Organophosphate pesticides an emerging environmental contaminant: Pollution, toxicity, bioremediation progress, and remaining challenges.

Organophosphates (OPs) are an integral part of modern agriculture; however, due to overexploitation, OPs pesticides residues are leaching and accumulating in the soil, and groundwater contaminated terrestrial and aquatic food webs. Acute exposure to OPs could produce toxicity in insects, plants, animals, and humans. OPs are known for covalent inhibition of acetylcholinesterase enzyme in pests and terrestrial/aquatic organisms, leading to nervous, respiratory, reproductive, and hepatic abnormalities. OPs pesticides also disrupt the growth-promoting machinery in plants by inhibiting key enzymes, permeability, and trans-cuticular diffusion, which is crucial for plant growth. Excessive use of OPs, directly/indirectly affecting human/environmental health, raise a thoughtful global concern. Developing a safe, reliable, economical, and eco-friendly methods for removing OPs pesticides from the environment is thus necessary. Bioremediation techniques coupled with microbes or microbial-biocatalysts are emerging as promising antidotes for OPs pesticides. Here, we comprehensively review the current scenario of OPs pollution, their toxicity (at a molecular level), and the recent advancements in biotechnology (modified biocatalytic systems) for detection, decontamination, and bioremediation of OP-pesticides in polluted environments. Furthermore, the review focuses on onsite applications of OPs degrading enzymes (immobilizations/biosensors/others), and it also highlights remaining challenges with future approaches.

Bio-catalytic system of metallohydrolases for remediation of neurotoxin organophosphates and applications with a future vision.

Organophosphates (OPs) compounds are universally used as pesticides and maintained as chemical warfare agents by many nations across the globe. These OPs compounds due to their molecular structure are highly persistent in nature, contaminating soil and water equally, thereby adversely affecting terrestrial and aquatic life, and contributing to millions of poisoning cases every year worldwide. Therefore, there are urgent requirements for safe and rapid method for environmental restoration and therapeutic detoxications. Organophosphate hydrolyzing enzymes are emerging as an attractive candidate for the degradation of OPs compounds. The biologically driven approach is safe, rapid, and environment-friendly. As genetically modified microbes are not in practice worldwide, scientists are exploring different bioremediation approaches that mainly focus on cell-free biocatalytic systems. In this review, we have discussed the prevalence of OPs hydrolyzing enzymatic systems and the recent advancement of enzyme engineering in enhancing the catalytic activity, substrate specificity, and half-life. It highlights the application in OPs detection, decontamination (environmental bioremediation), and therapeutic detoxification using approaches like immobilization. We have also described the remaining challenges and future prospects.

Improved live-cell PCR method for detection of organophosphates degrading opd genes and applications.

Organophosphates are becoming an emerging pollutant due to their various applications, particularly as pesticides. In this study, an improved Colony (Live-cell) PCR method was developed for the detection of opd genes from bacteria encoding the organophosphate hydrolase enzymes capable of degrading various organophosphates. The improved method does not require pre-heating or pre-lysis of bacterial cells as essential in the conventional colony PCR. The reaction volume was scaled down to 10 µl by optimizing the PCR buffer and amplification conditions. The improved method was used for Gram positive and negative bacteria, glycerol stocks, liquid cultures, recombinant and mutant strains. Also, 16S rRNA gene was amplified from unknown environmental isolates and known E. coli strains. The amplified opd and 16S rRNA genes from the improved colony PCR method and by conventional PCR were sequenced, and similar results were obtained from both techniques. Thus, the improved method can be further explored in molecular biology or during biomarker studies. KEY POINTS: • Improved colony PCR method was developed for screening of opd genes from bacteria. • Method was validated for Gram positive/negative bacteria from solid as well as liquid media. • The improved method was rapid, efficient, and can be applied under various conditions.

A novel organophosphate hydrolase from Arthrobacter sp. HM01: Characterization and applications.

Bioremediation systems coupled to efficient microbial enzymes have emerged as an attractive approach for the in-situ removal of hazardous organophosphates (OPs) pesticides from the polluted environment. However, the role of engineered enzymes in OPs-degradation is rarely studied. In this study, the potential OPs-hydrolase (opdH) gene (Arthrobacter sp. HM01) was isolated, cloned, expressed, and purified. The recombinant organophosphate hydrolase (ropdH) was âˆ¼29 kDa; which catalyzed a broad-range of OPs-pesticides in organic-solvent (∼99 % in 30 min), and was found to increase the catalytic efficiency by 10-folds over the native enzyme (kcat/Km: 107 M-1s-1). The degraded metabolites were analyzed using HPLC/GCMS. Through site-directed mutagenesis, it was confirmed that, conserved metal-bridged residue (Lys-127), plays a crucial role in OPs-degradation, which shows âˆ¼18-folds decline in OPs-degradation. Furthermore, the catalytic activity and its stability has been enhanced by >2.0-fold through biochemical optimization. Thus, the study suggests that ropdH has all the required properties for OPs bioremediation.

Degradation insight of organophosphate pesticide chlorpyrifos through novel intermediate 2,6-dihydroxypyridine by Arthrobacter sp. HM01.

Organophosphates (OPs) are hazardous pesticides, but an indispensable part of modern agriculture; collaterally contaminating agricultural soil and surrounding water. They have raised serious food safety and environmental toxicity that adversely affect the terrestrial and aquatic ecosystems and therefore, it become essential to develop a rapid bioremediation technique for restoring the pristine environment. A newly OPs degrading Arthrobacter sp. HM01 was isolated from pesticide-contaminated soil and identified by a ribotyping (16S rRNA) method. Genus Arthrobacter has not been previously reported in chlorpyrifos (CP) degradation, which shows 99% CP (100 mg L-1) degradation within 10 h in mMSM medium and also shows tolerance to a high concentration (1000 mg L-1) of CP. HM01 utilized a broad range of OPs pesticides and other aromatic pollutants including intermediates of CP degradation as sole carbon sources. The maximum CP degradation was obtained at pH 7 and 32 °C. During the degradation, a newly identified intermediate 2,6-dihydroxypyridine was detected through TLC/HPLC/LCMS analysis and a putative pathway was proposed for its degradation. The study also revealed that the organophosphate hydrolase (opdH) gene was responsible for CP degradation, and the opdH-enzyme was located intracellularly. The opdH enzyme was characterized from cell free extract for its optimum pH and temperature requirement, which was 7.0 and 50 °C, respectively. Thus, the results revealed the true potential of HM01 for OPs-bioremediation. Moreover, the strain HM01 showed the fastest rate of CP degradation, among the reported Arthrobacter sp.