Characterisation of non-toxigenic Clostridium spp. strains, to use as surrogates for non-proteolytic Clostridium botulinum in chilled food challenge testing

• Non-toxigenic clostridia strains are characterised as surrogates for C. botulinum.
• These clostridia strains are safer to handle and work with than C. botulinum.
• A surrogate cocktail could be used in chilled food challenge tests for growth.
• Screening studies using surrogates could reduce the number of mouse bioassays.
• Surrogates could also be used to study thermal inactivation processes.

Under many of the conditions studied, a two-strain cocktail of non-toxigenic Clostridium spp. was found to be suitable as a surrogate for non-proteolytic Clostridium botulinum, and has the potential for use in chilled food challenge tests measuring growth. Non-toxigenic surrogates could also be used in thermal process screening studies.