Characterization of yeast strains isolated from bloaters of fermented green table olives during storage

Abstract

Fermented green olives stored in bulks (200 litres plastic containers) were sampled from two factories in Morocco to collect the attacked fruits (bloaters). The microbial species present in the bloaters were isolated by taking a loop from the attacked regions of the fruits and streaked onto appropriate media for the determination of yeasts, Gram negative bacteria and lactic acid bacteria. Results showed that only yeast colonies appeared and no growth of other microorganisms was detected. One handered and four isolates of yeasts were collected for the characterization and research of the killer activity on selected target strains. Results showed that the isolates fit into four species: Saccharomyces cerevisiae, Pichia anomala, Candida etchellsii, Candida versatilis, and Rhodotorula glutinis. Some of the studied isolates from each species showed killer activity on the target strains. Strains of P. anomala and C. etchelsii were the most active followed by the strains belonging to S. cerevisiae.