Bioavailability of Cd, Zn and Hg in Soil to Nine Recombinant Luminescent Metal Sensor Bacteria

Sensors (Impact Factor: 2.25). 11/2008; 8(8):6899-6923. DOI: 10.3390/s8116899
Source: DOAJ


A set of nine recombinant heavy metal-specific luminescent bacterial sensors belonging to Gram-negative (Escherichia and Pseudomonas) and Gram-positive (Staphylococcus and Bacillus) genera and containing various types of recombinant metal-response genetic elements was characterized for heavy metal bioavailability studies. All nine strains were induced by Hg and Cd and five strains also by Zn. As a lowest limit, the sensors were detecting 0.03 μg·L-1 of Hg, 2 μg·L-1 of Cd and 400 μg·L-1 of Zn. Limit of determination of the sensors depended mostly on metal-response element, whereas the toxicity of those metals towards the sensor bacteria was mostly dependent on the type of the host bacterium, with Gram-positive strains being more sensitive than Gram-negative ones. The set of sensors was used to evaluate bioavailability of Hg, Cd and Zn in spiked soils. The bioavailable fraction of Cd and Zn in soil suspension assay (2.6 – 5.1% and 0.32 – 0.61%, of the total Cd and Zn, respectively) was almost comparable for all the sensors, whereas the bioavailability of Hg was about 10-fold higher for Gram-negative sensor cells (30.5% of total Hg), compared to Gram-positive ones (3.2% of the total Hg). For Zn, the bioavailable fraction in soil-water suspensions and respective extracts was comparable (0.37 versus 0.33% of the total Zn). However, in the case of Cd, for all the sensors used and for Hg concerning only Gram-negative sensor strains, the bioavailable fraction in soil-water suspensions exceeded the water-extracted fraction about 14-fold, indicating that upon direct contact, an additional fraction of Cd and Hg was mobilized by those sensor bacteria. Thus, for robust bioavailability studies of heavy metals in soils any type of genetic metal-response elements could be used for the construction of the sensor strains. However, Gram-positive and Gram-negative senor strains should be used in parallel as the bioavailability of heavy metals to those bacterial groups may be different.

Download full-text


Available from: Taisia Rolova, Apr 18, 2014
  • Source
    • "Recently, recombinant bacteria have been extensively used for bioassay to determine the levels of Pb(II)[7,12,13], Cd(II)[7,13,14], Cu(II)[13,15], and Zn(II) toxicities[13,15]. E. coli (Alux gene) has been utilized to evaluate Zn(II)[16,17], Cd(II)[16], Hg(I)161718, and As(II) toxicities[17]. The bioassays based on recombinant bacterial cells were found to be effective for the assessment of heavy metal toxicity in water[12], sediment, and soil samples[7]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: A fluorescence-based fiber optic toxicity biosensor based on genetically modified Escherichia coli (E. coli) with green fluorescent protein (GFP) was developed for the evaluation of the toxicity of several hazardous heavy metal ions. The toxic metals include Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(III). The optimum fluorescence excitation and emission wavelengths of the optical biosensor were 400 ± 2 nm and 485 ± 2 nm, respectively. Based on the toxicity observed under optimal conditions, the detection limits of Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(III) that can be detected using the toxicity biosensor were at 0.04, 0.32, 0.46, 2.80, 100, 250, 400, 720 and 2600 μg/L, respectively. The repeatability and reproducibility of the proposed biosensor were 3.5%-4.8% RSD (relative standard deviation) and 3.6%-5.1% RSD (n = 8), respectively. The biosensor response was stable for at least five weeks, and demonstrated higher sensitivity towards metal toxicity evaluation when compared to a conventional Microtox assay.
    Full-text · Article · Jun 2015 · Sensors
  • Source
    • "Hence, to survive a Zn-polluted environment, a situation common due to industrialization and anthropogenic activity, organisms have evolved a plethora of intricate strategies to combat this divalent metal (Bondarenko et al. 2008). Its intracellular immobilization in phytochelatins , metalothioneins and other cysteine-rich moieties has been observed (Blindauer et al. 2002; Di Baccio et al. 2005). "
    [Show abstract] [Hide abstract]
    ABSTRACT: AimsTo identify the molecular networks in Pseudomonas fluorescens that convey resistance to toxic concentrations of Zn, a common pollutant and hazard to biological systems.Methods and ResultsPseudomonas fluorescens strain ATCC 13525 was cultured in growth medium with millimolar concentrations of Zn. Enzymatic activities and metabolite levels were monitored with the aid of in-gel activity assays and high performance liquid chromatography, respectively. As oxidative phosphorylation was rendered ineffective, the assimilation of citric acid mediated sequentially by citrate lyase (CL), phosphoenolpyruvate carboxylase (PEPC) and pyruvate phosphate dikinase (PPDK) appeared to play a key role in ATP synthesis via substrate level phosphorylation (SLP). Enzymes generating the anti-oxidant, reduced nicotinamide adenine dinucleotide phosphate (NADPH) were enhanced while metabolic modules mediating the formation of the pro-oxidant, reduced nicotinamide adenine dinucleotide (NADH), were downregulated.Conclusions Pseudomonas fluorescens reengineers its metabolic networks to generate ATP via SLP, a stratagem that allows the microbe to compensate for an ineffective electron transport chain provoked by excess Zn.Significance and Impact of the StudyThe molecular insights described here are critical in devising strategies to bioremediate Zn-polluted environments.This article is protected by copyright. All rights reserved.
    Full-text · Article · Mar 2014 · Journal of Applied Microbiology
  • Source
    • "Because the toxicity of a particular metal is greatly dependent on the form in which it exists, analysis using bioreporters yields more biologically relevant information than conventional chemical methods. Many reports using artificially amended samples have demonstrated in proof-of-concept that whole-cell bacterial bioreporters can be used for assessment of bioavailability and toxicity of metals in different sample matrices (Bondarenko et al., 2008; Brandt et al., 2006; Ivask et al., 2009, 2002) (a more detailed review is available in Hynninen and Virta, 2010). Rather than discussing the entire inventory of bacterial metal bioreporters, here we present a brief overview of their applications in field samples and refer the reader to Table 1 for a more comprehensive list. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Living whole-cell bioreporters serve as environmental biosentinels that survey their ecosystems for harmful pollutants and chemical toxicants, and in the process act as human and other higher animal proxies to pre-alert for unfavorable, damaging, or toxic conditions. Endowed with bioluminescent, fluorescent, or colorimetric signaling elements, bioreporters can provide a fast, easily measured link to chemical contaminant presence, bioavailability, and toxicity relative to a living system. Though well tested in the confines of the laboratory, real-world applications of bioreporters are limited. In this review, we will consider bioreporter technologies that have evolved from the laboratory towards true environmental applications, and discuss their merits as well as crucial advancements that still require adoption for more widespread utilization. Although the vast majority of environmental monitoring strategies rely upon bioreporters constructed from bacteria, we will also examine environmental biosensing through the use of less conventional eukaryotic-based bioreporters, whose chemical signaling capacity facilitates a more human-relevant link to toxicity and health-related consequences.
    Full-text · Article · May 2013 · Ecological Indicators
Show more