Phytoremediation of Petrochemicals form Wastewater using Endophytic Bacteria

Abstract

Phytoremediation in association with endophytic bacteria has been proposed as a promising approach to remediate environmental contaminants. The main aim of present work was to assess in-situ association potential of isolated endophytic bacterial strain Pseudomonas sp. J10 (KY608252) with two cultivars of L. perenne (small and jumbo) and Arabidopsis thaliana, diesel hydrocarbons degradation, alkb gene expression and phytotoxicity analysis. A plant-microbe phytoremediation system was established to investigate the bacteria’s ability to colonize the plant body and quantification of alkane monooxygenase (alkb) gene to help withstand diesel hydrocarbon stress in soil as well as in hydroponics. A real-time PCR method was developed to analyze bacterial colonization and survival within the plant body while GC-FID was used to observe diesel hydrocarbon degradation within the system. The analysis revealed that Pseudomonas sp. (J10) efficiently colonized all the tested plant species and expressed alkb gene under hydrocarbon stress ranging between 3.7x102 - 3.9x106 in A. thaliana and L. perenne (small), respectively. The colonization was more pronounced in soil as compared to hydroponics. Pseudomonas sp. (J10) inoculation reduced phytotoxicity in all the systems and suggested that inoculation had a positive effect on plant growth under stress conditions as compared to control. L. perenne (small) showed significant total petroleum hydrocarbon (TPH) removal efficiency (45.6%) followed by L. perenne jumbo (24.5%) and A. thaliana (6.2%). In hydroponics, L. perenne (small) degraded about 28.2% TPH followed by L. perenne (jumbo) as 24.4%. The potential of the indigenously isolated plant endophytes may be exploited further for phytoremediation efficiency and industrial applications. Keywords: Lolium perenne; Arabidopsis thaliana; alkb gene; endophytic relationship; petroleum hydrocarbon degradation.