Identification by PCR and evaluation of probiotic potential in yeast strains found in kefir samples in the city of Santa Maria, RS, Brazil

Abstract

Kefir is a product elaborated from the symbiotic fermentation of different microorganisms. The Kluyveromyces and Saccharomyces genera are the major representatives of the yeasts found in kefir microbiota. The only pobiotic yeast commercialized as an oral medication, is the Saccharomyces boulardii. The present work involved the microbiological quality examination of six kefir samples in the city of Santa Maria/RS, the yeasts isolation present in the samples and the identification of them by PCR (Polymerase chain reaction). Then, their probiotic potential was evaluated by in vitro technique. After that, microbiological analysis confirmed that kefir samples were suitable for consumption once the microbiological quality was established. Nineteen yeast strains were isolated from six different kefir samples; it was identified, by PCR analysis, but only three species were identified from these microorganisms in the present article: Saccharomyces cerevisiae, Hanseniospora uvarum and Kazachstania unispora. Nevertheless, by simulating the passage of isolated strains through the gastrointestinal environment, it was observed that they could not be considered probiotics. The results indicate that, in an isolated way, the yeast presents in kefir samples, in the city of Santa Maria, RS, can´t be considered probiotics according to the tests performed.

Isolation and Molecular Identification of Potential Probiotic Yeast Strains Found in Malaysian Kefir Drinks Samples

“…These results are consistent with a previous research [16] where the most common yeast species that can be found in the microbial mixture in the kefir is Saccharomyces cerevisiae. Another study done from Brazil reported that Saccharomyces, Candida and Kluyveromices are the abundance genera that can be found in the kefir drink in the region [17].…”

Kefir micro-organisms: their role in grain assembly and health properties of fermented milk

“…de found that S. cerevisiae strains isolated from Brazilian kefir presented interesting in vitro probiotic properties. However, Cassanego et al (2017) observed that S. cerevisiae, Hanseniospora uvarum and K. unispora isolated from other Brazilian kefir were not able to tolerate the passage through the simulated gastrointestinal tract. Xie et al (2012) studied the positive effect of the kefir yeasts on Lactobacillus probiotic potentials and Cho et al (2018) recently found that a combination of kefir-derived Kluyveromyces KU140723-02 and polyphenol-rich grape seed flour or its extract has an incremented antioxidant activity.…”

“…However, Cassanego et al . () observed that S. cerevisiae, Hanseniospora uvarum and K. unispora isolated from other Brazilian kefir were not able to tolerate the passage through the simulated gastrointestinal tract. Xie et al .…”

Brewing and Probiotic Potential Activity of Wild Yeasts Hanseniaspora Uvarum PIT001, Pichia Kluyveri LAR001 and Candida Intermedia ORQ001

“…Several microorganisms demonstrate their probiotic potential through pathogens inhibition, however they still need to overcome barriers during passage through GI tract, which involves gastric juice, digestive enzymes, organic acids, bile salts and considerable variations in temperature and pH, such as acidic pH of gastric juice and alkaline pH existing in the intestine 2017) demonstrated GD solution is not usually aggressive to yeasts, as also observed in our study; nevertheless, isolates showed to be sensitive to pancreatic conditions, with a decrease of living cells between 1 log 10 -2 log 10 . In the studies of Cassanego et al (2017), isolates classi ed as S. cerevisiae and H. uvarum were not able to survive after exposure to this condition, however we presented in our work that yeast isolates were able to resist to PD solution. Cell viability analysis during in vitro GI tract simulation proves to be important because it is believed that effects related to probiotics are dose-dependent, it being suggested as effective a dosage between 10 7 -10 9 CFU/mg per day (Minelli and Benini, 2008).…”