Jean-Michel PANOFF - Academia.edu (original) (raw)

Papers by Jean-Michel PANOFF

National audienceUne approche transdisciplinaire La vie, évènement perdu dans l'espace et le ... more National audienceUne approche transdisciplinaire La vie, évènement perdu dans l'espace et le temps, créatrice d'ordres et d'amours, lutte sans relâche pour reproduire indéfiniment des structures et des fonctions dans le chaos cosmique. Paradoxalement, les biologistes nous disent que cette vie est créatrice de risques pour l'homme et son environnement, que la vie s'oppose à la vie. L'approche anthropocentrique historique du risque biologique s'est longtemps limitée à l'étude des microbes pathogènes, d'abord pour l'espèce humaine et ensuite pour les plantes et animaux domestiqués. Cette vision, malheureusement toujours très actuelle, est devenue clairement réductionniste avec les développements de la génétique moléculaire et de la biologie synthétique, développements qui conduisent à la confiscation de la science par ses techniques, de la biologie par le biologisme. Mais faut-il être biologiste ou biotechnologue pour avoir le privilège d'étudier le risque biologique ? Juristes, sociologues, théologiens, paysans, historiens, psychologues et d'autres encore, nous avertissent : la biologie, avant tout science des « yeux », glisse insidieusement vers une science des « mains », de l'étude de la vie vers la manipulation du vivant. Par ailleurs, la biologie du « faire », contrairement à la biologie du « voir », génère des besoins financiers et des compromissions politico-scientifiques incomparables, à l'origine de questions d'éthique sans cesse croissantes. Dans ces conditions, nombreux universitaires et professionnels d'origines très diverses tentent de sortir de l'autoroute réductionniste et déterministe qu'on leur impose en empruntant des bretelles transdisciplinaires qui les conduisent à la construction d'une pensée complexe autour de la question du risque biologique, question qui nécessite urgemment d'être collectivement posée. Ont collaboré à ce volume

Research Journal of Microbiology, 2020

Applied and Environmental Microbiology, 1989

The degree of retention of whole cells of Synechocystis strain PCC 6803 on DEAE-cellulose columns... more The degree of retention of whole cells of Synechocystis strain PCC 6803 on DEAE-cellulose columns was shown to depend on their content of exopolysaccharides, which are at least in part responsible for the external negative charge of the cells. This feature was used for the isolation of mutants modified in the apparent viscosity caused by these macromolecular constituents. When a wild-type suspension was loaded onto a DE52 column, the cells eluting in the two extreme fractions of a 0 to 5 M NaCl step gradient represented 10 −9 to 10 −7 of the total eluted population. The accuracy of the procedure was established through the analysis of four clones: Suc(0)32 and Suc(0)65 (0 M) and Suc(5)64A and Suc(5)61 (5 M). The decreased viscosity of the exopolymers of the two 0 M clones, which appeared identical, could be related to the production of molecules less charged in uronic acids and more readily liberated from the cells. The two 5 M clones exhibited a lower sedimentation velocity, correl...

International Journal of Risk Assessment and Management, 2020

Journal of Bacteriology, 1997

Transfer of Enterococcus faecalis to a cold temperature (8 degrees C for 4 to 30 h) led to increa... more Transfer of Enterococcus faecalis to a cold temperature (8 degrees C for 4 to 30 h) led to increased expression of 11 cold shock proteins (CSPs). Furthermore, this mesophilic prokaryote synthesized 10 cold acclimation proteins, five of them distinct from CSPs, during continuous growth (4 days) at the same temperature (8 degrees C).

