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研究报告

Biodegradation of carbendazim by a highly effective combined bacterial culture

摘要：将多菌灵降解菌Alcaligenes sp.和Rhodococcus sp.(编号为A和R)按不同比例进行复配,并采用三波长校正法和HPLC法测定不同复配降解体系中多菌灵的残留量,比较了纯培养和复合菌群对多菌灵的降解效果,最后对高效复合菌的降解条件进行了优化.试验结果表明,得到的高效降解复合菌群AR5(A:R复配比例1:4),培养24h后可完全降解100mg·L^-1的多菌灵,对200mg·L^-1多菌灵的降解率为74.25%,明显优于单一菌株的降解效果.同时,该复合菌群对高浓度多菌灵也具有较好的耐受和降解能力,72h内可将初始浓度为600mg·L^-1的多菌灵降解至10mg·L^-1左右.正交优化试验结果表明,该复合菌群的最优降解条件为温度30℃、pH=6.0、接种量7%,该条件下多菌灵的降解率可达75.76%.添加少量氮源(如尿素和酵母浸粉)可以促进复合菌对多菌灵的生物降解.

Abstract：Two carbendazim-degrading strains,an Alcaligenes sp.designated Aand a Rhodococcus sp.designated R,were mixed in different proportions to develop a highly effective bacterial consortium,whose degradation conditions were then optimized.During the test,a ternary wavelength spectrophotometric method and HPLCwere used to determine the residual carbendazim in the culture medium,based on which the degradation rates of individual strains and the combined bacteria were calculated.The combined bacterial consortium AR5 showed optimal degradation capability and could completely degrade 100 mg·L^-1 carbendazim within 24 hours of cultivation,while the degrading rate for 200 mg·L^-1 carbendazim reached 74.25%,which was superior to that of either individual strain alone.Moreover,the mixed culture had excellent tolerance and degradation ability against carbendazim of high concentrations,as carbendazim at 600 mg·L^-1 was degraded to about 10 mg·L^-1 within 72 hours.The result of an orthogonal optimization experiment showed that the optimal degradation conditions for AR5 were 30 ℃,initial pH 6.0 and 7% inoculation volume,under which the degradation rate reached 75.76%.The addition of carbon and nitrogen sources,especially urea and yeast extract,could further promote the biodegradation of carbendazim by the combined bacterial culture AR5.

Key words：carbendazim Rhodococcus sp. Alcaligenes sp. combined bacteria biodegradation orthogonal optimization