Cytotoxicity and genotoxicity evaluation of urban surface waters using freshwater luminescent bacteria Vibrio-qinghaiensis sp.-Q67 and Vicia faba root tip

The freshwater luminescent bacteria Vibrio-qinghaiensis sp.-Q67 test and the Vicia faba root tip test associated with solid-phase extraction were applied for cytotoxicity and genotoxicity assessment of organic substances in three rivers, two lakes and effluent flows from two wastewater treatment plants （WWTPs） in Xi＇an, China. Although the most seriously polluted fiver with high chemical oxygen demand （COD） and total organic carbon （TOC） showed high cytotoxicity （expressed as TIIs0, the toxicity impact index） and genotoxicity （expressed as RMCN, the relative frequency of micronucleus）, no correlative relation was found between the ecotoxicity and organic content of the water samples. However, there was a linear correlative relation between TIIs0 and RMCN for most water samples except that from the Zaohe River, which receives discharge from WWTP and untreated industrial wastewaters. The ecotoxicity of the organic toxicants in the Chanhe River and Zaohe River indicated that cytotoxic and genotoxic effects were related to the pollutant source. The TII50 and RMCN were also found to correlate roughly to the dissolved oxygen concentration of the water. Sufficient dissolved oxygen in surface water is thus proved to be an indicator of a healthy water environmental condition.

Study on the Application of Luminescent Bacteria to the Evaluation and Analysis of the UV-shielding Property of Nanooxide

In this paper, it was found that luminescent bacteria could be killed by UV light and the bioluminescence intensity would be decreased. With the protection of nanooxide, the decrease of the bioluminescence could be supressed, therefore luminescent bacteria could be utilized to analyze and evaluate the UV-shielding property of nanooxide. Vibrio-qinghaiensis Q67, a kind of luminescent bacteria, was used here to study the influence of different kinds and concentrations of nanooxide on the luminescence intensity of bacteria, which were illuminated by UVA, UVB or UVC light, respectively. A method was established according to the relative value of the decrease of the luminescence intensity, which can be used to analyze and evaluate the UV-shielding property of nanooxide against UVA, UVB or UVC light, respectively. It also provided an effective way to analyze and evaluate the UV-shielding property of sunscreen for cosmetic and other industries.

Application of internal standard method in recombinant luminescent bacteria test

Mercury and its organic compounds have been of severe concern worldwide due to their damage to the ecosystem and human health. The development of effective and affordable technology to monitor and signal the presence of bioavailable mercury is an urgent need.The Mer gene is a mercury-responsive resistant gene, and a mercury-sensing recombinant luminescent bacterium using the Mer gene was constructed in this study. The mer operon from marine Pseudomonas putida strain SP1 was amplified and fused with prompterless lux CDABE in the p UCD615 plasmid within Escherichia coli cells, resulting in p THE30–E. coli.The recombinant strain showed high sensitivity and specificity. The detection limit of Hg^2＋was 5 nmol/L, and distinct luminescence could be detected in 30 min. Cd^2＋, Cu^2＋, Zn^2＋, Ca^2＋,Pb^2＋, Mg^2＋, Mn^2＋, and Al^3＋did not interfere with the detection over a range of 10-5–1 m M.Application of recombinant luminescent bacteria testing in environmental samples has been a controversial issue： especially for metal-sensing recombinant strains, false negatives caused by high cytotoxicity are one of the most important issues when applying recombinant luminescent bacteria in biomonitoring of heavy metals. In this study, by establishing an internal standard approach, the false negative problem was overcome;furthermore, the method can also help to estimate the suspected mercury concentration,which ensures high detection sensitivity of bioavailable Hg2＋.