Abstract
Rhizophora mucronata
is an important ecosystem entity of the Malaysian mangrove forest. Since the species grows in a harsh environment, any organism that is isolated from this species would be of huge interest due to its potential in having novel bioactive compounds. In the present work, we isolated, identified and characterized, a total of 78 fungal isolates harboring inside the leaf tissues of
R. mucronata
. Molecular identification using the nuclear ribosomal DNA internal transcribe spacer (ITS) sequences returned with high similarity matches to known sequences in the GenBank. Maximum likelihood analysis revealed the phylogenetic relationship of all isolates from this study. Most of the dominating fungal endophytes were from the genera
Pestalotiopsis
, followed by
Alternaria
and
Cladosporium
. Six isolates representing the genera
Alternaria, Fusarium, Nigrospora, Pestalotiopsis, Phoma
, and
Xylaria
, were further screened for their antagonism activities. Dual culture test assay revealed their inhibition percentages against the phytopathogenic fungus
Fusarium solani
between 45–66%, and 0.8–23% when using non-volatile test assay. Of the six isolates, only
Fusarium lateritium
and
Xylaria
sp. showed antibacterial activities against the pathogenic bacteria,
Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa
, and
Staphylococcus aureus
, with the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) ranging from 0.5 to 2 mg/mL. The DPPH radical scavenging assay recorded a high level of antioxidant activity in
Xylaria
sp., 3-fold above that of
F
.
lateritium
. We demonstrate for the first time, two members belonging to the endophytic fungal community in the tropical mangrove species that have potential use as antagonists and antibacterial agents for future biotechnological applications.