Aims: This study aimed to isolate and identify hydrocarbon-utilising bacteria from oil- polluted sites and to develop a microbial consortium for use in pilot trial and commercial scale bioremediation treatment systems in the future. Methodology and results: Ten hydrocarbon-utilising bacterial strains were isolated using enrichment culture technique from oil-polluted sites using crude oil as sole carbon source. The strains were tentatively identified on the basis of colony morphology, microscopic examination and biochemical characteristics. The growth of each strain was assessed by growing the bacteria in mineral salt medium amended with diesel oil as sole carbon source. The isolates exhibited differences in growth with the order of biomass production being Enterobacter sp. (OD620=1.283)> Bacillus subtilis subsp. subtilis (OD620=1.245) > Aerococcus sp. (OD620=1.100) > Bacillus firmus (OD620=0.970) > Corynebacterium sp. (OD620=0.886) > Bacillus lentus (OD620=0.743) > Micrococcus luteus (OD620=0.656) > Bacillus subtilis (OD620=0.367) > Bacillus cereus (OD620=0.110) > Kocuria flavus (OD620=0.065). Conclusion, significance and impact of study This study is a prerequisite for the design of future full-scale bioremediation treatment of oil-polluted sites using hydrocarbon-utilising bacteria. An efficient consortium was developed comprising the best three hydrocarbon-utilising strains, which include Enterobacter sp., Bacillus subtilis subsp. subtilis and Aerococcus sp. This efficient microbial consortium is suggested to be used in future to rehabilitate oil-polluted sites in Sudan.
Oil and Gas Fields--microbiology

Most main oilfields in China have already entered a "double high" development stage (high water cut, high recovery degree). To further enhance oil recovery in reservoirs after polymer flooding (RAPFs), an efficient activator formulation for promoting metabolism of endogenous microorganism was studied by aerogenic experiments, physical simulation experiments, electron microscopy scanning and pyrophosphate sequencing. Results show that the activator could activate the endogenous microorganisms in the injected water and make the pressurized gas reach 2 MPa after 60 d static culture of the activator in a high pressure vessel. The oil recovery efficiency of natural core physical simulation flooding can be improved by more than 3.0% (OOIP) in RAPFs when injected 0.35 PV activator with 1.8% mass concentration, and a lot of growth and reproduction of activated endogenous microorganism in the core was observed by electron microscopy scanning. Field trial with 1 injector and 4 producers was carried out in the east of south II block of Sa Nan in December 2011. By monitoring four effective production wells, changes of carbon isotope δ13C (PDB) content of methane and carbon dioxide were -45 per thousand to -54 per thousand and 7 per thousand to 12 per thousand. Compared with east II of Sa Nan block, the oil amount increased by 35.9%, water cut stabled at 94%. The incremental oil was 5 957 t during the three and a half years, which provides an alternative approach for further improving oil recovery in similar reservoirs.
Carbon Dioxide ; chemistry ; Carbon Isotopes ; analysis ; China ; Diphosphates ; chemistry ; Methane ; chemistry ; Oil and Gas Fields ; microbiology ; Polymers ; Water ; Water Microbiology