Akbar Shamsa, Sultan Sikander, Kertesz Michael
Department of Microbiology and Molecular genetics, University of the Punjab, Lahore, Pakistan.
Faculty of Agriculture and Environment, Department of Environmental Sciences, University of Sydney, Sydney, Australia.
J Basic Microbiol. 2015 Jul;55(7):819-29. doi: 10.1002/jobm.201400805. Epub 2015 Feb 5.
Cypermethrin is widely used for insect control; however, its toxicity toward aquatic life requires its complete removal from contaminated areas where the natural degradation ability of microbes can be utilized. Agricultural soil with extensive history of CM application was used to prepare enrichment cultures using cypermethrin as sole carbon source for isolation of cypermethrin degrading bacteria and bacterial community analysis using PCR-DGGE of 16 S rRNA gene. DGGE analysis revealed that dominant members of CM enrichment culture were associated with α-proteobacteria followed by γ-proteobacteria, Firmicutes, and Actinobacteria. Three potential CM-degrading isolates identified as Ochrobactrum anthropi JCm1, Bacillus megaterium JCm2, and Rhodococcus sp. JCm5 degraded 86-100% of CM (100 mg L(-1) ) within 10 days. These isolates were also able to degrade other pyrethroids, carbofuran, and cypermethrin degradation products. Enzyme activity assays revealed that enzymes involved in CM-degradation were inducible and showed activity when strains were grown on cypermethrin. Degradation kinetics of cypermethrin (200 mg kg(-1)) in soils inoculated with isolates JCm1, JCm2, and JCm5 suggested time-dependent disappearance of cypermethrin with rate constants of 0.0516, 0.0425, and 0.0807 d(-1), respectively, following first order rate kinetics. The isolated bacterial strains were among dominant genera selected under CM enriched conditions and represent valuable candidates for in situ bioremediation of contaminated soils and waters.
氯氰菊酯被广泛用于害虫防治；然而，其对水生生物的毒性要求将其从受污染区域彻底清除，在这些区域可利用微生物的自然降解能力。使用有长期氯氰菊酯施用历史的农业土壤，以氯氰菊酯作为唯一碳源制备富集培养物，用于分离氯氰菊酯降解菌，并通过16S rRNA基因的PCR-DGGE进行细菌群落分析。DGGE分析表明，氯氰菊酯富集培养物的优势成员与α-变形菌纲有关，其次是γ-变形菌纲、厚壁菌门和放线菌门。鉴定出的三株潜在氯氰菊酯降解菌分别为嗜水气单胞菌JCm1、巨大芽孢杆菌JCm2和红球菌属JCm5，它们在10天内降解了86%-100%的氯氰菊酯（100 mg L(-1)）。这些菌株还能够降解其他拟除虫菊酯、克百威和氯氰菊酯降解产物。酶活性测定表明，参与氯氰菊酯降解的酶是可诱导的，当菌株在氯氰菊酯上生长时表现出活性。接种菌株JCm1、JCm2和JCm5的土壤中氯氰菊酯（200 mg kg(-1)）的降解动力学表明，氯氰菊酯随时间消失，遵循一级动力学，速率常数分别为0.0516、0.0425和0.0807 d(-1)。分离出的细菌菌株是在氯氰菊酯富集条件下选择的优势属之一，是受污染土壤和水体原位生物修复的有价值候选菌株。
