Isolation, Identification And Degradation Characteristics Of Tipical Organic Pollutant-Degrading Bacteria

Bioremediation using microbes has incomparable advantages compared with other remediation methods. The practical application of micro-bioremediation related to the selected strains and many other factors. Therefore, it has become an important research field for how to development microbial resources and study the mechanisms of its degradation.This thesis studied on the microbial degradation of organic pollutants using acetochlor herbicide and n-hexadecane as the researchful objective. The major results were summarized as follows:1. Five acetochlor degrading strains were isolated from the sludge of pesticide factory and long-term acetochlor-contaminated soil using enrichment culture method. All the strain degraded acetochlor slowly when using acetochlor as the sole carbon source. Among the five strains, A-5 had higher degradability; the degradation rate was 17%. The strain A-3 grew faster and had higher degradability when using acetochlor as the sole nitrogen source. Under the treatment of 10 mg/L acetochlor, the degradation rate of acetochlor by A-3 was up to 33.6% after 10 days culture at 30℃. So the strain A-3 was studied deeply. 2. The composition of culture medium could impact the degradation of acetochlor of A-3. Under the treatment of 10,20 mg/L acetochlor, the degradation rate of acetochlor by A-3 was 33.6%,31.5%. When the acetochlor concentration was up to 100 and 200 mg/L, the degradation rate of acetochlor by A-3 was only 10.1% and 5.4%. It indicated that the strain A-3 was fit for degrading low concentration acetochlor. When the carbon source of culture medium was different, the growth and degradation ability of strain A-3 were different. The strain had the strangest growth capability with the OD600 value of 0.55 when using sucrose as carbon source. The strain A-3 had the highest degradation rate up to 29.2% with glucose as carbon source. This paper also indicated that the NaCl concentration could affect the growth and degradation of A-3. The strain A-3 grew best and had the highest degradability under 0.5% NaCl, and the degradation rate was up to 35%. But when the NaCl concentration was up to 7%, the growth of A-3 and the degradability were inhibited severely, and the degradation rate was only 2.6%.3. Two hydrocarbon-biodegrading bacteria B1 and B2 isolated from Tianjin petroleum contaminated soil by enrichment culture were identified as Pseudomonas aeruginosa and Acinetobacter Junii. The degradation rate of n-hexadecane by B1 and B2 was up to 96% and 78% respectively after 7 days. B1, B2 had highly degradability of n-hexadecane, but the mechanisms of degradation were different. The results showed that B2 could not use glucose as carbon source; B1 could produce glycolipid surfactant using glucose as the carbon source, according to the results of blue agar plate analysis and thin layer chromatography (TLC) analysis, and the culture of B1 had highly oil discharge activity and emulsification activity. Both B1 and B2 could produce biosurfactant with hexadecane as the sole carbon source, but the modes of action were different. Carbon source could affect the cell surface hydrophobicity and the degradability to organic pollutant. The cell surface hydrophobicity was poor with glucose as the carbon source, but the cell surface hydrophobicity enhanced when hexadecane as carbon source.