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.