Enhancement of metal bioremediation by use of microbial surfactants

Singh, Pargat

doi:10.1016/s0006-291x(04)00891-5

Cited by 26 publications

(35 citation statements)

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“…Bacteria are often involved in the fate and transport of toxic metals in soil (35,36,50,62). Both abiotic and biotic processes catalyze the reduction of Cr(VI) to Cr(III) in the natural environment (20), but bacterial reduction of Cr(VI) to Cr(III) can occur under nutrient-amended vadose zone conditions, which implies that biostabilization is a viable management option (42).…”

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confidence: 99%

Enhanced Exopolymer Production and Chromium Stabilization inPseudomonas putidaUnsaturated Biofilms

Priester

Olson

Webb

et al. 2006

Appl Environ Microbiol

202

102

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Chromium-contaminated soils threaten surface and groundwater quality at many industrial sites. In vadose zones, indigenous bacteria can reduce Cr(VI) to Cr(III), but the subsequent fate of Cr(III) and the roles of bacterial biofilms are relatively unknown. To investigate, we cultured Pseudomonas putida, a model organism for vadose zone bioremediation, as unsaturated biofilms on membranes overlaying iron-deficient solid media either containing molecular dichromate from potassium dichromate (Cr-only treatment) or with deposits of solid, dichromate-coated hematite (Fe؉Cr treatment) to simulate vadose zone conditions. Controls included iron-deficient solid medium and an Fe-only treatment using solid hematite deposits. Under iron-deficient conditions, chromium exposure resulted in lower cell yield and lower amounts of cellular protein and carbohydrate, but providing iron in the form of hematite overcame these toxic effects of Cr. For the Cr and Fe؉Cr treatments, Cr(VI) was completely reduced to Cr(III) that accumulated on biofilm cells and extracellular polymeric substances (EPSs). Chromium exposure resulted in elevated extracellular carbohydrates, protein, DNA, and EPS sugars that were relatively enriched in N-acetyl-glucosamine, rhamnose, glucose, and mannose. The proportions of EPS protein and carbohydrate relative to intracellular pools suggested Cr toxicity-mediated cell lysis as the origin. However, DNA accumulated extracellularly in amounts far greater than expected from cell lysis, and Cr was liberated when extracted EPS was treated with DNase. These results demonstrate that Cr accumulation in unsaturated biofilms occurs with enzymatic reduction of Cr(VI), cellular lysis, cellular association, and extracellular DNA binding of Cr(III), which altogether can facilitate localized biotic stabilization of Cr in contaminated vadose zones.

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confidence: 99%

Enhanced Exopolymer Production and Chromium Stabilization inPseudomonas putidaUnsaturated Biofilms

Priester

Olson

Webb

et al. 2006

Appl Environ Microbiol

202

102

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“…EPS encapsulation supports cell substance and growth through the trapping, binding and dissemination of external nutrients by charged polysaccharide groups (Cheng et al, 2007), and offers greater protection against external stresses within the environment relative to those residing in a planktonic state (Pang et al, 2005). Materials that allow a high degree of bacterial colonisation and possibly biofilm formation are potentially suited to facilitating biodegradation (Upadhyayula and Gadhamshetty, 2010), which is typically most effective when microorganisms are in a biofilm state as opposed to planktonic, due to greater bioavailability, protection and adaptability to toxic conditions and hence more rapid pollutant degradation (Singh and Cameotra, 2004;Singh et al, 2006). Furthermore, bacterial colonisation may stabilise nanoparticle aggregates as polysaccharides, such as those generated by bacteria, have been observed to significantly increase the aggregation of C 60 fullerene, reducing particle mobility within the environment (Espinasse et al, 2007).…”

Section: Microbial Sorption and Biofilm Formationmentioning

confidence: 99%

Carbon nanomaterials in clean and contaminated soils: environmental implications and applications

Riding

Martin

Jones

et al. 2015

SOIL

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Abstract. The exceptional sorptive ability of carbon nanomaterials (CNMs) for hydrophobic organic contaminants (HOCs) is driven by their characteristically large reactive surface areas and highly hydrophobic nature. Given these properties, it is possible for CNMs to impact on the persistence, mobility and bioavailability of contaminants within soils, either favourably through sorption and sequestration, hence reducing their bioavailability, or unfavourably through increasing contaminant dispersal. This review considers the complex and dynamic nature of both soil and CNM physicochemical properties to determine their fate and behaviour, together with their interaction with contaminants and the soil microflora. It is argued that assessment of CNMs within soil should be conducted on a case-by-case basis and further work to assess the long-term stability and toxicity of sorbed contaminants, as well as the toxicity of CNMs themselves, is required before their sorptive abilities can be applied to remedy environmental issues.

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“…Biofilms maintain optimal chemical and physiological conditions, localized solute concentrations and redox potential, allowing cells to improve mineralization processes [62]. Generally biofilm reactors are used to treat hydrocarbons, heavy metals and large volumes of dilute aqueous solutions such as industrial and municipal waste water [62][63].…”

Section: Bioremediation and Waste Water Treatmentmentioning

confidence: 99%

“…A major group of bacteria commonly found in metal contaminated waste waters are sulfate reducing bacteria (SRB). This group of bacteria has been shown to be highly efficient in anaerobic degradation of many organic pollutants and in the precipitation of heavy metals from waste water [63]. Other bacteria exhibiting biosorption of toxic heavy metals in bioremediation processes include Enterobacter and Pseudomonas species [64] …”

Section: Bioremediation and Waste Water Treatmentmentioning

confidence: 99%

Microbial Extracellular Polymeric Substances: Production, Isolation and Applications

Singha¹

2012

iosrphr

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AbstractsMicrobial polysaccharides have multiple functions and can be divided into intracellular polysaccharides, structural polysaccharides and extracellular polysaccharides or exopolysaccharides (EPS). EPS from both prokaryotes and eukaryotes has a great deal of research interest. Recent approaches are carried out to replace the traditionally used plant gums by their bacterial counterparts. The bacterial EPS represent a huge variety of chemical structures, but have not yet get appreciable significance. Chemically, EPS contains high molecular weight polysaccharides (10-30 kDa) and have homopolymeric as well as heteropolymeric composition. They have new-fangled applications due to their unique properties they possess. Therefore EPS have found multifarious applications in the food, pharmaceutical and other industries. It also possesses potential application on waste water treatment.

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Enhancement of metal bioremediation by use of microbial surfactants

Cited by 26 publications

References 0 publications

Enhanced Exopolymer Production and Chromium Stabilization inPseudomonas putidaUnsaturated Biofilms

Enhanced Exopolymer Production and Chromium Stabilization inPseudomonas putidaUnsaturated Biofilms

Carbon nanomaterials in clean and contaminated soils: environmental implications and applications

Microbial Extracellular Polymeric Substances: Production, Isolation and Applications

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