Abstract:
The endophytic fungus, Dothideomycete sp. CRI7, isolated from the terrestrial plant,
Tiliacora triandra, was salt tolerant, capable of growing in the culture medium prepared from
seawater; salts in seawater did not have any effects on the fungal growth. Metabolite
productions of the fungus CRI7 cultivated in media prepared from seawater (MSW), prepared
from deionized water supplemented with potassium bromide (MKBr) or potassium iodide
(MKI), and prepared from deionized water (MDW) were investigated. It was found that the
cultivation of the fungus CRI7 in MKBr and MSW enabled the fungus to produce nine new
metabolites (1-9). The production of an azaphilone, austdiol (10), of the fungus CRI7 grown
in MDW was 0.04g/L, which was much lower than that grown in MSW, MKBr, and MKI
media which provided the yields of 0.5, 0.9, and 1.2 g/L, respectively, indicating that halogen
salts significantly enhanced the production of the polyketide 10. The cultivation of terrestrial
fungi in media containing halogen salts could therefore be useful for the metabolite
diversification by one strain-many compounds (OSMAC) approach. Moreover, the isolated
polyketides had significant biosynthetic relationship, suggesting that the cultivation of fungi
in halogen containing media could provide the insights into certain polyketide biosynthesis.
One of the isolated compounds exhibited antibacterial activity with the MIC value of 100
µg/mL.
