Production of L(+) lactic acid from cassava starch hydrolyzate by immobilized Lactobacillus delbrueckii

A process based on low cost production media was developed for fermentative production of L(+) lactic acid. Various process parameters were optimized for the production of L(+) lactic acid from cassava starch hydrolyzate-based medium by immobilized whole cells of Lactobacillus delbrueckii. The parameters considered for optimization were concentration of alginate and CaCl2, initial cell concentration, curing time, bead size and incubation time of fermentation. Reusability of immobilized cells up to six batches was observed without any decline in lactate production. Lactate yield for L. delbrueckii was 0.93 g lactic acid x g(-1) reducing sugar with a production rate of 0.33 g x l(-1) x h(-1). A column bioreactor packed with immobilized L. delbrueckii was run for three weeks in a continuous mode with a lactate yield of 0.75-0.95 g lactic acid x g(-1) reducing sugar with an average production rate of 0.48 g x l(-1) x h(-1). The study revealed that ago residues like cassava bagasse could be used as source material for developing a low cost technology for lactate production.