Development of a Fully Automated Flow Injection Analyzer Implementing Bioluminescent Biosensors for Water Toxicity Assessment

This paper describes the development of an automated Flow Injection analyzer for water toxicity assessment. The analyzer is validated by assessing the toxicity of heavy metal (Pb2+, Hg2+ and Cu2+) solutions. One hundred μL of a Vibrio fischeri suspension are injected in a carrier solution containing different heavy metal concentrations. Biosensor cells are mixed with the toxic carrier solution in the mixing coil on the way to the detector. Response registered is % inhibition of biosensor bioluminescence due to heavy metal toxicity in comparison to that resulting by injecting the Vibrio fischeri suspension in deionised water. Carrier solutions of mercury showed higher toxicity than the other heavy metals, whereas all metals show concentration related levels of toxicity. The biosensor’s response to carrier solutions of different pHs was tested. Vibrio fischeri’s bioluminescence is promoted in the pH 5–10 range. Experiments indicate that the whole cell biosensor, as applied in the automated fluidic system, responds to various toxic solutions

Whole-Cell Fluorescent Biosensors for Bioavailability and Biodegradation of Polychlorinated Biphenyls

Whole-cell microbial biosensors are one of the newest molecular tools used in environmental monitoring. Such biosensors are constructed through fusing a reporter gene such as lux, gfp or lacZ, to a responsive promoter. There have been many reports of the applications of biosensors, particularly their use in assaying pollutant toxicity and bioavailability. This paper reviews the basic concepts behind the construction of whole-cell microbial biosensors for pollutant monitoring, and describes the applications of two such biosensors for detecting the bioavailability and biodegradation of Polychlorinated Biphenyls (PCBs)

Review of micro/nanotechnologies for microbial biosensors

A microbial biosensor is an analytical device with a biologically integrated transducer that generates a measurable signal indicating the analyte concentration. This method is ideally suited for the analysis of extracellular chemicals and the environment, and for metabolic sensory regulation. Although microbial biosensors show promise for application in various detection fields, some limitations still remain such as poor selectivity, low sensitivity, and impractical portability. To overcome such limitations, microbial biosensors have been integrated with many recently developed micro/nanotechnologies and applied to a wide range of detection purposes. This review article discusses micro/nanotechnologies that have been integrated with microbial biosensors and summarizes recent advances and the applications achieved through such novel integration. Future perspectives on the combination of micro/nanotechnologies and microbial biosensors will be discussed, and the necessary developments and improvements will be strategically deliberated.clos

Use of Tunable Whole-Cell Bioreporters to Assess Bioavailable Cadmium and Remediation Performance in Soils

It is important to have tools to measure the bioavailability to assess the risks of pollutants because the bioavailability is defined as the portions of pollutants showing the biological effects on living organisms. This study described the construction of tunable Escherichia coli whole-cell bioreporter (WCB) using the promoter region of zinc-inducible operon and its application on contaminated soils. It was verified that this WCB system showed specific and sensitive responses to cadmium rather than zinc in the experimental conditions. It was inferred that Cd(II) associates stronger with ZntR, a regulatory protein of zinc-inducible operon, than other metal ions. Moreover, the expression of reporter genes, egfp and mcherry, were proportional to the concentration of cadmium, thereby being a quantitative sensor to monitor bioavailable cadmium. The capability to determine bioavailable cadmium was verified with Cd(II) amended LUFA soils, and then the applicability on environmental systems was investigated with field soils collected from smelter area in Korea before and after soil-washing. The total amount of cadmium was decreased after soil washing, while the bioavailability was increased. Consequently, it would be valuable to have tools to assess bioavailability and the effectiveness of soil remediation should be evaluated in the aspect of bioavailability as well as removal efficiency