| Summary: | 碩士 === 東吳大學 === 微生物學系 === 93 === In this research, we investigated the effects of various factors on the biodegradation of nonylphenol (NP) by addition sludge and characterized the structure of the microbial community in soil. The results showed Taoyuan clay had better biodegradation rate than other soils . The degradation rate ( k ) and half-life ( t1/2 ) of 50 mg/Kg NP were 0.85 1/day and 8.9 days under aerobic conditions , and 0.03 1/day and 23.3 days under anaerobic condition , respectially. The biodegradation rate of NP under the aerobic condition was higher than under the anaerobic condition.
Under aerobic condition，the optimal solid/liquid ratio was 1:9, addition of surfactant such as Brij 35 or Tween 80 enhanced NP biodegradation , but addition of EDTA or dry sludge inhibited the biodegradation. Addition of the composting that larger than 0.105 mm enhanced the biodegradation of NP , but the addition of composting that smaller than 0.105 mm inhibited the degradation of NP . The microbial community changes in biodegradation process by the denaturing gradient gel electrophoresis (DGGE) analysis of the PCR amplified 16S rRNA gene fragments. The addition of different substrate treatments would change the microbial community. Band b was became darker when incubation time increased . The location of the band that belongs to strain BS5 was the same as band b. We proposed the strain BS5 was the dominant strain on NP biodegradation in soil . .
Under anaerobic condition, Addition of yeste extract or EDTA enhanced the NP biodegradation , but the addition of surfactant inhibited the biodegradation . Addition of the compost or dry sludge would inhibit the biodegradation . Under the different anaerobic conditions, we found methanogenic , denitrifying and sulfidogenic bacteria played important roles on NP degradation and the sulfidogenic bacteria were the major population on degradation.
We also isolated two bacteria which showed the greatest degradation potential were strains BS5 and A4, the NP degradation rate were 0.72 1/day and 0.08 1/day ; the half-life were 6.9 days and 35.5 days, respectially. Our results could offer the feasibility for removal of NP in soil environment by microbial biodegradation.
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