Production of L-lactic acid with immobilized cells of Rhizopus oryzae on a novel matrix

A novel matrix was developed for fermentation to produce L-lactic acid by Rhizopus oryzae at shaker-level.Fungal mycelia were immobilized on the matrices to study the fermentation conditions and process stability.During the seed culture process,all the spores were adsorbed after only 5 h,biomass concentration was up to 6.8g/L after 24 h.Under optimized conditions using three matrices at 33 ℃ and 180 r/min with volume ratio of 20% by adding CaCO3 in time,L-lactic acid was obtained after 48 h fermentation with concentration of 50.00 g/L in 65.0% yield and the productivity was 1.0 g/(L·h).Compared with cell-free fermentation,the concentration of L-lactic acid,the yield and the productivity increased by 79%,250% and 150%,respectively,and the fermentation period decreased by 24 h.The process of immobilized fermentation showed good stability in seven repeated batches.