利用竹基纤维素为碳源生物转化L-乳酸的潜力研究

Study on potential of bioconversion of L-lactic acid using bamboo-based cellulose as carbon source

以竹材制浆厂备料工段产生的废弃竹屑为原料,采用蒸汽爆破预处理且提取半纤维素后的竹基纤维素为碳源,同时对预处理前后竹屑采用扫描电子显微镜&能谱仪和激光粒度分析仪进行表征;用分步水解发酵工艺,结合高效液相色谱对发酵L-乳酸工艺关键参数进行了分析,探究了该碳源生物转化L-乳酸的潜力。结果表明,蒸汽爆破预处理提高了原料酶解还原糖释放量,在总固体(total solids,TS)质量浓度140 g/L、酶添加量60 FPU/g、酶解54 h条件下糖化,总糖质量浓度可达31.19 g/L。将糖化液用于发酵试验,在起始糖质量浓度19.43 g/L,发酵初始pH 6.5、菌株接种量5%、发酵17 h条件下,L-乳酸质量浓度可达6.28 g/L,其糖酸转化率高达80.87%。综上,该实验为竹基纤维素的利用提供了高值化途径参考。

Using the waste bamboo sawdust produced in the material preparation section of bamboo pulping plant as raw materials,bamboo-based cellulose after steam explosion pretreatment and extraction of hemicelluloses was used as carbon source.The bamboo sawdust before and after pretreatment were characterized by scanning electron microscopy&energy dispersive spectrometer and laser particle size analyzer.The key parameters of the fermentation process of L-lactic acid were analyzed by step hydrolysis fermentation and high performance liquid chromatography,and the potential of bioconversion of L-lactic acid from the carbon source was investigated.Results showed that steam explosion pretreatment increased the release of reducing sugar from the raw material,and the total sugar concentration reached 31.19 g/L under the conditions of 140 g/L of total solid concentration,60 FPU/g of enzyme addition,and enzymatic hydrolysis for 54 h.The saccharification solution was used in the fermentation test.Under the conditions of initial sugar concentration of 19.43 g/L,initial pH 6.5,inoculation amount of 5%,and fermentation for 17 h,the L-lactic acid concentration could reach 6.28 g/L,and the saccharic acid conversion rate was as high as 80.87%.In conclusion,the experiment provides a reference for the utilization of bamboo-based cellulose.