EFFECT OF LACTIC ACID ON ENTODINIUM CAUDATUM MONOCULTURE

This experiment was carried out to evaluate the effect of lactic acid on Entodinium caudatum monoculture in vitro. After thawing, E. caudatum was grown at 39o C under anaerobic condition to yield 105 . Four groups were established by inclusion of 0, 0.5, 1, and 2 mM DL-lactic acid (Fluka Chemica, 69775). E. caudatum started to selectively use lactate to maintain 1.2 mM concentration at the highest lactic acid concentration. Increasing lactic acid concentration in medium was associated with reduction in pH (P<0.0001) and increase in total volatile fatty acids (P<0.0001), but no change in ammonia concentration. There was a reduction in acetate (P<0.04) and increases in propionate (P<0.02) and butyrate (P<0.0001) proportions as lactic acid concentration in medium increased. Stoichiometrically calculated gas production and CH4 amount increased accordingly with total volatile fatty acid production. In conclusion, E. caudatum grows to utilize lactate in case of acidosis.