ABSTRACT
This chapter discusses the various short-and long-term methods available for microorganism preservation and focuses on inocula preparation considerations in preservation efficacy testing. Cosmetic microbiologists require maintenance and preservation of microbial cultures for research, training, and testing purposes. No fixed pattern for rechallenging products with microorganisms has so far emerged for challenge tests of cosmetics and toiletries. Preservation means including protective mechanisms in the cosmetic in order to avoid microbial growth. The physiological status of microbial inocula is one of the major sources of variation in microbiological tests. The types of microorganisms included within a challenge test are a major factor in assessing preservation capacity. The preservative efficacy test strains must be chosen for their known association with cosmetic contamination, resistance to preservatives, opportunistic contamination capacity, low nutrient demand, and adaptability. If type-strains only are employed, then master cultures, and subsequently inocula, should be prepared from cultures received from internationally recognized culture collections.
