Effect of nutrient supplements from food manufacturing waste on L-lactic acid production by Streptococcus bovis using fresh cassava roots in tofu liquid waste

To improve the production of L-lactic acid by Streptococcus bovis using an original medium of fresh cassava roots (FCR) in tofu liquid waste (TLW), three nutrient supplements, skim milk (SM), the residue of the yeast extract waste (YEW) from beer manufacturer and concentrated maguro waste (CMW) from fish manufacturing were independently added to the original medium (FCR-TLW). Maximum fermentation properties (fermented L-lactic acid concentration, productivity of L-lactic acid and specific growth rate) were obtained at about 2% w/w crude protein concentration in the original medium for three nutrient supplements. The highest fermentation properties were shown by CMW supplement, and they were comparable with those in the standard medium. The medium supplemented with 2% w/w crude protein concentration of CMW in the original medium (FCR-TLW-CMW2) clearly gave the greatest effects on L-lactic acid production.