Research on L-lactic acid fermentation for hydrolysate of tilapia wastes with Lactobacillus

By hot water extraction method,we extracted the protein hydrolysate of tilapia wastes,which is used as a nitrogen source for L-lactic acid fermentation.Compared with yeast extract,we studied the growth of Lactobacillus bulgaricus,Streptococcus thermophilus and L.rhamnosus in fermentation medium of hydrolysate of tilapia wastes,and observed the yield of L-lactic acid.Results show that the 3 lactic acid bacteria grow better in 2 fermentation mediums and pH decreases obviously.The production of L-lactic acid varies with different lactic acid bacteria.The net yield of L-lactic acid is 3.38 g·L-1 after 10 h fermentation with L.rhamnosus in the fermentation medium of hydrolysate of tilapia wastes.The yield is considerable to that of the yeast extract.Therefore,the hydrolysate of tilapia wastes can be a substitute for yeast extract and is a low-cost nitrogen source for the yield of L-lactic acid.