Anti-salmonella properties of kefir yeast isolates : An in vitro screening for potential infection control

Abraham Majak Gut; Todor Vasiljevic; Thomas Yeager; Osaana N Donkor

doi:10.1016/j.sjbs.2021.09.025

Anti-salmonella properties of kefir yeast isolates : An in vitro screening for potential infection control

Saudi J Biol Sci. 2022 Jan;29(1):550-563. doi: 10.1016/j.sjbs.2021.09.025. Epub 2021 Sep 20.

Authors

Abraham Majak Gut^{1

2}, Todor Vasiljevic^{1

2}, Thomas Yeager^{1

3}, Osaana N Donkor^{1

2}

Affiliations

¹ Institute for Sustainable Industries and Liveable Cities, Victoria University, Werribee Campus, PO Box 14428, Melbourne, Victoria 8001, Australia.
² College of Health and Biomedicine, Victoria University, Werribee Campus, PO Box 14428, Melbourne, Victoria 8001, Australia.
³ First YearCollege, Victoria University, Werribee Campus, PO Box 14428, Melbourne, Victoria 8001, Australia.

Abstract

The rise of antibiotic resistance has increased the need for alternative ways of preventing and treating enteropathogenic bacterial infection. Various probiotic bacteria have been used in animal and human. However, Saccharomyces boulardii is the only yeast currently used in humans as probiotic. There is scarce research conducted on yeast species commonly found in kefir despite its claimed potential preventative and curative effects. This work focused on adhesion properties, and antibacterial metabolites produced by Kluyveromyces lactis and Saccharomyces unisporus isolated from traditional kefir grains compared to Saccharomyces boulardii strains. Adhesion and sedimentation assay, slide agglutination, microscopy and turbidimetry assay were used to analyze adhesion of Salmonella Arizonae and Salmonella Typhimurium onto yeast cells. Salmonella growth inhibition due to the antimicrobial metabolites produced by yeasts in killer toxin medium was analyzed by slab on the lawn, turbidimetry, tube dilution and solid agar plating assays. Alcohol and antimicrobial proteins production by yeasts in killer toxin medium were analyzed using gas chromatography and shotgun proteomics, respectively. Salmonella adhered onto viable and non-viable yeast isolates cell wall. Adhesion was visualized using scanning electron microscope. Yeasts-fermented killer toxin medium showed Salmonella growth inhibition. The highest alcohol concentration detected was 1.55%, and proteins with known antimicrobial properties including cathelicidin, xanthine dehydrogenase, mucin-1, lactadherin, lactoperoxidase, serum amyloid A protein and lactotransferrin were detected in yeasts fermented killer medium. These proteins are suggested to be responsible for the observed growth inhibition effect of yeasts-fermented killer toxin medium. Kluyveromyces lactis and Saccharomyces unisporus have anti-salmonella effect comparable to Saccharomyces boulardii strains, and therefore have potential to control Salmonella infection.

Keywords: AGC, Automatic Gain Control; ATCC, American type Culture Collection; ATP, Adenosine triphosphate; CFS, Cell Free Supernatant; CFU, Colony Forming Unit; DNA, Deoxyribonucleic Acid; DSR, Desk Sputter Coater; DTT, Dithiothreitol; FAO, Food Agriculture Organization; GIT, The gastrointestinal tract; HCL, Hydrochloric Acid; HPLC, High-performance liquid chromatography; IBM, International Business Machines; KTM, Killer Toxin Cedium; Kefir; Kluyveromyces lactis; LC-MS/MS, Liquid Chromatography with tandem mass spectrometry/Liquid Chromatography with tandem mass spectrometry; LFQ, Label Free Quantitation; Min, Minute; NaOH, Sodium hydroxide; PBS, Phosphate buffered saline; Probiotics; RNA, Ribonucleic Acid; RSLC, Rapid Separation Liquid Chromatography; SD, Standard Deviation; SPSS, Statistical Package for the Social Sciences; Saccharomyces boulardii; Saccharomyces unisporus; Salmonella; Shotgun proteomics; WHO, World Health Organization; YEPDA, Yeast Extract Peptone Dextrose Agar; YEPDB, Yeast Extract Peptone Dextrose Broth; Yeasts; h, Hour; mL, Milliliter.