= Microbial culture authentication
<Microbial culture authentication> checks whether cultured material has the identity and relevant properties claimed for it. Within a <culture collection>, it connects a named <strain (biology)> to observations of the actual material. Tests of <phenotype>, purity and <genotype> can supply complementary evidence; growth alone does not identify the organism.<Authentication of Prokaryotes at ATCC by ATCC>[opening description; Morphology and purity; Genotypic characterization]{ref}
ATCC describes comparisons at both the <cell> and <colony (biology)> level, biochemical characterization and sequence-based identification. Its account also explains that identifying some organisms or confirming a particular feature requires information beyond one commonly used marker.<Authentication of Prokaryotes at ATCC by ATCC>[Morphology and purity; Biochemical analyses; Genotypic characterization, Genes of interest]{ref}
A constructed coverage example makes the limit precise. Suppose a reference and an isolate agree at all one thousand positions examined in a hypothetical million-position <genome>. That establishes agreement at the tested positions, not at the remaining 999,000. Two preparations could share the tested sequence while differing elsewhere. Conversely, an observed difference needs interpretation in the context of assay quality and what kind of identity the comparison is intended to establish.
Purity is another distinct question. A result identifying the dominant sequence does not by itself exclude a second <microorganism> that the measurement fails to detect. The reference material, tested features and detection capability should therefore accompany an authentication claim.
The WFCC guidelines emphasize comparing a recovered strain with the originally deposited material and retaining supporting records.<Guidelines for the Establishment and Operation of Collections of Cultures of Microorganisms by the World Federation for Culture Collections>[sections 8 and 11, authentication and documentation]{ref} Authentication supplies evidence about identity; <microbial culture preservation> maintains the material on which that evidence depends.
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