Lactate is mainly fermented to butyrate by human intestinal microfloras but inter-individual variation is evident

Abstract

Aim: To assess the role of lactate as a precursor for butyrate biosynthesis in human colonic microflora. Methods and Results: Three human faecal microfloras were incubated in vitro with media supplemented with 30 mmol l )1 unenriched or 13 C-enriched lactate. Lactate metabolism and short-chain fatty acid (SCFA) production were quantified. Lactate conversion to butyrate was investigated by gas chromatography-mass spectrometry and the pathways involved were identified by 13 C nuclear magnetic resonance spectroscopy. All human faecal microfloras rapidly and completely fermented lactate, yielding approx. 19 mmol l )1 total SCFAs. However, the SCFA composition varied markedly between microfloras. Butyrate was the main end-product for two microfloras but not for the third (60 and 61% vs 27% of the net concentration of SCFA produced respectively). The latter was typified by its ability to produce propionate as a major product (37%), and valerate (3%). 13 C-Labelling showed that butyrate was produced through the acetyl-CoA pathway and that the three microfloras possessed significant differences in their metabolic pathways for lactate consumption. Conclusions: In contrast to the ruminal microflora, the human intestinal microflora can utilize both D D-and L L-lactate as precursors for butyrate synthesis. Inter-individual variation is found. Significance and Impact of the Study: This study suggests that the butyrogenic capability of colonic prebiotics could be related to lactate availability. These findings will direct the development of selection strategies for the isolation of new butyrate-producing bacteria among the lactate-utilizing bacteria present in the human intestinal microfloras.

Phylogenetic distribution of three pathways for propionate production within the human gut microbiota

“…This pathway is also present in the rumen bacterium Megasphaera elsdenii within the Negativicutes (Hino and Kuroda, 1993), which produces butyrate during growth on glucose, but propionate during growth on lactate (Hino and Kuroda, 1993). It is possible to distinguish the succinate pathway from the acrylate pathway by incubation with stable isotope-labelled substrates (Bourriaud et al, 2005;Morrison et al, 2006). Finally, several different bacteria are known to produce 1,2-propanediol from deoxy sugars such as fucose and rhamnose, or via different pathways from dihydroxyacetonephosphate or lactate (Saxena et al, 2010).…”

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

“…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.…”

Dietary supplementation with β-glucan enriched oat bran increases faecal concentration of carboxylic acids in healthy subjects

“…Lactic acid can be further metabolized for example by propionibacteria to propionic acid and acetic acid (Macfarlane and Cummings, 1991). Furthermore, butyric acid can be produced from lactic acid through the acetyl-CoA pathway (Bourriaud et al, 2005). A decreased lactate level may thus reflect decreased formation as well as increased metabolism.…”