一株厌氧发酵木糖产氢菌的分离鉴定及功能评价
发布时间：2018-12-10 19:53
【摘要】：氢能是一种理想的替代能源,具有安全、低耗、廉价、绿色等优点。木质纤维素是生物炼制过程中重要的原料,其结构稳定,难以被有效转化。木糖作为木质纤维素水解后的重要成分,只有转化为木酮糖后才能被微生物利用,而许多微生物不具有相关的酶类,使得木糖的转化效率低。目前绝大多数已知的利用木糖发酵产氢细菌中,产氢能力不能达到生产需求。本研究针对以上问题,以实验室富集的厌氧降解纤维素产甲烷菌系FSC为材料,通过厌氧亨盖特技术分离纯化了一株厌氧发酵木糖产氢细菌FSC-15,对其系统发育学地位、生理生化特征、产氢能力进行了分析。通过末端代谢产物抑制实验,研究了菌株对末端产物的耐受性;通过单因素实验和正交实验对其发酵木糖的最佳产氢条件进行了优化;解析了戊糖、己糖及混合糖对菌株生长和产氢代谢的影响;评价了菌株FSC-15对纤维素厌氧降解产甲烷菌系FSC水解滤纸和水稻秸秆产甲烷的影响。研究结果如下:(1)菌株FSC-15的16S rRNA序列与Clostridium dioils DSM 5431T(AJ458418)和Clostridium beijerinckii NCIMB 8052T(CP000721)相似性都为99.6%,但菌株FSC-15的生理特性与Clostridium beijerinckii NCIMB 8052T(CP000721)更接近。最佳生长温度为35℃-40℃,最适生长p H 7.5。菌株可以耐受初始浓度为1500 mg/L的乙酸,2000 mg/L的丁酸;当培养基中乙醇初始浓度为400mg/L时,菌体的生长和产氢分别降低了57.4%和61.2%;顶空氢分压为134.2 k Pa时,菌体的生长被抑制了19.8%。(2)单因素实验和正交实验结果表明,菌株FSC-15的最佳产氢条件为:YE 0.1 g/L,BBL 0.1g/L,NH4Cl 1g/L,Na HCO3 0.8 g/L,Fe3+75μmol/L,Ni2+5μmol/L,培养基初始p H 7.5,培养温度40℃。(3)混合糖发酵体系中,不仅菌株的生长延滞期显著缩短,生长速率加快,生物量显著提高,并且氢气产量更高。菌株FSC-15分别以木糖和葡萄糖作为底物时,生长速率没有明显差异,但是随着发酵时间继续延长,以木糖为底物的发酵体系中氢气产量比其他发酵体系中高。菌株利用木糖发酵的转化率为1.845 mol H2/mol木糖;以葡萄糖为底物进行发酵菌株的产氢效率为1.179mol H2/mol葡萄糖。(4)添加2%的菌株FSC-15后,厌氧降解纤维素产甲烷菌系FSC产氢速度明显加快,氢气产量提高41.8%。以秸秆为发酵底物时,加入菌株FSC-15的厌氧降解纤维素产甲烷菌系FSC产甲烷的速率显著提高,甲烷产量提高1倍。FSC和添加菌株FSC-15后的共培养体系相比,滤纸和秸秆的总降解率没有显著差异。添加菌株FSC-15后,菌系FSC中细菌和古菌的种类和丰度都有一定的变化。
[Abstract]:Hydrogen energy is an ideal alternative energy, with the advantages of safety, low consumption, cheap, green and so on. Lignocellulose is an important raw material in the process of biological refining, and its structure is stable and difficult to be effectively transformed. Xylose, as an important component of lignocellulose hydrolysis, can only be used by microorganisms after conversion to xylose. However, many microbes do not have related enzymes, which makes the conversion efficiency of xylose low. At present, most of the known hydrogen producing bacteria using xylose fermenting can not meet the production demand. In order to solve the above problems, a strain of anaerobic fermentative xylose hydrogen producing bacteria (FSC-15,) was isolated and purified from methanogenic cellulose-producing bacteria (FSC), which was enriched in laboratory, and its phylogenetic status was studied by anaerobic Hangate technique. Physiological and biochemical characteristics and hydrogen production capacity were analyzed. The tolerance of the strain to the end product was studied by the end metabolite inhibition test, and the optimum hydrogen production conditions of xylose fermentation were optimized by single factor experiment and orthogonal experiment. The effects of pentose, hexose and mixed sugar on the growth and hydrogen production of the strain were analyzed, and the effects of strain FSC-15 on cellulose anaerobic degradation methanogenic strain FSC hydrolysate filter paper and rice straw methanogenesis were evaluated. The results were as follows: (1) the similarity of 16s rRNA sequence of strain FSC-15 with Clostridium dioils DSM 5431T (AJ458418) and Clostridium beijerinckii NCIMB 8052T (CP000721) was 99.6T, but the physiological characteristics of FSC-15 were closer to Clostridium beijerinckii NCIMB 8052T (CP000721). The optimum growth temperature is 35 鈩，
本文编号：2371111
[Abstract]:Hydrogen energy is an ideal alternative energy, with the advantages of safety, low consumption, cheap, green and so on. Lignocellulose is an important raw material in the process of biological refining, and its structure is stable and difficult to be effectively transformed. Xylose, as an important component of lignocellulose hydrolysis, can only be used by microorganisms after conversion to xylose. However, many microbes do not have related enzymes, which makes the conversion efficiency of xylose low. At present, most of the known hydrogen producing bacteria using xylose fermenting can not meet the production demand. In order to solve the above problems, a strain of anaerobic fermentative xylose hydrogen producing bacteria (FSC-15,) was isolated and purified from methanogenic cellulose-producing bacteria (FSC), which was enriched in laboratory, and its phylogenetic status was studied by anaerobic Hangate technique. Physiological and biochemical characteristics and hydrogen production capacity were analyzed. The tolerance of the strain to the end product was studied by the end metabolite inhibition test, and the optimum hydrogen production conditions of xylose fermentation were optimized by single factor experiment and orthogonal experiment. The effects of pentose, hexose and mixed sugar on the growth and hydrogen production of the strain were analyzed, and the effects of strain FSC-15 on cellulose anaerobic degradation methanogenic strain FSC hydrolysate filter paper and rice straw methanogenesis were evaluated. The results were as follows: (1) the similarity of 16s rRNA sequence of strain FSC-15 with Clostridium dioils DSM 5431T (AJ458418) and Clostridium beijerinckii NCIMB 8052T (CP000721) was 99.6T, but the physiological characteristics of FSC-15 were closer to Clostridium beijerinckii NCIMB 8052T (CP000721). The optimum growth temperature is 35 鈩，
本文编号：2371111
本文链接：https://www.wllwen.com/kejilunwen/huaxuehuagong/2371111.html
