Lactate-utilizing bacteria, isolated from human feces, that produce butyrate as a major fermentation product

• Published in: Applied and Environmental Microbiology Vol. 70; no. 10; pp. 5810 - 5817
• Main Authors: Duncan, S.H, Louis, P, Flint, H.J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.10.2004
• Subjects: Acids; Adult; Anaerostipes cacae; Anaerostipes caccae; Bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; Bacteria - metabolism; Bacteriology; Base Sequence; Bifidobacterium adolescentis; Biological and medical sciences; biosynthesis; Butyrates; Butyrates - metabolism; butyric acid; Carbon; Carbon - metabolism; chemistry; classification; colon; DNA, Bacterial; DNA, Bacterial - genetics; Electron Transport; Energy sources; Eubacterium; Eubacterium - classification; Eubacterium - genetics; Eubacterium - isolation & purification; Eubacterium - metabolism; Eubacterium hallii; Eubacterium rectale; Faecalibacterium prausnitzii; Feces; Feces - microbiology; Female; Fermentation; Fundamental and applied biological sciences. Psychology; genetics; Humans; intestinal microorganisms; isolation & purification; lactic acid; Lactic Acid - chemistry; Lactic Acid - metabolism; metabolism; Metabolism. Enzymes; Microbial Ecology; microbial physiology; Microbiology; Models, Biological; Phylogeny; RNA, Bacterial; RNA, Bacterial - genetics; RNA, Ribosomal, 16S; RNA, Ribosomal, 16S - genetics; Starch; Stereoisomerism; Human; Lactates; Bacteria; Colon; Feces; Fermentation; Butyrate
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.70.10.5810-5817.2004

The microbial community of the human colon contains many bacteria that produce lactic acid, but lactate is normally detected only at low concentrations (<5 mM) in feces from healthy individuals. It is not clear, however, which bacteria are mainly responsible for lactate utilization in the human colon. Here, bacteria able to utilize lactate and produce butyrate were identified among isolates obtained from 10(-8) dilutions of fecal samples from five different subjects. Out of nine such strains identified, four were found to be related to Eubacterium hallii and two to Anaerostipes caccae, while the remaining three represent a new species within clostridial cluster XIVa based on their 16S rRNA sequences. Significant ability to utilize lactate was not detected in the butyrate-producing species Roseburia intestinalis, Eubacterium rectale, or Faecalibacterium prausnitzii. Whereas E. hallii and A. caccae strains used both D- and L-lactate, the remaining strains used only the D form. Addition of glucose to batch cultures prevented lactate utilization until the glucose became exhausted. However, when two E. hallii strains and one A. caccae strain were grown in separate cocultures with a starch-utilizing Bifidobacterium adolescentis isolate, with starch as the carbohydrate energy source, the L-lactate produced by B. adolescentis became undetectable and butyrate was formed. Such cross-feeding may help to explain the reported butyrogenic effect of certain dietary substrates, including resistant starch. The abundance of E. hallii in particular in the colonic ecosystem suggests that these bacteria play important roles in preventing lactate accumulation.