[Antibacterial activity of secondary metabolites from Aspergillus awamori F12 isolated from rhizospheric soil of Rhizophora stylosa Griff].

OBJECTIVE

To identify Aspergillus awamori strain F12 isolated from rhizospheric soil of Rhizophora stylosa Griff and to characterize antibacterial compounds from the ethyl acetate extracts of its fermentation broth.

METHODS

Strain F12 was identified based on its morphological characters and internal transcribed spacer (ITS) sequence. Its secondary metabolites were purified by chromatography, and elucidated by mass spectroscopy, H-NMR, 13C-NMR and physicochemical characters. The antibacterial activities of these compounds were tested against Staphyloccocus aureus and Bacillus subtilis.

RESULTS

Strain F12 was identified as Aspergillus awamori. Three compounds, including 1,4-dimethoxybenzene (1), emodin (2) and 3, 6-dibenzylpiperazine-2, 5-dione (3), were purified and elucidated from the ethyl acetate extracts of fermentation broth, among which compound 1 was first reported for the genus of Aspergillus. Compound 2 suppressed the growth of Staphyloccocus aureus and Bacillus subtilis with MIC values of 16 microg/mL and 32 microg/mL respectively, while the other two compounds have no effects on these bacteria.

CONCLUSIONS

Aspergillus awamori strain F12 isolated from rhizospheric soil of Rhizophora stylosa Griff can produce 1, 4-dimethoxybenzene and emodin, among which the latter can suppress the growth of bacteria apparently.