African Journal of Agricultural Research, 2017

Earthworms might be limited in their activities on soil by pesticides used at important rates in ... more Earthworms might be limited in their activities on soil by pesticides used at important rates in agriculture and human pathogenic microorganisms introduced in soil by excreta. This study using a modified toxicity filter paper contact test from Organisation for Economic Cooperation and Development (OECD), aimed at assessing the toxicity of six pesticides formulations and six microorganisms on the earthworm Eisenia fetida. The study performed over 7 months at the laboratory QAlEA (University of Caen Normandie, France), analysed the mortality every 24 h for 96 h and at 96 h of E. fetida when exposing to pesticides and microbial suspensions. The statistical test used is the Student's t-test at the significant level of 0.05. No mortality of earthworms was observed when testing these pesticides at their recommended agricultural concentrations. Toxicity order from the highest to the lowest, based on LC 50 , was Capiscol, Stratos Ultra Jardin, Polyvalent, Roundup GT Plus, Polyflor and KB Limace. Among tested microorganisms , only Enterobacter cloacae (culture broth) and Listeria monocytogenes (culture broth and supernatant) generate mortalities of E. fetida. Finally, all these tested pesticides do not lead to E. fetida mortality if they are used at their recommended agricultural concentrations. Earthworms species E. fetida are also stressed by some microorganisms. Furthermore, the filter paper contact test OECD might be used as a tool to evaluate the response of E. fetida to abiotic and biotic stresses.

Biofutur, 2006

Dans l'evaluation des risques associes a la dissemination des OGM, les transferts horizontaux... more Dans l'evaluation des risques associes a la dissemination des OGM, les transferts horizontaux jouent un role preponderant, a ne pas negliger.

Http Www Theses Fr, 1989

Isolement par chromatographie par echange d'ions de mutants de synechocystis dont la producti... more Isolement par chromatographie par echange d'ions de mutants de synechocystis dont la production d'exopolyosides (eps) est modifiee. La diminution de viscosite des eps de 2 mutants est correlee a une baisse de la proportion en acides uroniques. Dans un autre mutant, la viscosite des eps et leur contenu en acides uroniques sont augmentes

Microbiology, 2002

International audienc

Cell Preservation Technology, 2005

... 2Present address: Emmanuel Denou, Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausan... more ... 2Present address: Emmanuel Denou, Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausanne 26, Switzer-land ... L. bulgaricus cells in stationary phase (OD460nm 1) were mixed with the extracellu-lar fractions or the cell envelope extracts and transferred to 8°C for 3 h ...

World Review of Science, Technology and Sustainable Development, 2014

Because of the complexity of many environmental problems, we need their holistic assessment. That... more Because of the complexity of many environmental problems, we need their holistic assessment. That is why, in such a matter, a multidisciplinary approach is necessary. It has also been the guiding line for this present study on the European regulation of the GMOs, crossing the different points of view of a lawyer and a biologist. According to the European legislation, molecular biology and dissemination of genetically modified organisms are mainly regulated by two major directives of the European Parliament and of the Council: Directive 2009/41/EC on the contained use of genetically modified microorganisms, and Directive 2001/18/EC on the deliberate release into the environment of genetically modified organisms. Two different approaches are possible to analyse those directives and suggest possible improvements.

Microbes and Environments, 2009

Any modification of the environment that leads to a physiological, genetic, or epigenetic adaptiv... more Any modification of the environment that leads to a physiological, genetic, or epigenetic adaptive response in microorganisms may be considered as a stress. Historically, forms of stresses affecting biological structures were classified either as non-thermal, such as osmotic, oxidative, or acid stress or as thermal stress, hot or cold. Currently, the classification in biology is as abiotic, including physical and chemical stress, or biotic. The aim of this mini-review is to show, through the example of microorganisms, that the response to stress can be considered, in biology, as a global phenomenon, which can be extended to anthropogenic pressure.

Sciences des Aliments, 2000

ABSTRACT The necessity for better control of lactic acid bacteria (LAB) which are widely used in ... more ABSTRACT The necessity for better control of lactic acid bacteria (LAB) which are widely used in food biotechnology, requires an increase in our knowledge concerning the behaviour at low temperature of these organisms (starter freezing, ripening at positive low temperature, food storage). Study of the cold stress responses in LAB needs to consider: (i) positive and negative low temperatures, (ii) the duration of the exposure to low temperature leading to a "shock" or an "acclimation", (iii) microorganism grouping according to their cardinal growth temperatures. Furthermore, the connection between the stress generated by transfer of LAB to a low temperature environment and the correlated response, may be analysed by three approaches: (i) the physiological response of the cell (growth and cryotolerance), (ii) the generated biochemical modifications (degree of fatty acid desaturation and protein profile), (iii) the control of the response. Recent results in molecular genetics concerning the cold stress responses in LAB seems to be insufficiently correlated to current understanding of biochemical and physiological behaviours, such as cryotolerance.

