Research Article
Asghari Bano, Asim Shahzad, Sa
Abstract
Rhizoremediation involves the use of plant growth promoting rhizobacteria (PGPR) to remove organic pollutants from terrestrial environment. The main objective of this study was to evaluate the efficiency of rhizoremediation through inoculation of hydrocarbon degrading bacterial strains with and without nutrients in the rhizosphere sporadically become contaminated with oily sludge. Bacterial strains viz. Bacillus cereus (Acc KF859972), Bacillus altitudinis (Acc KF859970), comamonas (Acc KF859971) and Stenotrophomonas maltophilia (Acc KF859973) were isolated from various oily waste pits of oil fields. Autoclaved soil was treated with oily sludge at 7:3 ratio and Alfalfa plant was inoculated with individual plant growth promoting rhizobacteria (PGPR) with and without diammonium phosphate and ammonium nitrate. The different saturates and total hydrocarbon was extracted by Soxhelt extraction and was analyzed by GC-FID at 0, 5 and 10 d of incubation. The inoculation 30% sludge with B. altitudinis accelerated the rate of degradation of n-alkanes and some methyl branched than un-inoculated soils. Oily sludge inoculated with B. altitudinis indicated that more than 80% of hydrocarbons were degraded at day 5 of incubation. No further degradation was observed till the end of the incubation period. B. altitudinis is capable of degrading straight chain hydrocarbons rapidly than any other strains. Alfalfa is a N-symbiotic plant and increased nutrient content under the rhizosphere promote degradation of n-alkanes. All other bacterial strains also showed significant interaction with alfalfa for the biodegradation of oily sludge but the rate of degradation remained slow than with B. altitudinis. Inoculation with B. altitudinis accelerated the rehabilitation process and within 5 days the rehabilitation occurs.