáveis sobre o total de células do biofilme para o software Imaris 5.0. No teste de contato direto, o Tetraclean® eliminou completamente o E. faecalis em 30 s, enquanto o MTAD® e o MTAD® + CTR 0,01% eliminaram após 10 min, e o MTAD® + CTR 0,1% resultou em culturas negativas após 3 min de contato com a suspensão bacteriana. Quando removido o Tween 80 do MTAD®, e acrescida a CTR 0,01%, obteve-se culturas negativas após 1 minuto. Os resultados obtidos pelo método de exposição ao biofilme confirmaram os achados do teste de contato direto. / Abstract: The aim of this study was to evaluate the antibacterial effect of MTAD® and Tetraclean®. The tests were performed on Enterococcus faecalis using the direct exposure test and an in vitro biofilm model. Alternative formulations to MTAD® were also included in the experiments: MTAD® + 0.01% cetrimide (CTR); MTAD® + 0.1% CTR; MTAC (the detergent Tween 80 was substituted for cetrimide) with 0.01% CTR and MTAC (0.1% CTR). In the direct exposure test, a bacterial suspension was mixed with the irrigation solutions. After 30 seconds, 1 minute, 3 minutes and 10 minutes, an inactivator agent was used. The number or viable colonies were calculated after serial 10-fold dilutions and culture in agar plates. To calculate the initial number of colonies, sterilized water was used as a control. Dental biofilm samples were suspended in BHI broth and incubated in anaerobic conditions in hidroxiapatite discs. After incubation for 14 days, the biofilms were exposed to the irrigation solutions for 30 seconds, 1 minute and 3 minutes. Live/Dead Baclight stain (Molecular Probes, Europe BV) was used to diferentiate viable cells (Green) and non viable cells (Red). The samples were observed in the Confocal Laser Microscope. The biofilm images in 3D obtained in the EZ-C1 for Nikon software were transfered to quantitative analysis in the Imaris 5.0 software. The software calculated the ratio of green cells. In the direct exposure test, Tetraclean® and MTAC (0.1% CTR) erradicated E. faecalis in 30 s. MTAD® and MTAD® + 0.01% CTR eliminated E. faecalis after 10 min. MTAD® + 0.1% CTR resulted in negative culture after 3 min. Negative cultures were obtained after 1 min when MTAC (0.01% CTR) was used. The findings from the biofilm exposure method confirmed the results from direct exposure test. The Kruskal-Wallis statistical analysis showed a significant difference in time exposure to irrigant (P<0.001). / Orientador: Mario Roberto Leonardo / Coorientador: Markus Haapasalo / Banca: Mario Tanomaru Filho / Banca: Idomeo Bonetti Filho / Banca: Izabel Yoko Ito / Banca: Antonio Carlos Pizzolitto / Doutor

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The bacterial deposition on surface and also the biofilm form occurring widely in the nature as a protection strategy developed for the bacteria against the harmful external factors. Microorganism, when was in biofilm form was able to generate several problems for the public heath justly for showed a higher resistance from the action of antibacterial agents when compared with the planktonic form. Bacteria are the microorganism more involved with the biofilm production in the presence of beneficial environmental conditions. In this way, Escherichia coli were the strain more involved with the process of adhesion in the surfaces. Few studies were developed to found new antimicrobial drugs precisely because the researches presented more interest to improve the known drugs. Thus, the present study was evaluated the antibiofilm capability of sulfamethoxazole (SMTZ) alone and when complexed with metals as mercury, copper, cadmium and silver. The compounds were tested against Escherichia coli (ATCC 25922). For evaluated the inhibition of the biofilm formation we were used microplates of polystyrene to observe the turbidity through the 