考察了两种不同的米根霉发酵生产L-乳酸的策略：一步发酵法（OSF）和传统乳酸发酵（CF）对L-乳酸合成的影响。将孢子液直接接入到装有不同氮源，不同初始蛋白胨浓度的发酵培养基中，控制不同菌体密度进行一步发酵合成L-乳酸。与CF相比，OSF策略能极大的降低米根霉产酸过程的延滞期，同时提高米根霉合成L-乳酸的生产强度。然而，一步发酵法中的qp 值极大地低于传统发酵。基于动力学参数μ, qs 和 qp的分析，优化了米根霉一步发酵法合成L-乳酸的策略。在该策略条件下，产酸阶段，乳酸的生产强度达到了4.62 g/(l·h)，比传统发酵提高了288%。更重要的是，qp值和糖酸转化率并未降低。该策略实现了L-乳酸高效的积累，是一种利用米根霉发酵生产L-乳酸的方便、经济的方法。
In this study, lactic acid fermentation by R.oryzae was investigated using the two different fermentation strategies of one-step fermentation (OSF) and conventional fermentation (CF). The lactate production medium, which included different nitrogen sources, different peptone concentration, was inoculated directly from the spore suspension. The different cell density was controlled in the fermentation. Compared to CF, OSF reduced the demurrage of the production process and increased the production of lactic acid. However, the unit biomass utilization rate was significantly lower than during CF. Based on analysis of μ, qs and qp, a novel modified OSF strategy was proposed. This strategy aimed to achieve a high final concentration of lactic acid, and a high unit biomass utilization rate by R.oryzae. In this strategy, the maximum lactic acid concentration and productivity of the lactic acid production stage reached 158 g/l and 5.45 g/(l·h), which were177 % and 366 % higher, respectively, than the best results from CF. Importantly, the qp and yield did not decrease. This strategy is a convenient and economical method for L-lactic acid fermentation by R.oryzae.
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