Integration of biosorption and biodegradation in a fed‐batch mode for the enhanced crude oil remediation

Microbial bioremediation of oil‐contaminated sites is still a challenge due to the slower rate and susceptibility of microbes to a higher concentration of oil. The poor bioavailability, hydrophobicity, and non‐polar nature of oil slow down microbial biodegradation. In this study, biodegradation of crude oil is performed in fed‐batch mode using an oil‐degrader Pseudomonas aeruginosa to address the issue of substrate toxicity. The slower biodegradation was integrated with faster biosorption for effective oil remediation. Highly fibrous and porous sugarcane bagasse was surface modified with hydrophobic octyl groups to improve the surface‐oil interactions. The microbe showed 2 folds enhanced oil degradation in the fed‐batch study, which was further increased by 1·5 folds in the integrated biosorption coupled biodegradation approach. The biosorption‐assisted biodegradation approach supported the microbial growth to 2 folds higher than the fed‐batch study without biosorbent. The analysis of biosurfactant production indicated the 3 folds higher concentration in fed‐batch modes as compared to batch study. In the integrated strategy, the concentration of contaminant (oil) reduces to quite a tolerable level to microbes, which improved effective metabolism and thus overall biodegradation. This study puts forward a promising strategy for improved degradation of hazardous hydrophobic contaminants in a sustainable, economic and eco‐friendly manner. Significance and Impact of the Study: Crude oil bioremediation exploits the hydrocarbon utilization ability of microbes for the synthesis of biosurfactants. The viscous complex mixtures of hazardous hydrocarbons make the crude oil poorly bioavailable decreasing the overall microbial biodegradation and biosurfactant production. This study puts forward an approach of integration of biosorption coupled microbial biodegradation technique in a fed‐batch mode. While hydrophobically modified biosorbent improves the oil affinity and thus bioavailability towards the microbes. The Fed‐batch approach further decreases the risk of substrate toxicity by intermittently feeding a lower concentration of oil. This approach thus improved biomass growth and in turn resulted in better oil degradation. Overall, this bioremediation approach mitigates the hazardous effects of crude oil and explores it as a potential substrate for microbial degradation and also biosurfactant production.