Limitation of Shiga-toxin producing Escherichia coli (STEC) asymptomatic carriage by cattle, bio-protective potential of Lactic Acid Bacteria in cattle feed

Les Escherichia coli producteurs de Shiga-Toxines (STEC) sont responsables de maladies humaines sévères. Les ruminants sont considérés comme étant leur principal réservoir. La dissémination des STEC au sein des élevages est liée en partie à l’alimentation des animaux et donc potentiellement à l’ingestion d’ensilages contaminés. Les bactéries lactiques peuvent être employées comme agents technologiques ou dans des stratégies de bio-protection. Sur le plan de l’ensilage, elles jouent un rôle de préservation mais peuvent également représenter une barrière à la survie de pathogènes comme les STEC. Ce travail a permis de sélectionner des bactéries lactiques inhibitrices de la croissance de divers sérogroupes de STEC. Les études de compétitions ont mis en évidence un phénomène bactéricide sur certaines souches, dont le mécanisme reste encore non élucidé. Le potentiel inhibiteur des bactéries lactiques sélectionnées a été testé indépendamment dans des ensilages de maïs contaminés à différentes étapes de leur réalisation : à la mise en silos, à l’ouverture ou après une période d’exposition aérobie. En cas de contamination à la mise en silos, les souches de STEC testées n’ont pas survécu dans des ensilages correctement menés. Une souche de Ln. mesenteroides a permis de limiter la survie des souches de STEC dans les ensilages contaminés à l’ouverture. Cependant, après 144h d’aération, aucun additif n’a montré d’effet protecteur avéré. Le contrôle de l’alimentation animale afin de limiter l’entrée des STEC dans le cycle épidémiologique pourrait donc passer par l’emploi de bactéries lactiques ; sans négliger cependant les Bonnes Pratiques nécessaires à la réalisation de l’ensilage.Shiga-toxin producing Escherichia coli (STEC) are responsible for severe human diseases. Cattle are considered as the main reservoir of this pathogen. STEC dissemination in farm environment is linked to cattle feed and potentially to ingestion of contaminated silage. Lactic Acid Bacteria (LAB) could be employed as starters in fermentations or in strategies of bioprotection. In silage, LAB play a preservative role and could also represent a barrier for the survival of pathogenic bacteria such as STEC. The selection of LAB strains, able to inhibit the growth of several serogroups of STEC strains, was performed in this study. Competitions assays have shown a bactericidal effect on some STEC strains, but reasons of this phenomenon remain unclear. Inhibiting potential of the selected LAB strains was tested independently in corn silages contaminated at different steps of their realizations : at ensiling, at opening or after aerobic exposure. In case of contamination at ensiling, STEC strains tested did not survive in well-made silages. A Ln. mesenteroides strain allowed the limitation of the STEC strains survival in silage contaminated at opening. However, after 144 h of aerobic exposure, no inoculant showed any protective effect. Control of cattle feed, in order to limit STEC entry in their epidemiological cycle, could be reached through LAB utilization ; however, Good Manufacturing Practices involved in silage making should not be omitted

Stratégies de limitation du portage sain des Escherichia coli producteurs de Shigatoxines (STEC) par les bovins. Potentiel bio-protecteur des bactéries lactiques en alimentation animale

Shiga-toxin producing Escherichia coli (STEC) are responsible for severe human diseases. Cattle are considered as the main reservoir of this pathogen. STEC dissemination in farm environment is linked to cattle feed and potentially to ingestion of contaminated silage. Lactic Acid Bacteria (LAB) could be employed as starters in fermentations or in strategies of bioprotection. In silage, LAB play a preservative role and could also represent a barrier for the survival of pathogenic bacteria such as STEC. The selection of LAB strains, able to inhibit the growth of several serogroups of STEC strains, was performed in this study. Competitions assays have shown a bactericidal effect on some STEC strains, but reasons of this phenomenon remain unclear. Inhibiting potential of the selected LAB strains was tested independently in corn silages contaminated at different steps of their realizations : at ensiling, at opening or after aerobic exposure. In case of contamination at ensiling, STEC strains tested did not survive in well-made silages. A Ln. mesenteroides strain allowed the limitation of the STEC strains survival in silage contaminated at opening. However, after 144 h of aerobic exposure, no inoculant showed any protective effect. Control of cattle feed, in order to limit STEC entry in their epidemiological cycle, could be reached through LAB utilization ; however, Good Manufacturing Practices involved in silage making should not be omitted.Les Escherichia coli producteurs de Shiga-Toxines (STEC) sont responsables de maladies humaines sévères. Les ruminants sont considérés comme étant leur principal réservoir. La dissémination des STEC au sein des élevages est liée en partie à l’alimentation des animaux et donc potentiellement à l’ingestion d’ensilages contaminés. Les bactéries lactiques peuvent être employées comme agents technologiques ou dans des stratégies de bio-protection. Sur le plan de l’ensilage, elles jouent un rôle de préservation mais peuvent également représenter une barrière à la survie de pathogènes comme les STEC. Ce travail a permis de sélectionner des bactéries lactiques inhibitrices de la croissance de divers sérogroupes de STEC. Les études de compétitions ont mis en évidence un phénomène bactéricide sur certaines souches, dont le mécanisme reste encore non élucidé. Le potentiel inhibiteur des bactéries lactiques sélectionnées a été testé indépendamment dans des ensilages de maïs contaminés à différentes étapes de leur réalisation : à la mise en silos, à l’ouverture ou après une période d’exposition aérobie. En cas de contamination à la mise en silos, les souches de STEC testées n’ont pas survécu dans des ensilages correctement menés. Une souche de Ln. mesenteroides a permis de limiter la survie des souches de STEC dans les ensilages contaminés à l’ouverture. Cependant, après 144h d’aération, aucun additif n’a montré d’effet protecteur avéré. Le contrôle de l’alimentation animale afin de limiter l’entrée des STEC dans le cycle épidémiologique pourrait donc passer par l’emploi de bactéries lactiques ; sans négliger cependant les Bonnes Pratiques nécessaires à la réalisation de l’ensilage

