Ethanol production system from livestock increments by transgenic thermophile

点击翻译按钮获取中文摘要

After isolation of cellulase gene by PCR from Clostridium stercorarium, this fragment was transfected into Thermoanaerobacter ethanolicus by using transposon. However, any effective recombinant Was not obtained. For homologous recombination, hydrogenase gene was isolated. A fragment of putative hydrogenase gene was isolated, but the homologous recombination was not succeeded yet. As the creation of genetically modified thermophile was difficult, isolation of useful thermophile was also tried from environment. We succeeded in the isolation of highly ethanol producing anaerobic bacteria, strain 003 and 004. They showed broad substrate specificities including xylan, but not cellulose. For their practical use, another problems must be occurred such as removing oxygen from the fermentor, generating bad smell because of anaerobic fermentation. To resolve these problems, it is thought that co-culture with an effective aerobic thermophile would be active. Aerobic bacteria, strain A1 and B3 were isolated, which enhanced ethanol production by the anaerobes. However, only 3-4 mM ethanol was produced in any case of co-culture, probably because inhibitors derived from lignocellulose degradation may suppress their activities. So, after removing large debris of plant fiber in the medium, co-culture with aerobe A1 strain and anaerobe 003 strain led to 24 mM ethanol production. In conclusion, the isolation of effective microorganisms converting livestock increments to ethanol was succeeded, which making it possible to construct the ethanol production system by utilizing live stock increments. To enhance its production further more, it is thought that the isolation of cellulose degrading and ethanol producing bacteria is essential. This trial is in progress now.