Heavy Metal Tolerance profile among Bacterial species Isolated from Hydrocarbon polluted sites and their mobile genetic elements

Abstract

This present study evaluated the plasmid incidence in bacteria and their genetic elements in heavy metals tolerant-antibiotics resistant microbes isolated from petroleum hydrocarbon polluted sites. The plasmid isolation was carried out using the fermentas Genejet plasmid miniprep kit (Thermofisher Scientific Inc, USA). Screening for class 1, 2, and 3 integrons, incompatibility group P testing, plasmid replicon typing, plasmid restriction analysis, and other analysis was performed using standard laboratory procedures. Plasmid incidences were higher among multiple heavy metal-tolerant bacterial species from hydrocarbon-polluted sites than those from the pristine site. Further, Class 1 integron incidence was significantly higher among the integrons in heavy metal tolerant bacterial isolates isolated from the polluted ecosystems than those from pristine ecosystems. Plasmid replicon type of bacteria with multiple heavy metal tolerance and antibiotics resistance indexes revealed that IncN plasmid replicon type carrying class 1 integron. This encodes resistance to sulphamethazole/trimethoprim, ampicillin, and tolerance to Cd, Ni, and Cu in Klebsiella pneumoniae isolate from petroleum-polluted soil. This is the first report of IncN plasmid in environmental bacteria in Nigeria, particularly from petroleum polluted environment. The conjugation experiment confirmed the possible transferability of antibiotic resistance determinants among isolates in polluted ecosystems. From the results of this study, it can be concluded that petroleum hydrocarbon pollution vis-a-vis heavy metal selective pressure with the abundance of mobile genetic elements amongst isolates from polluted ecosystems could contribute to the dispersing of antibiotic resistance genes, thus posing a serious public health concern.