Date Published: May 28, 2018
Publisher: Springer Berlin Heidelberg
Author(s): Inga Bazukyan, Lusine Matevosyan, Anna Toplaghaltsyan, Armen Trchounian.
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.
Food and feed spoiling moulds and yeasts can be potential hazards and cause great economic losses worldwide (De Muynck et al. 2004). The reduction of mould and yeast growth in food and feed production and their storage is of the primary importance. There is a great interest in developing efficient and safe strategies for this purpose. Thus, the application of biological preservation has received much attention in recent years. The natural origin and the good examination of producers which were isolated from nature are the primary demands to these new agents. The best candidates satisfying these demands are lactic acid bacteria (LAB) (Gerez et al. 2009).
Armenian dairy products are rich in proteins and important nutrients and can be a good source of unique combinations of LAB. The latter can produce several antimicrobials, proteolytic and antifungal compounds. The antibacterial and proteolytic activity of some isolated strains had been shown before (Bazukyan et al. 2010; Movsesyan et al. 2010). That is why it was interesting to study the antifungal activity as well. The investigation of antifungal activity showed the high specificity of LAB to inhibit the growth of fungi species. Like this, the strains RIN-2003, MDC 9661, MDC 9632 and MDC 9633 blocked the growth of Fusarium CB 1853, although the growth of M. plumbeus was inhibited by MDC 9661 strain only (see Table 1). Moreover, the growth of P. aurantioviolaceum and C. albicans was suppressed by MDC 9661, INA-5.1 and INA-21.1.