Characterization of germination of spores of Clostridium estertheticum, the primary causative agent of blown pack spoilage of vacuum packaged beef

• Germination conditions for C. estertheticum spores were investigated.
• Germination was affected by pH, with pH 7.0–7.5 being most effective pH.
• Germination was not affected by temperature or O2.
• Lactate was a primary germinant for C. estertheticum spores.

The aim of this study was to investigate the effect of various factors on the germination of Clostridium estertheticum endospores (spores) in relation to beef. The effect of heat on germination was determined by recovering C. estertheticum on Columbia agar from spore suspensions not heated or heated at 63, 70 or 80 °C for various times. The effects of pH, temperature and oxygen were determined, by enumeration of remaining ungerminated spores during incubation in Meat Juice medium (MJM). Amino acids and lactate were tested for their ability to trigger germination of C. estertheticum spores by monitoring dipicolinic acid (DPA) release. Heat treatment of spores at 80 °C for ≤ 20 min significantly (p < 0.05) increased the numbers of spores recovered on blood agar. Neither incubation temperature nor oxygen affected germination in MJM. The optimal pH for germination was 7.0 to 7.5. Incubation with leucine or aspartic acid caused a 1.3% release of DPA, the highest among all amino acids tested. Incubation with lactate resulted in a 4.1% release of DPA, which was significantly (p < 0.05) higher than those from incubation with amino acids. The DPA release from incubation with lactate, lactate with amino acids, or MJM was similar (p > 0.05).

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