莠去津高效降解细菌HB-5的固定化研究

Immobilization Research of High-Efficiency Atrazine-Degrading Bacterium HB-5

以莠去津降解细菌HB-5作为研究对象,探索了降解菌HB-5的固定化方法,并对降解菌HB-5及其固定化菌对土壤中莠去津的降解能力进行了比较。采用注射器滴定方法对细菌HB-5进行了固定化,并对海藻酸钠、聚乙烯醇、卡拉胶、脱乙酰壳多糖4种包埋材料从成本、固定时间等方面进行了比较,筛选出最佳固定条件。研究确定海藻酸钠为最佳包埋剂,并对包埋剂的浓度、包埋粒径等进行了探索,测定了降解菌HB-5及其固定化菌对土壤中莠去津的降解率。结果表明,以浓度为2.5%￣3.5%的海藻酸钠溶液作为包埋剂进行固定化,生产的HB-5固定化菌机械强度和物理稳定性好,分离度高,符合实验和应用的要求。菌株经固定化后,降解莠去津的能力大大提高,在第1 d以后,其降解率均高于未固定化菌;在第1￣7 d,随培养时间的延长,降解菌与固定化菌HB-5的降解率迅速提高,在第7 d达到85%;在第7￣13 d,两者的降解率增长缓慢,但在第10 d均可达到90%。

The high-efficiency atrazine-biodegrading bacterium from industrial sewerage, named as HB-5, was filtrated. The immobilization method for bacterium HB-5 was studied. The differences of biodegradation data between bacterium HB-5 and immobilized HB-5 on soil were compared. Bacterium HB-5 was cultured in basic liquid inorganic medium at 30 ℃, 48 h with 5% inoculation. The bacterial pellet was sonificated and centrifuged at 8 000 r·min^-1 for 6 min at 15 ℃. After washed, wet thallis were put into refrigerator at 4℃. After processed by iatrieal syringe titration method, four kinds of embedding materials were compared in price and other factors, sodium alginate, poly vinyl alcohol, carrageenan and chitosan, and sodium alginate was finally considered, as the best embedding material. Concentration of sodium alginate and diameter of immobilized HB-5 were also experimentalized. The degrading capacity of bacteria HB-5 and immobilized HB-5 for atrazine in soil was also determined. The results indicated that the particle manufactured by 2.5%-3.5% sodium alginate as embedding material with 4# iatrical syringe pinhead could meet the requirement of the dissertation because of its preferably mechanical intensity and physical stability. The capacity of bacteria HB-5 to degrade atrazine was superior to the immobilized HB-5＇ s at the first day by gas chromatogram, but from the 3rd day to the 13th day, just the reverse. The degradation rates of both increased dramatically with the days prolonged, and reached 85% on the 7th day. But from the 7th day to the 13th day, the degradation rates increased slowly and reached 90% on the 10th day.