利用天然纤维废弃物发酵生产L-乳酸的研究

Study on Fermentating Natural Fibers Waste to Product L-lactic Acid

为了降低L-乳酸的生产成本,更好的实现生物质秸秆的资源化,利用天然纤维素依次接种经离子注入诱变处理的木聚糖酶高产菌黑曲霉P602和米根霉RL6041高产菌进行固、液体二次发酵的方法,将其转化成用于工业生产的L-乳酸。结果表明:本实验条件下,未经过任何化学预处理的秸秆等物质接种黑曲霉P602进行固体发酵,产生的木聚糖酶活力为6 320 IU/g干(培养)基,纤维素酶活力为29 IU/g干基;加入100 mL水浸提后,产生的还原糖浓度为14.07 g/L,纤维物质糖化率为79.45%。取滤液接入米根霉RL6041进行液体发酵后,生成乳酸的量为7 g/L,糖酸转化率为47.6%,以(NH4)2SO4作为氮源时,最佳氮源浓度为3 g/L。

Fermentate on the natural fibers waste inoculated respectively with Aspergillus niger P602 and Rhizopus oryzae RL6041 was studied in order to produce L-lactic acid. Results showed that, during the solid fermentation of 7.5 g natural cellulose inoculated with Aspergillus niger P602, the produced xylanase activity was 6 320 IU/g dry medium and cellulase 29 IU/g dry medium. While the reducing sugar concentration and saccharification rate after 100 mL water added were 14.07 g/L and 79.45 % respectively. The L-lactic acid content and the conversion rate of sugar to acid is 7 g/L and 47.6 % during liquid fermentation of the filter inoculated with Rhizopus oryzae RL6041. The optimal concentration of nitrogen was 3 g/L when （NH4 ）2SO4 was used as nitrogen resource.