Killer yeasts isolated from olive brines: Technological and probiotic aptitudes. (May 2022)

• Record Type: Journal Article
• Authors: Parafati, Lucia; Palmeri, Rosa; Pitino, Iole; Restuccia, Cristina
• Is Part Of: Food microbiology. Volume 103(2022)
• Publication Date: 2022-05
• Subjects: Table olives -- Killer phenotype -- Yeast identification -- Enzyme assays -- Probiotic traits; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2021.103950
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: Table olive brines, inoculated with six different starters of lactic acid bacteria (LAB) or spontaneously fermented, have been used as isolating source of killer yeasts throughout the fermentation process (120 d). Killer yeast isolates were identified and evaluated for technological and probiotic traits. Although the count of yeast population did not markedly vary among the different vessels and over time, the killer yeast phenotype was mainly present in yeast strains isolated from spontaneous fermentation; the number of killer isolates decreased over fermentation time. Killer phenotype was found in species identified as Pichia kluyveri, Zygoascus hellenicus, Wickerhamomyces anomalus, Pichia membranifaciens, Candida boidinii, Candida diddensiae and Saccharomyces cerevisiae . Among all tested isolates, W. anomalus strains evidenced the widest spectrum of enzymatic activities and the highest β-glucosidase and phtytase activity. These strains evidenced also the best growth at low pH and increasing bile salt concentration, when grown at 37 °C, as well as the most constant viability index (%) during in vitro digestion. Highlights: Killer yeasts were isolated from differently fermented table olives over 120 d. Yeast isolates were identified by RFLP analysis of ITS regions and D1/D2 sequences. Killer phenotype was mainly present in yeasts isolated from spontaneous fermentation. Wickerhamomyces anomalus strains displayed the widest spectrum of enzymatic activities. anomalus WA-2 showed the most constant viability index during in vitro digestion.