Function Of Formate Dehydrogenases On Hydrogen Production And Methyl Green Degradation

Triphenylmethane dyes are widely used in chemical industry,coloring and other industries,producing a large number of industrial effluents,harm to the environment and human health seriously.Microbial degradation of dyes is an important method for the decolorization of dyeing effluent.S.oneidensis MR-1 is a gram-negative microbe with strong reduction ability,which can reduct a variety of metal ions,dimethyl sulfoxide,fumarate.trimethylamine oxide and other compounds.In this paper,with methyl green as an example,exploring the electron transfer pathway under the natural condition when pyruvate is used as electron donor.There is no idea about the electron transfer pathway from substrate oxidation to hydrogenase in S.oneidensis MR-1.The electron transfer pathway of hydrogen production in S.oneidensis MR-1 without electron receptor is studied firstly.The following research results are obtained.The following results are obtained as follows:1.S.oneidensis MR-1 encode three formate dehydrogenases including FdhAlB1C1.FdhA2B2C2 and FdnGHI.and the proteins are located in the periplasm,the role of these formate dehydrogenases in hydrogen metabolism is not identical.We constructed mutants lacking one.two or all three of formate dehydrogenases in S.oneidensis MR-1.and all of the mutants had cultured under the same culture condition as the wild type,as the results show that FdhAlBIC1 and FdhA2B2C2 were active.while the effect of FdnGHI was not obvious.However,when the fdhA1B1C1 and fdhA2B2C2 genes in the cells were lacking,the transcription levels of the fdnGHI increased significantly,and the encoding formate dehydrogenase was involved in hydrogen production.2.The menaquinone was indispensable for the hydrogen production when bacterias are cultured with formate as electron donor for hydrogen metabolism.The results also indicated that there is no formate hydrogen lyase in S.oneidensis MR-1 which producing hydrogen from formate directly).3.There is a proposed fdh in an operon encoding[Fe-Fe]hydrogenase HydAB is a cytochrome b HydC.We conclude that the gene was responsible for electron transfer from the quinol pool to the[Fe-Fe]hydrogenase.At the same time,the effect of various cultivations on the degradation of methyl green was evaluated.And the decolorization products were analyzed.The analysis method of methyl green degradation was established for subsequent experiments carrying on smoothly.