Biodegradation of aliphatic and polycyclic aromatic hydrocarbons by the thermophilic bioemulsifier-producing Aeribacillus pallidus strain SL-1

The utilization of thermophilic hydrocarbon-degrading microorganisms is a suitable strategy for improving biodegradation of petroleum hydrocarbons and PAHs, as well as enhancing oil recovery from high-temperature reservoirs. In this study, the thermophilic strain Aeribacillus pallidus SL-1 was evaluated for the biodegradation of crude oil and PAHs at 60 °C. Strain SL-1 was found to preferentially degrade short-chain n-alkanes (<C17) and aromatic hydrocarbons from crude oil. The highest degradation rate of 84% was obtained with 1000 mg/l naphthalene as sole carbon source. Additionally, the strain was able to degrade 80% of phenanthrene (200 mg/l) and 50% of pyrene (50 mg/l) within 5 days at 60 °C. The SL-bioemulsifier produced by strain SL-1 was identified as a glycoprotein with stable emulsifying activity over a wide range of environmental conditions. Chemical composition studies exhibited that the SL-bioemulsifier consisted of polysaccharides (65.6%) and proteins (13.1%), among them, proteins were the major emulsifying functional substrates. Furthermore, the SL-bioemulsifier was able to enhance the solubility of PAHs. Thus, the bioemulsifier-producing strain SL-1 has great potential for applications in high-temperature bioremediation.