Purification, characterization and in vivo biocontrol efficiency of killer toxins from Debaryomyces hansenii strains

Nowadays, the biological control of various yeast and mold pathogens that cause diseases in humans, animals, and plants is an increasing of interest. The discovery of novel agents allows prevention of infectious diseases and post-harvest losses reported every year. In the study, we aimed to investigate the production, purification, and characterization as well as in vivo biocontrol efficiency of killer toxins produced by Debaryomyces hansenii strains TEM8 and TEM17. The molecular mass of the killer toxins was 31.5 kDa and they showed high stability at pHs between 2.5 and 5.5 and up to 37 degrees C. Their internal amino acid sequences matched the DEHA2G18766g (CAG90862.1) from D. hansenii CBS767, which is similar to Saccharomyces cerevisiae YGR282C BGL2 endo-beta-1,3-glucanase. The yeasts and their purified killer toxins significantly inhibited the growth of plant pathogenic fungi Alternaria brassicicola, Alternaria citri, Aspergillus niger and Rhizopus stolonifer in fruits. The findings of this paper have recommended these yeast strains and their toxins as effective biocontrol agents against fungi that cause post-harvest diseases. (C) 2018 Published by Elsevier B.V.