Influences Of Phenanthrene On Microbial Diversity In Flooded Paddy Soil, Polyphenoloxidase And GSTs In Phenanthrene-degrading Bacteria

The effects of phenanthrene on soil microbial community structure, and PAHs on polyphenoloxidase and GSTs in PAHs-degrading bacteria were studied using the traditional and innovative molecular biological methods. The result will be valuable to build up alert index systems in phenanthrene-contaminated paddy soil, and evaluate environmental quality of phenanthrene polluted paddy soil. The main results obtained are as follows:1. Effect of phenanthrene on the bacterial diversity in paddy soilPolymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE), as a innovative molecular ecological method, was applied to analyze the microbial gene diversity in flooded paddy soil treated with phenanthrene. The results demonstrated that the development of bacterial population in soil was affected by phenanthrene at the earlier time, and the microbial community structures in the phenanthrene-treated and non-treated soils were not significantly different each other after 8 weeks of phenanthrene treatment.2. Variation of polyphenoloxidase in phenanthrene-degrading and other aromatic compounds-degrading bacteriaThe effects of phenanthrene on phenol oxidase of Sphingomonas paucimobilis ZX4 were studied by mensurating polyphenoloxidase activity and PAGE combined with enzyme activity staining phenol oxidase. When induced by phenanthrene, the activity and constitution of polyphenoloxidase of strain ZX4 changed obviously, so did other bacteria, like nicotine-degrading bacterium HF-1, nicotine-degrading bacterium HF-2 and tobacco tar-degrading bacteria MR4. It showed that intracellular polyphenoloxidase moved to out-side of cell membrane or outside the cell at the existence of PAHs.3. Variation of GSTs in phenanthrene-degrading and other aromatic compounds-degrading bacteriaGSTs, purified from Sphingomonas paucimobilis ZX4 capable of degrading phenanthrene, by affinity chromatography, were injected in two male rabbits to obtain the immune serum. The effect of aromatic compounds on aromatic compounds-degrading bacteria, strains ZX4, HF-1 and HF-2, both capable of degrading nicotine, were detected using ELISA method. It suggested that the GSTs contents of aromatic compounds-degrading bacteria at the presence of aromatic compounds were higher than those at no-presence of aromatic compounds. This result provides that GSTs have the function of reliefing oxidative damage from aromatic compounds in bacteria.