Bacteria Deterioration of Polyaromatic Hydrocarbon (PAH) Component of Premium Motor Spirit (PMS) from Underground Storage Tanks

Abstract

The study of Biodeterioration of Premium Motor Spirit (PMS) by bacterial deteriogens was conducted to ascertain the level of spoilage on petroleum samples obtained from two Petroleum Service Stations in Lagos State, Nigeria. The Spread plate technique was employed for the enumeration of the microorganisms. The samples were cultured on petri-dishes containing nutrient media and were incubated at a temperature of 30°C for 48 hours for bacterial growth. The bacterial isolates were further tested for hydrocarbon utilization potential with a modified mineral salt solution at room temperature for 48 hours. The bacterial isolates were aseptically reintroduced into freshly sterilized PMS samples and their deteriorating actions on the Polyaromatic hydrocarbon (PAH) component of these samples was verified using the gas chromatographic technique. PMS samples were sterilized using the membrane filtration technique. Results for the isolation showed a high range of total viable counts of Bacterial species such as Pseudomonas aeruginosa, Clostridium sporogenes, Bacillus subtilis, Aerococcus viridians, Staphylococcus aureus and Mycobacteria spp. associated with the PMS samples from the underground storage tanks. Bacillus subtilis was capable of causing a remarkable reduction in the PAH components (naphthylene, acenaphthalene and fluorine) of the PMS samples. The abundance in microbial growth in the petrol substrates was probably as a result of heavy contamination of the samples when in the underground storage tanks, and also the presence of moisture. It is therefore recommended that adequate spoilage-control measures, such as the prevention of the infiltration of moisture should be taken in order to prevent bio-attack of the petroleum products.