570 nm in an ELISA plate reader. The results presented that the sulfamethoxazole compounds had an excellent antibiofilm activity and also that the complex SMTZ-Ag showed the best inhibitory activity against E. coli biofilm formation. Therefore, we conclude that these sulfamethoxazole complexed compounds require more researches in order to expand their antimicrobial activity. / A deposição de bactérias em uma superfície e a sucessiva formação de biofilmes são fenômenos que ocorrem naturalmente na natureza, servem como estratégia de proteção frente a fatores agressivos externos. Os micro-organismos, quando em biofilme, geram grande impacto à saúde pública, pois possuem maior resistência à ação de agentes antibacterianos e métodos de desinfecção quando comparados aos micro-organismos na forma planctônica. As bactérias são os agentes microbianos que mais comumente produzem biofilmes em condições favoráveis. Neste contexto, Escherichia coli inclui-se como uma das bactérias com maior participação nos processos de adesão. Pesquisas visando a descoberta de novos antibacterianos são escassas, uma vez que os esforços estão mais direcionados no aprimoramento da das drogas já existentes. Dessa forma, o presente trabalho se propôs avaliar a capacidade antibiofilme do sulfametoxazol complexado com os metais mercúrio, cobre, cádmio e prata. Esses foram testados frente a bactéria Escherichia coli (ATCC 25922). Para avaliar o grau de inibição da formação do biofilme foram utilizadas microplacas de poliestireno e a leitura da turvação bacteriana foi realizada em densidade óptica de 570nm em leitor de ELISA. Os resultados obtidos demonstram que os compostos de sulfametoxazol apresentaram uma excelente atividade antibiofilme, sendo que o complexo SMTZ-Ag foi o que exibiu melhor atividade contra a formação do biofilme de E. coli. Em vista disso torna-se válido investir em pesquisas no sentido de ampliar as atividades desses compostos.

Les premiers stades larvaires chez l’huitre creuse, nommée Magallana gigas, constituent une étape clé du bondéroulement du parcours zootechnique et également pour la pérennisation de la production en écloserie. Dans l’objectifde réduire les mortalités observées en écloserie, nous avons recherché de nouveaux peptides antimicrobiens. Larecherche de ces PAM a été réalisée à partir de deux organismes marins, le poisson-lion invasif en mer des caraïbes,Pterois volitans, et la seiche commune présente sur les zones ostréicoles, Sepia officinalis. La recherche de PAM a étéréalisée préférentiellement à partir de transcriptomes de novo obtenus chez ces deux animaux. Chez le poisson lion, àpartir de BLAST, 7 transcrits codant pour des PAM ont été identifiés. Quatre de ces PAM partagent de fortes homologiesde séquences (>90% d’identité) avec des PAM riches en cystéines proches de l’hepcidine, la LEAP-2, la NK-lysine et la bdéfensineidentifiées chez d’autres poissons. Les 3 autres transcrits annotés pteroicidines A, B et C codent pour despeptides apparentés aux piscidines. La présence de la b-défensine et de la pteroicidine a codée par la pteroicidine A a puêtre confirmée dans les extrait de peau du poisson lion par spectrométrie de masse. Une étude approfondie a été menéesur deux formes amidée et non amidée de la ptéroicidine a ainsi que sur plusieurs peptides de différentes tailles issusdes pteroicidines B et C. Les résultats ont permis de mettre en évidence une relation entre la structure, l’amidation et lesactivités antibactériennes et hémolytiques de ces différentes ptéroicidines. Sur le modèle Sepia officinalis, par lesapproches classiques couplant la purification et les tests antibactériens ou par des approches utilisant les BlAST, aucunPAM n’a été mis en évidence. Nous avons donc développé une approche plus originale qui repose sur le « design » depeptides à partir du