Microbial Degradation of Disinfectants. II. Complete Degradation of Chlorhexidine

The complete microbial degradation of chlorhexidine is described. Two new isolates of bacteria (strains No. A-1 and No. A-3) utilized chlorhexidine as a sole nitrogen source for growth. The growth yield of both strains was about 60 g of protein per mol of nitrogen of chlorhexidine, and was similar to that in the case of ammonium ion as a nitrogen source. Different degradation patterns of chlorhexidine were observed on the high-performance liquid chromatograms (HPLC) of the culture filtrates of the strains. The strain No. A-3 (Pseudomonas sp.) was found to form transient intermediates, detectable on the HPLC, during the microbial degradation, whereas the strain No. A-1 (Flavobacterium sp.) degraded chlorhexidine without formation of such transient intermediates.