玉米芯载体吸附法固定化米根霉发酵L-乳酸的工艺条件

Process Conditions for L-Lactic Acid Production by Corncob-immobilized Rhizopus oryzae

研究玉米芯作为部分替代碳源及载体固定化米根霉R-1发酵L-乳酸的工艺条件,考察玉米芯作为替代碳源的利用率及作为载体的添加比例和最佳粉碎粒度。研究表明:米根霉R-1以玉米芯为碳源,其利用率达14.9%;玉米芯作为部分替代碳源与葡萄糖混合发酵时最佳比例为1:4,此比例下葡萄糖对L-乳酸的转化率高达82.5%,较纯葡萄糖发酵提高了14.6%;玉米芯载体的最佳粉碎粒度为40目,此条件下米根霉R-1发酵混合碳源产酸达到34.68g/L,并形成直径为0.5～1.0mm具有连续发酵能力的固定化菌丝球,连续发酵6批,葡萄糖对L-乳酸的平均转化率为83.1%。由此得出,玉米芯可以作为良好的载体及原料直接发酵产L-乳酸。

The process conditions for L-lactic acid fermentation with immobilized Rhizopus oryzae R-1 using corncob as immobilization carrier and a partial substitute for carbon source were studied. The utilization rate of corncob as a carbon source substitute and its mass ratio to glucose and optimal grinding granularity were investigated. The utilization rate of corncob by Rhizopus oryzae R-1 was 14.9%, and the optimal mass ratio between corncob and glucose was 1：4, yielding a conversion rate of glucose into L-lactic acid was 82.5%, 14.6% higher than that obtained from pure glucose fermentation. A granularity of 40 mesh was found optimal for corncob powder, resulting in an L-lactic acid yield as high as 34.68 g/L in mixed carbon source fermentation and with immobilized mycelial pellets with excellent continuous fermentation performance and a diameter ranging from 0.5 to 1.0 mm. After sixth repeated fermentation, the average conversion of glucose into L-lactic acid was 83.1%. From these result, we conclude that corncob can be a good carrier and base material for the production of lactic acid.