Submitted by Cleber Casali (clebercasali@ufv.br) on 2017-06-28T17:49:26Z No. of bitstreams: 1 texto completo.pdf: 513358 bytes, checksum: 7242180a7732569bdf7d045237f2e6ba (MD5) / Made available in DSpace on 2017-06-28T17:49:26Z (GMT). No. of bitstreams: 1 texto completo.pdf: 513358 bytes, checksum: 7242180a7732569bdf7d045237f2e6ba (MD5) Previous issue date: 2001-03-20 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / A seqüência completa de nucleotídeos do gene pepg1 foi determinada. A análise desta seqüência mostrou que este gene apresenta dois possíveis introns de 58 pares de bases, um potencial cis elemento TATA na posição -151 e um potencial CAAT Box na posição -273. A região codificadora contém 1110 pb, após a retirada dos introns, e a partir dessa seqüência foi deduzida uma proteína com 370 aminoácidos. A seqüência de aminoácidos apresenta grande homologia com poligalacturonases de outros fungos filamentosos, com massa molecular deduzida de 38,4 KDa e ponto isoelétrico teórico de 8,31. Quatro fagos recombinantes foram isolados a partir do banco genômico de Pencillium expansum, utilizando-se como sonda um fragmento de DNA de 1,6 Kb contendo o gene pgg1 de P. griseoroseum, os quais foram denominados λPEPG1, λPEPG2, λPEPG3 e λPEPG4. Os fagos λPEPG3 e λPEPG4 apresentaram fragmentos genômicos clonados de 14,5 e 16,6 Kb. Fragmentos de DNA de Bam HI de 3,6 e 5,1 Kb dos fagos λPEPG3 e λPEPG4 respectivamente, que hibridizaram com a sonda, foram subclonados no vetor pBluescript® SK+, originando os plasmídeos recombinantes pEPG3 e pEPG4. O gene pepg1 foi usado na transformação de protoplastos do mutante nia/pab/faw de P. expansum na presença de polietilenoglicol e CaCl2. Para a seleção dos transformantes, em meio mínimo contendo nitrato de sódio como fonte de nitrogênio, foi usado o gene nia de Fusarium oxysporum. Cento e cinqüenta e cinco, dentre os 234 transformantes obtidos, foram considerados estáveis quanto ao gene de nitrato redutase, e foram analisados quanto à produção de pectinase total em meio mineral sólido tamponado contendo pectina. Foram observadas linhagens transformantes apresentando halos de degradação da pectina maiores e menores que os da linhagem selvagem e mutante, mas a maioria dos transformantes apresentou resultado similar ao dessas linhagens. Cinqüenta e três transformantes foram caracterizados quanto à produção de poligalacturonase. Foram observados transformantes com atividade de PG inferior à da linhagem selvagem, mas a maioria dos transformantes analisados apresentou aumento na atividade dessa enzima, variando de 10 a 89 % em relação à linhagem selvagem. A hibridização do DNA total dessas linhagens, clivado com enzimas de restrição, revelou a ocorrência de integração heteróloga e de múltiplas cópias em tandem do gene pepg1 no genoma de P. expansum. / The nucleotide sequence of a polygalacturonase encoding gene (pepg1) from Penicillium expansum was determined. Putative TATA and CAAT motifs were seen at position -151 and -273, respectively, from the translation start site. The pepg1 gene encodes a predicted protein of 370 aas after splicing of two introns of 58 bp. The estimated molecular mass of the polypeptide is 38.4 KDa with pI of 8.31. Multiple sequence alignment of PG protein sequences revealed high homology between PEPG1 and PG from several filamentous fungi. In order to isolate other PG genes a genomic bank from Penicillium expansum was reprobed with a 1.6 Kb DNA fragment which corresponds to a PG gene from P. griseoroseum. Four recombinant phages were isolated and designated λPEPG1, λPEPG2, λPEPG3 and λPEPG4. DNA fragments of 3.6 Kb and 5.1 Kb from phages λPEPG3 and λPEPG4, respectively, were subcloned into pBluescript® SK+ vector. These plasmids were named pEPG3 and pEPG4. Protoplasts of the mutant strain nia/pab/faw of P. expansum were transformed with the pepg1 gene in the presence of polyethylene glycol and CaCl2 . Transformants were selected in minimal medium containing sodium nitrate as nitrogen source, using the nia gene of Fusarium oxysporum. One hundred and fifty-five transformants among 234, stably maintained the nia gene and were screened for PG overproduction by a plate assay on minimal medium containing pectin. Most transformants showed halo size similar to the mutant and wild-type strains, although smaller and larger halos were also detected. The PG production of fifty-five transformants was analyzed and some transformants had lower PG activity when compared to the wild-type strain. However, most transformants produced significantly more PG than the wild type. Southern analysis of the transformed strains detected heterologous and tandem integration of multiple copies of the pepg1 gene.

Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-07-10T16:44:41Z No. of bitstreams: 1 texto completo.pdf: 604815 bytes, checksum: 299964cd825884ce449176c3d3e98887 (MD5) / Made available in DSpace on 2017-07-10T16:44:41Z (GMT). No. of bitstreams: 1 texto completo.pdf: 604815 bytes, checksum: 299964cd825884ce449176c3d3e98887 (MD5) Previous issue date: 2001-02-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O gene que codifica nitrato redutase em Penicillium expansum foi isolado de um banco genômico construído no vetor fago lambda EMBL3. Um fragmento de DNA de 3,17 Kb, contendo parte da região codificadora do gene da nitrato redutase de Penicillium chrysogenum, foi utilizado como sonda. Quatro fagos recombinantes foram isolados e denominados λPENR1, λPENR3, λPENR5 e λPENR6, com fragmentos de DNA clonados de 14,4; 14,4; 12,3 e 12,6 Kb, respectivamente. A análise por hibridização do DNA dos fagos recombinantes, clivado com Sal I, identificou fragmentos cujos tamanhos correspondiam a 4,7 Kb (λPENR1), 6,0 Kb (λPENR3), 8,4 Kb (λPENR5) e 7,6 Kb (λPENR6). Para a construção do mapa físico de restrição do fago recombinante λPENR3, foram feitas clivagens simples e duplas com enzimas de restrição. A análise de restrição e hibridização dos fragmentos de DNA do fago recombinante λPENR3 revelou que o gene nia estava presente em um fragmento de 6,5 Kb. Este fragmento foi subclonado no plasmídeo pBluescript SK+, e o plasmídeo recombinante foi denominado pPENR. Para a construção do mapa físico de restrição de pPENR, foram feitas clivagens simples e duplas com enzimas de restrição. O plasmídeo recombinante pPENR foi utilizado na transformação dos mutantes Nia^- de P. expansum e Penicillium griseoroseum, sendo obtida uma freqüência de 16 transformantes por μg de DNA. / The gene encoding nitrate reductase from Penicillium expansum was isolated from a lambda EMBL3 genomic DNA library. A 3.17 Kb DNA fragment containing part of the coding region for nitrate reductase from Penicillium chrysogenum was used as a probe. Four recombinant phages were isolated and the recombinant phages were labeled λPENR1, λPENR3, λPENR5 e λPENR6, containing cloned DNA fragments of 14.4; 14.4; 12.3 and 12.6 Kb, respectively. DNA hybridization analysis of the recombinant phages cleaved with Sal I identified DNA fragments whose sizes were 4.7 Kb (λPENR1), 6.0 Kb (λPENR3), 8.4 Kb (λPENR5) and 7.6 Kb (λPENR6). For the construction of the a physical restriction map of the recombinant phage λPENR3, single and double digestions with restriction enzimes were performed. Restriction and hybridization analysis of the recombinant phage λPENR3 DNA fragments showed that the nia gene was present in a 6.5 Kb DNA fragment. This fragment was subcloned in the plasmid pBluescript SK+ resulting in plasmid pPENR. For the construction of the a physical restriction map of pPENR, single and double digestions with restriction enzymes were carried out. The recombinant plasmid pPENR was used for transformation of nitrate non-utilising strains of P. expansum and Penicillium. griseoroseum, and a frequency of 16 transformants per μg of DNA was achieved.

La géosmine est un terpénoïde, provoquant un goût moisi-terreux associée à des flaveurs atypiques dans l'eau et le vin. Chez les bactéries, la voie de biosynthèse de la géosmine est bien caractérisée, mais peu de connaissance sont disponibles au sujet de sa biosynthèse chez les eucaryotes, en particulier dans les champignons filamenteux. L'origine de la géosmine dans la vigne est en grande partie attribuable à la présence de Penicillium expansum sur les raisins. Dans cette thèse, afin de mieux comprendre la voie de biosynthèse de la géosmine chez Penicillium expansum, nous avons décrit la caractérisation et l'analyse de "gpe1", un gène codant pour une cytochrome P450 monooxygénase impliquée dans la biosynthèse de la géosmine. Nous avons démontré que les deux fragments d'ADN: p450-1 et p450-2 appartiennent à un seul gène du cytochrome p450 (gpe1). La séquence d'acides aminés déduite de gpe1 a une identité moyenne de 40 % avec les enzymes PbP450-2 et P450-4 qui ont été trouvées impliquées respectivement dans la synthèse d'indole diterpène et dans la synthèse des gibbérellines. Les amplifications par PCR effectuée sur quatorze espèces de Penicillium ont montré que seules les espèces producteurices de la géosmine ont donné le même fragment de ~1,2 kb que gpe1. L'analyse du gène gpe1 nous a permis d'identifier la présence de certains domaines conservés de cytochromes P450 monooxygénases. Ensuite, la caractérisation fonctionnelle du gène gpe1 chez P. expansum M2230 a été décrite. Nous avons montré que les mutants de gpe1 ont perdus leur pouvoir de produire la géosmine alors que les révertants de gpe1 ont rétablis leur pouvoir de production. Enfin, nous avons démontré qu'une polykétide synthase putative et une putative NRPS sont présentes sur le côté droit du gène gpe1 proposant que le gène gpe1 pourrait être une partie d'un «Cluster» codant pour la biosynthèse de métabolites secondaires. / Geosmin is a terpenoid, an earthy-musty compound associated with off-flavors in water and wine. In bacteria, the biosynthesis pathway of geosmin is well characterized, but little is known about its biosynthesis in eukaryotes, especially in filamentous fungi. The origin of geosmin in grapevine is largely attributable to the presence of Penicillium expansum on grapes. In this thesis, we have described the characterization and analysis of "gpe1", a gene encoding a cytochrome P450 monooxygenase probably involved in the biosynthesis of geosmin in P. expansum M2230, in order to better understand of the biosynthesis pathway of geosmin in this species. We demonstrated that the two DNA fragments i.e. p450-1 and p450-2 belong to a single cytochrome p450 gene (gpe1). We showed that the deduced amino acid sequence of gpe1 has an average identity of 40 % with PbP450-2 and P450-4 enzymes which have been found involved in indole diterpene synthesis and in gibberellin synthesis respectively. Then, the results of PCRs performed on the fourteen Penicillium species showed that only Penicillium species which were producers of geosmin gave the same fragment of ~1.2 kb like gpe1. Analysis of the gpe1 gene enabled us to identify the presence of some conserved domains of cytochromes P450 monoxygenases in the amino acid sequence of gpe1. Then, the functional characterization of the gpe1 gene in P. expansum M2230 was described. We illustrated that the mutants of gpe1 lost their potential to produce geosmin whereas the reverse complements of gpe1 restored their potential to produce geosmin. Finally, we demonstrated that a putative polyketide synthase and a putative NRPS-like enzyme are present on the right side of the gpe1 gene suggesting that gpe1 gene might be the part of a gene cluster encoding the biosynthesis of secondary metabolites.

