Different strains of lactobacilli isolated from Armenian dairy products (matsoun, sour cream and different types of cheeses), were studied for antifungal activity. Lactobacillus rhamnosus MDC 9661 strain was shown to have inhibitory activity against Penicillium aurantioviolaceum and Mucor plumbeus growth. Bacterial cell-free supernatant didn’t show antifungal activity. The L. rhamnosus antifungal activity was stable to the wide range of pH from 3 to 10. This activity was high after treatment with both low temperature (− 30 °C) and lysozyme and with ultrasound. However, it was sensitive to high temperature from 45 to 80 °C and proteolytic enzymes. The results suggest the proteinaceous nature of L. rhamnosus antifungal activity associated with bacterial cell wall. L. rhamnosus MDC 9661 could be recommended as a starter for production of dairy products, functional food and preserving strain in food production.

Lactobacillus rhamnosus R-2002 strain isolated from Armenian pickled cheese sample has a fungicide effect, which was carried out by the first-time designed method. The fungicide effect of LAB strain was expressed after 5 days of co-cultivation with Mucor plumbeus and 6 days of co-cultivation with Penicillium aurantioviolaceum. The growth as well as the antifungal activity of L. rhamnosus R-2002 was shown to directly depend on the nature of the medium's carbon source. The antifungal activity of this strain against both moulds was inhibited when the combination of 10 g l glucose and 10 ml l ethanol in the medium was used as a carbon source. The results could be applied in food industry, medicine, and veterinary.

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