Microbiological quality of probiotic dietary supplements

Abstract

Today people focus on healthy lifestyle. It is well known that probiotics have a number of beneficial health effects in humans. They play an important role in protecting the host against harmful microorganisms, reduce metabolic disorders and support immune functions. In the present study, we investigated 26 probiotic products: 16 commercially available ones and 10 from a local manufacturer. None of the commercial products contained all labelled LAB and some of them contained unacceptable microorganisms. Of 890 isolated strains only 420 met the criteria for LAB. Ninetyseven strains were investigated by phenotypic and genotypic methods. 16S-23S rDNA amplification was performed for all putative LAB isolates. Fifty-seven rod-shaped bacteria referred to genus Lactobacillus and 16 coccus bacteria, to genus Weissela. Two-step multiplex PCR identified the rodshaped strains to belong to four species: Lactobacillus delbrueckii ssp. bulgaricus (three strains), Lactobacillus acidophilus (four strains), Lactobacillus casei (three strains), Lactobacillus rhamnosus (two strains), Lactobacillus reuteri (four strains) and Lactobacillus plantarum (one strain). The transit tolerance of the isolated bacteria to in vitro simulated gastric juice (pH 2) was examined. Only four strains survived after 90 min of incubation. The antimicrobial activity of the native supernatants of the isolates was tested and 10 of them showed slight activity against three pathogenic bacteria. Our results demonstrated that only freshly produced products possessed the expected number of viable cells. The data revealed that one of the most common problems is the lower concentration of viable cells, misidentification and the presence of undesired microflora.

Spotlight on the Compositional Quality of Probiotic Formulations Marketed Worldwide

“…All the Polish probiotic formulations included in the study by Szajewska et al (2004) complied with the label claims for content of viable cells. The analysis of the content of living microbes in 26 supplements sold in Bulgaria revealed that for 10 there was concordance with the label claims (Yonkova Marinova et al, 2019).…”

“…In this study, we also evidenced that the labels of some formulations, particularly functional foods, did not comply general guidelines for probiotic labeling, since not indicating the contained microbes or only reporting a general and inaccurate description (e.g., "LAB, " "probiotics, " "lactic ferment, " "lactic acid bacillus, " "live probiotic AB cultures, " "active bifidus, " "special live cultures, " "viable LAB, " "bifidus essensis, " "life yeast") (Fasoli et al, 2003;Temmerman et al, 2003a,b;Elliot and Teversham, 2004;Masco et al, 2005;Theunissen et al, 2005;Lin et al, 2006;Perea Vélez et al, 2007;Angelakis et al, 2011;Chen et al, 2014;Kesavelu et al, 2020). In addition, we found that some preparations only indicated the contained microbes at the genus level, thus resulting in disagreement with the FAO/WHO guidelines (Fasoli et al, 2003;Temmerman et al, 2003a,b;Masco et al, 2005;Theunissen et al, 2005;Lin et al, 2006;Perea Vélez et al, 2007;Chen et al, 2014;Yonkova Marinova et al, 2019).…”

“…In culture-dependent analyses, enumeration of different species in multi-species formulations can be critical. To overcome this limit, selective media are commonly used to discriminate species with different metabolic features (Fasoli et al, 2003;Elliot and Teversham, 2004;Aureli et al, 2010;Drago et al, 2010;Toscano et al, 2013;Chen et al, 2014;Di Pierro et al, 2019;Korona-Glowniak et al, 2019;Yonkova Marinova et al, 2019;Kesavelu et al, 2020). Nevertheless, this aim remains challenging, particularly for Lactobacillus and Bifidobacterium species.…”

“…This study showed that only three products completely complied the labeled information in terms of composition, while the other two contained other species than those declared (Szajewska et al, 2004). Investigation of 26 Bulgarian dietary supplements by twostep multiple PCR indicated that none contained all the species claimed on the labels (Yonkova Marinova et al, 2019).…”

“…Nevertheless, none of these microbes were isolated from the products by using culture-dependent methods, thus suggesting that they could be present in a killed form (Chen et al, 2014). Microorganisms belonging to the genus Weissella were isolated from some products marketed in Bulgaria (Yonkova Marinova et al, 2019). Lastly, contamination of a dietary supplement for preterm newborns by Rhizopus oryzae was evidenced by culture-dependent methods (Vallabhaneni et al, 2015).…”