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Soil bacteria showing a potential of chlorpyrifos degradation and plant growth enhancement.

ABSTRACT: Since 1960s, the organophosphate pesticide chlorpyrifos has been widely used for the purpose of pest control. However, given its persistence and toxicity towards life forms, the elimination of chlorpyrifos from contaminated sites has become an urgent issue. For this process bioremediation is the method of choice.Two bacterial strains, JCp4 and FCp1, exhibiting chlorpyrifos-degradation potential were isolated from pesticide contaminated agricultural fields. These isolates were able to degrade 84.4% and 78.6% of the initial concentration of chlorpyrifos (100mgL(-1)) within a period of only 10 days. Based on 16S rRNA sequence analysis, these strains were identified as Achromobacter xylosoxidans (JCp4) and Ochrobactrum sp. (FCp1). These strains exhibited the ability to degrade chlorpyrifos in sterilized as well as non-sterilized soils, and were able to degrade 93-100% of the input concentration (200mgkg(-1)) within 42 days. The rate of degradation in inoculated soils ranged from 4.40 to 4.76mg(-1)kg(-1)d(-1) with rate constants varying between 0.047 and 0.069d(-1). These strains also displayed substantial plant growth promoting traits such as phosphate solubilization, indole acetic acid production and ammonia production both in absence as well as in the presence of chlorpyrifos. However, presence of chlorpyrifos (100 and 200mgL(-1)) was found to have a negative effect on indole acetic acid production and phosphate solubilization with percentage reduction values ranging between 2.65-10.6% and 4.5-17.6%, respectively. Plant growth experiment demonstrated that chlorpyrifos has a negative effect on plant growth and causes a decrease in parameters such as percentage germination, plant height and biomass. Inoculation of soil with chlorpyrifos-degrading strains was found to enhance plant growth significantly in terms of plant length and weight. Moreover, it was noted that these strains degraded chlorpyrifos at an increased rate (5.69mg(-1)kg(-1)d(-1)) in planted soil.The results of this study clearly demonstrate that the chlorpyrifos-degrading strains have the potential to develop into promising candidates for raising the productivity of crops in pesticide contaminated soils.

SUBMITTER: Akbar S

PROVIDER: S-EPMC4927687 | biostudies-literature | 2016 Jul-Sep

REPOSITORIES: biostudies-literature

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Soil bacteria showing a potential of chlorpyrifos degradation and plant growth enhancement.

Akbar Shamsa S Sultan Sikander S

Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology] 20160420 3

<h4>Background</h4>Since 1960s, the organophosphate pesticide chlorpyrifos has been widely used for the purpose of pest control. However, given its persistence and toxicity towards life forms, the elimination of chlorpyrifos from contaminated sites has become an urgent issue. For this process bioremediation is the method of choice.<h4>Results</h4>Two bacterial strains, JCp4 and FCp1, exhibiting chlorpyrifos-degradation potential were isolated from pesticide contaminated agricultural fields. Thes ...[more]

PMID: 27266625

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Project description:Among the biotic and abiotic stress affecting the physical, chemical, and biological properties of soil, salinity is a major threat that leads to the desertification of cultivable land throughout the world. The existence of diverse and versatile microbial populations inhabiting the nutrient-rich soil and varied soil conditions affects the soil dynamism. A normal soil constitutes 600 million bacteria belonging to about 20,000 species, which is reduced to 1 million with 5,000-8,000 species in stress conditions. Plant growth-promoting rhizobacteria (PGPR) are in symbiotic association with the plant system, which helps in combating the abiotic stress and increases the overall productivity and yield. These microorganisms are actively associated with varied cellular communication processes through quorum sensing and secondary metabolites such as the production of Indole-3-acetic acid (IAA), exopolysaccharide (EPS) siderophore, ammonia, ACC deaminase, and solubilization of phosphate. The present study focused on the isolation, identification, and characterization of the microorganisms isolated from the seacoast of Dandi, Navsari. Twelve isolates exhibited PGP traits at a high salt concentration of 15-20%. AD9 isolate identified as Bacillus halotolerans showed a higher ammonia production (88 ± 1.73 μg/mL) and phosphate solubilization (86 ± 3.06 μg/mL) at 15% salt concentration, while AD32* (Bacillus sp. clone ADCNO) gave 42.67 ±1.20 μg/mL IAA production at 20% salt concentration. AD2 (Streptomyces sp. clone ADCNB) and AD26 (Achromobacter sp. clone ADCNI) showed ACC deaminase activity of 0.61 ± 0.12 and 0.60 ± 0.04 nM α-ketobutyrate/mg protein/h, respectively. AD32 (Bacillus sp. clone ADCNL) gave a high siderophore activity of 65.40 ± 1.65%. These isolates produced salinity ameliorating traits, total antioxidant activities, and antioxidant enzymes viz. superoxide dismutase (SOD), Glutathione oxidase (GSH), and catalase (CAT). Inoculation of the multipotent isolate that produced PGP traits and salinity ameliorating metabolites promoted the plant growth and development in rice under salinity stress conditions. These results in 50% more root length, 25.00% more plant dry weight, and 41% more tillers compared to its control.

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Soil bacteria showing a potential of chlorpyrifos degradation and plant growth enhancement.

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Soil bacteria showing a potential of chlorpyrifos degradation and plant growth enhancement.

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