Bioremediation of Methomyl by Soil Isolate - Pseudomonas aeruginosa

Abstract

Bioremediation is emerging as one of the most promising technology for the removal of xenobiotics. Bioremediation of xenobiotic compounds by microorganisms is a crucial phenomenon by which these compounds can be detoxified or removed from the environment, thus preventing pollution, where screening of the potential degrading organism is one of the key step. Methomyl belonging to N-methyl carbamate group of insecticide is the most commonly used pesticide on fruits and vegetables. It is classified as a toxic, hazardous and restricted use pesticide by the World Health Organization (WHO), European Commission (EC) and Environmental Protection Act (EPA). The present study is therefore aimed to isolate a soil bacterium, characterize the most potential degrader of methomyl and further determine the role of plasmid in bioremediation. Soil samples were collected from different areas around Karnatak University campus, Dharwad and inoculated in minimal medium containing methomyl (10-3 M). Morphological characteristics of ten isolates were studied and subjected to HPLC analysis where methomyl degradation (%) was observed. The most potential strain with the ability to degrade methomyl was inoculated in synthetic medium containing methomyl (10-3 M) for 96 hrs. This strain was further identified morphologically, biochemically and genetically. The results indicated that the isolated strain was gram-ve rods and biochemical characteristics showed that indole, methyl red, vogues prauskauer and H 2 S test was negative and citrate, catalase, gelatin hydrolysis and oxidase test was positive. The 16Sr DNA reports revealed that the accession number was G01801181 and showed 99% similarity to Pseudomonas aeruginosa.The present study on HPLC analysis at regular intervals of 24 hrs of the soil isolate-Pseudomonas aeruginosa in synthetic medium containing methomyl (10-3 M) incubated for 96 hrs revealed that there was a significant decrease in the methomyl content in the treated group when compared with the initial control demonstrating its potential use in bioremediation. The plasmid isolation and curing study confirmed that the genes of the plasmid of Pseudomonas aeruginosa are involved in the methomyl degradation and such plasmids could be used as recombinant DNA technology for bioremediation.

Chromosomal and plasmid mediated degradation of crude oil by Bacillus coagulans, Citrobacter koseri and Serratia ficaria isolated from the soil

“…It must be mentioned that Bacillus spp. have been isolated from different environment including extreme environment, implicated in many hydrocarbon biodegradation researches and also known to be versatile in their substrate usage (Sepahi et al, 2008;Olukunle andBoboye, 2013: Lateef andOluwafemi, 2014;Kulkarni and Kaliwal, 2015;Maduka and Okpokwasili, 2016). These are the reasons why B. coagulans had the shortest adjusting period (lag phase) which resulted to highest degradation percentage Table 3.…”

“…Plasmid mediated degradation of substances by some bacteria have also been documented. Plasmid-mediated degradation of dimethoate was observed in Pseudomonas aeruginosa and Bacillus licheniformis; Chlorpyrifos by Micrococcus, Enterobacter and Pseudomonas with plasmid borne genes for its degradation (Guha et al, 1997;Singh et al, 2003;Bhagobaty and Malik, 2008;Kulkarni and Kaliwal, 2015).…”

“…These degradative abilities occur in high frequencies with much greater quantitative prominence after pollution (Shukla et al, 2006). There was proposition that the development of resistant/degradative population in a polluted site can lead to gene transfer (vertical or horizontal gene transfer), transposons transfer, plasmids transfer and possible spontaneous mutants due to the presence of pollutants (Kulkarni and Kaliwal, 2015). A plasmid is a DNA molecule that is separate and can replicate independently of the chromosomal DNA.…”

“…Plasmids are sub-grouped into five main types based on phenotypes: Fertility-F-plasmids, virulence plasmids, resistance-(R) plasmids, col-plasmids and degradative plasmid. Degradative plasmid enables the digestion of unusual substances, such as hydrocarbons, pesticides, plastic and other xenobiotics (Kulkarni and Kaliwal, 2015). The degradative ability of a bacteria which could be chromosomal or plasmid mediated can be improved by conducive environment, long time exposure to materials been degraded and producing mutant species or engineered species.…”

Biodegradation of the fungicide propiconazole by Pseudomonas aeruginosa PS-4 strain isolated from a paddy soil

“…Hence, soil microorganisms are considered a key reservoir of biological activity with the potential to significantly enhance environmental cleanup (Dong et al 2008;Satapute et al 2012;Kulkarni and Kaliwal 2014). Many pesticide-degrading microorganisms have been reported belonging to various species of bacteria, fungi, algae and yeast.…”