Production of L-Lactic Acid from Corn Starch Hydrolysate by Immobilized Rhizopus oryzae on a New Asterisk-Shaped Matrix
A new asterisk-shaped matrix composed of stainless-steel mesh and cotton cloth was emloyed for immobilizing Rhizopus oryzae As3.3462 cells. The ability of the immobilized cells to produce L-lactic acid was evaluated by using corn starch hydrolysate as carbon sources. The cells were attached onto the matrix with nearly 100% efficiency within 5 h and demonstrated asterisk mycelia morphology rather than a pellet-like cake as exhibited by the free-cells. Consequently, the immobilization fermentation resulted in higher L-lactic acid concentration (82.79 g.L-1 vs 48.23 g.L-1) within a shorter time (60 h vs 72 h) than the free fermentation. In addition, the stability of the immobilized cells for a long-term fermentation was investigated in 8 consecutive fermentation batches for 30 days. The maximum variation of L-lactic acid concentration among these batches was less than 10%. These results imply that the proposed asterisk matrix is good for Rhizopus oryzae immobilization and provids a simple and feasible fermentation strategy for L-lactic acid production.
Weiguo Pan, Jianxing Ren and Yongguang Li
X. Chen et al., "Production of L-Lactic Acid from Corn Starch Hydrolysate by Immobilized Rhizopus oryzae on a New Asterisk-Shaped Matrix", Advanced Materials Research, Vols. 347-353, pp. 1193-1197, 2012