Lactate-Utilizing Bacteria, Isolated from Human Feces, That Produce Butyrate as a Major Fermentation Product

Abstract

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 starchutilizing 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.

Production of Butyrate from Lactate by a Newly Isolated Clostridium sp. BPY5

“…Based on 16S rRNA sequencing, the isolate belongs to Clostridium XIVa cluster. This cluster represents one of the most abundant bacterial groups in human feces and plays a significant role in lactate metabolism [7]. However, substantial production of butyrate from lactate is not previously reported among Clostridium clusters XIVa species.…”

“…Generally, lactate can be converted to low molecular VFAs (C 2 -C 4 ) by many anaerobic microbes [7,9,15] and even high molecular VFAs (C 5 -C 6 ) by some specific species [8]. In the case of BPY5, lactate was converted exclusively to butyrate.…”

“…in this study, given that Clostridium cluster XIVa represents a suprageneric or family group [25], the exact taxonomic position of strain BPY5 may be changed in accordance with further progress in the taxonomic study of Clostridium cluster XIVa. Lactic acid is produced by many of the microorganisms that colonize the digestive tract of animals and humans [7]. High concentrations of lactate are usually associated with short bowel syndrome and ulcerative colitis and can lead to neurotoxicity and cardiac arrhythmia [26].…”

Cryopreservation of artificial gut microbiota produced with in vitro fermentation technology

“…We reported similar increases for batch fermentation of effluents derived from IFT mimicking healthy elderly colonic microbiota (Fekry et al ., 2016). The competitiveness of E. hallii in batch fermentation could be due to its ability to feed on lactate and acetate (Duncan et al ., 2004; Belenguer et al ., 2006). Because growth was not impacted after cryopreservation, our results also suggest that E. hallii is highly resistant against damage caused by freezing.…”

Increased rectal microbial richness is associated with the presence of colorectal adenomas in humans

“…Lactobacillus is considered a beneficial microbe (Gibson and Roberfroid, 1995;Duncan et al, 2004) with relatively low abundance in the gut (Eckburg et al, 2005). We propose that Lactobacillus spp.…”