Résumé
During extraction of starch from cassava, fibrous residue is a major waste released into the environment. Owing to the high starch content (60- 65% on dry weight basis) and organic matter of cassava fibrous residue (CFR), an attempt has been made to utilize it for the production of lactic acid (LA) in semi- solid state fermentation using Mann Rogassa Sharpe medium containing [5 % (wv-1)] CFR in lieu of glucose [2 % (wv-1)] as the carbon source. Response Surface Methodology (RSM) was used to evaluate the effect of main variables, i.e. incubation period, temperature and pH on LA production. The experimental results showed that the optimum incubation period, temperature and pH were 120 hr, 350C and 6.5, respectively. Maximum starch conversion by Lactobacillus plantarum MTCC 1407 to LA was 63.3%. The organism produced 29.86 g of (L+) LA from 60 g of starch present in 100 g of CFR. The LA production yield (i.e. mass LA produced mass starch present in CFR-1 x 100) was 49.76 %.