Bioremediation Potential of Plant-Bacterial Consortia for Chlorpyrifos Removal Using Constructed Wetland

Abstract

The extensive and unchecked application of chlorpyrifos against crop insects has caused contamination of various ecosystems, such as soil, sediments, and water, posing harm to plants, animals, useful arthropods, and humans. The present study aimed at evaluating the ability of proto-type constructed wetland to biodegrade chlorpyrifos and its major metabolites especially 2-hydroxy-3, 5, 6-trichloropyridine/ol (TCP) using chlorpyrifos-degrading indigenous bacterial strains, namely, Acinetobacter baumanni and Bacillus cibi with Canna spps. and indigenous Mentha spps. as a bacterial–plant consortium. Soil and plant samples were collected at regular time intervals for 12 weeks; analytes were extracted using the toluene method and evaluated through gas chromatography–mass spectrometry (GC-MS). In case of wetland vegetation with Canna and Mentha, 2-hydroxy-3, 5, 6-trichloropyridine (TCP, m/z = 198) and 2- hydroxypyridine (m/z = 97) with deprotonated molecular ions at m/z = 69 (M-H)−were detected as the intermediate metabolites, while in the bacterial–plant consortium, instead of TCP, 3, 5, 6-trichloro-2-methoxypyridine (TMP, m/z = 212) was formed along with di-ethylthiophosphate (DETP, m/z = 169). Based on the metabolite analysis using GC-MS, the biodegradation pathway for chlorpyrifos degradation through bacterial–plant consortia is predicted. The constructed wetland with the bacterial–plant consortium showed its potential to either bypass TCP generation, or TCP may have been immediately biodegraded by the plant part of the consortium. The designed constructed wetland provided a novel remedial measure to biodegrade chlorpyrifos without producing harmful metabolites.