Stratégies de limitation du portage sain des Escherichia coli producteurs de Shigatoxines (STEC) par les bovins. Potentiel bio-protecteur des bactéries lactiques en alimentation animale

Les Escherichia coli producteurs de Shiga-Toxines (STEC) sont responsables de maladies humaines sévères. Les ruminants sont considérés comme étant leur principal réservoir. La dissémination des STEC au sein des élevages est liée en partie à l alimentation des animaux et donc potentiellement à l ingestion d ensilages contaminés. Les bactéries lactiques peuvent être employées comme agents technologiques ou dans des stratégies de bio-protection. Sur le plan de l ensilage, elles jouent un rôle de préservation mais peuvent également représenter une barrière à la survie de pathogènes comme les STEC. Ce travail a permis de sélectionner des bactéries lactiques inhibitrices de la croissance de divers sérogroupes de STEC. Les études de compétitions ont mis en évidence un phénomène bactéricide sur certaines souches, dont le mécanisme reste encore non élucidé. Le potentiel inhibiteur des bactéries lactiques sélectionnées a été testé indépendamment dans des ensilages de maïs contaminés à différentes étapes de leur réalisation : à la mise en silos, à l ouverture ou après une période d exposition aérobie. En cas de contamination à la mise en silos, les souches de STEC testées n ont pas survécu dans des ensilages correctement menés. Une souche de Ln. mesenteroides a permis de limiter la survie des souches de STEC dans les ensilages contaminés à l ouverture. Cependant, après 144h d aération, aucun additif n a montré d effet protecteur avéré. Le contrôle de l alimentation animale afin de limiter l entrée des STEC dans le cycle épidémiologique pourrait donc passer par l emploi de bactéries lactiques ; sans négliger cependant les Bonnes Pratiques nécessaires à la réalisation de l ensilage.Shiga-toxin producing Escherichia coli (STEC) are responsible for severe human diseases. Cattle are considered as the main reservoir of this pathogen. STEC dissemination in farm environment is linked to cattle feed and potentially to ingestion of contaminated silage. Lactic Acid Bacteria (LAB) could be employed as starters in fermentations or in strategies of bioprotection. In silage, LAB play a preservative role and could also represent a barrier for the survival of pathogenic bacteria such as STEC. The selection of LAB strains, able to inhibit the growth of several serogroups of STEC strains, was performed in this study. Competitions assays have shown a bactericidal effect on some STEC strains, but reasons of this phenomenon remain unclear. Inhibiting potential of the selected LAB strains was tested independently in corn silages contaminated at different steps of their realizations : at ensiling, at opening or after aerobic exposure. In case of contamination at ensiling, STEC strains tested did not survive in well-made silages. A Ln. mesenteroides strain allowed the limitation of the STEC strains survival in silage contaminated at opening. However, after 144 h of aerobic exposure, no inoculant showed any protective effect. Control of cattle feed, in order to limit STEC entry in their epidemiological cycle, could be reached through LAB utilization ; however, Good Manufacturing Practices involved in silage making should not be omitted.CLERMONT FD-Bib.électronique (631139902) / SudocSudocFranceF

Conditioner application improves bedding quality and bacterial composition with potential beneficial impacts for dairy cow’s health

