Molecular Characterisation and Plasmid Profiling of Hydrocarbon Utilizing Bacteria Isolates from Wetlands in Rivers State, Southern Nigeria

Abstract

Wetlands can intercept runoff from surfaces prior to reaching open water and remove pollutants through physical, chemical, and biological processes thereby protecting and preserving the environment.  Because of unsustainable oil exploration activities, most wetlands in Rivers State, Southern Nigeria have suffered severe petroleum-damaged ecosystems. This research was carried out to characterize and identify the hydrocarbon utilizing bacteria associated with crude oil polluted wetlands and to screen for the presence of plasmids that could confer resistance to antibiotics using both cultural and molecular methods. Soil samples were collected from three different wetlands across the state with hand auger at two depths of 0-15cm and 15-30cm twice monthly for three months. The presence of microbial activity was determined by the enumeration and isolation of total heterotrophic and hydrocarbon utilizing bacteria. Eight (8) most occuring hydrocarbon utilizing bacterial isolates were isolated and identified culturally and phenotypically from the 54 wetland soil samples. These bacteria isolates were confirmed to be Bacillus flexus, Bacillus subtilis, Lysinibacillus macroides, Staphylococcus aureus, Chryseobacterium aquifrigidense, Pseudomonas aeruginosa and Salmonella enterica molecularly via sequencing of the 16S rRNA gene. The most common bacteria isolated were Bacillus species, followed by Pseudomonas at a dilution of 106.   Seven (7) out of the eight (8) isolates (except Salmoella enterica) showed the presence of the 25kb plasmids at various intensities.