Screening of Dairy Yeast Strains for Probiotic Applications

Abstract

To evaluate the potential of yeasts of dairy origin as probiotics, we tested 8 species including Candida humilis, Debaryomyces hansenii, Debaryomyces occidentalis, Kluyveromyces lactis, Kluyveromyces lodderae, Kluyveromyces marxianus, Saccharomyces cerevisiae, and Yarrowia lipolytica, isolated from commercial blue cheese and kefir. Strains were randomly selected from each species and tested for their ability to adhere to human enterocyte-like Caco-2 cells in culture. Among the 8 species, K. lactis showed higher adhesive ability than K. marxianus, K. lodderae, and D. hansenii. The other 4 species were poorly adhesive. All species other than K. marxianus and C. humilis were resistant to acidic conditions. In the presence of bile acid, growth inhibition was undetectable when incubation was carried out at 27 degrees C; however, it was evident for C. humilis and a strain of D. occidentalis when incubated at 37 degrees C. Moreover, the influence of proteinase treatment of living cells of K. lactis and K. lodderae on their adhesion to Caco-2 cells was evaluated. Although a slight reduction was recognized when K. lactis was treated with proteinase K, the influence of intestinal protease treatments of pepsin followed by trypsin was negligible. These results indicated that a proteinaceous factor was unlikely to be involved in adhesion of K. lactis and K. lodderae to Caco-2 cells. No stimulation of IL-8 synthesis by Caco-2 cells was recognized in the presence of K. lactis. In conclusion, K. lactis was the most attractive to continue study for use as probiotic microorganisms.

Screening for the potential probiotic yeast strains from raw milk to assimilate cholesterol

“…The adhesive values of HT-29 cells ranging from 2 to 80 were similar to values reported by Kumura et al [12] regarding yeast adhesion to Caco-2 cells.…”

“…Adhesion of probiotic bacteria to the intestinal mucosa is an effective way to exclude pathogens and undesirable bacteria [2,12]. Figure 1 shows the number of yeast cells that adhered to 100 HT-29 cells.…”

“…It has been reported that Saccharomyces boulardii was effective as a biotherapeutic agent in the prevention or treatment of antibioticassociated diarrhea and human colitis, especially for the treatment of acute diarrhea in children [25]. Recently, many researchers have focused on the antioxidant ability and cholesterol assimilation of yeasts [12,16,17,21]. Some reports indicated that yeasts can remove cholesterol in vitro [21].…”

“…To benefit human health, probiotic microorganisms have been increasingly incorporated into food as dietary adjuncts. The usual microbial inhabitants of the intestinal tracts of human beings and other vertebrates are typically lactobacilli or bifidobacteria [1,12]. The use of yeasts, as potential probiotics, has also been reviewed [9,11].…”

Adhesion to the yeast cell surface as a mechanism for trapping pathogenic bacteria by Saccharomyces probiotics

“…Until now, Saccharomyces boulardii has been the only yeast commercialized worldwide as a probiotic for humans, but some authors have suggested the use of other yeast species or genera based essentially on in vitro assays and a few clinical trials (Kovacs & Berk, 2000;Kumura et al, 2004;van der Aa Kühle et al, 2005). We demonstrated previously that Saccharomyces cerevisiae strain UFMG 905 has potential as a probiotic due to its ability to protect mice against Salmonella enterica serovar Typhimurium and Clostridium difficile infection in a murine model (Martins et al, 2005), and to inhibit bacterial translocation and modulate both local and systemic immunity of mice (Martins et al, 2007;Generoso et al, 2010).…”