Remediation of chromium contaminants using bacteria

Abstract

Chromium contaminants emanating from industrial activities pose a significant threat to human's wellbeing. Chromium (III) and Chromium (VI) are the forms in which they are commonly encountered, of which the trivalent form is relatively benign. Hence, biological reduction of hexavalent chromium has been widely explored by researchers, yielding fruitful outcomes, opening up exciting avenues and also throwing up new challenges. This article attempts to review this area of research. Microbes, especially bacteria capable of Chromium (VI) reduction, belonging to a heterogeneous group have been isolated from contaminated sites. They exhibit plasmid-mediated chromate resistance and the reduction is enzymatically mediated. Reduction studies have been carried out with free and immobilized enzymes as well as whole cells. Experiments have been carried out in specifically designed bioreactors operated in batch and continuous modes. Although significant progress has been made, much needs to be done for its successful in situ application as the organism may not withstand the Chromium concentration or may be impeded by the presence of other toxicants. With molecular engineering, it may be possible to derive strains with improved performance even under stressful field conditions.

Biotechnological advances in bioremediation of heavy metals contaminated ecosystems: an overview with special reference to phytoremediation

“…Biostimulation activity through microbe is stimulated by supplementing nutrients (nitrogen and phosphorus), electron acceptors (oxygen), and substrates (methane, phenol and toluene), or introducing microorganisms with desired catalytic capabilities (Ma et al 2007;Baldwin et al 2008). Recently, Kanmani et al (2012) reviewed chromium bioremediation and outlined heterogeneous group of bacteria isolated from contaminated sites to remediate chromium. These bacteria exhibit plasmid-mediated chromate resistance and the reduction is enzymatically mediated.…”

“…Although significant progress has been made, much needs to be done for its success during in situ application as the organism may not withstand at the higher metal concentration or may be impeded by the presence of other toxicants (Kanmani et al 2012). The possibility of metal recovery biostimulation is also negligible.…”

“…Systems biology approach has been adopted to identify viable plant species, bacteria, fungi and specific genes for bioremediation and to understand the mechanisms involved in processes such as resistance, tolerance, accumulation, filtration and metabolism of toxic metals in biological systems in order to remediate or mitigate environmental pollution (Kanmani et al 2012;Dong et al 2013;Vrionis et al 2005). In order to identify and track the entire microbial community during bioremediation processes, metagenomic analysis including 16S rRNA-based clone libraries have been broadly utilized for heavy metals (Vrionis et al 2005;Cardenas et al 2008;Hemme et al 2010).…”

Formaldehyde degradation by a newly isolated fungus Aspergillus sp. HUA

“…Much more researches have been done to wastewater treatment (Moussavi and Heidarizad 2010). Biological control, such as microbial degradation, is the most commonly applied method for treatment of wastewaters containing biodegradable compounds (Bhakta et al 2012;Kanmani et al 2012;Ashraf et al 2011). Many microorganisms have been shown to degrade formaldehyde in the sewage, and bacterial degradability has been the research hotspot on formaldehyde degradation (Di Maiuta et al 2009;Arutchelvan et al 2005;Hidalgo et al 2002).…”

Modeling chromium(VI) reduction by Escherichia coli 33456 using ceramic pearl as a supporting medium

“…Chromium ions occur infrequently in nature, and their presence in soil and water is generally the result of industrial and domestic discharges (Lazaridis and Charalambous 2005;Kanmani et al 2012). Like all transition metals, chromium can exist in several oxidation states ranging from Cr(0), the metallic form, to Cr(VI), the hexavalent form (Baran et al 2007).…”