利用生物方法檢測環境中的污染物

Abstract

The environmental pollution threatens human health as well as wildlife in the past decades. As a result, it is necessary to develop sensitive, effective, and inexpensive methods which can efficiently monitor and determine the presence and amount of hazards in the environment. In this study, we report two biologically analytical methods to detect and measure the environmental pollutants. Firstly, we describe the construction and characterization of the fluorescent and the luminescent Escherichia coli whole-cell biosensors for the detection of bioavailable toluene and its related compounds. The biosensor strains Escherichia coli DH5α carrying pTOLGFP or pTOLLUX were developed based on the expression of reporter genes: gfp or luxCDABE under the control of the Pu promoter and xylR gene of Pseudomonas putita plasmid pWW0. To assess their applicability for analyzing environmentally relevant samples, the biosensor harboring pTOLLUX was field-tested on water and soil samples collected from toluene contaminated sites. Our results demonstrate that nonpathogenic bacterial biosensors developed in the present study is useful and applicable in determining the bioavailability of toluene and its related compounds with high sensitivity in environmental samples, and they suggest a potential for its inexpensive application in field-ready tests. Secondly, alterations of glutathione levels as well as the mRNA levels of HSP70 in tilapia fish were investigated under arsenite exposure. Tilapia fish were exposed to waterborne arsenite (0, 1, 2, and 4 ppm, respectively) for 1 day and 3 day exposure duration. After the treatment, arsenite concentrations in gill, intestine, liver, and muscle were measured by means of inductively coupled plasma (ICP). Meanwhile, the GSH contents in fish tissues were measured and the mRNA expression of HSP70 was analyzed with semi-quantitative RT-PCR. Our results indicate that HSP70 mRNA expression and GSH levels exhibited a correlation with the arsenite exposure condition as well as the arsenic accumulation, indicating their usefulness as the biomarker of arsenite exposure in tilapia. Furthermore, the bioaccumulations of arsenic differentially distributed in various fish tissues assist in providing information of bioavailability. We conclude that biological assays, such as bacterial biosensors and biomarker presented in this study, for detecting and determining the environmental contaminants can compensate the disadvantages of traditional analytical methods such as not capable to reflect the bioavailability and failing to show the effects of contaminants mixtures on organisms, and thus providing critical data that can be useful in risk assessment.