Adhesion of Saccharomyces cerevisiae to alumina surfaces and its removal by caustic alkali cleaning

摘要

The adhesion of Saccharomyces cerevisiae to hydrophilic alumina (Al_2O_3) particles and its removal by caustic alkali cleaning were studied. The surface charge properties of S. cerevisiae cells and Al_2O_3 particles were determined by potentiometrictitration as a function of pH. The cells could adhere spontaneously to Al_2O_3 surfaces even though they had the same type of net charge as that of Al_2O_3. The maximum adhesion of 44.0mg dry cell/m~2 was observed for the adhesion of negatively chargedcells to positively charged Al_2O_3 in the pH range of 4.2 to 6.6. Approximately 43 percent of S. cerevisiae cells adhering to Al_2O_3 were desorbed rapidly by rinsing alone and the remainder was removed by subsequent caustic alkali cleaning. The rate ofdesorption of S. cerevisiae cells during caustic alkali cleaning depended both on the pH and on temperature, and was analyzed by evaluating the first-order desorption rate constant as a measure of cleaning efficiency. After caustic alkali cleaning, whole S. cerevisiae cells were completely removed, but polymeric substances presumably originating from alkali cell lysis remained on the Al_2O_3 surface.