transcriptome. A partir de 811 petits peptides sans cystéines issus de la base de données APD, nousavons déterminé des critères récurrents concernant la charge, l’hydrophobicité et la composition en acides aminés. Surla base de ces critères et en s’appuyant sur les outils de prédiction de CAMP, douze peptides ont fait l’objet d’une synthèse.Cinq de ces peptides ont révélé un large spectre d’activités antibactériennes. Les peptides antibactériens issus de la seicheayant une activité non hémolytique ont fait l’objet d’un transfert en écloserie. Ce transfert a été optimisé à partir d’uneétude préliminaire sur le peptide de novo K4, particulièrement actif sur les vibrios. Cette étude a mis en évidencel’importance de l’innocuité du peptide antibactérien sur les différents maillons de la chaine trophique, notamment del’huitre, et sur l’importance du stade de développement ciblé. Par ailleurs, nous nous sommes intéressés au devenir despeptides antibactériens de manière à s’assurer de leur biodégradabilité. L’ensemble de ces travaux a permis nonseulement d’identifier de nouveaux PAMs mais également d’apporter les premières données portant sur le potentiel del’utilisation de ces peptides comme alternative aux antibiotiques. / The first larval stages of oyster (Magallana gigas) are key steps in the smooth running of the zootechnical course and inthe sustainability of hatcheries, where mortality levels can be high. That is why we searched for new antimicrobialpeptides (AMPs) on two marine organisms, i.e. lionfish (Pterois volitans), which is invasive in the Caribbean Sea, and thecommon cuttlefish (Sepia officinalis), which is present in French oyster production areas. The search for AMPs wascarried out preferentially from de novo transcriptomes from these two animals. In lionfish, BLAST analyses allowed forthe identification of 7 transcripts encoding AMPs. Four of them shared strong sequence homology (> 90% identity) withAMPs rich in cysteines and close to hepcidin, LEAP-2, NK-lysin and b-defensin identified in other fish. The other 3transcripts, annotated pteroicidins A, B and C, coded for piscidin-related peptides. The presence of b-defensin andpteroicidin a encoded by pteroicidin A was confirmed in lionfish skin extracts by mass spectrometry. An in-depth studywas conducted on two amide and non-amide forms of pteroicidin a, as well as on several peptides of different sizesderived from pteroicidins B and C. The results highlighted a relationship between structure, amidation, and theantibacterial and hemolytic activities of these different pteroicidins. On the other hand, no AMP was highlighted in theSepia officinalis model using conventional approaches coupling purification and antibacterial tests or BLAST approaches.We therefore developed a more original approach that relies on the design of peptides starting from the transcriptome.Starting from 811 small cysteine-free peptides from the APD database, we determined recurring criteria for charge,hydrophobicity, and amino acid composition. Based on these criteria and on CAMP prediction tools, twelve peptides weresynthesized. Five of them revealed a broad spectrum of antibacterial activities. Non-hemolytic antibacterial peptidesderived from cuttlefish were transferred to the hatchery. This transfer was optimized thanks to a preliminary study onthe de novo K4 peptide, which is particularly active on vibrios. The study highlighted the importance of antibacterialpeptide safety on the various links of the trophic chain including oyster, and the importance of the targeted stage ofdevelopment. In addition, we addressed the fate of antibacterial peptides to ensure their biodegradability. Altogether,this work not only helped to identify new AMPs but also to provide the first data on the potential use of these peptidesas an alternative to antibiotics.