Penicillium expansum est un contaminant commun des pomaceae (pommes et poires) causant la pourriture bleue. Ce champignon est le principal responsable de la présence de patuline dans les pommes et ses produits dérivés. Actuellement, la voie de biosynthèse de la patuline n’est que partiellement élucidée et le cluster de gènes correspondant n’est décrit que chez Aspergillus clavatus, champignon tellurique incapable de se développer dans les pommes. La caractérisation moléculaire de la voie de biosynthèse de la patuline est la condition sine qua none à toute étude visant à comprendre la régulation de la biosynthèse de la patuline, mais également à toute action permettant de limiter sa synthèse. C’est pourquoi le premier objectif de cette thèse a été de caractériser le cluster de gènes spécifique de la voie de biosynthèse chez Penicillium expansum. Celui-ci est caractérisé par une taille de 40 kb et contient les 15 mêmes gènes qu’Aspergillus clavatus, les seules différences résidant dans l’organisation et l’orientation des gènes. La caractérisation de la seconde étape de la voie de biosynthèse de la patuline a été ensuite entreprise chez Aspergillus clavatus, organisme modèle. Le gène patG code pour l’acide 6-méthylsalicylique décarboxylase responsable de la conversion de l’acide 6-méthylsalicylique en m-crésol. Pour faire suite au premier objectif, la régulation de la voie de biosynthèse de la patuline a été étudiée. Pour cela, une souche mutante pour le facteur de régulation spécifique à la patuline patL a été généré puis la production de patuline ainsi que l’expression des gènes du cluster analysés. Les résultats de cette étude ont montré que le gène patL joue le rôle d’interrupteur au sein du cluster. L’absence de patL conduit à une extinction totale de l’expression des gènes du cluster et à une abscence de production de patuline par Penicillium expansum. Dans cette même étude, des tests de pathogénicité ont été entrepris sur des pommes de différentes variétés démontrant ainsi que la patuline peut être un facteur de virulence facilitant l’infection de certaines variétés de pommes telles que la Golden Delicious ou la Pink Lady. Enfin, l’influence de la lumière a été évaluée en analysant l’impact de différentes longueurs d’ondes sur la croissance et la production de patuline de Penicillium expansum. Que ce soit in-vitro ou in-vivo, la croissance et la production de patuline sont très affectés par les lumières blanche, bleue et rouge. Favoriser le stockage des pommes sous les lumières blanche, bleue ou rouge plutôt qu’à l’obscurité pourrait devenir un moyen de prévention contre la contamination par Penicillium expansum. En conclusion, cette thèse présente un aspect fondamental avec la caractérisation du cluster de gènes chez Penicillium expansum et la caractérisation de la seconde étape de la voie de biosynthèse de la patuline ; mais aussi un aspect appliqué avec l’utilisation des lumières de différentes couleurs comme méthode de prévention contre Penicillium expansum durant le stockage des pommes. / Penicillium expansum is the common contaminant of apples and the causal agent of blue mold rot. This fungus is the main patulin producer in apple based products. Actually, the patulin biosynthesis is partially elucidates and the gene cluster has been elucidated in Aspergillus clavatus, a telluric fungi unable to grow on apples. The molecular characterization of the patulin biosynthetic pathway is the key step for a better understanding of the mechanisms leading to patulin production and will help to define strategies to reduce its presence in apple products. The first objective of this thesis was the characterization of the patulin gene cluster in Penicillium expansum. The latter includes the same 15 genes as in Aspergillus clavatus but in a different order and orientation. Then, the second step of this biosynthetic pathway has been characterized and the patG gene encode for the 6-methylsalicylic decarboxylase involved in the 6- methylsalicylic acid conversion into m-cresol. The second objective consists of the study of the patulin regulation. For that, a patL mutated strain was generated and the patulin production and the patulin gene cluster expression were assessed. The mutation of this gene results in a down-regulation of the rest of the genes in the cluster associated with a lack of patulin production. Pathogenicity tests on apples revealed that patulin could act as a virulence factor in some apple varieties, like Golden Delicious or Pink Lady. In the last part of this thesis, the influence of different wavelength lights on the growth and the patulin production by Penicillium expansum were assessed in vitro and in vivo. In both cases, growth and patulin production were significantly affected under white, blue and red lights. Consequently, the apple storage under these lights could be a good alternative to the storage in the dark. In conclusion, this thesis presents a fundamental aspect that consist in the characterization of the patulin gene cluster in Penicillium expansum and the characterization of the second step of this pathway. An applied aspect is also provided by the use of the different wavelength lights to prevent the Penicillium expansum contamination during apple storage.

Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-06-14T12:38:14Z No. of bitstreams: 1 resumo.pdf: 25134 bytes, checksum: d1f28b726d8703c03b84e1bff5ffec94 (MD5) / Made available in DSpace on 2017-06-14T12:38:14Z (GMT). No. of bitstreams: 1 resumo.pdf: 25134 bytes, checksum: d1f28b726d8703c03b84e1bff5ffec94 (MD5) Previous issue date: 2004-03-15 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A seqüência de nucleotídeos contendo o gene ple1 que codifica pectina liase em Penicillium expansum foi clonada. Esta seqüência contém 874 nucleotídeos da região promotora, 1342 nucleotídeos da região codificadora e 469 nucleotídeos da região terminadora. A região codificadora do gene ple1 é interrompida por dois íntrons, de 101 e 116 nucleotídeos, confirmados pela seqüência do cDNA. Na seqüência da região promotora de ple1 foi observado cis-elementos envolvidos na regulação da expressão desse gene, como TATA box (TATATAA) na posição -91 do códon de início da tradução, sendo esta seqüência precedida por uma região rica em pirimidinas e CAAT box (CCAATT) a -568 do códon de inicio da tradução. A proteína PLE1, deduzida a partir da seqüência de nucleotídeos possui 374 resíduos de aminoácidos, com massa molecular estimada de 40,1 KDa e pI calculado de 9,46. Análise por hibridização do DNA total de P. expansum e P. griseoroseum com um fragmento de DNA de 2,1 Kb que corresponde ao gene pelA de A. niger, indicou organização semelhante dos genes de PL no genoma destes fungos. A expressão do gene ple1, avaliada pela hibridização do RNA total com um fragmento de DNA que corresponde à região estrutural do gene ple1 mostrou que o transcrito foi detectado durante todo tempo de cultivo em presença de pectina. No entanto, quando cultivado em presença de sacarose, o transcrito somente foi detectado em 12 e 24 horas de cultivo, com adição de extrato de levedura. A caracterização morfológica de P. expansum e P. griseoroseum mostrou diferenças nítidas tanto no diâmetro quanto na coloração do verso das colônias destes fungos. Diferenças na organização da região subtelomérica dos cromossomos de P. expansum e P. griseoroseum, foram observadas quando o plasmídeo pTEL13 foi utilizado como sonda. A região ITS do rDNA de P. expansum tem 600 pb e de P. griseoroseum 594 pb. As linhagens transformantes obtidas com os plasmídeos pPlg1 e pNPG1, apresentaram aumentos na atividade de PL de no máximo 3 vezes. Análise por hibridização do DNA total dos transformantes indicou a ocorrência de integrações homólogas e heterólogas de pelo menos duas cópias do gene plg1. Foi construído um vetor de expressão, denominado pAN52-Plg1 que continha o gene plg1 sob o controle do promotor forte constitutivo do gene (gpdA) de A. nidulans. A transformação da linhagem mutante PG63 utilizando este vetor e o pNPG1, resultou na obtenção de uma linhagem recombinante (105) com aumento de 58 vezes na atividade de PL, quando cultivada em presença de glicose como fonte de carbono. Seis linhagens recombinantes foram avaliadas por hibridização apresentando integração heteróloga de mais de uma cópia do gene plg1 no genoma. Avaliação das proteínas extracelulares por eletroforese (SDS-PAGE) mostrou a presença de uma banda nítida e forte de aproximadamente 40 KDa presente no sobrenadante de cultivo da linhagem recombinante 105 que corresponde a PLG1. A atividade específica aparente de PL sintetizada por esta linhagem foi 44 e 27 vezes maior do que aquela obtida para linhagem mutante PG63 e de uma preparação comercial de pectinases “Citrus Clear”, respectivamente. O cultivo da linhagem recombinante 105 em meio contendo caldo de cana promoveu uma atividade de PL 132 vezes maior do que a atividade obtida pela linhagem PG63 cultivada nesta mesma fonte de carbono. A atividade de PL da linhagem recombinante 105, cultivada em diferentes volumes de meio, aumentou linearmente com o tempo. Pectina cítrica, quando utilizada como substrato, promoveu maior atividade de PL. A enzima mostrou ser estável em ampla faixa de pH e temperatura de armazenamento. Estes resultados mostram que a linhagem recombinante 105 é promissora para produção de PL em escala industrial, principalmente, para aplicação na indústria de sucos e vinhos, onde o emprego apenas da PL apresenta várias vantagens na qualidade do produto final. / The sequence of the pectin lyase-enconding gene ple1, from Penicillium expansum, was cloned. This sequence consists of 874 nucleotides of the promoter region, 1342 nucleotides of the coding region, and 469 nucleotides of the terminator region. The coding region of ple1 is interrupted by two introns of 101 and 116 nucleotides, confirmed by cDNA sequencing. Two cis-elements, TATA box (TATATAA) and CAAT box (CCAATT), were found at the positions 91 and 568 upstream from the translation start code, respectively. The deduced amino acid (aa) sequence (374 aa) of PLE1 has an estimated molecular mass of 40.1 KDa and a calculated pI of 9.46. One putative N- glycosylation site was found at Asn 112 . Southern blot analysis of genomic DNA from P. expansum and P. griseoroseum with a 2.1 kb-DNA fragment of the gene pelA from A. niger indicated that this gene is similarly organized in the genomes of these fungi. The hibridization of total RNA with a fragment of the coding region of ple1 showed that the transcript was detected diring the whole of cultivation in a medium containing pectin. However, when the fungus was cultivated in the presence of sucrose with addition of yeast extract, the transcript was detected only at 12 and 24 hours of cultivation. The morphologic characterization of P. expansum and P. griseoroseum showed clear differences in the xdiameter and in the coloration of the botton of the colonies. Differences in the organization of the subtelomeric region of chromosomes of P. expansum and P. griseoroseum, were observed when the plasmid pTEL13 was used as a probe. The ITS region of the rDNA of P. expansum has 600 bp and that of P. griseoroseum 594 bp. The transformants obtained with the plasmids pPlg1 and pNPG1 presented increases in the activity of PL of at the least 3 times the active of the wild type. The hibridization profile of the genomic DNA of the transformants showed the occurrence of homologous and heterologous integrations of at least two additional copies of the gene plg1 in the genome. It was not possible to define the exact number of copies and correlate it with PL activity. An expression vector was built, designated pAN52-Plg1 that contained the gene plg1 under the control of the strong constitutive promoter gpdA of A. nidulans. The transformation of the mutant strains PG63 using this vector and the pNPG1 resulted in the isolation of a recombinant strain (105) with a PL activity 58 times higher than that of the wild type, when cultivated in glucose as the sole carbon source. Six recombinants were analised by hybridization that presented heterologous integration of more than one copy of plg1. Evaluation of the extracellular proteins by electrophoresis (SDS-PAGE) showed the presence of a clear and strong band of approximately 40 KDa in the cultivation filtrate of the recombinant 105. This band corresponded to PLG1. The apparent specific activity of PL synthesized by this strain was 44 and 27 times higher than that obtained for the strain PG63 and for a commercial preparation of pectinolytic enzymes (Citrus Clear), respectively. The cultivation of the recombinant strain 105 in a medium containing sugar cane juice promoted a PL activity that was 132 times higher than that for the strain PG63 cultivated with the carbon source. PL activity of the recombinant strain 105, cultivated in different volumes of medium, increased linearly with time. Citric Pectin, when used as substrate, supported higher PL activity. The enzyme was stable in a wide range of pH and storage temperature.

