Biodegradation of Isoproturon by Bacillus pumilus K1 Isolated from Foothill Agroecosystem of North West Himalaya

Abstract

Isoproturon (IPU) degrading bacterium was isolated from herbicide treated soils. Morphological, biochemical and 16S rRNA sequencing revealed that the strain belonged to the phylogeny of the Bacillus sp. (99 % sequence similarity with Bacillus pumilus FM 201790.1) hence designated as B. pumilus K1. Biodegradation study was carried out using 200 mg L -1 IPU as sole source of carbon at three pH levels i.e. 6.5, 7.0 and 7.5 and three temperatures i.e. 25, 30 and 35°C. In the first 5-10 days IPU biodegradation was slow, which was later accelerated. The IPU degrading potential of B. pumilus K1 was strongly influenced by pH and temperature with maximum degradation at pH 7.0 and 30°C followed by pH 7.5 and 35°C at the end of 20 days. However, at pH 6.5 and 25°C least IPU degradation was observed. The optimum conditions for isoproturon degradation by this bacterial isolate were pH 7.0 and 30°C temperature. Addition of supplementary carbon source enhanced 4.07 % IPU degradation. 4-Isopropylaniline was detected as IPU degradation by-product in the medium. The study clearly exhibited that B. pumilus K1 was able to metabolize IPU effectively and thus could be employed for development of field scale bioremediation technology.

Biodegradation of isoproturon by Escherichia coli expressing a Pseudomonas putida catechol 1,2-dioxygenase gene

“…The expressed E. coli showed a high biodegradation efficiency compared with the P. putida wild-type. Biodegradation efficiency was determined using HPLC by determining the remaining IPU after the incubation period, it was observed that at first five days, the efficiency of expressed E. coli degradation was slow in comparison to P. putida , which could demonstrate the lag phase while it got accelerated as the incubation performed, most probable due to enzymes activation in the inoculated cultures (Giri et al 2017 ). In this study, gene expression analysis of cloned catA was compared to catA expression from P. putida using qPCR.…”

“…The HPLC analysis was carried out at room temperature. Residual IPU concentration was quantified utilizing a standard curve plotted between the IPU knew concentration and mass absorbance unit (mAU) (Giri et al 2017 ). All the HPLC solvents (the dichloromethane cat.…”

Biodegradation of isoproturon by Pseudoxanthomonas sp. isolated from herbicide-treated wheat fields of Tarai agro-ecosystem, Pantnagar

“…Residual IPU and its metabolites were extracted and processed using the previously described methodology (Giri et al 2015 ). The IPU extracts were then analyzed using Dionex HPLC equipped with auto sampler and Acclaim 120, C 18 5 µm 4.6 × 250 mm column.…”

“…Biostimulation involves the addition of adequate nutrients in the medium to enhance pesticide degradation potential of native microbes (Couto et al 2010 ) or to promote cometabolism (De Lorenzo 2008 ). Biostimulation is one of the major strategies, which has been implemented for the bioremediation of a wide variety of xenobiotics (Kadian et al 2008 ; Giri et al 2015 ). Although the microbial communities existing in contaminated sites harbour the pesticide catabolising genes and enzymes, lack of electron acceptors or donors, nutrient availability or delayed stimulation of the metabolic pathways essential for degradation acts as limiting factors for pesticide degradation.…”