Antagonistic Fungal Endophytes Colonizing Rhizome of Amomum centrocephalum A.D. Poulsen from North Sumatera, Indonesia

Abstract

Endophytic fungi were successfully isolated from healthy rhizomes of the wild ginger Amomum centrocephalum A.D. Poulsen from Hutan Sibayak, North Sumatera, Indonesia. This study aimed to evaluate the antagonistic properties of isolated endophytic fungi against selected pathogenic bacteria and phytopathogenic fungi assessed by dual culture plate assay. Methanolic extract of A. centrocephalum rhizome was also tested as a control. Nine morphotypes of endophytic fungi were differentiated morphologically with further molecular identification using ITS rDNA sequencing for potential antagonistic strains. Most isolates showed considerable inhibitory activities towards microbial indicators than MeOH extract of A. centrocephalum. All strains showed distinct inhibitory activities against bacterial pathogens. The strongest activity was shown against gram-positive, Staphylococcus aureus ATCC 29213â„¢ followed by gram-negative, Escherichia coli ATCC 25922â„¢ while there was no evidence of inhibition against clinical yeast strain, Candida albicans. All strains were known as prominent antagonists of phytopathogens against Fusarium oxysporum, Ganoderma boninense, and Rigidoporus ligneous. The five potential strains were identified as Aspergillus aculeatus, Clonostachys rosea, Daldinia caldariorum, and two strains of Trichoderma. Hence, we reported the newly found species of endophytic fungi colonizing rhizomes of Sumatran Zingiberacean species with prospects upon finding novel metabolite compounds combating bacterial infection and plant diseases.