Memoria para optar al título profesional de: Ingeniera Agrónoma / Uno de los factores que tiene mayor incidencia en la condición de la fruta son las enfermedades de poscosecha, conocidas comúnmente como “pudriciones”. Para el caso de manzanas las más frecuentes son las causadas por Penicillium expansum y Botrytis cinerea. Las aplicaciones de fungicidas sintéticos en poscosecha son una de las estrategias más utilizadas para su control; sin embargo, su uso continuado y prolongado ha generado una disminución de su efecto protector. Tiabendazol ha sido utilizado de manera prolongada como fungicida en el control de dichas enfermedades, pero su uso ha sido limitado por el desarrollo de cepas fitopatógenas resistentes. En el año 2004 fludioxonil fue registrado en Estados Unidos de Norte América para tratamientos de poscosecha en manzanas, siendo altamente efectivo en el control de los patógenos que causan dichas pudriciones incluyendo cepas resistentes a tiabendazol. También se han propuesto otras alternativas de control, como por ejemplo los compuestos antifúngicos naturales. El objetivo del presente estudio fue evaluar la sensibilidad de cepas de Botrytis cinerea y Penicillium expansum aisladas de manzanas, a los fungicidas tiabendazol (Tecto® 500 SC), fludioxonil (Scholar® 50 WP) y productos de origen natural (BC-1000®, Lonlife plus® SC y Biorend® SC). Se determinó in vitro la concentración media efectiva (EC50) y concentración mínima inhibitoria (CMI) la para micelio y conidias a cada fungicida, posteriormente se evaluaron las dosis comerciales de cada producto en condiciones in vivo. Un 10% y un 48% de las cepas de Botrytis cinerea y de Penicillium expansum respectivamente, resultaron ser resistentes a tiabendazol. Fludioxonil fue efectivo en la inhibición de ambos patógenos con valores de EC50 promedio para conidias de 0,02 μg·mL-1 para Botrytis cinerea y de 0,29 μg·mL-1 para Penicillium expansum. Los productos de origen natural presentaron resultados intermedios inhibiendo algunas de las cepas evaluadas, excepto la formulación de BC-1000® utilizada, que no inhibió a ninguno de los dos patógenos. En los ensayos in vivo, el mayor efecto se obtuvo con fludioxonil, y tiabendazol resultó efectivo solo contra las cepas sensibles de ambos patógenos. Las dosis comerciales de los productos naturales utilizados ejercieron un control relativo de ambos patógenos, salvo BC-1000® que no logró efecto de control alguno sobre ambos patógenos. / One of the factors that most affect the condition of the fruit are postharvest diseases, commonly known as "fruit rots”. The most common in apples are caused by Penicillium expansum and Botrytis cinerea. The application of synthetic fungicides in postharvest is one of the strategies used for their control; however, continued use of agrochemicals has led to a decrease in their protective effect. Thiabendazole as a fungicide has been used for a long time in the control of these diseases, but its use has been limited by the development of resistant phytopathogenic strains. In 2004 Fludioxonil was registered in United States of America for use in apples in postharvest treatments being highly effective in controlling these pathogens including resistant strains to thiabendazole. Natural antifungal compounds have also been proposed for postharvest fruit rot control. The aim of this study was to evaluate to sensitivity of Botrytis cinerea and Penicillium expansum strains isolated from apples, the fungicides thiabendazole (Tecto ® 500 SC), fludioxonil (Scholar ® 50 WP) and natural products (BC-1000 ®, Lonlife Plus® SC and Biorend® SC). EC50 and MIC were in vitro calculated for inhibition of mycelium growth and conidial germination for each fungicide, while the commercial dose of each product was in vivo evaluated. 10% and 48% of strains of Botrytis cinerea and Penicillium expansum respectively, were resistant to thiabendazole. Fludioxonil was effective in both pathogens with EC50 values of 0.02 average conidia μg·mL-1 to Botrytis cinerea and 0.29 μg·mL-1 for Penicillium expansum. The natural products showed intermediate results inhibiting some of the strains, except for the formulation of BC-1000 ® used, that did not inhibit any of the two pathogens. Fludioxonil was the most effective active ingredient reducing in vivo both decays, although thiabendazole was only effective against susceptible strains of both pathogens. BC-1000® formulation commercial doses of natural products used exerted a relative control of both pathogens.

