In vitro screening of Kluyveromyces strains isolated from Fiore Sardo cheese for potential use as probiotics

In this work, six Kluyveromyces strains isolated from artisanal Fiore Sardo cheese were evaluated for some functional properties relevant to their use as probiotics. All strains were able to grow in the presence of conjugated bile salts after 72 h of incubation, and four were able to hydrolyse both sodium glycodeoxycholate and taurodeoxycholate. All strains survived well under simulated gastric conditions (pH 3.0), but Kl. marxianus strains presented the best survival rates values (83–100%) after exposure to artificial duodenum juice. Autoaggregation ability showed a certain variability with mean values ranging between 39.1 and 59.2%, while the hydrophobicity index was higher than 50% in five strains. All strains were able to adhere to Caco-2 cells (values ranging from 4 to 68%), with two Kl. lactis strains exhibiting significantly higher percentage adhesion than S. boulardii Codex used as control (P < 0.05). Kl. lactis strains also showed the broadest inhibitory range against pathogens. Finally, all strains were non-hemolytic and sensitive to the antimycotic agents tested. In conclusion, our results indicate that Kluyveromyces strains isolated from artisanal cheese possess interesting functional traits and absence of undesirable properties, and could be considered appropriate probiotic candidates.