Application of SITS in the Electrochemical Biosensor Method for Characterization of Substrate Transport into...

Until recently, Na₂-salt of 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulfonic acid (SITS or stilbene reagent) was applied to study transport of anions into bacterial cells by conventional methods; SITS has not yet been used for biosensor investigations of transport. In this study, SITS was first employed in a biosensor method to examine the stilbene reagent effect on process of substrate transport into intact and immobilized cells of cultures-receptors of microbial sensor devices. The biosensor-based technique (biosensor method for assessment of features of metabolism, BMAFM) for studying transport of substrate into microbial cells is currently under further development. To explore substrate transport, laboratory models of reactor and membrane microbial electrochemical sensor devices with the Clark-type oxygen electrode as a transducer and Pseudomonas sp. or Rhodococcus opacus 1CP as a culture-receptor were used in this study. For R. opacus cells stored for 7 months in non-growth conditions, an activating effect on benzoate 1,2-dioxygenase was observed for cells washed after treating with SITS. Using the electrochemical biosensor method, it has been shown that SITS inhibited transport of maltose/benzoate into both intact and immobilized cells of P. sp. and R. opacus leading to a decrease in the cells' response to substrate. Thus, SITS can be used as an inhibitor of anion transport while studying substrate transport into microbial cells by means of the biosensor method. Furthermore, the stilbene reagent-assisted biosensor technique may significantly facilitate and provide rapid measurements during research process.