Isolate = A population of microbial cells from a pure culture derived from a single colony on an isolation
plate.
Strain = An isolate or group of isolates exhibiting phenotypic and/or genotypic traits which are distinctive
from those of other isolates of the same species
Species (In biology) = a group of organisms capable of interbreeding and producing fertile offspring.
(In microbiology-bacteria) = Bacteriologists have not yet adopted a concept for a bacterial species.