Biodegradation of hydrocarbons in marine sediment from Bangkhuntien, Bangkok, Thailand

Abstract

Biological method is an important alternative for solving petroleum hydrocarbon contamination issue because it is environmental friendly, low cost and has a potential to effectively remediate the oil. The objectives of this study were; 1) to estimate the biodegradation rate of diesel, hexadecane, and phenanthrene in marine sediment by using Gas Chromatography with Flame Ionization Detector (GC-FID) to monitor the remaining amount of hydrocarbons and constructing the degradation plot of each hydrocarbon per time for calculation of the degradation rate, 2) to investigate the hydrocarbon-degrading bacterial community in marine sediment by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) technique and 3) to isolate diesel-, hexadecane- and phenanthrene-degrading bacteria using media with each hydrocarbon as a sole carbon source. In this study, there were 3 interesting hydrocarbons including diesel, hexadecane and phenanthrene. The marine sediments were collected from Bangkhuntien, Thailand to use as a surrogate of a chronically hydrocarbon contaminated bay marine ecosystem. The results from hydrocarbon-contaminated microcosms showed that the removal percentage and the degradation rates for 500 mg kg sediment-1 diesel were 84% and 81.96 mg kg sediment-1 day-1, for 250 mg kg sediment-1 hexadecane were 99% and 86.43 mg kg sediment -1 day-1 and for 125 mg kg sediment-1 phenanthrene were 96% and 9.03 mg kg sediment-1 day-1, respectively. The dominant bacterial populations analyzed by PCR-DGGE technique were mostly recognized as halophilic- hydrocarbon degrading bacteria. The isolated strains from enrichment technique were belonged to Acinobacter sp., Bacillus sp. and Staphylococcus sp. from hexadecane supplemented broth. We also isolated Pseudomonas sp. from phenanthrene supplemented broth and Bacillus sp. and Pseudomonas sp. from diesel supplemented broth. Although, the species of isolated bacteria were different from those detected by PCR-DGGE technique. The overall results suggested that bioremediation and indigenous bacteria in marine sediments could be applied to treat the contaminated hydrocarbons.