The consumption of dietary supplements to treat health complications or to improve overall health conditions has become a globally increasing trend that leads to the development of a large number of health-related novel products and expands the associated manufacturing industries around the world. In the current study, we applied selective culturing combined with next-generation sequencing to examine the microbial viability in terms of its culturability on culture medium, composition, and possible contamination in the selected 17 commercial probiotic products sold in the mainland China market. Additionally, the relative abundance of each individual bacterial content was also evaluated by using the generated sequencing reads. The tested probiotic product samples were subjected to Illumina HiSeq-2000 sequencing platform and thoroughly analyzed by the in-house developed bioinformatics pipeline. The comprehensive culturing and sequencing analysis revealed both viability and composition inaccuracy among the several tested probiotic products, however, no contaminant was identified during the analysis. Among the total, five probiotic products (29.41%) were found with an inaccurate or lower colony-forming unit (CFU) counts on culture media while four probiotic products (23.52%) have inaccurately labeled classification. This study provides an ideal qualitative and quantitative assessment approach, which can be used as a diagnostic tool for the accurate assessment of commercial probiotic supplements.

Kluyveromyces marxianus is a rapidly growing thermotolerant yeast that secretes a variety of lytic enzymes, utilizes different sugars, and produces ethanol. The probiotic potential of this yeast has not been well explored. To evaluate its probiotic potential, the yeast strain Kluyveromyces marxianus DMKU3-1042 was analyzed using next-generation sequencing technology. Analysis of the genomes showed that the yeast isolates had a GC content of 40.10–40.59%. The isolates had many genes related to glycerol and mannose metabolism, as well as genes for acetoin and butanediol metabolism, acetolactate synthase subunits, and lactic acid fermentation. The strain isolates were also found to possess genes for the synthesis of different vitamins and Coenzyme A. Genes related to heat and hyperosmotic shock tolerance, as well as protection against reactive oxygen species were also found. Additionally, the isolates contained genes for the synthesis of lysine, threonine, methionine, and cysteine, as well as genes with anticoagulation and anti-inflammatory properties. Based on our analysis, we concluded that the strain DMKU3-1042 possesses probiotic properties that make it suitable for use in food and feed supplementation.