title: Bioavailability of heavy metals in soil: impact on microbial biodegradation of organic compounds and possible improvement strategies.
abstract: Co-contamination of the environment with toxic chlorinated organic and heavy metal pollutants is one of the major problems facing industrialized nations today. Heavy metals may inhibit biodegradation of chlorinated organics by interacting with enzymes directly involved in biodegradation or those involved in general metabolism. Predictions of metal toxicity effects on organic pollutant biodegradation in co-contaminated soil and water environments is difficult since heavy metals may be present in a variety of chemical and physical forms. Recent advances in bioremediation of co-contaminated environments have focussed on the use of metal-resistant bacteria (cell and gene bioaugmentation), treatment amendments, clay minerals and chelating agents to reduce bioavailable heavy metal concentrations. Phytoremediation has also shown promise as an emerging alternative clean-up technology for co-contaminated environments. However, despite various investigations, in both aerobic and anaerobic systems, demonstrating that metal toxicity hampers the biodegradation of the organic component, a paucity of information exists in this area of research. Therefore, in this review, we discuss the problems associated with the degradation of chlorinated organics in co-contaminated environments, owing to metal toxicity and shed light on possible improvement strategies for effective bioremediation of sites co-contaminated with chlorinated organic compounds and heavy metals.
authors.affiliation: Department of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, South Africa. olanirana@ukzn.ac.za.
authors.forename: Ademola O
authors.initials: AO
authors.lastname: Olaniran
authors.forename: Adhika
authors.initials: A
authors.lastname: Balgobind
authors.forename: Balakrishna
authors.initials: B
authors.lastname: Pillay
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D001682:Biological Availability; D004785:Environmental Pollutants / Q000378:metabolism* / Q000493:pharmacokinetics; D006801:Humans; D019216:Metals, Heavy / Q000378:metabolism* / Q000493:pharmacokinetics; D009930:Organic Chemicals / Q000378:metabolism* / Q000493:pharmacokinetics; D010944:Plants / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D004785:Environmental Pollutants; D019216:Metals, Heavy; D009930:Organic Chemicals; D012987:Soil