Characterization and Selection of Potential Antifungal Lactic Acid Bacteria Isolated from Turkish Spontaneous Sourdough

Abstract

The aim of this research was to investigate the antifungal potential of lactic acid bacteria (LAB) isolated from Turkish spontaneous sourdough collected in summer and winter seasons from 25 different small bakeries in Trabzon, Giresun, Ordu, and Samsun. Lactic acid bacteria (933 isolates) were screened for inhibition of three common food spoilage molds (Aspergillus flavus, Aspergillus niger, and Penicillium expansum). Eight LAB isolates identified as Weissella cibaria 908, Lactiplantibacillus plantarum subsp. plantarum 2114, Leuconostoc pseudomesenteroides 2619, L. plantarum subsp. plantarum 2702, Fructilactobacillus sanfranciscensis 2709, Levilactobacillus brevis 2216Y, L. pentosus Y118, and L. plantarum subsp. plantarum Y201 by 16 S rRNA sequencing, which were found to have high antifungal activity against all the test molds. The antifungal activity of cell free supernatants from LAB isolates was not altered after thermal treatment and proteolytic enzyme proteinase K. The cell free supernatants obtained from LAB showed a high antifungal effect against molds with inhibition zone diameter up to 20 mm at pH 3.0, but no inhibitory activity was determined after pH neutralization. Moreover, all cell free suspension samples were able to maintain their efficacy up to a 1:4 dilution. The antifungal activity of supernatants was mostly related to organic acid content, especially lactic acid ranged from 4.33 to 8.41 g/L. The results indicated that eight bacterial isolates obtained from spontaneous Turkish sourdough could constitute biopreservative cultures, which may be used in food industry.