Journal of Microbiological Methods, 2004

Freezing of prokaryotic and eukaryotic microorganisms is the main interest in the study of cold s... more Freezing of prokaryotic and eukaryotic microorganisms is the main interest in the study of cold stress responses of living organisms. In parallel, applications which arise from this approach are of two types: (i) optimization of the frozen starters used in food processing; and (ii) improvement of the ex situ preservation of microorganisms in collections. Currently, cryopreservation of microorganisms in collections is carried out in cryotubes, and bibliographical references related to freezing microorganisms packaged in straws are scarce. In this context, a preliminary study was completed to evaluate the technological potential of ionomeric resin straws compared to polycarbonate cryo-tubes. Survival under freezing stress was tested on three microorganisms selected for their biotechnological interest: two lactic acid bacteria, Lactococcus lactis subsp. cremoris and Lactobacillus delbrueckii subsp. bulgaricus and a deuteromycete fungus, Geotrichum candidum. The stress was carried out by repeated freezing-thawing cycles to artificially accelerate the lethal effect of freezing on the microorganisms. Two main results were obtained: (i) the survival rate values (per freezing-thawing cycle) seems to depend on the thermal type of the studied microorganism, and (ii) there was no, under our experimental conditions, significant difference between straws and tubes. However, conservation in the resin straws lead to a slight increase in the survival of L. cremoris and G. candidum compared to microtubes. In those conditions, straws seems an alternative system to securely store frozen microorganisms with three main characteristics: (i) a high resistance to thermal stress, (ii) a safe closing by hermetic weld, and (iii) a system for inviolable identification.

Journal of Dairy Research, 2010

Microscopic conformation, growth behaviour and freezing sensitivity of seven strains ofGeotrichum... more Microscopic conformation, growth behaviour and freezing sensitivity of seven strains ofGeotrichum candidum, a ripening starter, were studied and compared according to their macroscopic morphotypes. It has been shown that the thallus forming units (TFU)×ml−1/OD600nmratio as a function of time is an interesting parameter to followG. candidumsporulation through the growth behaviour. Microscopic conformation, growth behaviour and freezing sensitivity are clearly strain specific and mostly related to their corresponding morphotypes “yeast”, “mould” or “intermediate”. The two “mould” strains that sporulate weakly (UCMA103, UCMA499) showed a low survival rate to freezing stress whereas the “yeast” strains expressed a significant resistance owing to the arthrospore abundance. Interestingly, one strain (UCMA96) which appeared on solid medium in accord with the “mould” morphotype respond similarly to freezing stress.

Journal of Bacteriology, 2008

Lactobacillus johnsonii strains NCC533 and ATCC 33200 (the type strain of this species) differed ... more Lactobacillus johnsonii strains NCC533 and ATCC 33200 (the type strain of this species) differed significantly in gut residence time (12 versus 5 days) after oral feeding to mice. Genes affecting the long gut residence time of the probiotic strain NCC533 were targeted for analysis. We hypothesized that genes specific for this strain, which are expressed during passage of the bacterium through the gut, affect the phenotype. When the DNA of the type strain was hybridized against a microarray of the sequenced NCC533 strain, we identified 233 genes that were specific for the long-gut-persistence isolate. Whole-genome transcription analysis of the NCC533 strain using the microarray format identified 174 genes that were strongly and consistently expressed in the jejunum of mice monocolonized with this strain. Fusion of the two microarray data sets identified three gene loci that were both expressed in vivo and specific to the long-gut-persistence isolate. The identified genes included LJ1...

Journal of Bacteriology, 2007

Work with pathogens like Vibrio cholerae has shown major differences between genes expressed in b... more Work with pathogens like Vibrio cholerae has shown major differences between genes expressed in bacteria grown in vitro and in vivo. To explore this subject for commensals, we investigated the transcription of the Lactobacillus johnsonii NCC533 genome during in vitro and in vivo growth using the microarray technology. During broth growth, 537, 626, and 277 of the 1,756 tested genes were expressed during exponential phase, “adaptation” (early stationary phase), and stationary phase, respectively. One hundred one, 150, and 33 genes, respectively, were specifically transcribed in these three phases. To explore the in vivo transcription program, we fed L. johnsonii containing a resistance plasmid to antibiotic-treated mice. After a 2-day washout phase, we determined the viable-cell counts of lactobacilli that were in the lumina and associated with the mucosae of different gut segments. While the cell counts showed a rather uniform distribution along the gut, we observed marked differenc...

