Abstract:
Production of lactic acid from lignocellulosic biomass is becoming more popular as a way to solve the problem associated
with frst-generation biomass. In the present study, the optimum fermentation parameters for maximum lactic acid produc tion from khat waste biomass by using immobilized Lactobacillus plantarum were investigated. The efect of immobilizing
the cell on the yield of lactic acid has been investigated, and the yield obtained from immobilized Lactobacillus plantarum
cell is 32.78% higher than the free cells. The efects of three process parameters (incubation temperature, pH, and incubation
time) on lactic acid yield were investigated. The optimization of lactic acid yield and fermentation parameters was done via
response surface methodology with a central composite design. Based on the analysis, the optimum fermentation parameters
were found to be incubation temperature of 42.3 °C, incubation time of 40.0 h, and pH of 6.18. Under these conditions, the
maximum lactic acid yield obtained was 23.05 g/L. The experimental yield of lactic acid (22.98±0.10 g/L) is in smooth
agreement with the predicted one (23.05 g/L), indicating the ftness of the quadratic model used. Generally, the fndings
of the study suggest that utilization of khat waste as a potential carbohydrate source and immobilization of Lactobacillus
plantarum cells for lactic acid production is worthful.
