百菌清降解菌BJQ2的分离、鉴定及影响因素研究

采用未有百菌清用药史的土壤定向培养49 d,分离出50株百菌清耐受菌株,经初筛、复筛后得到1株降解能力最强的细菌BJQ2,经形态学、生理生化试验、16S rDNA序列同源性比对及系统发育树的分析,初步确定为阴沟肠杆菌(Enterobacter cloacae B9),BJQ2可以以百菌清为唯一碳源于基础培养基中生长.BJQ2降解百菌清的最适宜条件为:培养温度30～35℃,初始pH值为7.0～8.0,百菌清的初始浓度为20 mg· L-1,选用菌体母液(OD600=0.35),以10％的接种量接种,6d后提取百菌清,利用气相色谱进行检测分析,计算后发现百菌清的降解率可以达到79.2％.

Isolation, Identification and Degradative Characters of Chlorothalonil-degrading Bacteria BJQ2

Directionally cultivated for 49 days in the soil with no history of chlorothalonil(TPN, 2,4,5,6-tetrachloro-1,3-isophthalonitrile)application, 50 chlorothalonil-tolerant bacteria strains were isolated. The highest concentration of chlorothalonil was up to 600 mg·L-1. BJQ2, one with the best degradability among those strains, was obtained after prescreening and affination. It was initially identified as Enterobacter cloacae B9 on the basis of morphological approach, physiological-biochemical experiment, homology comparison of 16S rDNA and the analysis of phylogenetic tree. BJQ2 could be bred in the basic medium by using chlorothalonil as the unique carbon and energy source. The most appropriate condition for BJQ2 to degrade chlorothalonil was as follows:Breeding temperature was 30~35 ℃, original pH value was 7.0~8.0, original TPN concentration was 20 mg·L-1 and the inoculation amount was 10 percent(primary mother liquor,OD600=0.35) in the experiment(V/V). In this condition, chlorothalonil was extracted after 6 days. And its degradation rate was calculated to arrive at 79.2 percent by checking and analyzing with gas chromatography.