Journal of Bacteriology, 2008

Two independent isolates of the gut commensal Lactobacillus johnsonii were sequenced. These isola... more Two independent isolates of the gut commensal Lactobacillus johnsonii were sequenced. These isolates belonged to the same clonal lineage and differed mainly by a 40.8-kb prophage, LJ771, belonging to the Sfi11 phage lineage. LJ771 shares close DNA sequence identity with Lactobacillus gasseri prophages. LJ771 coexists as an integrated prophage and excised circular phage DNA, but phage DNA packaged into extracellular phage particles was not detected. Between the phage lysin gene and attR a likely mazE (“antitoxin”)/pemK (“toxin”) gene cassette was detected in LJ771 but not in the L. gasseri prophages. Expressed pemK could be cloned in Escherichia coli only together with the mazE gene. LJ771 was shown to be highly stable and could be cured only by coexpression of mazE from a plasmid. The prophage was integrated into the methionine sulfoxide reductase gene (msrA) and complemented the 5′ end of this gene, creating a protein with a slightly altered N-terminal sequence. The two L. johnsoni...

Journal of Applied Microbiology, 2002

Assessment of genetic diversity within the species Geotrichum candidum and development of tools t... more Assessment of genetic diversity within the species Geotrichum candidum and development of tools to trace the strains that play an important role in the agro food industry. Methods and Results: RAM-PCR and RAPD-PCR techniques were assessed for their ability to discriminate 57 strains of various morphotypes, substrates and geographical origin. The techniques were complementary and, when combined, allowed us to discriminate isolates. Moreover, we established a link between a taxon and its occupation of an ecological niche, which should not be confused with the substrate of isolation. Conclusions: We observed a high degree of diversity, which could be linked to the variety of the ecological niches chosen and to the high degree of morphological polymorphism encountered within the species. Signi®cance and Impact of the Study: Used in combination, RAM-PCR and RAPD-PCR permit traceability and monitoring systems for G. candidum strains during food processing.

National audienceUne approche transdisciplinaire La vie, évènement perdu dans l'espace et le ... more National audienceUne approche transdisciplinaire La vie, évènement perdu dans l'espace et le temps, créatrice d'ordres et d'amours, lutte sans relâche pour reproduire indéfiniment des structures et des fonctions dans le chaos cosmique. Paradoxalement, les biologistes nous disent que cette vie est créatrice de risques pour l'homme et son environnement, que la vie s'oppose à la vie. L'approche anthropocentrique historique du risque biologique s'est longtemps limitée à l'étude des microbes pathogènes, d'abord pour l'espèce humaine et ensuite pour les plantes et animaux domestiqués. Cette vision, malheureusement toujours très actuelle, est devenue clairement réductionniste avec les développements de la génétique moléculaire et de la biologie synthétique, développements qui conduisent à la confiscation de la science par ses techniques, de la biologie par le biologisme. Mais faut-il être biologiste ou biotechnologue pour avoir le privilège d'étudier le risque biologique ? Juristes, sociologues, théologiens, paysans, historiens, psychologues et d'autres encore, nous avertissent : la biologie, avant tout science des « yeux », glisse insidieusement vers une science des « mains », de l'étude de la vie vers la manipulation du vivant. Par ailleurs, la biologie du « faire », contrairement à la biologie du « voir », génère des besoins financiers et des compromissions politico-scientifiques incomparables, à l'origine de questions d'éthique sans cesse croissantes. Dans ces conditions, nombreux universitaires et professionnels d'origines très diverses tentent de sortir de l'autoroute réductionniste et déterministe qu'on leur impose en empruntant des bretelles transdisciplinaires qui les conduisent à la construction d'une pensée complexe autour de la question du risque biologique, question qui nécessite urgemment d'être collectivement posée. Ont collaboré à ce volume

