Evidence of biodegradation of chlorpyrifos by a newly isolated heavy metal-tolerant bacterium Acinetobacter sp. strain MemCl4

Abstract

A bacterial strain, designated as MemCl4, capable of utilizing chlorpyrifos as sole source of carbon was isolated by enrichment culture from an agricultural soil sample of Burdwan District, West Bengal, India. It was identified as Acinetobacter sp. by using phenotypic and 16S rRNA gene-based molecular phylogenetic approach. The strain could degrade 98 % of chlorpyrifos within 144 h. Through thin layer chromatography, high-performance liquid chromatography and gas chromatographymass spectrometry analyses, 3,5,6 trichloro-2-pyridinol (TCP) was identified as the only major intermediate during such degradation. The strain could also utilize TCP as sole source of carbon for growth. Degradation studies indicated utilization of chlorpyrifos with formation TCP, followed by decrease in amount of TCP with gradual passage of time. This indicated evidence of mineralization of both chlorpyrifos and TCP by the strain. The Gram-negative and esterase-positive strain was capable of tolerating various heavy metal salts such as arsenite, arsenate, cadmium, chromium, copper, iron, lead, nickel and zinc on sucrose low-phosphate medium. The strain MemCl4 might be considered biotechnologically potential for bioremediation and or restoration of chlorpyrifos-contaminated agricultural fields. This is the first report of a chlorpyrifos-degrading, heavy metal-tolerant bacterium belonging to the genus Acinetobacter, to the best of our knowledge. The strain, however, could not degrade chlorpyrifos in the presence of two heavy metal salts tested (viz. arsenate and zinc sulfate).

Isolation and characterization of chlorpyrifos-degrading bacteria in tea-growing soils

“…The strain Acinetobacter sp. MemCl4 isolated from agricultural soil in India has been demonstrated to degrade 98% of CPF within 144 h of incubation (Pailan et al 2016). The removal rate of CPF was found to be 89.5% to 91.1% by the bacterium Hortaea sp.…”