Lal Sadhana, Levin David B
Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, Canada, R3T 5V6.
Adv Biochem Eng Biotechnol. 2016;156:79-112. doi: 10.1007/10_2015_5007.
Microbial production of fuels such as ethanol, butanol, hydrogen (H), and methane (CH) from waste biomass has the potential to provide sustainable energy systems that can displace fossil fuel consumption. Screening for microbial diversity and genome sequencing of a wide-range of microorganisms can identify organisms with natural abilities to synthesize these alternative fuels and/or other biotechnological applications. Clostridium species are the most widely studied strict anaerobes capable of fermentative synthesis of ethanol, butanol, or hydrogen directly from waste biomass. Clostridium termitidis CT1112 is a mesophilic, cellulolytic species capable of direct cellulose fermentation to ethanol and organic acids, with concomitant synthesis of H and CO. On the basis of 16S ribosomal RNA (rRNA) and chaperonin 60 (cpn60) gene sequence data, phylogenetic analyses revealed a close relationship between C. termitidis and C. cellobioparum. Comparative bioinformatic analyses of the C. termitidis genome with 18 cellulolytic and 10 non-cellulolytic Clostridium species confirmed this relationship, and further revealed that the majority of core metabolic pathway genes in C. termitidis and C. cellobioparum share more than 90% amino acid sequence identity. The gene loci and corresponding amino acid sequences of the encoded enzymes for each pathway were correlated by percentage identity, higher score (better alignment), and lowest e-value (most significant "hit"). In addition, the function of each enzyme was proposed by conserved domain analysis. In this chapter we discuss the comparative analysis of metabolic pathways involved in synthesis of various useful products by cellulolytic and non-cellulolytic biofuel and solvent producing Clostridium species. This study has generated valuable information concerning the core metabolism genes and pathways of C. termitidis CT1112, which is helpful in developing metabolic engineering strategies to enhance its natural capacity for better industrial applications.
利用废弃生物质通过微生物生产乙醇、丁醇、氢气（H）和甲烷（CH）等燃料，有潜力提供可持续能源系统，以替代化石燃料消耗。对多种微生物进行微生物多样性筛选和基因组测序，可以识别出具有合成这些替代燃料天然能力的生物体和/或其他生物技术应用。梭菌属是研究最广泛的严格厌氧菌，能够直接从废弃生物质中发酵合成乙醇、丁醇或氢气。白蚁梭菌CT1112是一种嗜温性、纤维素分解菌，能够将纤维素直接发酵为乙醇和有机酸，并同时合成H和CO。基于16S核糖体RNA（rRNA）和伴侣蛋白60（cpn60）基因序列数据的系统发育分析表明，白蚁梭菌与纤维二糖梭菌关系密切。对白蚁梭菌基因组与18种纤维素分解梭菌和10种非纤维素分解梭菌进行比较生物信息学分析，证实了这种关系，并进一步表明，白蚁梭菌和纤维二糖梭菌中大多数核心代谢途径基因的氨基酸序列同一性超过90%。通过同一性百分比、更高得分（更好比对）和最低期望值（最显著“命中”），将每个途径的基因座和编码酶的相应氨基酸序列进行关联。此外，通过保守结构域分析对每种酶的功能进行了预测。在本章中，我们讨论了纤维素分解和非纤维素分解生物燃料及溶剂生产梭菌属物种合成各种有用产物所涉及的代谢途径的比较分析。这项研究已经获得了有关白蚁梭菌CT1112核心代谢基因和途径的有价值信息，这有助于制定代谢工程策略，以增强其天然能力，实现更好的工业应用。