ABSTRACTRecycled manure solids (RMS) is used as bedding material in cow housing but can be at risk for pathogens development. Cows spend several hours per day lying down, contributing to the transfer of potential mastitis pathogens from the bedding to the udder. The effect of a bacterial conditioner (Manure Pro, MP) application was studied on RMS-bedding and milk qualities and on animal health. MP product was applied on bedding once a week for 3 months. Bedding and teat skin samples were collected from Control and MP groups at D01, D51, and D90 and analyzed through 16S rRNA amplicon sequencing. MP application modified bacterial profiles and diversity. Control bedding was significantly associated with potential mastitis pathogens, while no taxa of potential health risk were significantly detected in MP beddings. Functional prediction identified enrichment of metabolic pathways of agronomic interest in MP beddings. Significant associations with potential mastitis pathogens were mainly observed in Control teat skin samples. Finally, significantly better hygiene and lower Somatic Cell Counts in milk were observed for cows from MP group, while no group impact was observed on milk quality and microbiota. No dissemination of MP strains was observed from bedding to teats or milk.IMPORTANCEThe use of Manure Pro (MP) conditioner improved recycled manure solids-bedding quality and this higher sanitary condition had further impacts on dairy cows' health with less potential mastitis pathogens significantly associated with bedding and teat skin samples of animals from MP group. The animals also presented an improved inflammation status, while milk quality was not modified. The use of MP conditioner on bedding may be of interest in controlling the risk of mastitis onset for dairy cows and further associated costs

Aspartate metabolism is involved in the maintenance of enterohaemorrhagic Escherichia coli O157:H7 in bovine intestinal content

International audienceThe gastrointestinal tract (GIT) of healthy cattle is the main reservoir of enterohaemorrhagic Escherichia coli (EHEC). Therefore, it is crucial to better understand the physiology of EHEC in the bovine GIT. In this study, we demonstrate that aspartate present in bovine small intestine content (BSIC), was exhausted after incubation of the reference EHEC strain EDL933 but was poorly assimilated by the endogenous microbiota. Furthermore, the bovine commensal E. coli strain BG1 appeared less efficient than EDL933 in aspartate assimilation suggesting a competitive ability of EHEC to assimilate this amino acid. Our results strongly suggest that aspartate, internalized via the DcuA aspartate:succinate antiporting system, is then converted to fumarate and carbamoyl-aspartate, the precursor for UMP biosynthesis. Aspartate assimilation by these two pathways conferred a competitive growth advantage to EHEC in BSIC. In summary, supply of intracellular fumarate due to aspartate deamination and used as an electron acceptor for anaerobic fumarate respiration, as well as de novo synthesis of pyrimidine from aspartate appear to be important pathways favouring EHEC persistence in the bovine gut. Aspartate probably represents an ecological niche for EHEC in the bovine small intestine

A live yeast supplementation to gestating ewes improves bioactive molecules composition in colostrum with no impact on its bacterial composition and beneficially affects immune status of the offspring

International audienceColostrum quality is of paramount importance in the management of optimal ruminant growth and infectious disease prevention in early life. Live yeast supplementation effect during the last month of gestation was evaluated on ewes’ colostrum composition. Two groups of ewes (n=14 for each group) carrying twin lambs were constituted and twins were separated into groups (mothered or artificially-fed) 12h after birth. Nutrients, oligosaccharides (OS), IgG and lactoferrin concentrations were measured over 72h after lambing, and bacterial community was described in colostrum collected at parturition (T0). Immune passive transfer was evaluated through IgG measurement in lamb serum. In both groups, colostral nutrients, OS concentrations and IgG concentrations in colostrum and lamb serum decreased over time (p < 0.01) except for lactose, which slightly increased (p < 0.001) and lactoferrin which remained stable. Bacterial population was stable over time with high relative abundances of Aerococcaceae, Corynebacteriaceae, Moraxellaceae and Staphylococcaceae in T0-colostrum. No effect of supplementation was observed in nutrient and lactoferrin concentrations. In supplemented ewes, colostral IgG level was higher at T0 and a higher level of serum IgG was observed in lambs born from supplemented mothers and artificially-fed, while no effect of supplementation was observed in the mothered lambs. Using a metabolomic approach, we showed that supplementation affected OS composition with significantly higher levels of colostral Neu-5Gc compounds up to 5h after birth. No effect of supplementation was observed on bacterial composition. Our data suggest that live yeast supplementation offsets the negative impact of early separation and incomplete colostrum feeding in neonate lambs

Silage review: Using molecular approaches to define the microbial ecology of silage