Made available in DSpace on 2015-03-26T13:51:52Z (GMT). No. of bitstreams: 1 texto completo.pdf: 270809 bytes, checksum: 2ca0830f4e6318653c848e9cda88dae8 (MD5) Previous issue date: 2002-11-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Penicillium expansum is a filamentous fungus that produces extracelular xylanase. An extracellular xylanase was found to be the major protein in the filtrated culture of P. expansum when grown on 0,3 % wheat bran. In contrast to other microorganism no xilanase multiplicity was found in P. expansum under the conditions used. The used partial purification estrategy was ammonium sulfate fractioning, molecular exclusion cromatography, ultrafiltration and anion exchange chromatography. The proteins eluation profile showed only one form of xylanase that was partially characterized. The optimum pH and temperature were 5,5 and 40 0C, respectively. The enzyme kept stable when preincubed for 1 h under pH between 5.5 and 6.5. It also kept stable when preincubed for 1h under temperature between 20-40 0C. The enzime showed km of 3,03 mg mL-1 and Vmax of 0,027 mmol min-1 μg –1 of protein. The enzymatic activity was increased by 34 % by Mg3(PO4)2 (1 mM); 31 % by MgSO4 (1 mM).and 28 % by Al2(SO4)3 (1 mM). / O Penicillium expansum é um fungo filamentoso produtor de xilanase extracelular. Uma xilanase extracelular foi encontrada como a principal proteína na cultura filtrada de P. expansum quando cultivado em farelo de trigo 0,3 %. Em contraste com outros microrganismos, não foi encontrada multiplicidade de xilanase de P. expansum sob as condições usadas. Como estratégia de purificação parcial da enzima, foram realizados fracionamento com sulfato de amônia, cromatografia de exclusão molecular, ultrafiltração e cromatografia de troca iônica. O perfil de eluição das proteínas mostrou uma única forma de xilanase, sendo esta parcialmente caracterizada. O pH ótimo e a temperatura ótima foram 5,5 e 40 0C, respectivamente. A enzima se manteve estável quando pré-incubada por 1 h em pH entre 5,5 e 6,5. Também manteve a estabilidade quando pré-incubada por 1 h em temperatura entre 20-40 0C. A enzima apresentou Km de 3,03 mg mL-1 e Vmax de 0,027 mmol min-1 μg-1 de proteína. A atividade enzimática foi aumentada 34 % por Mg3(PO4)2 (1 mM); 31 % por MgSO4 (1 mM) e 28 % por Al2(SO4)3 (1 mM).

Certains microorganismes qui coexistent sur la vigne, peuvent avoir des effets bénéfiques sur la qualité du vin alors que d'autres peuvent être à l'origine de déviations organoleptiques. Dans la dernière décennie, dans diverses régions viticoles de France, plusieurs odeurs de moisi ou de terre ont été mises en évidence. La (-)-géosmine a été considérée comme étant le principal composé responsable de ce défaut. Des moisissures comme Botrytis cinerea et d’autres appartenant au genre Penicillium ont été souvent isolées à partir des raisins présentant l’odeur « moisi-terreuse ». Les effets de cette molécule sur la qualité des vins a motivé notre étude sur la caractérisation des moisissures responsables de ce défaut organoleptique. A partir d'échantillons prélevés en 2007 en Bourgogne, on a identifié, par des méthodes morphologiques et moléculaires, les moisissures présentes sur les raisins, Une souche de Penicilium expansum (25.03) et deux souches de Botrytis cinerea (BC1 et BC2) ont été sélectionnées. Sur baies de raisin, la validation d’un modèle prédictif des effets combinés de la température et de l'activité de l’eau, sur la croissance des champignons, a pu être mise en oeuvre. Elle a montré, sur de larges gammes de T°C et d’aw, que les modèles cardinaux avec inflexion peuvent être validés sur les produits agro-alimentaires en utilisant le gamma concept. L’étude de l’effet du cuivre sur le taux de croissance radiale et le temps de latence des moisissures, a été entreprise afin de mieux comprendre les mécanismes de résistance au cuivre des champignons et d’en déduire des résultats pour une meilleure efficacité des fongicides. Les moisissures testées ont montré une grande tolérance au cuivre, jusqu’à 4,7 mM pour P. expansum et jusqu’à 8, 2 mM et 7,3 mM respectivement pour B. cinerea, BC1 et BC2. L’étude des effets combinés des facteurs environnementaux et nutritionnels (T°C, CO2; Cu+2) sur la production de géosmine par P. expansum, a conduit à définir les conditions minimisant la production de géosmine. Ainsi, on a pu déterminer que le cuivre (composant actif de nombreux fongicides) est un facteur clé dans la production de géosmine par P. expansum. / Some microorganisms that co-exist on the grapevine may have beneficial effects on the quality of wine whereas others may be at the origin of organoleptic deviations. In the last decade, several mouldy or earthy odors have been highlighted in various wine regions from France. (-)-geosmin was found to be the major compound responsible for this deviation, along with Botrytis cinerea and fungi belonging to the genus Penicillium, since they were frequently isolated from “earthy-musty” odor grapes. The extent of damage on the quality of wines, motivated our study on the caracterisation of grape rot fungi. First of all, the microflora of grapes from Burgundy vineyards was identified (morphological and molecular methods), from samples prelevated in 2007. A Penicilium expansum strain (25.03) and two Botrytis cinerea strains (BC1 and BC2) were chosen for further experiments. The validation of a predictive model for the combined effect of temperature and water activity, on the growth of fungi on grape berries, demonstrated that cardinal models with inflexion can be validated on agri-food products, over a wide range of T°C and aw, using the gamma concept. Further we were focused on the influence of copper on the lag time and radial growth rate of moulds in order to better understand copper resistance mechanisms of the fungi and the efficacity of fongicides. The moulds tested showed a great copper tolerance, 4.7 mM for P. expansum and 8.2 and 7.3 mM for B. cinerea strains, BC1 and BC2 respectively. These results motivated our study on the influence of environmental and nutritional factors (T°C, CO2; Cu2+), using a Doehlert matrix, on geosmin production of the fungi tested. Copper (the active component of the “Bordeaux mixture”) showed to be a key factor in the increase of geosmin production by P. expansum.

