嗜铁细菌枯草芽胞杆菌Bs-15对辛硫磷的降解特性

Characteristics in degradation of phoxim by siderophore producing bacterium Bacillus subtilis Bs-15

为探讨嗜铁细菌对农药辛硫磷的降解及其土壤修复的潜能,采用改良定向培育法,对嗜铁细菌枯草芽胞杆菌(Bacillus subtilis)Bs-15进行驯化,摸索其降解条件,并测定其土壤修复能力.结果显示,菌株Bs-15对辛硫磷有较高的耐受性,在辛硫磷浓度达到800 mg L-1时仍可生长;可以以辛硫磷为唯一碳源生长,适合其降解的最佳外加营养物质为酵母粉,无机盐为MgCl2.最适辛硫磷降解浓度为≤100 mg L-1,浓度继续升高时降解效能明显降低;最适降解温度为35℃;对pH值有较广的适应范围,在pH 5-9时降解率较高;最适降解时间为24 h,振荡速率为150 r min-1,接种量为8%;土壤修复试验表明,此菌株在第20天时对土壤中辛硫磷的降解率接近50%.本研究结果说明枯草芽胞杆Bs-15对辛硫磷具有较好的降解作用,对辛硫磷污染的土壤具有良好的修复潜能.

The aim of this work was to investigate phoxim degradation by siderophore producing bacteria Bacillus subtilis Bs- 15 and its potential in soil bioremediation. Bs-15 was acclimated by improved directive breeding via subculture in different concentrations of phoxim, then the degradation factors and bioremediation activity in the soil were analyzed. The results showed that Bs-15 grew well in phoxim-containing medium with tolerance up to concentration of 800 mg L^-1. Bs%-15 could utilize phoxim as the sole carbon source. The optimal additional nutrition and inorganic salt for phoxim degradation were yeast and MgCI： respectively. The optimal conditions for bacterial growth and phoxim degradation were no more than 100 mg L-~ phoxim, a temperature of 35 ℃ and pH value ranging from 5 to 9. The optimal fermentation occurred at 150 r min-1 for 24 h with an inoculum ratio of 8%. The experiment ofbioremediation activity in the soil indicated that Bs-15 could degrade nearly 50% phoxim after a 20-day treatment. Therefore we believed that B. subtilis Bs-15 has great potential in phoxim degradation and bioremediation ofphoxim-contaminated soils.