Comparison of Growth Response by Chemostat Cultured and Batch Cultured Clostridium perfringens Cells in Various Food Substrates

A constant source of exponential phase cells of Clostridium perfringens ATCC 3624 could reduce the time required to carry out the protein quality evaluation test of Solberg et al. (1979) to 4 hr. Clostridium perfringens ATCC 3624 was grown in an anaerobic chemostat using the chemically defined medium, R&S, with glucose as the growth limiting nutrient. The dilution rate was set at 0.06 hr −1 , the pH at 7.2, and the temperature at 43°C. In the transition from a batch culture to a continuous culture an initial oscillatory cell density response was observed. In the steady state, which was continued for as long as 50 days, the cells were typical Gram positive rods, occurring singly or in chains as long as 15 rods, which were occasionally without septa. The fermentative and biochemical responses of the cells did not change. No sporulation occurred when the cells were growing in the chemostat, but spores were observed in the glucose free culture effluent after incubation at 37°C for 24 hr. When cells produced in the chemostat, were cultured in complex media they demonstrated a growth response similar to cells which had been grown in a batch culture. In defined medium the generation time for the chemostat cultured cells was decreased approximately 17%. The chemostat cultured cells can be used as inoculum for the C. perfringens protein quality assay.