禾草丹降解菌分离筛选及其对秸秆饲料残留降解率的影响

Isolation and screening of degradation bacteria of thiobencarb and its effect on residue degradation rate of straw feed

试验以黑龙江省不同地区的玉米根际寒地黑土为供试土壤,从长期施用禾草丹玉米田土样中,通过微生物富集培养,采用平板涂布法进行禾草丹降解菌的初步分离,利用96孔板法对其进行进一步筛选,纯化出2株能够以禾草丹(0.1 mg/L)为唯一碳源生长的降解菌株C6和F6。根据形态特征及16S rDNA基因序列相似性分析,分别鉴定为C6阿氏芽孢杆菌(Bacillus aryabhattai)和F6苏云金芽孢杆菌(Bacillus thuringiensis)。采用L^(9)(3_(4))正交试验设计,研究阿氏芽孢杆菌培养基初始pH值、接种量、250 mL锥形瓶装液量3因素对禾草丹农药降解效率的影响。研究表明,阿氏芽孢杆菌的pH值为6.5、接种量为4%、装液量为90 m L时,禾草丹降解率达到96.5%,为降解玉米秸秆饲料中禾草丹农药的残留提供优良菌种。

The experiment studied the black soil of maize rhizosphere from different regions in Heilongjiang Province was used as the test soil.From the soil samples of long-term application of thiobencarb maize field,the plate coating method was used for the preliminary isolation of thiobencarb-degrading bacteria,through microbial enrichment culture and 96-well plate method was used for further screening.Two thiobencarb-degrading strains C6 and F6 that could grow with thiobencarb(0.2 mg/L)as the sole carbon source were purified.According to morphological characteristics and16 S rDNA gene sequence similarity analysis,they were identified as Bacillus aryabhattai and Bacillus thuringiensis,respectively.L^(9)(3_(4))orthogonal experimental design was used to study the effects of initial pH value,inoculum volume and250 mL conical flask liquid volume of Bacillus aryabhattai culture medium on degradation efficiency of thiobencarb.The results showed that the degradation rate of thiobencarb reached 96.5%with pH value of 6.5,inoculum volume of 4%and liquid volume of 90 mL,which provided excellent strains for the degradation of thiobencarb residues in corn straw feed.