Isolation of anti-fungal agent from a soil inhabitant Streptomyces albaduncus-M51 and its efficacy against osmophilic food spoilage by Saccharomyces cerevisiae

Abstract

Aim: This study was performed to isolate antifungal substance from actinomycetes species found in soil in order to avoid osmophilic food spoilage. Methods: Purified isolates of different actinomycetes collected from soil in Makkah region, Saudi Arabia were screened for their antifungal bioactivity against the unicellular fungal strain, Saccharomyces cerevisiae. The actinomycete isolate that showed the highest fungal inhibition potency was selected and identified. Antifungal metabolite fermented by identified isolate was extracted and minimum inhibitory concentration (MIC) was determined. Food preservative efficacy of the extracted crude fungicide was tested against osmophilic foods spoilage. Results: Among 59 actinomycetes strains, 10 isolates exhibited antifungal efficacy against S. cerevisiae. Only one isolate was the most potent fungicidal and identified as Streptomyces albaduncus-M51. Crude antifungal was extracted and MIC value found to be 25µg/ml against the tested yeast strain. Yeast colonies were completely undetected in treated food samples at crude extract concentration (150µl/100ml for liquid foods and 200µl/100mg for solid samples). Conclusion: The antifungal agent produced by S.albaduncus-M51 demonstrated an obvious inhibitory effect against S. cerevisiae that causes osmophilic foods spoilage.