International audienceEnsiling of forages was recognized as a microbial-driven process as early as the late 1800s, when it was associated with the production of "sweet" or "sour" silage. Classical microbiological plating techniques defined the epiphytic microbial populations associated with fresh forage, the pivotal role of lactic acid-producing bacteria in the ensiling process, and the contribution of clostridia, bacilli, yeast, and molds to the spoilage of silage. Many of these classical studies focused on the enumeration and characterization of a limited number of microbial species that could be readily isolated on selective media. Evidence suggested that many of the members of these microbial populations were viable but unculturable, resulting in classical studies underestimating the true microbial diversity associated with ensiling. Polymerase chain reaction-based techniques, including length heterogeneity PCR, terminal RFLP, denaturing gradient gel electrophoresis, and automated ribosomal intergenic spacer analysis, were the first molecular methods used to study silage microbial communities. Further advancements in whole comparative genomic, metagenomic, and metatranscriptomic sequencing have or are in the process of superseding these methods, enabling microbial communities during ensiling to be defined with a degree of detail that is impossible using classical microbiology. These methods have identified new microbial species in silage, as well as characterized shifts in microbial communities with forage type and composition, ensiling method, and in response to aerobic exposure. Strain- and species-specific primers have been used to track the persistence and contribution of silage inoculants to the ensiling process and the role of specific species of yeast and fungi in silage spoil-age. Sampling and the methods used to isolate genetic materials for further molecular analysis can have a profound effect on results. Primer selection for PCR amplification and the presence of inhibitors can also lead to biases in the interpretation of sequence data. Bioinformatic analyses are reliant on the integrity and presence of sequence data within established databases and can be subject to low taxonomic resolution. Despite these limitations, advancements in molecular biology are poised to revolutionize our current understanding of the microbial ecology of silage

Using molecular microbial ecology to define differential responses to the inoculation of barley silage

Previously, we investigated the impact of a mixed Lactobacillus buchneri, Lactobacillus plantarum, and Lactobacillus casei inoculant on fermentation and aerobic stability of barley silage over two years in 2009 and 2010. In 2009, a classical response to inoculation was obtained with an increase in acetic acid concentration of silage ensiled in both mini- and bag silos. In 2010, this classical response was not observed in mini-silos but was observed in bag silos. The objective of this study was to determine if molecular microbial ecology could explain the differential responses to the inoculation of barley silage between the two years. The Illumina MiSeq sequencing results showed that inoculation increased Lactobacillus and lowered Pediococcus, Weissella, and Leuconostoc in both types of silos in 2009. However, a similar trend was not observed in mini-silos, but was instead observed in bag silos in 2010. Inoculation did not alter the core fungal community in either silo type in either year. Cladosporium, Leptosphaeria, and Cryptococcus were abundant in fresh forage, but were superseded by Pichia and Kazachstania after ensiling. Our results suggest that changes in silage chemistry corresponded to differences observed in microbial ecology. Inoculation may have less impact when using more mature crops with shorter ensiling times.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Supplementation of live yeast based feed additive in early life promotes rumen microbial colonization and fibrolytic potential in lambs

Rumen microbiota is of paramount importance for ruminant digestion efficiency as the microbial fermentations supply the host animal with essential sources of energy and nitrogen. Early separation of newborns from the dam and distribution of artificial milk (Artificial Milking System or AMS) could impair rumen microbial colonization, which would not only affect rumen function but also have possible negative effects on hindgut homeostasis, and impact animal health and performance. In this study, we monitored microbial communities in the rumen and the feces of 16 lambs separated from their dams from 12 h of age and artificially fed with milk replacer and starter feed from d8, in absence or presence of a combination of the live yeast Saccharomyces cerevisiae CNCM I-1077 and selected yeast metabolites. Microbial groups and targeted bacterial species were quantified by qPCR and microbial diversity and composition were assessed by 16S rDNA amplicon sequencing in samples collected from birth to 2 months of age. The fibrolytic potential of the rumen microbiota was analyzed with a DNA microarray targeting genes coding for 8 glycoside hydrolase (GH) families. In Control lambs, poor establishment of fibrolytic communities was observed. Microbial composition shifted as the lambs aged. The live yeast supplement induced significant changes in relative abundances of a few bacterial OTUs across time in the rumen samples, among which some involved in crucial rumen function, and favored establishment of Trichostomatia and Neocallimastigaceae eukaryotic families. The supplemented lambs also harbored greater abundances in Fibrobacter succinogenes after weaning. Microarray data indicated that key cellulase and hemicellulase encoding-genes were present from early age in the rumen and that in the Supplemented lambs, a greater proportion of hemicellulase genes was present. Moreover, a higher proportion of GH genes from ciliate protozoa and fungi was found in the rumen of those animals. This yeast combination improved microbial colonization in the maturing rumen, with a potentially more specialized ecosystem towards efficient fiber degradation, which suggests a possible positive impact on lamb gut development and digestive efficiency