Isolation and characterization of bacteria from acidic pristine soil environment able to transform iprodione and 3,5-dichloraniline

Abstract

Iprodione is a fungicide commonly used in a range of crops resulting in its common detection in natural water resources. Biological degradation constitutes the major dissipation processes controlling its environmental dissipation. We aimed to isolate and characterize soil bacteria able to metabolize iprodione and its key metabolite 3,5-DCA. Initial microcosm laboratory studies in a pristine acidic soil (without previous exposure to the fungicide) showed a slow dissipation of iprodione. Subsequent enrichment cultures from the same soil as well as from a soil with previous exposure to iprodione resulted in the isolation of two bacterial cultures (C2.7 and A1.4) that degraded iprodione and 3,5-DCA respectively, both obtained from the pristine soil. Molecular fingerprinting revealed that C2.7 was composed of two strains, identified via cloning as Arthrobacter sp. (strain C1) and Achromobacter sp. (strain C2), whereas A1.4 was pure and it was identified as Pseudomonas sp. Degradation studies with the purified isolates Arthrobacter sp. strain C1, Achromobacter sp. strain C2 and their combination in minimal and rich media showed that Arthrobacter sp. strain C1 was the key iprodione-degrader, whereas Achromobacter sp. strain C2 was only able to slowly co-metabolize iprodione. Transformation of iprodione by Arthrobacter sp. strain C1 resulted in the formation of isopropylamine which could be used by the strain as C and N source. This finding suggests that iprodione degradation by our isolate proceeds via the formation of intermediate metabolites before final hydrolysis to 3,5-DCA. Arthrobacter sp. strain C1 showed maximal iprodione degradation and 3,5-DCA formation at the higher pH-temperature combination (7.5-35°C) and maintained its degradation capacity in the presence of a mixture of pesticides expected to co-occur in on-farm biobed systems. On-going studies will elucidate the metabolic pathway of iprodione by the isolated strains. © 2015 Elsevier Ltd.