A strain is a genetic variant or subtype of a microorganism (e.g., a virus, bacterium or fungus). Microbial strains can also be differentiated by their genetic makeup using metagenomic methods to maximize resolution within species.
Type strains are descendants of the original isolates used in species and subspecies descriptions, as defined by the Bacteriological Code [14], that exhibit all of the relevant phenotypic and genotypic properties cited in the original published taxonomic circumscription
Hope It Helps!