Orientador: Ary Fernandes Junior / Banca: Rosemeire C. L. R. Pietro / Banca: Maria de Lourdes Ribeiro da Cunha / Resumo: Esta dissertação encontra-se dividida em introdução geral e 3 capítulos, sendo estes no formato de manuscritos a serem enviados para publicação em 3 periódicos distintos. Considerando a crescente utilização dos produtos naturais, especialmente dos obtidos a partir de plantas, objetivou-se estudar a ação antibacteriana de 27 óleos essenciais de uso em aromaterapia, sobre linhagens de Staphylococcus aureus (n=10), Escherichia coli (n=9), e Pseudomonas aeruginosa (n=9), isoladas de casos clínicos humanos, utilizando a metodologia dos discos (difusão) e determinação da concentração inibitória mínima (CIM) (diluição) em Mueller Hinton Ágar (Capítulo I). Verificou-se que as linhagens de S. aureus foram mais susceptíveis que as de Gram negativas, sendo que os valores de CIM90% foi de 0,21mg/mL para os óleos de pimenta negra (Piper nigrum) e tea tree (Melaleuca alternifolia) e 26,52mg/mL para o óleo de copaíba (Copaíba officinalis). Para E. coli, o óleo de canela (Cinnamomum cassia) foi o mais efetivo, com 2,0 mg/mL para CIM90% enquanto para P. aeruginosa o valor foi de 8,29 mg/mL com cravo da índia (Syzigium aromaticum). Utilizando valores de CIM obtidos in vitro foram selecionados 5 óleos (cravo da índia-Syzygium aromaticum, gerânio-Pelargonium graveolens, lavanda -Lavandula angustifolia, palmarosa-Cymbopogon martini e tea tree-Melaleuca alternifolia) e novamente sobre linhagens de Escherichia coli, Staphylococcus aureus e Pseudomonas aeruginosa, foi verificada a ação antibacteriana através da diluição individual de cada óleo em água e salina visando redução na contagem bacteriana em função do tempo (Capítulo II). Tanto nos ensaios em água quanto salina, verificou-se que o perfil de sensibilidade das linhagens bacterianas aos óleos essenciais foram próximos entre si, porém significativamente distintos comparados aos ensaios controles... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This thesis is divided into general introduction and three chapters, which are in the format of manuscripts to be submitted for publication in three separate journals. Considering the increasing use of natural products, especially those obtained from plants, aimed to study the antibacterial activity of 27 essential oils used in aromatherapy, on Staphylococcus aureus (n=10), Escherichia coli (n=9), and Pseudomonas aeruginosa (n=9), isolated from human clinical cases, using the methodology of the disks (diffusion) and determination of minimum inhibitory concentration (MIC) (dilution) on Mueller Hinton Agar (Chapter I). It was found that the strains of S. aureus were more susceptible than the Gram negative, and the values of MIC90% was 0.21 mg/mL for the oils of black pepper (Piper nigrum) and tea tree (Melaleuca alternifolia) and 26.52 mg/mL for oil Copaiba (Copaiba officinalis). For E. coli strains, the oil of cinnamon (Cinnamomum cassia) was the most effective, with 2.0 mg/mL for MIC 90% while for P. aeruginosa, the value was 8.29 mg/mL with clove (Syzigium aromaticum). Using MIC values obtained in vitro were selected five oils (cloves-Syzygium aromaticum, geranium-Pelargonium graveolens, lavender- Lavandula angustifolia, palmarosa-Cymbopogon martini and tea tree-Melaleuca alternifolia) and the bacteria Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, antibacterial activity was checked by dilution of individual oil and saline water in order to reduce the bacterial count in function of time (Chapter II). Both tests in saline and water, it was found that the sensitivity of bacterial strains to essential oils were close together, but were significantly different compared to control tests. Essential oils have demonstrated the potential inhibitor of the three bacterial strains, and the results were different from those obtained in vitro-ágar with Gram negative... (Complete abstract click electronic access below) / Mestre

