Continuous fermentation of clarified corn stover hydrolysate for the production of lactic acid at high yield and productivity
Continuous fermentation of clarified corn stover hydrolysate for the production of lactic acid at high yield and productivity
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DOI：
10.1016/j.bej.2016.01.012
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发表时间：
2016-05-15
影响因子：
3.9
通讯作者：
Srinivas, Keerthi
中科院分区：
文献类型：
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作者：
Ahring, Birgitte K.;Traverso, Joseph J.;Srinivas, Keerthi
对木质纤维素生物质生产乳酸进行了大量的研究。然而，这些研究中的大多数已被限制为使用纯培养物的生产，其需要在高无菌性和清洁糖原料下操作的昂贵反应器系统，从而转化为高的总加工成本。我们生产了一个稳定的乳酸生产文化，通过延长非无菌培养的凝结芽孢杆菌菌株（AD菌株），在我们的实验室中分离的嗜热沼气反应器。该培养物以与纯培养物类似的方式以完全和一致的方式生产乳酸作为唯一的发酵产物。在本研究中，我们评估了pH值和停留时间的影响，连续发酵澄清玉米秸秆水解液乳酸生产使用我们的稳定文化。将连续发酵罐设置在50 ℃，pH条件为5.5至6.0，停留时间为6至96小时。在pH 6.0和停留时间为6 h时，乳酸产率最大，为3.69 g/L/h，乳酸产率为0.95 g/g生物质糖。结果发现，生产率随着停留时间的减少而增加，但pH或停留时间对总乳酸产率没有显着影响。发现最大乳酸产率在pH 6.0和24小时的停留时间下为1.086 g/g生物质糖，表明培养物消耗除用于产率计算的常规C5（木糖）和C6（葡萄糖）之外的糖。我们的研究显示了以低运营成本高速率生产乳酸的潜力。(C)2016爱思唯尔B. V.保留所有权利。
Significant amount of research has been done on the production of lactic acid from lignocellulosic biomass. However, most of these studies have been restricted to production using pure cultures that require expensive reactor systems operating with high sterility and clean sugar feedstocks translating into high overall processing costs. We produced a stable lactic acid producing culture through extended non-sterile cultivation of a strain of Bacillus coagulans (strain AD) isolated in our laboratory from a thermophilic biogas reactor. The culture operated with complete and consistent production of lactic acid as the only fermentation product in a similar manner to that of the pure culture. In the present study, we assessed the effect of pH and residence times on the continuous fermentation of clarified corn stover hydrolysate for lactic acid production using our stable culture. A continuous fermenter was set up at 50 degrees C with pH conditions ranging from 5.5 to 6.0 and residence times ranging from 6 to 96 h. Maximum lactic acid productivity of 3.69 g/L/h was found at pH 6.0 and residence time of 6 h with a lactic acid yield of 0.95 g/g biomass sugars. It was found that the productivity increased with decrease in residence time but there was no significant effect of pH or residence time on the overall lactic acid yield. Maximum lactic acid yield was found to be 1.086 g/g biomass sugars at pH 6.0 and a residence time of 24 h showing that the culture consumed sugars other than the conventional C5 (xylose) and C6 (glucose) that was used for the yield calculation. Our study shows the potential for high-rate production of lactic acid with low operational costs. (C) 2016 Elsevier B.V. All rights reserved.