Selection of Saccharomyces cerevisiae strains for use as a microbial feed additive

Saccharomyces cerevisiae ITCCF 2094, NCIM 3052, 1031, 1032, NCDC 42, 45, 47 , 49 and 50 were screened for their tolerance to pH2.0-7.0, various concent rations (0.00, 0.10, 0.25 0.50 and 1.0%) of a mixture of acetic, propionic and butyric acids (70:20:10), and bile salts (0.00, 0.30, 0.60 and 0.90%). Low pH (2.0-4.0) and addition of organic acids or bile salts in the medium inhibited the growth of all the strains tested, bur the percentage of inhib ition was variable in the different strains of yeast. Two of the strains sh oeing maximum tolerance, 42 and 49, were further tested for in vitro dry ma tter degradability (IVDMD) using green berseem, wheat straw and oat hay as substrates. Saccharomyces cerevisiae 49 enhanced the IVDMD of berseem and w heat straw whereas S. cerevisiae 42 was ineffective. Based on the results o f the present experiment, S. cerevisiae NCDC 49 can be considered as the be st strain which might tolerate the adverse conditions in the gastrointestin al tract when used as a live microbial feed supplement in the diet of the a nimals.