Bacterial strain
= Bacterial strain
A <bacterial strain> is a maintained lineage of <bacteria> descended from a particular isolation in <pure culture>. It is more specific than a <species> name. The naming code describes descent from an isolation and subsequent cultures; it does not require every cell forever to retain an identical genome.<International Code of Nomenclature of Prokaryotes. Prokaryotic Code (2022 Revision) by Aharon Oren and others>[Appendix 10, A(3), "Use of other terms": definition of a strain and succession of cultures]{ref}
A concrete example is Pm70, the avian isolate used for the published <Pasteurella multocida> genome. Naming both the <species> and the strain identifies the particular material behind a sequence or assay. The 2001 genome paper reported 2,014 predicted coding sequences for Pm70, not a measurement of every member of the <species>.<Complete genomic sequence of Pasteurella multocida, Pm70 by Barbara J. May and others>[Abstract, Introduction and Table1: Pm70 isolate and genome annotation]{ref}
For an illustrative experiment, compare a parent strain with a derivative in which one candidate <gene> has been removed, keeping culture conditions comparable. A change in the measured phenotype tests a claim about that derivative under those conditions. It does not make the two cultures different <species>, nor establish that all other strains would respond identically.
A useful laboratory record therefore connects the strain designation, source culture and any deliberate genetic changes. Otherwise two reports can use the same <species> name while testing materially different biological preparations.