Journal of Environmental Biology

Effects of heavy metals on diesel metabolism of psychrotolerant strains of Arthrobacter sp. from Antarctica 

M. Abdulrasheed^1,2, A.F. Roslee¹, N.N. Zakaria¹, A. Zulkharnain³, G.L.Y. Lee¹, P. Convey⁴, S. Napis⁵ and S.A. Ahmad¹* 

¹Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Malaysia

²Department of Microbiology, Faculty of Science, Gombe State University, P.M.B 127, Gombe State, Nigeria

³Department of Bioscience and Engineering, College of Systems Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama, 337-8570, Japan

⁴British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge CB3 0ET, UK

⁵Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

*Corresponding Author Email : aqlima@upm.edu.my

Paper received: 04.11.2019 ?????? ???????????????????????????????????????Revised received: 06.04.2020 ???????????? ????????????????????????Accepted: 15.04.2020

Abstract

Aim: This present study aimed at examining the ability of cold-adapted Antarctic bacteria to tolerate and degrade diesel in the presence of different types of heavy metal co-pollutants.

Methodology: Arthrobacter sp. strains AQ5-05 and AQ5-06, originally isolated from Antarctic soils, were grown on Bushnell-Haas medium containing 1 ppm of heavy metal ions (As, Ag, Cd, Co, Cu, Cr, Hg, Ni, and Pb) supplemented with 3% (v/v) diesel. Diesel degradation was determined gravimetrically, while bacterial growth was evaluated by measuring the optical density of media (OD_{600 nm}).            

Results: In the absence of heavy metal ions, strain AQ5-06 achieved 37.5% diesel mineralisation, while strain AQ5-05 achieved 34.5%. The diesel degrading abilities of both strains were significantly inhibited by exposure to < 1 ppm of Ag or Hg. In contrast, no change in degradation ability was observed using other tested heavy metals. The IC₅₀ of Ag and Hg on diesel degradation by the two strains were (0.2 and 0.4 ppm) and (0.3 and 0.2 ppm), respectively.      

Interpretation: Arthrobacter sp. Strains AQ5-05 and AQ5-06 may contain genes for alkane degradation and heavy metal resistance for remediating diesel-polluted soil in Antarctic and other cold regions.????   

Key words: Antarctica, Arthrobacter sp., Biodegradation, Diesel, Heavy metals

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