Statistical optimization of crude oil bioremediation using Streptomyces aurantiogriseus isolated from Egypt's Western Desert.

Abstract

One of the most common soil pollutants on a global scale is fuel, which is fundamental for daily activities. Biodegradation has been regarded as an ideal remediation technique for hydrocarbon pollution. We investigated the potential of 28 Streptomyces species inhabiting different hydrocarbon-polluted soils for the biodegradation of petroleum. The tested isolates were cultured on mineral salts broth containing 2% crude oil as the sole carbon source. Gravimetric analysis of residual crude oil was performed, and the samples that showed the highest percentage of biodegradation were also analyzed via gas chromatography. Among the isolated actinobacteria, Streptomyces aurantiogriseus strain NORA7 (EMCC 28565) stood out for its ability to degrade crude oil (66.28 ± 6.25%). Gas chromatography revealed that docosane, nonadecane, pentacosane, and 7-methylpentadecane were the major compounds detected in the residual treated crude oil. Plackett-Burman design (PB) was used to determine the critical factors impacting the biodegradation process. Response surface methodology (RSM) through Central Composite Design (CCD) was subsequently conducted, and the predicted optimum point of crude oil biodegradation was at 3% crude oil concentration, 0.15 g/L yeast extract, and 25 mm inoculum size. The experimental value after optimum conditions was 70% after 3 weeks, which was close to the predicted value. A pot experiment was performed to investigate the outcomes of ex situ soil bioremediation, and the results were consistent with those of the flask-scale biodegradation experiment with enhanced removal of crude oil (92%). The results revealed that the ability of S. aurantiogriseus NORA7 to biodegrade crude oil could significantly contribute to the eco-friendly recovery of oil-polluted ecosystems and reduce the long-term environmental impact of crude oil pollution.