La pourriture bleue causée par Penicillium expansum est l'une des maladies les plus dommageables des fruits pomaceae (pommes et poires). Outre des dégâts directs, cette maladie pose un problème de santé publique car l'agent pathogène produit des mycotoxines nocives pour l'homme et les animaux dont la plus sérieuse est la patuline. La croissance du champignon pathogène et la production de patuline requièrent des conditions physico-chimiques particulières. Les informations existantes à ce propos demeurent cependant modestes et insuffisantes pour envisager de développer des moyens de lutte contre l'apparition du champignon. Par ailleurs, la patuline reste avec l'ochratoxine A, les seules toxines dont la voie de biosynthèse n'a pas encore été complètement établie, tant sur le plan chimique que moléculaire. Cette étude apporte dans un premier temps des données complémentaires sur les facteurs physico-chimiques (température, pH….) qui conditionnent la croissance de P. expansum de même que sa capacité à produire la patuline. La connaissance de ces besoins et de ces conditions conduit en pratique à lutter et contrôler la contamination par la patuline tout le long de la chaine alimentaire. Dans un deuxième temps, cette thèse apporte des améliorations spectaculaires sur le plan fondamental, en termes d'élucidation de la voie de biosynthèse de la patuline. Le cluster des gènes impliqués dans la biosynthèse de cette mycotoxine chez l'espèce la plus préoccupante P. expansum a été entièrement identifié et caractérisé. Pour lever encore plus le voile sur la biosynthèse de cette mycotoxine, la caractérisation du facteur de régulation spécifique de cette voie (patL) a été également établie. Une perturbation de ce gène a provoqué une incapacité de production de patuline et une sévère diminution de l'expression des gènes Pat. De même, grâce à ce mutant déficient, il a été montré que la patuline pourrait agir comme facteur de virulence lors du développement de la moisissure dans les pommes. La caractérisation de la dernière étape de la voie de biosynthèse de la patuline a ensuite été entreprise par mutagenèse dirigée du gène patE du cluster de la patuline, chez la même espèce. Ce dernier code pour une Glucose méthanol Choline (GMC) oxydoréductase responsable de la conversion de l'ascladiol en patuline. L'ascladiol est également une molécule clé de la dégradation de la patuline par diverses espèces bactériennes ou de levures et plus particulièrement lors de la fermentation alcoolique. La non-toxicité de l'ascladiol accumulé chez le mutant ∆patE a été démontrée sur une lignée cellulaire intestinale humaine (Caco-2), suggérant que la patuline perd sa toxicité avec l'ouverture du deuxième cycle. Finalement, un système de détection et de quantification de P. expansum par PCR en temps réel a été développé en ciblant un gène hautement spécifique de la voie de biosynthèse de la patuline, patF. Cette approche préventive nous a ainsi permis d'avoir une estimation rapide de la contamination en patuline dans les pommes à partir de la quantification d'ADN de P. expansum. En conclusion, l'ensemble de ces travaux qui s'inscrivent dans le cadre de la gestion du risque « patuline » dans la filière fruit a permis d'amener des réponses tant sur le plan fondamental que sur le plan appliqué avec le séquençage du cluster, le développement d'un outil de diagnostic et la démonstration que l'ascladiol ne présentait aucune cytotoxicité. / Among diseases affecting apples, blue mold caused by Penicillium expansum is a major concern causing yield and quality losses due to the production of mycotoxins, of which patulin is the most alarming one. This mycotoxin was proven to be harmful for humans and animals. The pathogen growth and the patulin production occur under specific physico-chemical conditions (temperature, pH…). However, the description of these conditions in literature remains largely insufficient for the development of strategies to fight the development of the fungus. Furthermore, patulin remains, along with ochratoxin A, the only toxins for which the biosynthetic pathway is not fully established yet at both chemical and molecular levels. Firstly, this study provides supplementary data on the physico-chemical factors that modulate P. expansum growth and its ability to produce patulin. The acquaintance of these conditions leads, in practice, to the control of the patulin contamination along the food chain. Secondly, significant improvements were brought on the fundamental level, especially by elucidating the patulin biosynthetic pathway. The cluster of genes involved in the biosynthesis of this mycotoxin was fully identified and characterized in the species of greatest concern P. expansum. In order to reveal additional info on the biosynthesis of this mycotoxin, the specific factor of the pathway (patL) was characterized. The disruption of this gene has led to failure in patulin production and an important decrease in Pat genes expression. Furthermore, pathogenesis studies, using this same deficient strain showed that patulin potentially acts as a virulence factor during P. expansum development on apples. The last step of the patulin biosynthetic pathway was later characterized by site-directed mutagenesis of the patE gene in the same species. This gene encodes a Glucose Methanol Choline (GMC) oxidoreductase that is responsible for the conversion of ascladiol to patulin. Ascladiol is not only the last intermediate in the patulin pathway but also the main product of patulin degradation during the alcoholic fermentation of apple juice. The non-toxicity of ascladiol accumulated by the ΔpatE strain was proved against the human Caco-2 cell line. Finally a Real time PCR assay was developed to specifically detect and quantify P. expansum. This was done by targeting a highly specific gene from the patulin gene cluster in P. expansum, patF. This predictive approach allowed the quick estimation of the patulin content via the quantification of the P. expansum DNA in apples. To conclude, this thesis is part of the patulin's risk management study in the fruit sector; it provides significant improvements on both fundamental and practical levels. These advances are mainly characterized by the sequencing of the patulin gene cluster, the development of a molecular diagnostic tool and the demonstration of the non-cytotoxicity of ascladiol.

