Implications of the expression of Enterococcus faecalis citrate fermentation genes during infection

• Published in: PloS one 2018-10, Vol.13 (10), p.e0205787-e0205787
• Main Authors: Martino, Gabriela P, Perez, Cristian E, Magni, Christian, Blancato, Víctor S
• Format: Article
• Language: English
• Subjects: Acetolactate synthase; Animals; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biology and Life Sciences; Blood; Carboxy-Lyases - genetics; Carboxy-Lyases - metabolism; Care and treatment; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cheese; Chemical properties; Citric acid; Citric Acid - metabolism; Dairy products; Dehydrogenases; Disease Models, Animal; Enterococcal infections; Enterococcus faecalis; Enterococcus faecalis - genetics; Enterococcus faecalis - immunology; Enterococcus faecalis - metabolism; Enterococcus faecalis - pathogenicity; Enzymes; Fermentation; Fermentation - genetics; Fermentation - immunology; Food; Gene expression; Gene Expression Regulation, Bacterial; Genes; Genetic aspects; Genome, Bacterial - genetics; Genomes; Gram-Positive Bacterial Infections - immunology; Gram-Positive Bacterial Infections - microbiology; Hemolymph; Homeotherms; Humans; Infections; Insects; Intestinal microflora; Intestine; Larvae; Medicine and Health Sciences; Metabolic Networks and Pathways - genetics; Metabolism; Microbiota; Microorganisms; Moths - immunology; Moths - microbiology; Multigene Family - genetics; Opportunistic Infections - immunology; Opportunistic Infections - microbiology; Otolaryngology; Oxaloacetate decarboxylase; Pathogenicity; Pathogens; Physical Sciences; Preservation; Promoter Regions, Genetic - genetics; Research and analysis methods; Signal transduction; Strains (organisms); Urine; Whole Genome Sequencing
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0205787

Citrate is an ubiquitous compound in nature. However, citrate fermentation is present only in a few pathogenic or nonpathogenic microorganisms. The citrate fermentation pathway includes a citrate transporter, a citrate lyase complex, an oxaloacetate decarboxylase and a regulatory system. Enterococcus faecalis is commonly present in the gastro-intestinal microbiota of warm-blooded animals and insect guts. These bacteria can also cause infection and disease in immunocompromised individuals. In the present study, we performed whole genome analysis in Enterococcus strains finding that the complete citrate pathway is present in all of the E. faecalis strains isolated from such diverse habitats as animals, hospitals, water, milk, plants, insects, cheese, etc. These results indicate the importance of this metabolic preservation for persistence and growth of E. faecalis in different niches. We also analyzed the role of citrate metabolism in the E. faecalis pathogenicity. We found that an E. faecalis citrate fermentation-deficient strain was less pathogenic for Galleria mellonella larvae than the wild type. Furthermore, strains with deletions in the oxaloacetate decarboxylase subunits or in the α-acetolactate synthase resulted also less virulent than the wild type strain. We also observed that citrate promoters are induced in blood, urine and also in the hemolymph of G. mellonella. In addition, we showed that citrate fermentation allows E. faecalis to grow better in blood, urine and G. mellonella. The results presented here clearly indicate that citrate fermentation plays an important role in E. faecalis opportunistic pathogenic behavior.