EVALUATING STRATEGIES FOR INTEGRATING BACTERIAL CELLS INTO A BIOSENSOR DESIGNED TO DETECT ELECTROPHILIC TOXINS
Abstract:The biological element of a biosensor that was designed to detect electrophilic (oxidative) toxins was characterized. The biosensor element is based on the glutathione-gated potassium efflux (GGKE) stress response process, which results in a rapid export of cytoplasmic K+ in response to electrophilic chemical shock. The K+ efflux was activated in planktonic cultures of Psuedomonas aeruginosa and Escherichia coli using a model electrophile, N-ethylmaleimide to identify relative rates and extents of efflux. P. aeruginosa effluxed (4.50 ± 0.4) × 10−10 mg K+ per cell and E. coli effluxed (5.54 ± 0.8) × 10−10 mg K+ per cell during the mid-log growth state. P. aeruginosa was selected for further study because it is an environmental isolate and it effluxed comparable potassium per cell to E. coli. The P. aeruginosa culture was immobilized in a range of hydrogel polymers: a calcium alginate, a series of photopolymerizable polymers, and a thermally-reversible gel. Oxygen uptake rates and LIVE/DEAD staining were used to determine the activity and viability of the immobilized cultures, and potassium efflux caused by a model electrophile was elucidated. The alginate showed good viability, but poor mechanical stability. The deterioration in alginate polymer structure was determined to not be due to dissolution by the effluxed K+. The photopolymerizable polymers resulted in high mortality and were not pursued further. The thermal polymers showed both good viability and good mechanical stability during efflux experiments.
Document Type: Research Article
Publication date: January 1, 2004
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