More Veena S, Tallur Preeti N, Niyonzima Francois N, More Sunil S
Department of Biochemistry, MSRCASC, Mattikere, MSRIT Post, Bangalore, 560054, India.
Department of Chemistry, Government Arts and Science College, Karwar, 581301, India.
3 Biotech. 2015 Dec;5(6):967-974. doi: 10.1007/s13205-015-0299-0. Epub 2015 Apr 4.
A bacterium capable of degrading pendimethalin was isolated from the contaminated soil samples and identified as Bacillus lehensis XJU based on 16S rRNA gene sequence analysis. 6-Aminopendimethalin and 3,4-dimethyl 2,6-dinitroaniline were identified as the metabolites of pendimethalin degradation by the bacterium. The biodegradation of pendimethalin by freely suspended and the immobilized cells of B. lehensis on various matrices namely agar, alginate, polyacrylamide, and polyurethane foam was also investigated. The batch degradation rate was nearly the same for both free and immobilized cells in agar and alginate, whereas polyacrylamide- and PUF-immobilized cells degraded 93 and 100 of 0.1 % pendimethalin after 96 and 72 h, respectively. At higher concentration, the degradation rate of freely suspended cells decreased; whereas the same immobilized cells on polyurethane foam completely degraded 0.2 % pendimethalin within 96 h. The repeated batch degradation with the polyurethane foam-immobilized cells was reused for 35 cycles without losing the 0.1 % pendimethalin degrading ability. In contrast, agar-, alginate- and polyacrylamide-immobilized cells could be reused for 15, 18, and 25 cycles, respectively. When the pendimethalin concentration was increased to 0.2 %, the immobilized cells could be reused but the pendimethalin degradation rate was decreased. Polyurethane foam-immobilized cells exhibited better tolerance to pH and temperature alterations than freely suspended cells and could be stored for more than 3 months without losing pendimethalin degrading ability. The immobilization of cells capable of degrading pendimethalin may serve as an ideal technique for the complete degradation of the herbicide in the environment.
从受污染的土壤样本中分离出一株能够降解二甲戊灵的细菌，基于16S rRNA基因序列分析，将其鉴定为勒痕芽孢杆菌XJU。6-氨基二甲戊灵和3,4-二甲基-2,6-二硝基苯胺被鉴定为该细菌降解二甲戊灵的代谢产物。还研究了勒痕芽孢杆菌的游离悬浮细胞和固定在琼脂、海藻酸钠、聚丙烯酰胺和聚氨酯泡沫等各种基质上的固定化细胞对二甲戊灵的生物降解。琼脂和海藻酸钠中游离细胞和固定化细胞的分批降解率几乎相同，而聚丙烯酰胺和聚氨酯泡沫固定化细胞分别在96小时和72小时后降解了0.1%二甲戊灵的93%和100%。在较高浓度下，游离悬浮细胞的降解率降低；而固定在聚氨酯泡沫上的相同固定化细胞在96小时内完全降解了0.2%的二甲戊灵。聚氨酯泡沫固定化细胞的重复分批降解可重复使用35个循环，而不会丧失降解0.1%二甲戊灵的能力。相比之下，琼脂、海藻酸钠和聚丙烯酰胺固定化细胞分别可重复使用15、18和25个循环。当二甲戊灵浓度增加到0.2%时，固定化细胞仍可重复使用，但二甲戊灵降解率降低。聚氨酯泡沫固定化细胞比游离悬浮细胞对pH和温度变化表现出更好的耐受性，并且可以储存3个月以上而不会丧失降解二甲戊灵的能力。固定能够降解二甲戊灵的细胞可能是环境中除草剂完全降解的理想技术。