Research Journal of Microbiology, 2020

Applied and Environmental Microbiology, 1989

The degree of retention of whole cells of Synechocystis strain PCC 6803 on DEAE-cellulose columns... more The degree of retention of whole cells of Synechocystis strain PCC 6803 on DEAE-cellulose columns was shown to depend on their content of exopolysaccharides, which are at least in part responsible for the external negative charge of the cells. This feature was used for the isolation of mutants modified in the apparent viscosity caused by these macromolecular constituents. When a wild-type suspension was loaded onto a DE52 column, the cells eluting in the two extreme fractions of a 0 to 5 M NaCl step gradient represented 10 −9 to 10 −7 of the total eluted population. The accuracy of the procedure was established through the analysis of four clones: Suc(0)32 and Suc(0)65 (0 M) and Suc(5)64A and Suc(5)61 (5 M). The decreased viscosity of the exopolymers of the two 0 M clones, which appeared identical, could be related to the production of molecules less charged in uronic acids and more readily liberated from the cells. The two 5 M clones exhibited a lower sedimentation velocity, correl...

International Journal of Risk Assessment and Management, 2020

Journal of Bacteriology, 1997

Transfer of Enterococcus faecalis to a cold temperature (8 degrees C for 4 to 30 h) led to increa... more Transfer of Enterococcus faecalis to a cold temperature (8 degrees C for 4 to 30 h) led to increased expression of 11 cold shock proteins (CSPs). Furthermore, this mesophilic prokaryote synthesized 10 cold acclimation proteins, five of them distinct from CSPs, during continuous growth (4 days) at the same temperature (8 degrees C).

African Journal of Agricultural Research, 2017

Earthworms might be limited in their activities on soil by pesticides used at important rates in ... more Earthworms might be limited in their activities on soil by pesticides used at important rates in agriculture and human pathogenic microorganisms introduced in soil by excreta. This study using a modified toxicity filter paper contact test from Organisation for Economic Cooperation and Development (OECD), aimed at assessing the toxicity of six pesticides formulations and six microorganisms on the earthworm Eisenia fetida. The study performed over 7 months at the laboratory QAlEA (University of Caen Normandie, France), analysed the mortality every 24 h for 96 h and at 96 h of E. fetida when exposing to pesticides and microbial suspensions. The statistical test used is the Student's t-test at the significant level of 0.05. No mortality of earthworms was observed when testing these pesticides at their recommended agricultural concentrations. Toxicity order from the highest to the lowest, based on LC 50 , was Capiscol, Stratos Ultra Jardin, Polyvalent, Roundup GT Plus, Polyflor and KB Limace. Among tested microorganisms , only Enterobacter cloacae (culture broth) and Listeria monocytogenes (culture broth and supernatant) generate mortalities of E. fetida. Finally, all these tested pesticides do not lead to E. fetida mortality if they are used at their recommended agricultural concentrations. Earthworms species E. fetida are also stressed by some microorganisms. Furthermore, the filter paper contact test OECD might be used as a tool to evaluate the response of E. fetida to abiotic and biotic stresses.

Biofutur, 2006

Dans l'evaluation des risques associes a la dissemination des OGM, les transferts horizontaux... more Dans l'evaluation des risques associes a la dissemination des OGM, les transferts horizontaux jouent un role preponderant, a ne pas negliger.

Http Www Theses Fr, 1989

Isolement par chromatographie par echange d'ions de mutants de synechocystis dont la producti... more Isolement par chromatographie par echange d'ions de mutants de synechocystis dont la production d'exopolyosides (eps) est modifiee. La diminution de viscosite des eps de 2 mutants est correlee a une baisse de la proportion en acides uroniques. Dans un autre mutant, la viscosite des eps et leur contenu en acides uroniques sont augmentes

Microbiology, 2002

International audienc

Cell Preservation Technology, 2005

... 2Present address: Emmanuel Denou, Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausan... more ... 2Present address: Emmanuel Denou, Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausanne 26, Switzer-land ... L. bulgaricus cells in stationary phase (OD460nm 1) were mixed with the extracellu-lar fractions or the cell envelope extracts and transferred to 8°C for 3 h ...

