Tolerance and growth kinetics of bacteria isolated from gold and gemstone mining sites in response to heavy metal concentrations

Oluwatosin Gbemisola Oladipo; Obinna Tobechukwu Ezeokoli; Mark Steve Maboeta; Jacobus Johannes Bezuidenhout; Louwrens R Tiedt; Anine Jordaan; Cornelius Carlos Bezuidenhout

doi:10.1016/j.jenvman.2018.01.038

Tolerance and growth kinetics of bacteria isolated from gold and gemstone mining sites in response to heavy metal concentrations

J Environ Manage. 2018 Apr 15:212:357-366. doi: 10.1016/j.jenvman.2018.01.038. Epub 2018 Feb 22.

Authors

Oluwatosin Gbemisola Oladipo¹, Obinna Tobechukwu Ezeokoli², Mark Steve Maboeta³, Jacobus Johannes Bezuidenhout³, Louwrens R Tiedt⁴, Anine Jordaan⁴, Cornelius Carlos Bezuidenhout³

Affiliations

¹ Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa. Electronic address: tosin1oladipo@gmail.com.
² Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa; Microbiology and Environmental Biotechnology Research Group, Agricultural Research Council-Institute for Soil, Climate and Water, Pretoria 0001, South Africa.
³ Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa.
⁴ Laboratory for Electron Microscopy, Chemical Resource Beneficiation (CRB), North-West University, Private Bag X6001, Potchefstroom 2520, South Africa.

PMID: 29454247
DOI: 10.1016/j.jenvman.2018.01.038

Abstract

Response and growth kinetics of microbes in contaminated medium are useful indices for the screening and selection of tolerant species for eco-friendly bio-augmentative remediation of polluted environments. In this study, the heavy metal (HM) tolerance, bioaccumulation and growth kinetics of seven bacterial strains isolated from mining sites to 10 HMs (Cd, Hg, Ni, Al, Cr, Pb, Cu, Fe, Mn and Zn) at varied concentrations (25-600 mgL^-1) were investigated. The isolates were phylogenetically (16S rRNA gene) related to Lysinibacillus macroides, Achromobacter spanius, Bacillus kochii, B. cereus, Klebsiella pneumoniae, Pseudomonas mosselii and P. nitroreducens. Metal tolerance, effects on lag phase duration and growth rates were assessed using the 96-well micro-titre method. Furthermore, metal bioaccumulation and quantities within cells were determined by transmission electron microscopy and electron dispersive x-ray analyses. Tolerance to Ni, Pb, Fe and Mn occurred at highest concentrations tested. Growth rates increased with increasing Fe concentrations, but reduced significantly (p < .05) with increasing Zn, Cu, Hg, Cd and Al. Significantly higher (p < .05) growth rates (compared to controls) was found with some isolates in Hg (25 mgL^-1), Ni (100 mgL^-1), Cr (150 mgL^-1), Mn (600 mgL^-1), Pb (100 mgL^-1), Fe (600 mgL^-1) and Al (50 mgL^-1). Lag phase urations were isolate- and heavy metal-specific, in direct proportion to concentrations. A. spanius accumulated the most Mn and Zn, while B. cereus accumulated the most Cu. Metals accumulated intra-cellularly without cell morphology distortions. The isolates' multi-metal tolerance, intra-cellular metal bioaccumulation and growth kinetics suggest potentials for application in the synergetic biodegradation and bioremediation of polluted environments, especially HM-rich sites.

Keywords: Bacterial metal tolerance; Biodegradation; Bioremediation; Environmental contaminant; Metal bioaccumulation; Mining site.

MeSH terms

Bacteria / growth & development*
Environmental Monitoring
Gold
Kinetics
Metals, Heavy / toxicity*
Mining
RNA, Ribosomal, 16S

Substances

Metals, Heavy
RNA, Ribosomal, 16S
Gold