Chemotaxis and degradation of organophosphate compound by a novel moderately thermo-halo tolerant Pseudomonas sp. strain BUR11: evidence for possible existence of two pathways for degradation.

Santanu Pailan,Pradipta Saha

doi:10.7717/peerj.1378

Santanu Pailan, Pradipta Saha

Open Access

https://doi.org/10.7717/peerj.1378

Copy DOI

Journal: PeerJ	Publication Date: Nov 10, 2015
Citations: 23	License type: CC BY 4.0

Affiliation: University of Burdwan

Abstract

An organophosphate (OP) degrading chemotactic bacterial strain BUR11 isolated from an agricultural field was identified as a member of Pseudomonas genus on the basis of its 16S rRNA gene sequence. The strain could utilize parathion, chlorpyrifos and their major hydrolytic intermediates as sole source of carbon for its growth and exhibited positive chemotactic response towards most of them. Optimum concentration of parathion for its growth was recorded to be 200 ppm and 62% of which was degraded within 96 h at 37 °C. Growth studies indicated the strain to be moderately thermo-halo tolerant in nature. Investigation based on identification of intermediates of parathion degradation by thin layer chromatography (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC) and liquid chromatography mass spectrometry (LC-MS/MS) provided evidence for possible existence of two pathways. The first pathway proceeds via 4-nitrophenol (4-NP) while the second proceeds through formation of 4-aminoparathion (4-APar), 4-aminophenol (4-AP) and parabenzoquinone (PBQ). This is the first report of chemotaxis towards organophosphate compound by a thermo-halo tolerant bacterium.

Highlights

Organophosphate (OP) compounds are extensively used throughout the world as insecticides, nematicide as well as chemical warfare agents (Kanekar, Bhadbhade & Deshpande, 2004; Yang et al, 2006)
In this study we report for the first time positive chemotactic response of a novel, moderately thermo-halo tolerant bacterium Pseudomonas sp. strain BUR11 towards OP compound and some of their degradation intermediates such as 4-AP, TCP and 4-NP
Characterization and identification of parathion degrading bacterium Several bacterial strains capable of utilizing parathion as sole source of carbon for their growth were isolated from soil of an agricultural field by enrichment culture technique

Summary

Introduction

Organophosphate (OP) compounds are extensively used throughout the world as insecticides, nematicide as well as chemical warfare agents (Kanekar, Bhadbhade & Deshpande, 2004; Yang et al, 2006). These compounds are toxic to human and other animals since they inhibit acetylcholine esterase and are known to disrupt normal functions of central nervous system followed by severe muscle paralysis and death (Shen et al, 2010). Chlorpyrifos was reported to be degraded by Bacillus pumilus more efficiently (80%) at basic and neutral pH compared to acidic pH (only 50%) (Anwar et al, 2009). OP compounds are acutely toxic to mammals, for example the LD50 of parathion for mammals is in the range 2–10 mg kg−1 (Singh & Walker, 2006)

Methods

Results

Conclusion