The Construction And Evaluation Of Acid Resistant Components In Environmental Microbiology

Recently, bioremediation plays a pivotal role in the governance of environmental pollutants, and it has been successfully used to the degradation of some pollutants like polycyclic aromatic hydrocarbons. Owing to the diversity and complexity of the environmental pollution, the stress tolerance of environmental microbiology becomes the bottleneck lying in the practical application.This research focuses on the enhancement of acid resistance of environmental microbiology. We exploited the glutamate decarboxylase system related genes(gad BC) in E. coli and the global regulating gene irr E in D. radiodurans R1, and by means of gene clone and plasmid construction, we constructed two kinds of acid resistant vectors p ME-Gad and p ME-Girr E. Then we transformed the vectors into nicotine degradation strain P. putida S16 and biphenyl degradation strain P. putida B6-2 through the method of electroporation separately. The results shows that the constructed acid resistant vectors significantly improved the growth capacity of the two strains at acidic p Hs(p H 5.0, p H 4.5 and p H 4.0).The degradation experiments of P. putida S16 were conducted in the nicotine medium and sodium benzoate culture, both in the p H of 7.0 and 5.5. Each strain showed no differences in the medium with neutral p H. However, at p H 5.5, the P. putida S16 strain harboring p ME-Gad or p ME-Girr E showed distinct advantage in growth and degradation efficiency compared with control strains, with the fact that the former could degrade almost all the nicotine or sodium benzoate in the culture, while the later could hardly survive the acidic condition, let alone the degradation of the substrates. We have the similar conclusion in P. putida B6-2, since the acid resistant component harboring strains could degrade 1 g/L sodium benzoate within 24 h while the control strains couldn’t.The results can fully demonstrate that gad BC and irr E both can enhance the acid resistance of P. putida S16 and P. putida B6-2, as well as improve the degradation efficiency at acidic conditions, which have laid the foundation of pollutants degradation in the practical environment.