A Novel Saccharomyces cerevisiae Killer Strain Secreting the X Factor Related to Killer Activity and Inhibition of S. cerevisiae K1, K2 and K28 Killer Toxins

Abstract

It was determined that Kx strains secrete an X factor which can inhibit all known Saccharomyces cerevisiae killer toxins (K1, K2, K28) and some toxins of other yeast species-the phenomenon not yet described in the scientific literature. It was shown that Kx type yeast strains posess a killer phenotype producing small but clear lysis zones not only on the sensitive strain α'1 but also on the lawn of S. cerevisiae K1, K2 and K28 type killer strains at temperatures between 20 and 30 °C. The pH at which killer/antikiller effect of Kx strain reaches its maximum is about 5.0-5.2. The Kx yeast were identified as to belong to S. cerevisiae species. Another newly identified S. cerevisiae killer strain N1 has killer activity but shows no antikilller properties against standard K1, K2 and K28 killer toxins. The genetic basis for Kx killer/antikiller phenotype was associated with the presence of M-dsRNA which is bigger than M-dsRNA of standard S. cerevisiae K1, K2, K28 type killer strains. Killer and antikiller features should be encoded by dsRNA. The phenomenon of antikiller (inhibition) properties was observed against some killer toxins of other yeast species. The molecular weight of newly identified killer toxins which produces Kx type strains might be about 45 kDa.

Evaluation of the Antioxidant and Antimicrobial Activities of Ethyl Acetate Extract of Saccharomyces cerevisiae

“…Yeasts, including S. cerevisiae, possess the ability to produce antimicrobial and antifungal compounds that inhibit the growth of pathogenic bacteria and fungi ( 1 ). It produces toxic proteins or glycoproteins to combat other strains of yeast or bacteria ( 2 ). According to Hassan ( 3 ), glutathione (GSH), sulfur-containing amino acids and Maillard reaction products are the components that contribute to the antioxidative properties of S. cerevisiae .…”

In vitro inhibition of Saccharomyces cerevisiae growth by Metschnikowia spp. triggered by fast removal of iron via two ways

“…A sensitive strain for killer assay S. cerevisiae haploid strain α′1 (MATα leu2-2 [kil-0], diploid strains S. cerevisiae Rom 100 HM/HM [kil-K2], S. cerevisiae M437 HM/HM [kil-K2], wild-type wine yeast S. cerevisiae N1, a novel S. cerevisiae killer strain Kx [34], Candida vartiovaarae CV1, and Rhodotorula sp. R1 were from the collection of the Institute of Botany (Nature Research Centre, Vilnius, Lithuania).…”

The yeasts – versatile antimicrobial agents

“…However, the K28 toxin is characteristic for the S. cerevisiae wine strain 28, and the Klus toxin was identified in the S. cerevisiae strains isolated from spontaneous fermentations of grapes from vineyards of the Ribera del Guadiana (Spain), showing amino acid sequence homolgy with a protein encoded by the chromosomal ORF YFR020W (Rodriguez-Cousino et al, 2011;Becker and Schmitt, 2017). Lately, two killer toxins possibly encoded by chromosomal genes were isolated from Cf8 and M12 S. cerevisiae strains from wineries in Argentina, and a Kx killer factor able to inhibit growth of all known S. cerevisiae killer types was isolated from spontaneous fermentations of fruits and berries from Lithuania (Melvydas et al, 2016). Species from Hanseniaspora, Zygosaccharomyces and Ustilago genera also present virus-like particles responsable for producing killer toxins with similar structure and mechansim of action as S. cerevisiae (Csutak, 2014).…”