Microbial Degradation of Disinfectants. I. Chlorhexidine-Degrading Bacteria Isolated from Activated Sludge

Abstract

Aerobes or facultative anaerobes able to degrade chlorhexidine or resistant to it were isolated from activated sludge. Most of these microorganisms were Gram-negative rods. Degradation of chlorhexidine was measured by using a high-performance liquid chromatographic assay, and growth of bacteria was measured by the Kennedy and Fewson method as protein. Chlorhexidine-degrading activity of isolates could be categorized into three distinct types. Two Gram-negative, motility-positive rods were shown to utilize chlorhexidine as a sole nitrogen source for growth. On the other hands, other strains did not utilize chlorhexidine, though they were resistant to it.