Screening and Identification of Lactic Acid Bacteria from Airag for Antifungal Activity

The aims of this study were to isolate and identify antifungal Lactic Acid Bacteria (LAB) from Airag in Mongolia and Inner Mongolia of China and to evaluate their potential to prevent fungal spoilage of milk. A total of 520 strains were isolated from 20 Airag samples. Their antifungal activity against Penicillium chrysogenum was investigated using the overlay technique and 17 strains were found to have strong activity. The 17 strains were identified on the basis of morphological characteristics, biochemical properties and carbohydrate fermentation profiles through API50CH and 16S rDNA analyses. Leuconostoc (Leu.) mesenteroides 368 showed a broad spectrum of antifungal activity when its activity against eight molds was examined by the overlay technique. The antifungal activity was maximum (900 AU mL(-1)) at 54-60 h of cultivation. LAB can be used to prolong the shelf life of dairy products. To the knowledge, this is the first time that Leu. mesenteroides which exhibits a broad spectrum of antifungal activity against a wide range of food spoilage fungi was isolated from Airag.