知识与财富的链接
有机氯农药六六六曾被广泛用于卫生防疫和对抗农业病虫害,但由于其毒性和持久性引发了一系列环境问题.鉴于微生物降解方法在农药污染场地的修复中具有重要作用,采用摇瓶培养法研究了在α-、β-、γ-和δ-六六六(HCH)异构体混合体系中,农药浓度、共代谢底物和接种量对Sphingobium indicum B90A降解4种HCH异构体的影响.研究结果表明:S.indicum B90A对α-和β-HCH的利用较好,其次是γ-和δ-HCH.在10 mg·L-1混合HCH的无机盐培养液中,30℃下反应72 h,S.indicum B90A对α-、β-、γ-和δ-HCH的降解率分别为99％、86％、53％和33％.随着HCH浓度的增加,S.indicum B90A对4种HCH异构体降解率均逐渐降低.在共代谢底物的研究中,添加葡萄糖或酵母粉均能明显地提高S.indicum B90A对HCH的降解能力,在10 mg·L-1混合无机盐培养液中,添加1 00 mg·L-1葡萄糖或添加50 mg·L-1酵母粉,30℃下反应84h,S.indicum B90A对α-、β-、γ-和δ-HCH的降解率均接近100％.S.indicum B90A对HCH的降解率随着菌体接种量的增加而相应提高,适宜接菌量为5％.
HCH is one of the most extensively used organochlorine pesticides for public health and agricultural pests control. Soil pollution with HCH has caused serious environmental problems because of its toxicity and long persistence. Biodegradation has been suggested as a safe and effective way to remediate HCH contaminated soils. In our study, a bottle culture was used to investigate the effects of pesticides concentration, co-metabolic substrates and inoculum size on the degradation of mixed HCH isomers(α-, β-, γ- and δ-HCH) by Sphingobium indicum B90A. The results showed that the utilization of α- and β-HCH by S. indicum B90A was higher than that of γ- and δ-HCH. In the culture solution of 10 mg·L-1 mixed HCH, the degradation rates of α-, β-, γ- and δ-HCH with S. indicum B90A at 30 ℃ after 72 h were 99%, 86%, 53% and 33%, respectively. With the increase of HCH concentration, the biodegradation rates of α-, β-, γ- and δ-HCH all gradually declined. In the study of co-metabolic substrates, it was found that 100 mg·L-1 glucose or 50 mg·L-1 yeast extract added in the culture solution of 10 mg·L-1 HCH could promote biodegradation of HCH by S. indicum B90A close to 100%. With increase of inoculum size from 2% to 10%, the degradation rate of HCH isomers with S. indicum B90A increased. The most optimum inoculum size was 5%.
