E.T.S. de Ingeniería Agronómica, Alimentaria y de Biosistemas (UPM)
Abstract
Purothionins are basic polypeptides with antimicrobial properties that are
present in the endosperm of wheat and other Gramineae. Susceptibility to crude
and electrophoretically purified purothionins among brewing starters has been
investigated. Seven yeast strains of Saccharomyces uvarum (syn. carlsbergensis),
four strains of Saccharomyces cerevisiae, and four wild strains (Saccharomyces
spp.) have been tested in three culture media. All the strains were susceptible to
the crude preparation in a yeast extract-glucose medium. Determinations of
minimal inhibitory and biocidal concentrations yielded double end points in
about half of the assays. The highest sensitivity to purothionins was obtained in
malt extract medium. Sensitivity to electrophoretically purified purothionins
was of the same order or smaller than to the crude preparation. Possible
explanations for this unexpected result are presented