Achromobacter xylosoxidans and Stutzerimonas stutzeri from the phyllosphere of Eichhornia crassipes (water hyacinth) degrade chlorpyrifos as consortia

Abstract

Organophosphates (OPs) constitute a significant proportion of pesticides currently used worldwide in agriculture. Widespread and repeated application of these insecticides contaminates the soil and water, posing significant non-target toxicity risks to other organisms within the ecosystem. Acute pesticide exposure causes toxicity to insects, plants, animals, and humans, and thus emphasizes the need for sustainable management. Bacterial degradation of pesticides has been considered as a preferred strategy. In the present study, the phyllosphere of water hyacinth (Eichhornia crassipes) was explored for the chlorpyrifos degrading bacteria using Culture-independent and culture-dependent methods. Culture-independent study revealed 44,514 operational taxonomic units (OTUs) that were classified into 16 phyla and 330 genera, with dominating genera such as Acinetobacter, Paenibacillus, Pseudomonas, Sphingobacterium, and Achromobacter. Culture-dependent method yielded Achromobacter xylosoxidans and Stutzerimonas stutzeri as chlorpyrifos tolerant and degraders. These isolated strains exhibited enhanced growth as a consortium with chlorpyrifos as the only carbon source. The consortia effectively degrade 98% of chlorpyrifos within seven days, indicating its potential for pesticide degradation. Proteomics analysis revealed upregulation of key enzymes implicated in chlorpyrifos degradation, such as phosphodiesterase, metallo-beta-lactamases and oxidoreductase. The down-regulation of stress-response proteins suggests an adaptive tolerance to the pesticide. This study justifies the potential of consortia of isolated strains in the degradation of chlorpyrifos and may be developed into a promising and eco-friendly approach for remediating chlorpyrifos-contaminated environments.

Keywords: Bioremediation; Chlorpyrifos; Organophosphates; Phyllosphere; Water hyacinth.