Diversity and antibacterial activities of fungi derived from the Gorgonian Echinogorgia rebekka from the South China Sea

Abstract

The diversity of symbiotic fungi associated with the gorgonian coral Echinogorgia rebekka from the Weizhou coral reef in the South China Sea was investigated. Combined with morphologic traits, ITS-rDNA sequences revealed 18 fungal strains from this gorgonian. All of the 18 fungi belonged to the phylum Ascomycota and were distributed among seven genera in five orders: Eurotiales (Aspergillus and Penicillium), Pleosporales (Alternaria), Capnodiales (Cladosporium), Trichosphaeriales (Nigrospora) and Hypocreales (Hypocrea and Nectria). Antibacterial activities of these fungal strains were investigated with five pathogenic bacteria. All of the 18 fungal strains displayed different levels of antibacterial activities, most of which exhibited moderate to high antibacterial activities to the Gram-positive pathogens Staphylococcus aureus and Micrococcus tetragenus, and showed relatively low bioactivities to other three pathogenic bacteria. Several fungal strains in the genera Penicillium and Cladosporium with strong antibacterial activities provide potential for further research on isolation of bioactive secondary metabolites.

Keywords: Echinogorgia rebekka; antibacterial activity; diversity; fungi; gorgonian coral.

Figure 1.

Morphological photos of 18 gorgonian-derived fungal strains (WZL001–WZL018).

Figure 2.

Phylogenetic tree of partial ITS-rDNA sequences of gorgonian-derived fungal strains. Reference sequences were downloaded from NCBI with the accession numbers indicated in parentheses.