Standard Practice for Characterization of Bacillus Spore Suspensions for Reference Materials

Importancia y uso:

5.1 Standard practices for the characterization of spores used as reference materials are important to ensure a uniform basis for testing the performance of detection devices and laboratory instruments. Bacillus spore suspensions can be used for a large variety of purposes including testing environmental sampling techniques, inactivation methods, decontamination methods and basic research.

5.2 The practice is intended for both manufacturers and end users of Bacillus spore suspensions. The results of the characterization measurements are presented in a report of analysis (ROA). The ROA should provide sufficient detail about the measurement technique to enable the customers to replicate the measurements, allowing them to determine if the properties of the spore suspension changed during shipping and storage.

5.3 The enumeration of the viable spores and determination of homogeneity by microscopic analysis are two basic measurements required for the minimal characterization of reference materials. Phase contrast microscopy does not require staining to distinguish the “phase bright” dormant spores from phase dark spores, dark vegetative cells and clumps. When spores germinate they appear phase dark under phase contrast imaging (5). Germinated spores in a reference sample will soon die due to lack of nutrients. It is important in storing samples to prevent the premature germination of the spores. This standard practice includes the important steps for these measurements and includes guidance for advanced measurements. Additional guidance is given for advanced techniques to characterize spore suspensions that may be used to provide a higher level of characterized Bacillus spore reference samples.

5.4 The specific properties of the spores used for their intended application, such as susceptibility to disinfectant processes, should be determined in addition to the basic measurements covered in this practice. Additional information on the measurement of spore properties is located in the appendix.

Subcomité:

E54.01

Referida por:

E2771-11R19E01

Volúmen:

15.08

Número ICS:

07.100.99 (Other standards related to microbiology)

Palabras clave:

Bacillus; phase contrast microscopy; plate count; spores;