Adhesion of Rhodococcus ruber IEGM 342 to polystyrene studied using contact and non-contact temperature measurement techniques

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Adhesion of industrially important bacteria to solid carriers through the example of actinobacterium Rhodococcus ruber IEGM 342 adhered to polystyrene was studied using real-time methods, such as infrared (IR) thermography and thermometry with platinum resistance (PR) detectors. Dynamics of heat rate and heat production was determined at early (within first 80min) stages of rhodococcal cell adhesion. Heat rate was maximal (1.8 × 10-3-2.7 × 10-3W) at the moment of cell loading. Heat production was detected for the entire length of adhesion, and its dynamics depended on concentration of rhodococcal cells. At high (1 × 1010CFU/ml) cell concentration, a stimulative (in 1.7 and 1.4 times consequently) effect of polystyrene treatment with Rhodococcus-biosurfactant on the number of adhered rhodococcal cells and cumulative heat production at rhodococcal cell adhesion was revealed. The values of heat flows (heat rate 0.3 × 10-3-2.7 × 10-3W, heat production up to 8.2 × 10-3J, and cumulative heat production 0.20-0.53J) were 5-30 times higher than those published elsewhere that indicated high adhesive activity of R. ruber IEGM 342 towards polystyrene. To analyze experimental results and predict effects of boundary conditions on the temperature distribution, a mathematical model for heating a polystyrene microplate with distributed heat sources has been developed. Two independent experimental methods and the numerical modeling make it possible to verify the experimental results and to propose both contact and non-contact techniques for analyzing kinetics of bacterial adhesion.