Hyperlactate production is related to disorders of the large intestine such as inflammatory bowel diseases. Lactate, an intermediate in hindgut fermentation, is metabolized to SCFA. Megasphaera elsdenii can convert lactate to butyrate, a physiologically important organic acid for the hindgut mucosa. This experiment was conducted to determine whether M. elsdenii normalizes hyperlactate production and stimulates butyrate production in the rat large intestine. Specific pathogen-free Sprague-Dawley male rats (n = 12) were fed a fructooligosaccharide (FOS)-supplemented (100 g/kg), semipurified diet to induce lactate production. Lactate excretion in all rats was >30 mmol/kg fresh feces on d 2 of FOS-feeding. The rats were divided into two groups on the morning of d 4. One group (n = 5) was dosed orally with M. elsdenii JCM1772T (1.3 x 10(13) cells) for 3 d. The other group was treated with a vehicle solution. Fecal lactate was significantly lower in rats administered M. elsdenii than in controls. An increase in fecal butyrate compensated for the decrease in lactate. The number of cecal epithelial cells was greater in rats administered M. elsdenii than in controls. M. elsdenii has the potential to normalize hyperlactate accumulation in the large intestine, and lactate-utilizing butyrate producers may be useful probiotics when hyperlactate fermentation in the large intestine is a problem.

In this study, we examined the potential of Megasphaera elsdenii as a probiotic agent in combination with sodium gluconate. We also examined the combination of M. elsdenii with probiotic lactic acid bacteria (LAB), Lactobacillus acidophilus, to enhance butyrate production in the large intestine using a pig cecal in vitro model under the presence of sodium gluconate. Compared to the uninoculated control culture (with only diluted cecal digesta), the addition of M. elsdenii and LAB to the culture stimulated significantly the production of n-butyrate (60% increase) and n-valerate (50% increase) after 24 h incubation. n-Butyrate is regarded as the most important short-chain fatty acid in the large intestine because it stimulates the proliferation of epithelial cells, mucus release and water and mineral absorption. Therefore, lactate-utilizing butyrate producers such as M. elsdenii play a significant role in supporting the health-beneficial effects of lactogenic prebiotics and probiotics LAB. The potential of M. elsdenii as a probiotic was also suggested.

Fecal malodor is an acute environmental issue to be solved for the intensive animal agriculture in Japan. Among these substances volatile sulfur such as hydrogen sulfide (HS), methanethiol, and dimethyl sulfide, and dimethyl disulfide are the ones most strictly controlled in the Japanese national regulations. In this experiment, we have screened a range of standard strains of chemoheterotrophic bacteria and of the presently isolated soil bacteria for their capacity to decompose HS. We have demonstrated that Comamonas testosteroni JCM5832 T and our isolate Bacillus sp. had a potential to reduce malodor when applied to the pig feces.