Characterizing probiotic microorganisms.

Publisher Summary A strain is an isolate that can be differentiated from other isolates of the same genus, species, and subspecies by at least one phenotypic and/or genotypic characteristic. Strain differentiation depends on recognizing unique properties capable of discriminating at this level. A variety of molecular methods have been used to characterize and identify bifidobacteria. Generally, phenotypic methods of strain characterization are limited by the fact strains exhibit varying attributes under conditions of the assay, and often yield ambiguous or inconsistent results within and among species. Recent molecular methods are nucleic acid-based, and are typically more discriminatory and reproducible. However, an ‘ideal' method for strain identification would be able to type all strains and yield unambiguous results at the genus, species, and strain levels, would display high levels of stability, discriminatory power, reproducibility, and concordance with other typing methods. It also would not require great technical skill or be time-, cost-, or reagent-intensive. No one method can possibly fulfill all of these criteria. A polyphasic or consensus approach is best, which includes a combination of genomic and phenotypic methods to characterize and differentiate strains.