Transcriptomic analysis reveals specific metabolic pathways of enterohemorrhagic Escherichia coli O157:H7 in bovine digestive contents

• Published in: BMC genomics 2018-10, Vol.19 (1), p.766-766, Article 766
• Main Authors: Segura, Audrey, Bertoni, Marine, Auffret, Pauline, Klopp, Christophe, Bouchez, Olivier, Genthon, Clémence, Durand, Alexandra, Bertin, Yolande, Forano, Evelyne
• Format: Article
• Language: English
• Subjects: Animal genetics; Animals; Assimilation; Bacteria; Bioinformatics; Bovidae; Bovine gastrointestinal tract; Carbohydrates; Carbon; Carbon sources; Cattle; Cattle diseases; Cattle Diseases - microbiology; Causes of; Colonization; Computer Science; E coli; Ecosystems; EHEC O157:H7; Energy Metabolism - genetics; Escherichia coli; Escherichia coli O157 - genetics; Escherichia coli O157 - metabolism; Ethanolamine; Flexibility; Fucose; Gastrointestinal system; Gastrointestinal tract; Gastrointestinal Tract - microbiology; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Gene sequencing; Genes; Genetic aspects; Genetics; Genomes; Genomics; Glycerol; Health aspects; Hemolytic-Uremic Syndrome - veterinary; Host-bacteria relationships; Incubation; Infections; Life Sciences; Maltose; Mammals; Mannitol; Mathematics; Metabolic Networks and Pathways; Metabolic pathways; Metabolism; Microbial Viability; Microbiota; Mucus; Mucus-derived carbohydrates; Multiplication; Multiplication & division; Nitrogen; Nitrogen sources; Nutrients; Nutrition; Pathogens; Physiology; Rectum; Redundancy; Respiration; Ribonucleic acid; Ribose; RNA; RNA-seq; Rumen; Serine; Small intestine; Substrates; Survival; Transcription activation; Transcription factors; Transcriptome; Xylose
• ISSN: 1471-2164; 1471-2164
• DOI: 10.1186/s12864-018-5167-y

The cattle gastrointestinal tract (GIT) is the main enterohemorrhagic Escherichia coli (EHEC) reservoir. In order to identify nutrients required for the survival or multiplication of EHEC in the bovine GIT, we compared the transcriptomes of the EHEC O157:H7 reference strain EDL933 cultured in vitro in bovine digestive contents (DCs) (rumen, small intestine and rectum) using RNA-sequencing. Gene expression profiles showed that EHEC EDL933 activated common but also specific metabolic pathways to survive in the different bovine DCs. Mucus-derived carbohydrates seem important in EHEC nutrition in posterior DCs (small intestine and rectum) but not in rumen content. Additional carbohydrates (xylose, ribose, mannitol, galactitol) as well as gluconeogenic substrates (aspartate, serine, glycerol) would also be used by EHEC as carbon and/or nitrogen sources all along the bovine GIT including the rumen. However, xylose, GalNac, ribose and fucose transport and/or assimilation encoding genes were over-expressed during incubation in rectum content compared with rumen and intestine contents, and genes coding for maltose transport were only induced in rectum. This suggests a role for these carbohydrates in the colonization of the cattle rectum, considered as the major site for EHEC multiplication. In contrast, the transcription of the genes associated with the assimilation of ethanolamine, an important nitrogen source for EHEC, was poorly induced in EHEC growing in rectum content, suggesting that ethanolamine is mainly assimilated in the cattle rumen and small intestine. Respiratory flexibility would also be required for EHEC survival because of the redundancy of dehydrogenases and reductases simultaneously induced in the bovine DCs, probably in response to the availability of electron donors and acceptors. EHEC EDL933 showed a high flexibility in the activation of genes involved in respiratory pathways and assimilation of carbon and nitrogen sources, most of them from animal origin. This may allow the bacterium to adapt and survive in the various bovine GIT compartments. Obtaining a better understanding of EHEC physiology in bovine GIT is a key step to ultimately propose strategies to limit EHEC carriage and shedding by cattle.