Minimum Growth Temperature of Clostridium thermosaccharolyticum

Abstract

Clostridium thermosaccharolyticum is generally believed to be obligate thermophile. However the type strain (ATCC 7956) and 2 of 9 strains of the species isolated from spoiled canned foods grew well from spores with abundant gas productions in PE-2 medium (10ml of solution containing bactopeptone 0.5%, yeast extract 0.5%, L-cysteine hydrochloride 0.05% and agar 0.15% was placed in a screw-capped tube having an outside diameter of 16mm and a length of 150mm, containing 3 to 4 dried peas and 0.1g of calcium carbonate, and then the tube was autoclaved for 20min at 121°C) after 20 days at 29°C. Two strains in comminuted asparagus and 5 strains in comminuted baby clam grew with abundant gas from spores after 60 days at 30°C. Thus, the bacteria is not obligate but facultative thermophile. A possible cause of the canned food spoilage owing to the growth of C. thermosaccharolyticum might be under processing rather than exposure to unusual high temperature after thermal processing.