Effect of heat activation on the germination of superdormant Clostridium perfringens spores: A requirement for elevated temperature

Abstract

The “germination-inactivation” is a common strategy for controlling Clostridium perfringens spores in meat products. However, the presence of superdormant spores limits its effectiveness. This study investigated the factors contributing to germination defects, and elucidated the germination effect and mechanism of heat activation on superdormant spores. Compared with dormant spores, superdormant spores showed lower germination and higher heat resistance (P < 0.05). In contrast, re-sporulated spores exhibited similar germination, indicating that germination defect was not due to genetic changes. Elevated levels of pyridine-2,6-dicarboxylic acid (DPA) in the superdormant spores may be a potential contributor to their germination defect (P < 0.05). Treatment at 100 °C for 10 min efficiently promoted superdormant spore germination, as evidenced by enhanced ATP synthesis, colony formation efficiency and DPA release (P < 0.05). Further studies revealed that inner membrane permeability and fluidity of the spores were enhanced, which promoted K⁺ efflux. The efflux reduced the lag phase preceding DPA release by regulating the spores closer to germination threshold, ultimately facilitating germination. Furthermore, upregulation of germination-related genes also contributed to DPA release of the spores. In chicken meat, the treatment promoted the germination of approximately 99 % of superdormant spores, enhancing their subsequent inactivation at 90 °C. These findings provide novel insights for the germination characteristics of superdormant C. perfringens spores and their effective control in meat products.