Taxonomy of probiotic microorganisms

When referring to probiotics we refer to probiotic strains, i.e. the microbial individuals, sub-cultures of billion of almost identical cells ideally derived from the same mother cell. Therefore, beneficial effects attributed to probiotics are ascribed in fact to specific strains. However, these strains have to be, by law, clearly identified at the species level. In fact, probiotics have to be safe for consumption, and the evaluation of QPS – Qualified Presumption of Safety – status by the European Food Safety Authority (EFSA) is discussed for species, not for single strains. Also, corrected names have to be reported on products labels: failure of identification of the declared species is a commercial fraud and a consumer misleading, besides being an indication of unreliability of the product. These two examples should clarify how important is the correct taxonomic identification of probiotic strains in the assessment of their reliability and efficacy. The aim of the present contribution is to clarify which procedures, rules and scientific knowledge stand behind microbial names, as results of taxonomic analysis. Probiotic strains described to date fall in two different groups of microorganisms, namely bacteria and yeasts, which will be the focus of this treatment.