Parmi les maladies affectant les pommes, la moisissure bleue causée par Penicillium expansum est une préoccupation majeure. Elle cause des pertes de rendement et de qualité dues également à la production de mycotoxines telles que la patuline (PAT) et la citrinine (CIT). La PAT est la plus alarmante en raison de ses propriétés cytotoxiques, génotoxiques et immunosuppressives.L'Union européenne (UE) a établi des réglementations spécifiques pour protéger la santé des consommateurs et des niveaux maximaux de 50 g / kg sont fixés pour les jus de fruits et les produits dérivés, 25 g / kg pour les purées de pommes et les compotes et 10 g / kg pour les aliments destinés aux bébés et aux jeunes enfants. En dépit de ces mesures, la PAT continue à être présente dans les aliments et / ou les boissons commerciaux, dépassant parfois les limites maximales. Des recherches supplémentaires sont par conséquent nécessaires pour minimiser la contamination des produits alimentaires par cette mycotoxine et son champignon producteur. Bien que la plupart des études sur P. expansum soient essentiellement centrées sur la PAT, le génomede ce champignon présente d'autres clusters de métabolites secondaires (SM) prédits dont certains peuvent être associés à des métabolites potentiellement toxiques. Afin de contrôler la synthèse de SM, l'étude des facteurs de transcription globaux régulant leur production est essentielle. Dans une première partie, le gène veA, appartenant à la famille des protéines du complexe velvet, a été caractérisé et son impact sur le développement du champignon, sa virulence et son métabolisme secondaire a été élucidé. La délétion de ce gène a conduit à une réduction de la production de PAT et de CIT et à une diminution de l'expression de leurs clusters de gènes. VeA a également un impact global sur le métabolisme secondaire, puisque 15 des 35gènes de structure présentent une régulation différentielle sur les milieux testés. Dans une deuxième partie, l’influence de l’acide ascorbique (AA) sur la concentration de PAT dans le jus de pomme trouble a été étudiée à la fois en laboratoire et en milieu semi-industriel. Une méthodologie analytique séparant la PAT et d'autres composés générés au cours de la réaction aété optimisée. Les conditions optimales d'action de l’AA sur la PAT ont été analysées. De plus,nous avons identifié des produits de dégradation moins toxiques que la PAT et résultant du traitement par l’AA. Pour conclure, cette thèse se rattache à la gestion des risques de la PAT dans le secteur des fruits ; elle apporte des connaissances et des améliorations significatives tant sur le plan fondamental que sur le plan pratique. Ces avancées résident principalement dans la description d'une souche mutée de P. expansum moins toxique que celle naturellement retrouvée dans la nature, et décrivant un additif alimentaire améliorant les qualités de nombreux produits transformés et diminuant la concentration de PAT en générant des composés moins toxiques. / Among diseases affecting apples, blue mould caused by Penicillium expansum is a major concern. It causes yield and quality losses, as well as food safety issues due to the production of mycotoxins such as patulin (PAT) and citrinin (CIT). PAT is the most worrying one and has cytotoxic, genotoxic and immunosuppressive properties. The European Union (EU) has established specific regulations to protect the consumer’s health and maximum levels of PAT of 5 g/kg is set for fruit juices and derived products, 25 g/kg for apple purees and compotes and 10g/kg for food intended for babies and young children. However, PAT is still found in commercial food and/or beverage products, sometimes exceeding the maximum limits and more research is needed to minimize contamination of food products by this mycotoxin and its fungus. Even though most studies on P. expansum have focused on PAT itself, the genome of this fungus exhibits other predicted secondary metabolite (SM) clusters, some of which may be associated with potentially toxic metabolites. In order to control the synthesis of SMs, the study of global transcription factors regulating their production is essential. In a first part, the veA gene, belonging to the velvet family, was characterised and its impact on the development of the fungus, its virulence and its secondary metabolism was elucidated. The disruption of this gene led to the failure in PAT and CIT production and a decrease in the expression of their gene cluster. It also revealed a global impact on the secondary metabolism, as 15 of 35 backbone genes showed differential regulation on the media tested. In a second part, the influence of ascorbic acid (AA) on the concentration of PAT in cloudy apple juice was studied on both lab and semi-industrial scale. An analytical methodology separating PAT and other compounds generated during the reaction was optimized. Optimal conditions of action of AA on PAT were studied. In addition, degradation products less toxic than PAT and resulting from AA treatment were identified. To conclude, this thesis is part of the risk management of PAT in the fruit sector; it provides significant improvements at both fundamental and practical levels. These advances are mainly characterized by the description of a mutated strain of P. expansum that is less toxic than that naturally occurring in nature, and the description of a food additive that improves numerous products qualities and affects PAT concentration, thusgenerating less toxic compounds