Isolation and Identification of Predominant Lactic Acid Bacterial Flora From Oat Bran Sourdough and Their Antifungal Ability

Abstract

Background: The widespread consumption of industrial fermented products instead of traditional products leads to the loss of various lactic acid bacteria (LAB), especially the strains producing bioactive compounds. The present study aimed to isolate and molecularly identify LAB and investigate their antifungal impact on Aspergillus niger growth. Materials & Methods: Oat bran was purchased from the Gorgan city market in 2019 and sourdough was prepared. Afterwards, bacteria were isolated and identified in the Microbiology Laboratory of Golestan University of Medical Sciences, Gorgan, Iran. Next, the antifungal activity of LAB and their supernatant against A. niger was investigated. Finally, the identification of the cellfree supernatant of LAB was completed using gas chromatography-mass spectrometry. Results: Findings of the current study demonstrated that Lactobacillus brevis and Lactobacillus sakei had the highest inhibitory effects of 30.25% and 18.47% against A. niger, respectively. Moreover, the minimum inhibitory concentration of L. brevis and L. sakei supernatants against A. niger was found as 3%. We observed that the greater effect of the supernatant of L. brevis could be due to the presence of ester, phenolic, and barbiturate compounds. Conclusion: According to our results, dominant LAB from oat bran sourdough, as well as their cultured pellets have suitable antifungal potential against A. niger. Therefore, these bacteria can be used as a starter culture or co-culture in the fermentation products process, such as sourdough to decrease fungal contamination.