Influence of oxygen limitation on the cell surface properties of bacteria from activated sludge

Cell surface hydrophobicity is believed to be important to flocculation in activated sludge and biofilm systems. Optimization of these processes includes changes in the growth conditions of the bacteria. A number of factors influence cell surface hydrophobicity. The influence of oxygen on the cell surface hydrophobicity of 4 bacteria isolated from activated sludge was tested. The bacteria were grown in batch cultures with and without oxygen limitation. It was found that oxygen limitation generally caused a lowering of the cell surface hydrophobicity. The study also showed that there are many difficulties in measuring cell surface hydrophobicity since other cell surface properties, such as surface charge. influence the measurement methods. The MATH test was employed to establish how assay conditions influenced the results. (C) 1998 IAWQ. Published by Elsevier Science Ltd.