PDF(Pubmed)
Abstract：
Growing interest in renewable energy continues to motivate new work on microbial biohydrogen production and in particular utilizing Escherichia coli a well-studied, facultative anaerobe. Here we characterize, for the first time the H2 production rate and capacity, of E coli isolates from the 50 000th generation of the Long-Term Evolution Experiment. Under these reaction conditions, peak production rates near or above 5 mL per hour for 100 mL of lysogeny broth (LB media) was established for the ancestral strains and batch efficiencies between 0.15 and 0.22 mL H2 produced per 1 mL LB media were achieved. All 11 isolates studied, which had been aerobically cultured in minimal media since 1988, exhibited a decreased H2 production rate or capacity with many strains unable to grow under anaerobic conditions at all. The genomes of these strains have been sequenced and a preliminary analysis of the correlations between genotype and phenotype shows that mutations in gene ydjO are exclusively observed in the two isolates which produce H2, potentially suggesting a role for this gene in the maintenance of wild type metabolic pathways in the context of diverse mutational backgrounds. These results provide hints towards uncovering new genetic targets for the pursuit of bacterial strains with increased capacity for H2 production as well as a case study in speciation and the control of phenotypic switching.
摘要：
对可再生能源日益增长的兴趣继续激发微生物生物氢生产的新工作，特别是利用大肠杆菌，兼性厌氧菌。在这里我们描述，首次提高了H2的生产率和产能，来自长期进化实验第5000代的大肠杆菌分离株。在这些反应条件下,对于祖先菌株，建立了100mL溶生肉汤（LB培养基）每小时接近或高于5mL的峰值生产率，并实现了每1mLLB培养基产生的0.15至0.22mLH2的批次效率。研究的所有11个分离株，自1988年以来一直在基本培养基中进行需氧培养，其H2生产率或容量降低，许多菌株根本无法在厌氧条件下生长。已经对这些菌株的基因组进行了测序，并且对基因型和表型之间的相关性的初步分析表明，在产生H2的两个分离物中只能观察到基因ydjO的突变，这可能表明该基因在维持野生型中的作用。不同突变背景下的代谢途径。这些结果为寻找具有增加H2生产能力的细菌菌株以及物种形成和表型转换控制的案例研究提供了线索。
