Potential of Stenotrophomonas maltophilia GB1 in the Biodegradation of weathered heavy crude oil (Maya)

Background. CC (GB1) strain was isolated from a crude oil flow station saver pit effluent in Nigeria. Our original observation of it as an organism of medical importance was borne on its multiple resistance to antibiotics. However, its ability to utilize hydrocarbons solely as a carbon source biodegradation encouraged our assessing its potential for use in bioremediation of crude oil polluted environment. Methods. In this study, the potential of a Stenotrophomonas maltophilia (GB1) strain in the degradation of weathered heavy Mexican crude oil (Maya) using 0.1 and 0.4% (w/v) concentrations of the oil was examined. Results. In both concentrations, multiphasic biomass peaks were observed with average growth rates of 0.055 hr-1 and 0.036 hr-1 for 0.1% and 0.4% oil respectively. The corresponding biodegradation rates were 0.007 mg·day-1 and 0.0023 mg·day-1, with the total metabolized oil being 2.9 mg and 6.5 mg during 12 days reaction period for the two concentrations respectively. The bacterium carries a multiple antibiotic resistant factor for ten of the twelve antibiotics used, and was sensitive only to sulfamethoxazol-trimethoprim. It also harbours a plasmid of about 10 kb that lacked restriction sites for six base cutters KpnI, BamHI, BglII, EcoRI, XbaI, EcoRV, Pst1 and HindIII, but was digested by the four base cutters Rsa1 and Sau3a1. Conclusions. This Stenotrophomonas maltophilia has a potential for application in bioremediation of crude oil pollution but its multiple resistance to antibiotics constitutes a serious setback and emphasises the need for proper scrutiny of candidate organisms for bioremediation applications.