Patil Yogita, Junghare Madan, Müller Nicolai
Department of Biology, Microbial Ecology, University of Konstanz, Konstanz, D-78457, Germany.
Konstanz Research School of Chemical Biology, University of Konstanz, Konstanz, D-78457, Germany.
Microb Biotechnol. 2017 Jan;10(1):203-217. doi: 10.1111/1751-7915.12484. Epub 2016 Dec 22.
Growth of biodiesel industries resulted in increased coproduction of crude glycerol which is therefore becoming a waste product instead of a valuable 'coproduct'. Glycerol can be used for the production of valuable chemicals, e.g. biofuels, to reduce glycerol waste disposal. In this study, a novel bacterial strain is described which converts glycerol mainly to ethanol and hydrogen with very little amounts of acetate, formate and 1,2-propanediol as coproducts. The bacterium offers certain advantages over previously studied glycerol-fermenting microorganisms. Anaerobium acetethylicum during growth with glycerol produces very little side products and grows in the presence of maximum glycerol concentrations up to 1500 mM and in the complete absence of complex organic supplements such as yeast extract or tryptone. The highest observed growth rate of 0.116 h is similar to that of other glycerol degraders, and the maximum concentration of ethanol that can be tolerated was found to be about 60 mM (2.8 g l ) and further growth was likely inhibited due to ethanol toxicity. Proteome analysis as well as enzyme assays performed in cell-free extracts demonstrated that glycerol is degraded via glyceraldehyde-3-phosphate, which is further metabolized through the lower part of glycolysis leading to formation of mainly ethanol and hydrogen. In conclusion, fermentation of glycerol to ethanol and hydrogen by this bacterium represents a remarkable option to add value to the biodiesel industries by utilization of surplus glycerol.
生物柴油产业的发展导致粗甘油的联产增加，因此粗甘油正成为一种废品而非有价值的“副产品”。甘油可用于生产有价值的化学品，如生物燃料，以减少甘油废料的处理。在本研究中，描述了一种新型细菌菌株，它能将甘油主要转化为乙醇和氢气，副产物乙酸盐、甲酸盐和1,2 -丙二醇的量很少。与先前研究的甘油发酵微生物相比，这种细菌具有一定优势。乙酰乙基厌氧杆菌在以甘油为生长底物时产生的副产物很少，能在高达1500 mM的最大甘油浓度下生长，且完全不需要酵母提取物或胰蛋白胨等复杂有机补充剂。观察到的最高生长速率为0.116 h，与其他甘油降解菌相似，发现可耐受的乙醇最大浓度约为60 mM（2.8 g·l），由于乙醇毒性，进一步生长可能受到抑制。蛋白质组分析以及在无细胞提取物中进行的酶分析表明，甘油通过3 -磷酸甘油醛降解，后者通过糖酵解的下游进一步代谢，主要生成乙醇和氢气。总之，利用这种细菌将甘油发酵为乙醇和氢气，是通过利用过剩甘油为生物柴油产业增加价值的一个显著选择。
