Effect of different yeasts on Selenomonas ruminantium utilizing lactate In vitro

The objective of this study was to determine the effects of six yeast (Saccharomyces cerivisiae, Candida tropicalis, Pichia burtonii, Candida utilis, Rhodothece glutinis, Geotrichum candidum) on lactate utilization by the predominant ruminal bacterium Selenomonas ruminantium (S. ruminantium). Four different concentration of these yeasts (6g/l, 8g/l, 109/l, l2g/l) and non-yeast control group were set. The pH and the concentration of lactate, acetate, and propionate in the culture fluids were detected at 12h after adding these different yeasts. The results indicated that lactate uptake can be stimulated by all the six yeast at all of six concentration. When the added yeast concentration was 109/l-12g/1, lactate uptake by S. ruminantium was achieved the greatest promote. The six yeasts also increased the production of acetate and propionate and the ratio of propionate to acetate. Among the six yeasts, Candida tropicalis, Geotrichum candidum and Candida utilis affecting on above indexes were better than Saccharomyces cervisiae, Pichia burtonii and Rhodothece glutinis.