Bondarenko Olesja, Rõlova Taisia, Kahru Anne, Ivask Angela
Laboratory of Molecular Genetics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618, Tallinn, Estonia.
Sensors (Basel). 2008 Nov 4;8(11):6899-6923. doi: 10.3390/s8116899.
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 metalresponse 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 of Hg, 2 μg·L of Cd and 400 μg·L 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 soilwater 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.
为了进行重金属生物可利用性研究，对一组九个重组重金属特异性发光细菌传感器进行了表征。这些传感器属于革兰氏阴性菌（大肠杆菌和假单胞菌）和革兰氏阳性菌（葡萄球菌和芽孢杆菌）属，包含各种类型的重组金属反应遗传元件。所有九种菌株都能被汞和镉诱导，五种菌株还能被锌诱导。作为最低检测限，这些传感器能检测到0.03μg·L的汞、2μg·L的镉和400μg·L的锌。传感器的检测限主要取决于金属反应元件，而这些金属对传感细菌的毒性主要取决于宿主细菌的类型，革兰氏阳性菌株比革兰氏阴性菌株更敏感。这组传感器用于评估添加了重金属的土壤中汞、镉和锌的生物可利用性。在土壤悬浮液试验中，镉和锌的生物可利用部分（分别占总镉和锌的2.6 - 5.1%和0.32 - 0.61%）对所有传感器来说几乎相当，而与革兰氏阳性传感器细胞相比，革兰氏阴性传感器细胞对汞的生物可利用性约高出10倍（占总汞的30.5%），革兰氏阳性传感器细胞对汞的生物可利用性为总汞的3.2%。对于锌，土壤 - 水悬浮液和相应提取物中的生物可利用部分相当（分别占总锌的0.37%和0.33%）。然而，对于镉，就所有使用的传感器以及仅针对革兰氏阴性传感器菌株的汞而言，土壤 - 水悬浮液中的生物可利用部分比水提取物中的部分高出约14倍，这表明在直接接触时，这些传感细菌会使额外部分的镉和汞被 mobilized。因此，为了对土壤中的重金属进行可靠的生物可利用性研究，任何类型的遗传金属反应元件都可用于构建传感菌株。然而，革兰氏阳性和革兰氏阴性传感菌株应并行使用，因为重金属对这些细菌群体的生物可利用性可能不同。 （注：最后一句中“mobilized”未找到合适中文，保留英文）
