Identification and antibacterial characteristics of an endophytic fungus Fusarium oxysporum from Lilium lancifolium.

AIMS: The aim of this study is to isolate and identify an endophytic fungus with antibacterial activity from the Asian medicinal and culinary plant Lilium lancifolium and to study the characteristics of its major antibacterial fractions. METHODS AND RESULTS: After strict sample sterilization, an endophytic fungus BH-3 with great antibacterial activity against Leuconostoc mesenteroides was isolated from the bulbs of L. lancifolium and was identified as Fusarium oxysporum on the basis of internal transcribed spacer (ITS) rDNA sequence and morphological traits. After partial purification including superfiltration and gel filtration, the major antibacterial fractions were found to be the substances with the molecular mass ranging from 35 to 60kDa, mainly 55kDa. The partially purified antibacterial fractions were stable at thermal processes, with more than 80% of activity left at 60°C for 1h, and even 70·75% left at 121°C for 15min. 90·33-98·97% of activity was observed in the pH range of 4·0-7·0. But the fractions were sensitive to different proteases. CONCLUSIONS: Endophytic strain F. oxysporum BH-3 isolated from the bulbs of L. lancifolium produced protein-like antibacterial metabolites. The antibacterial assay against Leuc. mesenteroides indicated that the fractions were stable at thermal processes and wide pH conditions, but sensitive to proteolyses. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides an increasing understanding of endophytic F. oxysporum in L. lancifolium and its metabolites, which have a great potential in food industry as antibacterial agents.