World Review of Science, Technology and Sustainable Development, 2014

Because of the complexity of many environmental problems, we need their holistic assessment. That... more Because of the complexity of many environmental problems, we need their holistic assessment. That is why, in such a matter, a multidisciplinary approach is necessary. It has also been the guiding line for this present study on the European regulation of the GMOs, crossing the different points of view of a lawyer and a biologist. According to the European legislation, molecular biology and dissemination of genetically modified organisms are mainly regulated by two major directives of the European Parliament and of the Council: Directive 2009/41/EC on the contained use of genetically modified microorganisms, and Directive 2001/18/EC on the deliberate release into the environment of genetically modified organisms. Two different approaches are possible to analyse those directives and suggest possible improvements.

Microbes and Environments, 2009

Any modification of the environment that leads to a physiological, genetic, or epigenetic adaptiv... more Any modification of the environment that leads to a physiological, genetic, or epigenetic adaptive response in microorganisms may be considered as a stress. Historically, forms of stresses affecting biological structures were classified either as non-thermal, such as osmotic, oxidative, or acid stress or as thermal stress, hot or cold. Currently, the classification in biology is as abiotic, including physical and chemical stress, or biotic. The aim of this mini-review is to show, through the example of microorganisms, that the response to stress can be considered, in biology, as a global phenomenon, which can be extended to anthropogenic pressure.

Sciences des Aliments, 2000

ABSTRACT The necessity for better control of lactic acid bacteria (LAB) which are widely used in ... more ABSTRACT The necessity for better control of lactic acid bacteria (LAB) which are widely used in food biotechnology, requires an increase in our knowledge concerning the behaviour at low temperature of these organisms (starter freezing, ripening at positive low temperature, food storage). Study of the cold stress responses in LAB needs to consider: (i) positive and negative low temperatures, (ii) the duration of the exposure to low temperature leading to a "shock" or an "acclimation", (iii) microorganism grouping according to their cardinal growth temperatures. Furthermore, the connection between the stress generated by transfer of LAB to a low temperature environment and the correlated response, may be analysed by three approaches: (i) the physiological response of the cell (growth and cryotolerance), (ii) the generated biochemical modifications (degree of fatty acid desaturation and protein profile), (iii) the control of the response. Recent results in molecular genetics concerning the cold stress responses in LAB seems to be insufficiently correlated to current understanding of biochemical and physiological behaviours, such as cryotolerance.

Journal of Microbiological Methods, 2004

Freezing of prokaryotic and eukaryotic microorganisms is the main interest in the study of cold s... more Freezing of prokaryotic and eukaryotic microorganisms is the main interest in the study of cold stress responses of living organisms. In parallel, applications which arise from this approach are of two types: (i) optimization of the frozen starters used in food processing; and (ii) improvement of the ex situ preservation of microorganisms in collections. Currently, cryopreservation of microorganisms in collections is carried out in cryotubes, and bibliographical references related to freezing microorganisms packaged in straws are scarce. In this context, a preliminary study was completed to evaluate the technological potential of ionomeric resin straws compared to polycarbonate cryo-tubes. Survival under freezing stress was tested on three microorganisms selected for their biotechnological interest: two lactic acid bacteria, Lactococcus lactis subsp. cremoris and Lactobacillus delbrueckii subsp. bulgaricus and a deuteromycete fungus, Geotrichum candidum. The stress was carried out by repeated freezing-thawing cycles to artificially accelerate the lethal effect of freezing on the microorganisms. Two main results were obtained: (i) the survival rate values (per freezing-thawing cycle) seems to depend on the thermal type of the studied microorganism, and (ii) there was no, under our experimental conditions, significant difference between straws and tubes. However, conservation in the resin straws lead to a slight increase in the survival of L. cremoris and G. candidum compared to microtubes. In those conditions, straws seems an alternative system to securely store frozen microorganisms with three main characteristics: (i) a high resistance to thermal stress, (ii) a safe closing by hermetic weld, and (iii) a system for inviolable identification.

Journal of Dairy Research, 2010

Microscopic conformation, growth behaviour and freezing sensitivity of seven strains ofGeotrichum... more Microscopic conformation, growth behaviour and freezing sensitivity of seven strains ofGeotrichum candidum, a ripening starter, were studied and compared according to their macroscopic morphotypes. It has been shown that the thallus forming units (TFU)×ml−1/OD600nmratio as a function of time is an interesting parameter to followG. candidumsporulation through the growth behaviour. Microscopic conformation, growth behaviour and freezing sensitivity are clearly strain specific and mostly related to their corresponding morphotypes “yeast”, “mould” or “intermediate”. The two “mould” strains that sporulate weakly (UCMA103, UCMA499) showed a low survival rate to freezing stress whereas the “yeast” strains expressed a significant resistance owing to the arthrospore abundance. Interestingly, one strain (UCMA96) which appeared on solid medium in accord with the “mould” morphotype respond similarly to freezing stress.

