Surface properties and adhesion of Bacillus cereus and Bacillus subtilis to polyurethane - Influence of growth temperature

ABSTRACT

We sought to determine the influence of the growth temperature on the surface physicochemical properties and adhesion of Bacillus cereus and Bacillus subtilis. Growth temperature did not affect the surface characteristics of Bacillus cereus. With respect to the surface characteristics of the bacteria, water contact angle values indicated a hydrophilic nature for the vegetative forms of Bacillus subtilis with the exception of vegetative form cultured at 44^°C which, like the sporulated forms of the two species, was more hydrophobia When Bacillus subtilis was cultured at a temperature other than the optimum growth temperature, its global charge was increased; the more distant the culture temperature from the optimum temperature (30^°C), the higher the negative charge. Furthermore, using a tensiometric method, we demonstrated a production of surfactant by Bacillus subtilis. The rate of production rose the closer the growth temperature was to the optimum temperature. In line with the forecasts made on the basis of bacterial energy characteristics and those of a polyurethane surface, the growth and adhesion temperature only had a slight influence on the number of adherent cells.