Buscou-se identificar e comparar a atividade antibacteriana do extrato alcoólico de três acessos de Allium tuberosum - Rottler ex Sprengl – Liliaceae - originários da região metropolitana de Porto Alegre/RS frente a agentes de toxinfecções alimentares, especificamente: Staphylococcus aureus (ATCC 25.923), Enterococcus faecalis (ATCC 19.433), Salmonella Enteritidis (ATCC 11.076) Escherichia coli (ATCC 11.229). Inicialmente, in vitro, através de Teste de Diluição, por meio de Sistema de Tubos Múltiplos e o emprego de desinibidores bacterianos, determinou-se a Intensidade da Atividade de Inibição Bacteriana (IINIB) e a Intensidade de Atividade de Inativação Bacteriana (IINAB), revelando-se capacidades seletivas sobre os diferentes inóculos Gram-negativos, que atingiram inibição e inativação máximas e permanentes para Salmonella às 48 horas de confrontação inóculo/extrato, e às 72 horas de confrontação para Escherichia coli, respectivamente. As bactérias Gram-positivas ( Staphylococcus e Enterococcus) apresentaram resistência total nas diferentes confrontações. Não houve diferença significativa na atividade antibacteriana das três amostras de alho em estudo. Em um segundo momento, para um dos acessos de alho, através de Teste de Suspensão, determinou-se IINAB em duas simulações de preparação alimentar, requeijão cremoso e caldo de carne, condimentados com alho nirá, respectivamente. No modelo requeijão, E.coli mostrou-se completamente resistente em concentrações finais de 103, 104 e 105 U.F.C./mL, estas imediatamente acima da concentração máxima tolerada pela legislação brasileira, em três tempos de confrontação (24, 48, 72 horas), nas concentrações finais do extrato alcoólico de 10, 20 e 30 %, atendendo à legislação quanto à padrão de identificação e qualidade deste alimento. No caldo de carne, na concentração constante de 50 % de planta originalmente verde, Salmonella foi inativada totalmente na concentração de 105 U.F.C./mL já às 24 horas de confrontação, enquanto Escherichia atingiu este patamar às 48 horas de confrontação,Comenta-se, outrossim, o significado da inibição bacteriana demonstrada, relacionada à preditividade dos resultados de diagnóstico bacteriológico em protocolos de investigação de surtos toxinfectivos alimentares. / It was looked for to identify and to compare the antibacterial activity of the alcoholic extract of three accesses of Allium tuberosum - Rottler ex Sprengl - Liliaceae - original from Porto Alegre (RS/BR) metropolitan area, confronted to alimentary toxic infections agents, specifically: Staphylococcus aureus (ATCC 25.923), Enterococcus faecalis (ATCC 19.433), Salmonella Enteritidis (ATCC 11.076) Escherichia coli (ATCC 11.229). Initially, in vitro, through Test of Dilution, System of Multiple Tubes and the use of bacterial uninhibitors, was determined the Intensity of the Activity of Bacterial Inhibition (IINIB) and the Intensity of Activity of Bacterial Inactivation (IINAB), being revealed selective capacities on the different Gram-negative inoculums, that reached inhibition and maximum and permanent inactivation for Salmonella at 48 hours of confrontation inoculum/extract, and 72 hours of confrontation for Escherichia coli. The Gram-positive bacteria (Staphylococcus and Enterococcus) presented total resistance in the different confrontations. There was not significant difference in the antibacterial activity of the three accesses of garlic in study. Subsequently, for one of the samples of garlic, through Test of Suspension, was determined IINAB in alimentary simulation of creamy cheese seasoned with alcoholic extract in final concentration of 10, 20 and 30%, assisting to the legislation as for to identification pattern and quality of this food; as well as in simulation of alimentary preparation of bouillon, with the plant recently picked, in the final concentration of 50%. In the model creamy cheese, E.coli was shown completely resistant in final concentrations of 103, 104 and 105 U.F.C./mL, these immediately above the maximum concentration tolerated by the Brazilian legislation, in three times of confrontation (24, 48, 72 hours), in all of the final concentrations of the alcoholic extract. In the conditions of the simulated bouillon, Salmonella was totally inactivated in the concentration of 105 U.F.C./mL already at 24 hours of confrontation, while Escherichia reached this point at 48 hours of confrontation. Is commented, likewise, the meaning of the demonstrated bacterial inhibition, related to the prediction of the results of bacteriological diagnosis in protocols of alimentary toxic infective outbreaks investigation.