Journal of Bacteriology, 2008

Lactobacillus johnsonii strains NCC533 and ATCC 33200 (the type strain of this species) differed ... more Lactobacillus johnsonii strains NCC533 and ATCC 33200 (the type strain of this species) differed significantly in gut residence time (12 versus 5 days) after oral feeding to mice. Genes affecting the long gut residence time of the probiotic strain NCC533 were targeted for analysis. We hypothesized that genes specific for this strain, which are expressed during passage of the bacterium through the gut, affect the phenotype. When the DNA of the type strain was hybridized against a microarray of the sequenced NCC533 strain, we identified 233 genes that were specific for the long-gut-persistence isolate. Whole-genome transcription analysis of the NCC533 strain using the microarray format identified 174 genes that were strongly and consistently expressed in the jejunum of mice monocolonized with this strain. Fusion of the two microarray data sets identified three gene loci that were both expressed in vivo and specific to the long-gut-persistence isolate. The identified genes included LJ1...

Journal of Bacteriology, 2007

Work with pathogens like Vibrio cholerae has shown major differences between genes expressed in b... more Work with pathogens like Vibrio cholerae has shown major differences between genes expressed in bacteria grown in vitro and in vivo. To explore this subject for commensals, we investigated the transcription of the Lactobacillus johnsonii NCC533 genome during in vitro and in vivo growth using the microarray technology. During broth growth, 537, 626, and 277 of the 1,756 tested genes were expressed during exponential phase, “adaptation” (early stationary phase), and stationary phase, respectively. One hundred one, 150, and 33 genes, respectively, were specifically transcribed in these three phases. To explore the in vivo transcription program, we fed L. johnsonii containing a resistance plasmid to antibiotic-treated mice. After a 2-day washout phase, we determined the viable-cell counts of lactobacilli that were in the lumina and associated with the mucosae of different gut segments. While the cell counts showed a rather uniform distribution along the gut, we observed marked differenc...

Journal of Bacteriology, 2008

Two independent isolates of the gut commensal Lactobacillus johnsonii were sequenced. These isola... more Two independent isolates of the gut commensal Lactobacillus johnsonii were sequenced. These isolates belonged to the same clonal lineage and differed mainly by a 40.8-kb prophage, LJ771, belonging to the Sfi11 phage lineage. LJ771 shares close DNA sequence identity with Lactobacillus gasseri prophages. LJ771 coexists as an integrated prophage and excised circular phage DNA, but phage DNA packaged into extracellular phage particles was not detected. Between the phage lysin gene and attR a likely mazE (“antitoxin”)/pemK (“toxin”) gene cassette was detected in LJ771 but not in the L. gasseri prophages. Expressed pemK could be cloned in Escherichia coli only together with the mazE gene. LJ771 was shown to be highly stable and could be cured only by coexpression of mazE from a plasmid. The prophage was integrated into the methionine sulfoxide reductase gene (msrA) and complemented the 5′ end of this gene, creating a protein with a slightly altered N-terminal sequence. The two L. johnsoni...

Journal of Applied Microbiology, 2002

Assessment of genetic diversity within the species Geotrichum candidum and development of tools t... more Assessment of genetic diversity within the species Geotrichum candidum and development of tools to trace the strains that play an important role in the agro food industry. Methods and Results: RAM-PCR and RAPD-PCR techniques were assessed for their ability to discriminate 57 strains of various morphotypes, substrates and geographical origin. The techniques were complementary and, when combined, allowed us to discriminate isolates. Moreover, we established a link between a taxon and its occupation of an ecological niche, which should not be confused with the substrate of isolation. Conclusions: We observed a high degree of diversity, which could be linked to the variety of the ecological niches chosen and to the high degree of morphological polymorphism encountered within the species. Signi®cance and Impact of the Study: Used in combination, RAM-PCR and RAPD-PCR permit traceability and monitoring systems for G. candidum strains during food processing.