Oil Spill Bioremediation by Pseudomonas sps and its Potential in Energy Recovery using Microbial Fuel Cells

Oil contamination in soils poses a significant environmental challenge, necessitating effective and sustainable remediation strategies. Bioremediation employs microbes to break down pollutants into non-toxic products. Pseudomonas spp. metabolically versatile, gram-negative bacteria are especially effective, using enzymes (e.g., lipases, oxygenases) and biosurfactants to degrade hydrocarbons into CO₂, water, and biomass. Various factors, such as bacterial concentration, temperature, pH, and the specific carbon source used influence degradation. Pseudomonas employs a variety of enzymes, including mono- and dioxygenases, for hydrocarbon and aromatic compound oxidation. Moreover, it secretes biosurfactants like rhamnolipids, which enhance the bioavailability of hydrophobic substrates like oil by emulsification. Key species such as P. putida, P. aeruginosa, and P. mendocina can degrade diverse oil components, including aromatic compounds.

This study investigates the bioremediation potential of Pseudomonas species for the degradation of oil contaminants in soils collected from various anthropogenic sources. Pure cultures of Pseudomonas were isolated, screened, and evaluated for their efficiency in degrading oil under controlled conditions using oil-spiked minimal media. The degradation efficiency was assessed based on microbial growth and reduction in oil content. The biodegradation of pollutants in oil blends by Pseudomonas sps results in the production of biomass, carbon dioxide (CO₂), and water (H₂O). The increase in optical density, which denotes higher cell proliferation, is evidence of hydrocarbon elimination during the study period. In this study, microbial growth is demonstrated in minimal Bushnell-Haas media, with the only carbon source being the supplied oil that was to be tested, for pure isolates of Pseudomonas.

Among the isolates, the strains demonstrating the highest adaptability and degradation rate were selected for further application. These selected strains were subsequently employed in a microbial fuel cell system to evaluate their potential for simultaneous bioremediation and energy recovery. In MFCs, bacteria oxidise organic matter at the anode, releasing electrons that generate current, enabling concurrent bioremediation and energy recovery. The constructed MFCs were able to generate small amounts of voltage individually. Peak voltage was obtained after 2 days of inoculation. Connecting multiple microbial fuel cells in series shows a stable power output and a higher combined voltage than individual cells, validating the feasibility of scaling up for bioremediation sites. However, a slight decline in voltage over time suggests possible substrate depletion, reduced microbial metabolic activity, or increased internal resistance within the system.

The study highlights the feasibility of utilizing Pseudomonas species in integrated systems for environmental cleanup and sustainable energy generation, with prospects for future scale-up and practical applications.