L-lactic acid production from Lactobacillus casei by solid state fermentation using rice straw

In order to make full use of rice straw (RS) produced at large quantity in China and to reduce the production cost of L-lactic acid, attempts were made to utilize the hydrolysate of RS as sole carbon source and the lignocellulose as inert support for producing L-lactic acid using solid state fermentation (SSF). The pretreated rice straw was enzymatically hydro- lyzed by cellulase, and the hydrolyzate, containing reducing sugars supplemented with a minimum of (NH4)2SO4, MnSO4, and yeast extract, was used as moistening agent to impregnate 5g of RS, which was used as the inert support for SSF. Maximum L-lactic acid production of 3.467g per 5g of support was obtained at 37 oC, using Lactobacillus casei as inoculum, after 5 days of fermentation with optimized process parameters such as 72% moisture content, 4g per 5g support of reducing sugars, 2.5ml per 5g support of inoculum size, 3g per 5g support of CaCO3, and pH 6.5.