Efficient Bioremediation of Petroleum Hydrocarbon Wastes by Some Bacterial Strains Isolated from Soil in Yemen

Abstract

Petroleum pollution is a well-known problem identified both locally and internationally, which can cause multiple environmental damages and may lead to significant disturbances in the biotic and abiotic components of ecosystems. This study aims to determine certain physical properties of one type of Yemeni crude oil, isolate and identify bacteria that degrade petroleum hydrocarbons, and screen the identified bacterial isolates for their ability to degrade petroleum hydrocarbon wastes. Twenty soil samples (contaminated and non-contaminated with petroleum derivatives) were collected from 4 different governorates (Capital Secretariat, Sana'a, Al-Hudaydah, and Marib). The serial dilution method was used from 10^-2 dilution on Bushnell and Haas agar medium containing 1% v/v of crude oil by using the spreading method.  Colorimetric assay by 2,6-Dichlorophenol indophenol (2,6-DCPIP indicator) was done to screen identified bacterial isolates for their ability to degrade petroleum hydrocarbon wastes. The results showed that crude oil, which was used as a sole carbon source and other additives, was identical to local and international standards according to the Yemeni petroleum company databases.  All soil samples that contained bacteria were able to grow on BHA medium.  From 40 bacterial isolates, only 26 were identified to genus / species and selected for screening of petroleum hydrocarbon waste degradation. Most common bacterial isolates were Pseudomonas spp. (23.07%), followed by Bacillus spp., and Streptococcus spp. (19.23%) each, Enterococcus spp. (11.53%), Staphylococcus aureus and Enterobacter spp. (7.69%) each and the least common were Morganella morganii, Providencia stuartii, and Proteus vulgaris each represents 3.84%. Our results showed that 13 identified bacterial isolates represented 50% of the total identified isolates showed the highest ability to degrade petroleum hydrocarbon wastes at the shortest time (3- 12 hrs.), 9 identified bacterial isolates represented 34.61% showed moderate ability of degradation at 13-24 hrs. Therefore, this study concluded that bioremediation using bacteria is sustainable and cost-effective. More attention to the management and cleanup efforts of these pollutants based on their type.