Les interactions cellules épithéliales-bactéries peuvent conduire à l'établissement d'une tolérance vis-à-vis des bactéries commensales ou à l’élimination des bactéries pathogènes par le système immunitaire. La détection des bactéries est une étape indispensable à l’orientation de cette réponse. Contrairement aux mammifères, la reconnaissance des bactéries chez la drosophile repose principalement sur la détection d’un composant de la paroi bactérienne, le peptidoglycane (PG), par une famille de récepteurs, les "PeptidoGlycan Recognition Receptors" (PGRPs). Chez la drosophile, le PG des bactéries intestinales extracellulaires peut pénétrer dans les entérocytes et aussi traverser l’épithélium intestinal. Dans l’intestin la détection du PG est régionalisée, elle implique en fonction des domaines deux récepteurs PGRPs distincts (PGRP-LC et PGRP-LE). L'activation de ces PGRPs déclenche une même voie de signalisation NF-kB et conduit à la production de peptides antimicrobiens. La sur-activation de cette voie peut être néfaste pour l'hôte, son intensité est notamment contrôlée par des PGRPs à activité enzymatique qui clivent le PG pour le rendre non immunogène.Au cours de ma thèse, j’ai développé des outils visant à étudier le double mode de détection du PG dans l’intestin. J’ai également testé si les transporteurs de la famille SLC15 étaient impliqués dans le trafic cellulaire du PG. Une partie de ma thèse a aussi été consacrée à préciser le rôle des PGRPs catalytiques dans la réponse immunitaire. / Bacterial interactions with the host epithelium can lead to the establishment of a tolerance regarding commensal bacteria or to the triggering of an immune response to eliminate pathogenic bacteria. The detection of bacteria is an essential step in the orientation of this response. In contrast to mammals, the bacteria recognition in Drosophila is mainly based on the detection of a bacterial wall component, peptidoglycan (PG), by a family of receptors, the PeptidoGlycan Recognition Receptors (PGRP). In Drosophila, the PG of extracellular intestinal bacteria can enter the enterocytes and also cross the intestinal epithelium. In the intestine, the detection of PG is regionalized and involves, depending on the domains, two distinct PGRP receptors (PGRP-LC and PGRP-LE). The activation of these PGRPs leads to the activation of the same NF-kB signaling pathway and triggers the production of antimicrobial peptides. The over-activation of this pathway can be harmful to the host, and therefore its intensity is controlled by PGRP proteins which have an enzymatic activity that degrades the elicitor activity of PG.During my thesis, I have generated tools to study the dual mode of PG detection in the intestine. I also tested whether the carriers of the SLC15 family were involved in PG cell trafficking. Part of my thesis was also devoted to clarify the role of catalytic PGRPs in the immune response.

Probiotics are live microorganisms which when administered in adequate amounts confer one or more health benefits on the host. Different processing conditions, the acidic condition of the stomach and exposure to hydrolytic enzymes affect the viability and efficacy of probiotic organisms. This study investigated the protective effects of two biopolymers poly-gamma-glutamic acid (γ-PGA) and bacterial cellulose (BC) on probiotics during freeze drying and during exposure to simulated intestinal juices and bile salts. The antibacterial property of Bifidobacterium strains was also investigated against four pathogenic bacteria. γ-PGA, a naturally occurring biopolymer was produced by two bacteria (Bacillus subtilis ATCC 15245 and B. licheniformis ATCC 9945a) in GS and E media, γ-PGA yields of about 14.11g/l were achieved in shake flasks and molecular weight of up to 1620 k Da was recorded, γ-PGA production was scaled up in a fermenter with B. subtilis using GS medium. BC, an edible biopolymer was produced by Gluconacetobacter xylinus ATCC 23770 in HS medium and a modified HS (MHS) medium. A yield of about 1.37g/l was recorded and BC production with MHS medium was used for probiotic application. B. longum NCIMB 8809 B. breve NCIMB 8807 and B. animalis NCIMB 702716 showed the best antimicrobial properties against the investigated pathogens. Survival of Bifidobacterium strains was improved when protected with powdered BC (PBC) although γ-PGA offered better protection than PBC. Viability of B. longum NCIMB 8809, B. breve NCIMB 8807 and B. animalis NCIMB 702716 in simulated gastric juice (SGJ) and simulated intestinal juice with bile salts was improved when protected with 5% γ-PGA and 5% γ-PGA+PBC with a reduction of < 1 Log CFU/ml while a reduction of ≤2 Log CFU/ml was recorded in PBC protected cells. Protecting Bifidobacterium strains with γ-PGA, PBC or a novel γ-PGA + PBC combination is a promising method to deliver probiotic bacteria to the target site in order to confer their health benefits on the host.