外源微生物对土壤中烟嘧磺隆的降解作用研究

Bioremediation of exogenous degrading bacteria to the nicosulfuron-contaminated soil

为了探索外源微生物N80（Serratia marcecens）对烟嘧磺隆污染土壤生物修复的可行性,在实验室条件下,分析了温度、土壤pH值、接菌量、农药初始质量比等因素对N80降解烟嘧磺隆效果的影响.同时以小白菜、甜菜、菠菜为供试作物,采用室内盆栽试验法处理污染土壤,液相色谱仪（UVD）测定土壤中烟嘧磺降残留量.结果表明：1）向污染土壤中添加外源微生物菌株N80可以促进土壤中烟嘧磺隆的降解,第30d时,最高降解率可达79.7％ 2）N80降解污染土壤中烟嘧磺隆的最适宜条件为25℃,pH=7.0,接种量108 cfu/g,初始质量比10mg/kg.研究表明,向污染土壤中接种一定量的外源微生物菌株N80可以有效降低土壤中烟嘧磺隆的残留量,减轻烟嘧磺隆对敏感作物的药害,达到了预期的生物修复效果.

The present essay is to give a general introduction to our experimental study of the biorcmediation for the nicosulfuron contami- nated soil by using exogenous microbial N80 （serratia marcecens, isolated in our lab）. First of all, we have examined the bioremediate function of NS0 strain-a kind of serratia marcecens in the nicosulfuron contaminated soil under laboratory conditions. Analyzing it carefully let us make clear that of all the essential factors of degrading nicosul- furon by NS0, the temperature, pH of the soil, the inoculation and initial nicosulfuron concentration are the key ones. It has also become possible to measure the soil residues of the nicosulfuron because of using the liquid chromatography （UVD）. The results of our measure- ments indicate that N80 grows with nicosulfuron as the unique nitro-gen source at the optimal temperature range of 25 ~C with its pH val- ue being 7.0 in the soil. As a result of the nicosulfuron degradation by N80, the enzyme activity tends to be reduced by the improper temperature and pH value. However, adding NSO can speed up the nicosulfuron degradation in the soil at a rate of 10 mg/kg than at oth- er experimental nicosuffuron concentrations. Moreover, higher initial concentrations of nicosulfuron prove to help restrain the growth of mi- croorganism N80. It is also found that degradation in the soil inocu- lated with N80 fits the first order kinetics equation. Furthermore, the half-life of nicosulfuron in the soil is found to be 13.48 days, whose height is 10 mg/kg, higher than 20 mg/kg, if added by N80. The effect of bioremediation can be measured by using pot-cultured exper- iments. The results of the experiment indicate that unsterilized soil in- oculated with N80 〉 sterilized soil inoculated with N80 〉 unsteril- ized soil 〉 sterilized soil. When N80 was inoculated into the soil at the density of l0s - 109 cfu/g dry soil, nicosulfuron（ 10 mg/kg dry soil）in the soil turned to get degraded by 74.3% -76.2% after in- cubated for 30 days. With blank control of 14.6%, it was possible to increase the degradation rate by 59.7% and 61.6%. Adding 10 mg/kg nicosulfuron to the soil with the strain of N80 in 108 efu/g, the emergency rates of beet, pakchoi, and spinach help to increase the product by 84%, 82% and 81%, respectively. Moreover, the plant heights were seen growing up in comparison with the blank con- trol plant. The current study shows that the hand-handled inoculation of N80 strain has enabled to effectively increase the degradation rate of nicosulfuron in the contaminated soil.