Identity of Mesophilic Anaerobic Sporeformers Cultured from Recycled Cannery Cooling Water.

Chlorinated, recycled water for cooling of containers in still retorts was sampled over a 27-month period at one food processing plant. Of 274 samples taken, 28 contained mesophilic, anaerobic spores in numbers that ranged from 0.04-4.6/ml (MPN). Though all isolates were characterized as Clostridium species, 11% could not be matched with named species. Clostridium butyricum and Clostridium barati (synonyms: C. paraperfringens , C. perenne ) comprised 55% of isolates. Excepting Clostridium sticklandii , which is neither proteolytic nor saccharolytic, all isolates were saccharolytic. This contrasted with the finding of both proteolytic and saccharolytic clostridial spores in the municipal water feeding the recycle water reservoir. An apparent selection for saccharolytic strains could not be explained on the basis of published resistance of anaerobic spores to free available chlorine.