Bioprospecting of potential petroleum hydrocarbon degraders using bacterial strains isolated from soils around transformer installation areas

ABSTRACT

The study assessed the contamination levels of the soils around transformer installation areas in Ile-Ife, which were contaminated with transformer oil. Contamination levels are determined by using some soil physicochemical properties (pH, electrical conductivity, and organic matter) and also identifying some hydrocarbon utilizing bacteria in the oil-contaminated soils. Soil samples were collected from transformer oil-contaminated and uncontaminated soils at 5−15-cm depth. Soil physicochemical properties were determined using standard methods. The soil samples were screened for hydrocarbon-degrading bacteria; the isolates were duly identified using the matrix-assisted laser desorption/ionization-time of flight/mass spectrometry technique. The growth rate of the bacterial isolates in the hydrocarbon medium was monitored. Thereafter, the residual oil was analyzed quantitatively and qualitatively using gravimetric and gas chromatography–mass spectrometry techniques, respectively. The results of the physiochemical parameters of the oil-contaminated soils showed that the soils had mean values of pH (5.01 ± 0.22), electrical conductivity (574.45 ± 63.35 µs/cm), and soil organic matter (50.53 ± 5.67 g/kg). The chromatogram of the residual oils from the biodegradation process showed the efficacy of Providencia stuartii and Bacillus pseudomycoides in degrading alkyl polycyclic aromatic hydrocarbons (PAHs), cycloalkanes, unsaturated alkanes, and unsaturated-branched alkanes, while Providencia rettgeri could adequately degrade cycloalkenes, cycloalkanes, unsaturated alkanes, and unsaturated-branched alkanes. In this study, novel hydrocarbon-degrading bacterial isolates were identified, and the extent of their hydrocarbon and complex organic compound utilization was shown, it suggests the need for further studies to explore their potentials in bioremediation programs.

KEYWORDS:

• Bioremediation
• hydrocarbon pollutants
• transformer oil
• soil
• hydrocarbon utilizing bacteria

Disclosure statement

The authors declare no conflict of interest.

Additional information

Notes on contributors

Nkem Torimiro

Nkem Torimiro holds a B.Sc. degree in Botany from the University of Port-Harcourt, Port Harcourt, Nigeria; MSc., PhD in Microbiology and Master in Public Health (MPH) degrees from the Obafemi Awolowo University, Ile-Ife, Nigeria. She is a senior lecturer of Medical Microbiology and Public Health with 12 years of teaching and research experience at the Department of Microbiology, Obafemi Awolowo University, Ile-Ife, Nigeria. She has peer reviewed published articles in Scientific journals of repute. She has successfully Co-supervised a Doctor of Philosophy student and supervised nine Master of Science students in the area of Medical Microbiology, Environmental and Public Health. She has served in many administrative positions in her institution. She has obtained international travel awards, Fellowship and a research grants. She possesses a robust work ethic and can work cohesively within a group. Dr. Torimiro is a certified biosafety professional. She has made concerted efforts towards sensitizing healthcare and biological agent workers on the importance of working responsibly with biological agents through seminars and training workshops. She is also a member of the pioneer team that revived the Ife Biotechnology Group at the Obafemi Awolowo University. The group has been organising yearly workshop on Southwest Agroecological Biosafety Awareness since 2016. Dr. Torimiro is a member of the Nigerian society of Microbiology, Nigerian Biosafety Association, American Microbiology Association amongst others. She can be contacted at: [email protected]; [email protected]; [phone]

Godswill E. Akhigbe

Godswill E. Akhigbe holds B.Sc. degree (Industrial chemistry) from Ambrose Alli University, Ekpoma; M.Sc. and Ph.D. Degree in Chemistry from Obafemi Awolowo University, Ile Ife, Nigeria. He is currently lecturing at the department of Chemical sciences, McPherson University, Seriki Sotayo, Nigeria. He has published some scholarly articles in reputable scientific journals. He is a member of the Royal Society of Chemistry and American Chemical Society. Godswill Ehimengbale Akhigbe is the corresponding author and can be contacted at: [email protected]; [email protected]. 

Festus M. Adebiyi

Festus M. Adebiyi holds a BTech Degree from the Federal University of Technology, Akure, Nigeria; MSc, PhD (Chemistry) and MBA Degrees from Obafemi Awolowo University (OAU), Ile-Ife, Nigeria; He is Professor of Analytical/Environmental and Petroleum Chemistry with 16 years of teaching and research experience at the OAU, Ile-Ife, Nigeria and was also a visiting Don to Westley University of Science and Technology, Ondo, Nigeria. He has completed supervision of crops of Masters and PhD research students and up to press, he presently has 72 publications in peer reviewed journals. He has also served in many administrative positions in his institution including the Vice Dean of his Faculty. He has also obtained prestigious overseas Commonwealth Research Fellowship, the United Kingdom and Wolfson Foundation Research Fellowship, the UK; acquired International Grant (TWAS-COSMTECH Research Grant for Individual Scientist) and attained 2nd best position of Dapo Afolabi Most Productive Science Scholar in his Faculty, and has been a Guest Lecturer/Speaker in academic and public fora. He serves as a reviewer for many national and international scholarly journals; an internal examiner to some Departments/Institute in his institution and an External Examiner to the Department of Environmental Health, School of Health Technology, Akure, Nigeria. Professor Festus M. Adebiyi is a member of the Nigerian Society for Environmental Management, Chemical Society of Nigeria and Royal Society of Chemistry. He can be contacted at: [email protected]; [email protected].