兼性厌氧芽胞杆菌TSH1丁醇代谢途径中关键酶的检测

Key enzymes in butanol fermentation by a facultative anaerobe Bacillus sp. TSH1

摘要:

传统的丁醇生产菌均严格厌氧，本实验室分离了一株兼性厌氧的芽胞杆菌TSH1 (Bacillus sp. TSH1)，丁醇梭菌具有相似的丁醇代谢通路及产物。通过研究乙醇和丁醇生成途径中关键酶的活性，分析乙醇脱氢酶、丁醇脱氢酶及丁醛脱氢酶的活性变化与产物生成的关系。结果表明，在发酵初期，3种酶的活性均迅速升高并在21 h前达到最大值，丁醇、乙醇浓度也逐渐增加，乙醇脱氢酶在12 h酶活达到最大值0.054 U/mg，丁醛脱氢酶在21 h酶活达到最大值0.035 U/mg，丁醇脱氢酶则在15 h酶活达到最大值0.055 U/mg。24 h后，3种酶活均开始下降，并维持在较低水平，而这段时间内产物浓度仍持续增长直至发酵结束。研究结果深化了对微生物丁醇代谢机理的认识，并为进一步研究芽胞杆菌丁醇代谢途径提供参考。

Abstract:

Bacillus sp. TSH1 is a butanol-producing microorganism newly isolated in our laboratory; it can grow and ferment under facultative anaerobic conditions, while sharing similar fermentation pathways and products with Clostridium acetobutylicum. To illustrate the relationships between the products and the enzyme activities in Bacillus sp. TSH1, key butanol- and ethanol-forming enzymes were studied, including butyraldehyde dehydrogenase, butanol dehydrogenase and alcohol dehydrogenase. The activities of the three enzymes increased rapidly after the initiation of fermentation. Activities of three enzymes peaked before 21 h, and simultaneously, product concentrations also began to increase gradually. The maximum activity of alcohol dehydrogenase was 0.054 U/mg at 12 h, butyraldehyde dehydrogenase 0.035 U/mg at 21 h and butanol dehydrogenase 0.055 U/mg at 15 h. The enzyme activities then decreased, but remained constant at a low level after 24 h, while the concentrations of butanol, acetone, and ethanol continued increasing until the end of the fermentation. The results will attribute to the understanding of the butanol metabolic mechanism, and provide a reference for further study of a facultative Bacillus metabolic pathway.