利用攪拌式生物反應槽培養菌絲狀的米根黴,以葡萄糖為碳源,開發一種提高L型乳酸產量的醱酵方法。本文對於醱酵過程所控制的酸鹼度以及起始添加的硫銨濃度對於L型乳酸產量的影響,做詳細的研究。最適的條件是pH 4.3–4.4以及每升4克的硫銨添加量,醱酵進行36小時後,得到L型乳酸的最終濃度是每升104克,葡萄糖轉換成乳酸的轉化率是87%。重複批次醱酵,用每升3克的硫銨為氮源,最初的4槽得到L型乳酸的最終濃度是每升109克,葡萄糖轉換成乳酸的轉化率高達91%,每槽醱酵完成的時間是28小時。
A fermentation process for enhanced production of L(+)-lactic acid was developed. Rhizopus oryzae cultured with glucose as carbon source exhibited floc morphology in a stirred tank bioreactor. The effects of fermentation pH as well as the initial concentration of ammonium sulfate added to the culture medium on LA production were investigated. Optimal production of LA was achieved in the condition of pH 4.3 – 4.4 with initial concentration of AS at 4 g/L after 36 h of fermentation. The final concentration of LA was 104 g/L with a yield of 87%. Furthermore, the average concentration and the yield of lactic acid in the following four cycles of the 28-h repeated batch fermentation were up to 109 g/L and 91%, respectively, using 3 g/L of ammonium sulfate as nitrogen source.