A simple most probable number method for the enumeration of sulphate-reducing bacteria in biocide containing waters.

A simple most probable number (MPN) method has been developed for the enumeration of sulphate-reducing bacteria (SRB) in biocide-containing waters. The medium used is based on source water, it contains no toxic thioglycollate and is resistant to oxidation through mishandling. Reduction is by a suspension of Pseudomonas putida which acts as a powerful adsorbent of biguanide, phenolic, quaternary ammonium compound, glutaraldehyde and isothiazolone biocides. Good recoveries of SRB type strains were obtained using this method and were comparable to other published techniques. Recovery of SRB in mixed culture was comparable to that using a standard laboratory technique.