Production of L-Lactic Acid from Raw Cassava Starch by Rhizopus oryzae NRRL 395

Abstract

Lactic acid, which is commonly used in food, chemical and pharmaceutical industries, has recently received much attention for the production of biodegradable plastic. L-lactic acid production by Rhizopus oryzae NRRL 395 from raw cassava starch as a sole carbon source was studied. The optimum production medium was as follows (g/l) : raw cassava starch, 120; (NH₄) ₂ SO₄, 3.0; KH₂PO₄, 1.0; MgSO₄.7H₂O, 0.25; ZnSO₄.7H₂O, 0.04; pH 6.0. The maximum L-lactic acid production in shake flasks was 68.32 g/l on day 5 with the shaking speed of 200 rpm at 30°C. L – lactic acid yield and productivity were 0.59 g/g substrate and 0.57 g/lh, respectively. In a jar fermentor, the maximum L-lactic acid production was 54.62 g/l on day 4 of cultivation at the agitation speed of 400 rpm and the aeration rate of 1.5 vvm. The L – lactic acid yield was 0.49 g/g substrate with the productivity of 0.56 g/lh.