Yeasts represent an important category of microorganisms used in biocontrol of diseases affecting postharvest fruits or vegetables, food-born microorganisms being previously reported as also having important antimicro...Yeasts represent an important category of microorganisms used in biocontrol of diseases affecting postharvest fruits or vegetables, food-born microorganisms being previously reported as also having important antimicrobial activity against human pathogens. However, the action of yeasts against species with pathogen potential for plants or humans is less understood. Our research was conducted on three Metschnikowia pulcherrima yeast strains isolated from white grapes （SG1, SG2） and cherries （CPMI） from Romania. The screening tests performed on yeast peptone glucose （YPG） medium on isolates from human infections revealed reduced antimicrobial activity with narrow inhibition zones against strain M6 （Candidaparapsilosis）. In the presence of C3 （Candida albicans）, SGI was the most active forming wider halos, followed closely by SG2, while for CPM1, no activity was described. Improvement of antagonistic action was observed especially for mixtures of SG1 with 0.5% and 1% sodium bicarbonate （NaHCO3）, respectively, 1% and 2% calcium chloride （CaCI2）. Utilization of yeast malt extract agar （YMA） medium favoring mycelium formation in cultures representing potential sensitive substrates seemed to facilitate the antimicrobial action of SG1. When compared to reference M. pulcherrima MUCL 29874, the Metschnikowia strains isolated from fruits were better antagonists probably due to variation of gene regulation or existence of adaptative responses.展开更多
文摘Yeasts represent an important category of microorganisms used in biocontrol of diseases affecting postharvest fruits or vegetables, food-born microorganisms being previously reported as also having important antimicrobial activity against human pathogens. However, the action of yeasts against species with pathogen potential for plants or humans is less understood. Our research was conducted on three Metschnikowia pulcherrima yeast strains isolated from white grapes （SG1, SG2） and cherries （CPMI） from Romania. The screening tests performed on yeast peptone glucose （YPG） medium on isolates from human infections revealed reduced antimicrobial activity with narrow inhibition zones against strain M6 （Candidaparapsilosis）. In the presence of C3 （Candida albicans）, SGI was the most active forming wider halos, followed closely by SG2, while for CPM1, no activity was described. Improvement of antagonistic action was observed especially for mixtures of SG1 with 0.5% and 1% sodium bicarbonate （NaHCO3）, respectively, 1% and 2% calcium chloride （CaCI2）. Utilization of yeast malt extract agar （YMA） medium favoring mycelium formation in cultures representing potential sensitive substrates seemed to facilitate the antimicrobial action of SG1. When compared to reference M. pulcherrima MUCL 29874, the Metschnikowia strains isolated from fruits were better antagonists probably due to variation of gene regulation or existence of adaptative responses.
