Characterization of the Saccharomyces cerevisae Y500-4L killer toxin

Abstract

The strain Saccharomyces cerevisiae Y500-4L, selected from the must of alcohol producing plants, liberates a toxin which is lethal to the commercial yeast produced by Fleischmann Royal Nabisco and other strains of yeast. This toxin was characterized, and the maximum production was obtained after 24 hours of incubation at 25 o C in YEPD medium. The maximum activity was achieved between pH 4.1 and 4.5 and between 22 and 25 o C and maximum stability in the pH range 3.8 to 4.5 at-10 o C. The killer toxin was inactivated by heating at 40 o C for 1 hour at pH 4.1. After concentration by ultrafiltration of culture supernatants and purification by gel filtration chromatography, the molecular weight of the purified toxin was estimated by SDS-PAGE to be about 18-20 kDa.

Killer toxin from several food-derived Debaryomyces hansenii strains effective against pathogenic Candida yeasts

“…We found that mycocin from the strains Dh-274, Dh-237 andDh-65 exhibited temperature-dependent killer activity against C. albicans up to pH 5.5 and against C. tropicalis up to pH 6.0,with activity decreasing abruptly at nonpermissive temperatures and pH values. Most published studies on mycocin activity report that mycocins are generally stable only over narrow pH ranges and each mycocin has a defined optimal pH for killer activity against the sensitive yeast species (Chen et al, 2000;Soares and Sato, 2000). A previous report by Marquina et al (2001) stated that mycocin from D. hansenii isolated from olive brines had an optimal stability and activity against Candida boidinii (IGC3430) between pH 4.5 and pH 5.1, congruent with our observations.…”

Isolation of Saccharomyces cerevisiae from pineapple and orange and study of metal’s effectiveness on ethanol production

“…Presence of clear inhibition zone in a petri dish was considered to be the key evidence of this property, which was not observed. Investigations revealed that the occurrence of the killer phenotype in yeast is widespread in alcohol fermentations for beverage production such as in breweries, wine, plants, and, more recently, in sugar-producing plants [26]. The concentration of sensitive cells influenced the sensitivity of the bioassay.…”

“…The capability to produce killer toxin can confer an advantage over more sensitive competitive strains growing in a fermentative process [26]. …”

“…Then, it was poured on a plate and allowed to solidify. Yeast was streaked on a plate in 2–3 rows and incubated at 25 °C for 24 h. Clear zone of inhibition was observed to recognize the yeast strain as “killer strain” [25, 26]. …”

Anthraquinones As Pharmacological Tools and Drugs

“…This blue polymer, supplied mainly at that time by the Swedish company Pharmacia Fine Chemicals, was found to be completely excluded from the stationary gel phase . Therefore, it has been commonly used as a marker for the determination of the void volume during calibration of gel filtration columns, whereby the shape of the band is additionally helpful for assessment of column packing and resolution. Moreover, blue dextran is utilized as a molecular weight standard ( M r 2,000,000 g/mol) for the determination of the molecular weight of proteins, which was first proposed by Andrews …”