Pseudomonas sp.JM2菲降解酶基因解析

Gene Analysis on Phenanthrene-degrading Enzyme System by Pseudomonas sp.JM2

Pseudomonas sp.JM2是一株新发现的菲好氧高效降解菌,文章通过对该菌株菲降解基因簇的解析,发现降解关键酶基因均处于质粒上。获得了该菌菲双加氧酶、顺-3,4-二氢二羟基菲脱氢酶、3,4-双羟基菲双加氧酶、2-羟基-2H-苯芘[h]色原烯-2-羧酸盐异构酶、水合-醛缩酶、1-羟基-2-萘甲醛脱氢酶、1-羟基-2-萘甲酸双加氧酶、反式-2'-羧基苄基丙酮酸水合-醛缩酶、2-羧基苯甲醛脱氢酶的基因序列。通过与14种多环芳烃降解菌的基因序列比对,发现JM2降解关键酶的基因序列与产碱杆菌AFK2有96%的同源性,而与同种属的假单胞菌的同源性仅有约55%。进一步用同源模建的方法获得了JM2菲双加氧酶α亚基的关键氨基酸,并结合已知的代谢产物分析,推测该菌株通过邻苯二甲酸途径降解菲,该降解途径与目前已知的假单胞菌菲降解途径不同。实验结果对于评价JM2菲降解物的环境影响、进一步通过基因调控和改造提高JM2的降解能力奠定了基础。

Pseudomonas sp. JM2 is a newly efficient phenanthrene-degrading strain. Analysis of the gene cluster showed the degrading enzymes were located on the plasmid. The gene sequences encoding phenanthrene dioxygenase, cis-3,4- dihydrophenanthrene dehydrogenase, 3,4-dihydroxyphenanthrene dioxygenase, 2 -hydroxy -2H -benzo [h]chromene -2 - carboxylate isomerase, hydratase -aldolase, 1 -hydroxy -2 -naphthaldehyde dehydrogenase, 1 -hydroxy -2 -naphthoate dioxygenase, trans-2＇-carboxybenzal pyruvate hydratase-aldolase and 2-carboxybenzaldehyde dehydogenase were obtained. Comparing with 14 other PAHs-degrading bacteria, it was found that the key enzyme of JM2 had a homology of 96% with strain AFK2, whereas showed approximately 55% homology with the same genus Pseudomonas. The key amino acid of ctsubunit of phenanthrene dioxygenase of JM2 was obtained through homology modeling method. Combined with the known metabolites, it was proposed that JM2 degraded phenanthrene through phthalate way which was different from those Of Pseudomonas. The study would not only evaluate the environmental impact of degradation products by strain JM2, but also lay the foundation for further improving the degradability of JM2 through gene regulation and transformation.