Characterization Of Microbial Distribution In Sediments From Polluted Sections Of The Liao River And Primary Research On Remediation With Gene-augmentation

Liao River, one of the greatest water systems in China, was serious water environmental pollution. Recognition on Distribution characteristics of sediment microorganism at representative pollution sites in Liao River, and studying of the influence factors and control methods on gene-augmentation by mobile genetic elements (MGEs) in contaminated system, which have theory value and practice significance to control and remedy pollution for Liao River. This research analyze the amount and distribution of microorganism in surface sediments retrieved from the eleven representative pollution sites and Columnar sediment at one site by FISH technique and staining technique with DTAF. In order to study the influence factors of the horizontal gene transfer and the removal effect of contaminant in sediment system by gene-augmentation, 2,4-Dichlorophenoxyacetic Acid(2,4-D) was selected as target contaminant and plasmid pJP4 as mobile genetic element. Based on the studies mentioned, The main conclusions are as follows:1) The result based on the analysis of the eleven surface sediments indicate that the total cell count of surface sediment decrease gradually at representative pollution sites in Liao River from the upstream to downstream; the total cell count of surface sediment increase gradually at representative pollution sites in Liao River Estuary from from close to far away from the Estuary. Alpha proteobacteria,Beta proteobacteria and Gamma proteobacteria are widely distributed in surface sediment and Alpha proteobacteria and Gamma proteobacteria are the dominant bacteria of it.2) The results based on the analysis of the one column sediments show that Alpha proteobacteria,Beta proteobacteria and Gamma proteobacteria are widely distributed in column sediment, and Alpha proteobacteria and Gamma proteobacteria are the dominant bacteria of it. The percentage of Alpha proteobacteria with Total prokaryotic counts generally increases with the depth, and the reverse is true of Beta proteobacteria and Gamma proteobacteria. The results also show that bacterial number in sediment is largely influenced by environmental factors;Bacterial number in sediment is positively correlated to organic content and cohesive clay content in sediment, and is negatively correlated to Hg content.3) The result based on the experiment of influence factors on horizontal gene transfer shows that: General microorganism can be accepted as recipient in horizontal gene transfer; Population density of both donor and recipient will affect transfer frequence. And the optimal population density should be: donor is 6×1010;recipient is. 6×109; The starvation time of both donor and recipient will affect the metabolic activity, and thus affect the occurrence of transfer. The longer the time, the more restrained the transfer would be; Environmental factors during horizontal gene transfer will also affect its transfer frequency. Transfer frequency reaches the highest level when mating time is 4.8h, mating temperature is 30℃and concentration of 2,4-D is 0.2mM; When HgCl2 concentrationxceeds the limiting concentration of 1μg/L, the rise of HgCl2 concentration will restrain the transfer, or will be completely devoid of transfer.4) The result based on gene-augmentation in contaminated system shows that the degrading bacteria sieved from the activated sludge and the genetic engineering bacteria (Pseudomonas putida SM1443::gfp2x)harboring plasmid pJP4 promote the removal effect of contaminant in bioaugmentation system, and the conjugant may be effectively preserved for a long time (24d) in the gene-augmentation system with the selection pressure of 2,4-D...