Influence of humic acid, iron and copper on microbial degradation of fungicide Carbendazim

Abstract

Abstract Carbendazim (CBZ) is a systemic fungicide utilized for the control fungal diseases in forestry and agricultural crops. Its severe toxicity and residual nature mandated its removal and biodegradation by biological, eco-friendly and sustainable methods. Towards this direction, we searched for CBZ utilizing bacterial strains from the agricultural soils. Based on morphological, biochemical and molecular characterisation the isolates were identified as Streptomyces sp. CB1, Bacillus subtilis CB2, Pseudomonas aeruginosa CB3 and Rhizobium leguminosarum CB4. The effect of CBZ on isolates in the presence and absence of Fe(II), Cu(II) and humic acid was determined. It was found that humic acid supplementation resulted in enhanced and extended growth of bacterial isolates. Among the four isolates, P. aeruginosa CB3 exhibited highest CBZ degradation followed capability by B. subtilis CB2, Streptomyces sp. CB1 and R. leguminosarum CB4. Supplementation with Cu(II) ions resulted in higher degradation of CBZ. However, humic acid was only moderately effective, whereas Fe(II) failed to show any appreciable increase in CBZ degradation by bacterial isolates. Our study suggests that CBZ adapted bacterial strains can offer a biologically and sustainable solution for bioremediation of contaminated agricultural fields and reservoir sites.