Antifungal Activity of Pediococcus pentosaceus Isolated from Whole Barley Sourdough

Background: Lactic acid bacteria (LAB) isolated originally from sourdough are probably the best candidates as biopreservatives, because they are well adapted to the non-aseptic conditions in sourdough fermentation. The aim of the present study was to study antifungal properties of a dominant endogenous LAB isolated from whole barley sourdough. Methods: Whole barley flour from a mixture of barley varieties was purchased from a local market. The pure and single colonies obtained from streak plate of these bacteria, were subjected to species specific PCR. By sequencing of the PCR products, the dominant LAB isolate was identified. Antifungal activity of mentioned isolate and its cell-free culture filtrate (CCF) were evaluated against Aspergillus flavus and A. niger based on overlay method and fungal spore spot on mixture of medium-CCF, respectively. Statistical analyzing was performed by ANOVA and by post hoc Tukey using SAS-9.1 software. Results: The dominant LAB isolate was identified as Pediococcus pentosaceus that had significant (p<0.05) antifungal effect compared to control group. Furthermore, among all CCF treatments, CCF obtained from stationary phase (CCF-S) had the highest antagonistic effect (p<0.05). The antifungal activity was also observed in neutral pH. Conclusion: It was concluded that the secondary metabolites of P. pentosaceus were more effective than the primary metabolites in antifungal properties. Also, its antifungal activity in neutral pH indicated this isolate produced some antifungal compounds in both logarithmic and stationary phases. Therefore, P. pentosaceus with antifungal potential would be a proper candidate as biopreservative starter or adjunct culture in sourdough bread processing.