Indigoidine biosynthesis triggered by the heavy metal-responsive transcription regulator: a visual whole-cell biosensor

Heavy metals cause various fetal diseases in humans. Heavy metals from factory wastewater can contaminate drinking water, fish, and crops. Inductively coupled plasma-mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS) are commonly used to analyze heavy metal contents; however, these methods require pre-treatment processes and are expensive and complex. To overcome these limitations, three metal-sensing materials using a whole-cell biosensor in Escherichia coli (E. coli) were developed. Strains were engineered to harbor three kinds of plasmids containing the copA, zntA, and mer promoters for sensing copper, cadmium, and mercury, respectively. The luciferase (lux) gene was inserted as a reporter into the plasmid, which was later replaced with a fused protein sequence containing OmpA (1–159) and mCherry for optical detection. The constructed strains could detect mercury, cadmium, and copper at 0.1–0.75 ppm, 0.2–0.75 ppm, and 2–7.5 ppm, respectively, with linearity values of 0.99030, 0.99676, and 0.95933, respectively. The immobilization linearity value was 0.99765. Notably, these three heavy metals could be detected by visual analysis of the strains. Overall, these findings establish this novel sensor as a potential approach for heavy metal detection in biological samples and foods.

Download Full-text

Development of Colorimetric-Based Whole-Cell Biosensor for Organophosphorus Compounds by Engineering Transcription Regulator DmpR

ACS Synthetic Biology ◽

10.1021/acssynbio.6b00061 ◽

2016 ◽

Vol 5 (11) ◽

pp. 1290-1298 ◽

Cited By ~ 21

Author(s):

Huiqing Chong ◽

Chi Bun Ching

Keyword(s):

Organophosphorus Compounds ◽

Whole Cell ◽

Transcription Regulator ◽

Whole Cell Biosensor ◽

Cell Biosensor

Download Full-text

Influence of the luxR Regulatory Gene Dosage and Expression Level on the Sensitivity of the Whole-Cell Biosensor to Acyl-Homoserine Lactone

Biosensors ◽

10.3390/bios11060166 ◽

2021 ◽

Vol 11 (6) ◽

pp. 166

Author(s):

Sergey Bazhenov ◽

Uliana Novoyatlova ◽

Ekaterina Scheglova ◽

Vadim Fomin ◽

Svetlana Khrulnova ◽

...

Keyword(s):

Gene Dosage ◽

Regulatory Gene ◽

Homoserine Lactone ◽

Threshold Concentration ◽

Expression Level ◽

Whole Cell ◽

Lux Biosensors ◽

Order Of Magnitude ◽

Whole Cell Biosensor ◽

Cell Biosensor

Aliivibrio fischeri LuxR and Aliivibrio logei LuxR1 and LuxR2 regulatory proteins are quorum sensing transcriptional (QS) activators, inducing promoters of luxICDABEG genes in the presence of an autoinducer (3-oxo-hexanoyl-l-homoserine lactone). In the Aliivibrio cells, luxR genes are regulated by HNS, CRP, LitR, etc. Here we investigated the role of the luxR expression level in LuxI/R QS system functionality and improved the whole-cell biosensor for autoinducer detection. Escherichia coli-based bacterial lux-biosensors were used, in which Photorhabdus luminescensluxCDABE genes were controlled by LuxR-dependent promoters and luxR, luxR1, or luxR2 regulatory genes. We varied either the dosage of the regulatory gene in the cells using additional plasmids, or the level of the regulatory gene expression using the lactose operon promoter. It was shown that an increase in expression level, as well as dosage of the regulatory gene in biosensor cells, leads to an increase in sensitivity (the threshold concentration of AI is reduced by one order of magnitude) and to a two to threefold reduction in response time. The best parameters were obtained for a biosensor with an increased dosage of luxRA. fischeri (sensitivity to 3-oxo-hexanoyl-l-homoserine lactone reached 30–100 pM).

Download Full-text

Detection of Bioavailable Cadmium by Double-Color Fluorescence Based on a Dual-Sensing Bioreporter System

Frontiers in Microbiology ◽

10.3389/fmicb.2021.696195 ◽

2021 ◽

Vol 12 ◽

Author(s):

Chang-ye Hui ◽

Yan Guo ◽

Jian Wu ◽

Lisa Liu ◽

Xue-qin Yang ◽

...

Keyword(s):

Anthropogenic Activities ◽

Simultaneous Detection ◽

Environmental Water ◽

High Concentration ◽

Whole Cell ◽

Specificity And Sensitivity ◽

Improved Performance ◽

Whole Cell Biosensor ◽

Cell Biosensor ◽

Dual Sensing

Cadmium (Cd) is carcinogenic to humans and can accumulate in the liver, kidneys, and bones. There is widespread presence of cadmium in the environment as a consequence of anthropogenic activities. It is important to detect cadmium in the environment to prevent further exposure to humans. Previous whole-cell biosensor designs were focused on single-sensing constructs but have had difficulty in distinguishing cadmium from other metal ions such as lead (Pb) and mercury (Hg). We developed a dual-sensing bacterial bioreporter system to detect bioavailable cadmium by employing CadC and CadR as separate metal sensory elements and eGFP and mCherry as fluorescent reporters in one genetic construct. The capability of this dual-sensing biosensor was proved to simultaneously detect bioavailable cadmium and its toxic effects using two sets of sensing systems while still maintaining similar specificity and sensitivity of respective signal-sensing biosensors. The productions of double-color fluorescence were directly proportional to the exposure concentration of cadmium, thereby serving as an effective quantitative biosensor to detect bioavailable cadmium. This novel dual-sensing biosensor was then validated to respond to Cd(II) spiked in environmental water samples. This is the first report of the development of a novel dual-sensing, whole-cell biosensor for simultaneous detection of bioavailable cadmium. The application of two biosensing modules provides versatile biosensing signals and improved performance that can make a significant impact on monitoring high concentration of bioavailable Cd(II) in environmental water to reduce human exposure to the harmful effects of cadmium.

Download Full-text