A simple chromogenic whole-cell arsenic biosensor based onBacillus subtilis

Abstract

Arsenic contaminated ground water is a serious public health issue, and recent estimates place 150 million people worldwide at risk. Current chemical field test kits do not reliably detect arsenic at the lower end of the relevant range, and may generate toxic intermediates and waste. Whole-cell biosensors potentially provide an inexpensive, robust and analyte-specific solution to this problem. The second generation of a Bacillus subtilis-based arsenic biosensor, designated Bacillosensor-II, was constructed using the native chromosomal ars promoter, arsR and the reporter gene xylE encoding catechol-2,3-dioxygenase. Within four hours, Bacillosensor-II can detect arsenic in the form of arsenate (AsO4 3-) at levels more than one order of magnitude below the recommended safe limit for drinking water suggested by the World Health Organisation (10 µg/L). Detection is reported by the enzymatic conversion of the inexpensive substrate catechol to 2-hydroxy-cis,cis-muconic semialdehyde, a bright yellow product visible by eye. We hope that this work will aid in developing a simple inexpensive field test kit for screening of drinking water for arsenic contamination.

Flagellin-based electrochemical sensing layer for arsenic detection in water

“…Engineered microorganisms and biological macromolecules immobilized on an electrode surface can provide a sufficiently sensitive sensing alternative for arsenic detection, often accompanied by appropriate selectivity. In the last two decades both cell-free (DNA-or protein-based) and cell-based sensing layers have been developed for the detection of inorganic and organic arsenicals in environmental samples 11,[13][14][15][16][17][18] . Some of the whole-cell based sensors reach the maximum allowable concentration (MAC) limit and are highly selective, however, the time of response of cell-on-a-chip type sensors are still challenging 14 .…”

In-situ monitoring of xenobiotics using genetically engineered whole-cell-based microbial biosensors: recent advances and outlook

“…The baculosensor was fabricated that composed of ars promoter, repressor arsR of B. subtilis fused with a xylE reporter on a pVK168 plasmid with an enhanced detection limit as suggested by the WHO. This biosensor is more sophisticated for arsenic recognition, as the output was reported simply by analysing the yellow-coloured dye within 4 h of exposure with arsenic (Wicke et al 2018). Most of the bacteria with an operon on a plasmid show resistance against arsenate by establishing a robust e ux system.…”

Design of a Whole-Cell Biosensor Based on Bacillus subtilis Spores and the Green Fluorescent Protein To Monitor Arsenic

“…However, these analytical techniques, which require high-cost equipment and specialized operation, are not accessible to all the world’s populations. Biosensors for monitoring As can be a reliable alternative to these sophisticated but costly approaches; biosensors are composed mainly of a module of recognition (nucleic acids, antibodies, enzymes) and a signal transducer (thermal, optical, piezoelectrical, or electrochemical) ( 14 , 15 ). Most sophisticated whole-cell biosensors, which can include one or more of the cited transduction and sensing elements, have also been reported ( 16 , 17 ).…”