Identification of potentially probiotic yeasts from Thayir prepared by Backslopping

Abstract

This study investigated the probiotic properties of two yeasts isolated from traditionally fermented milk, thayir. The isolates were identified at the molecular level as Pichia kudriavzevii strain DMYNG01 and Kluyveromyces marxianus strain DMYA04 and have been deposited in the NCBI with accession numbers PP956861 and PQ098053, respectively. Both showed maximum growth at 37 °C. Kluyveromyces marxianus utilized lactose, while Pichia kudriavzevii was incapable of fermenting lactose. Both isolates exhibited lipolytic activity but were negative for proteolytic and amylolytic activities. Acid tolerance and bile tolerance of the isolates were evaluated, revealing their ability to withstand low pH levels (2 and 3) and bile salt concentrations (0.3% and 0.6%) for 4h. Both the isolates showed good adhesion properties. Auto aggregation, coaggregation, and hydrophobicity values of Pichia kudriavzevii and Kluyveromyces marxianus were found to be 83.33% and 71.42%, 39.09% and 25.91%, and 28.64% and 40.41% respectively. Pichia kudriavzevii exhibited higher antioxidant activity (61.43%) than Kluyveromyces marxianus (35.87%). Both the strains were negative for haemolysis and gelatin liquefaction, indicating the absence of these virulence factors.