Diversity of fungal endophytes in the semi evergreen vine thickets of the southern Brigalow Belt bioregion and their production of antimicrobial secondary metabolites.

Diversity of fungal endophytes in the semi evergreen vine thickets of the southern Brigalow Belt bioregion and their production of antimicrobial secondary metabolites.

Endophytes are thought to make up at least half of the diversity within the fungal kingdom and yet they remain one of the least explored functional groups. What research that has been conducted has focused on tropical rainforests or grasses with comparatively little research examining diversity within other ecosystems. Semi-evergreen vine thickets (SEVT) are remnant dry rainforests which form part of the Brigalow Belt along the eastern coast of Australia. Due to the fertile soil on which they grow, SEVT are frequently cleared for agricultural use, currently no information exists regarding fungi within this ecosystem.

Leaves from 23 plants at 3 sites of SEVT were sampled and fungal endophytes were isolated and identified. Fungal specificity was examined by collecting leaves from 22 Geijera salicifolia plants from 5 sites of SEVT. In total, 228 and 187 fungal endophytes were isolated from the two studies. Multi-gene phylogenetic analysis was further conducted on Nigrospora, Preussia, Guignardia and Pezizales - four of the most commonly occurring taxa. Endophytes obtained from the diversity study were screened for antimicrobial capabilities and HPLC analysis was conducted on crude extracts obtained from endophytes showing bioactivity. Pure compounds were retested for their ability to inhibit the growth of microbial pathogens.

A wealth of novel fungal endophytes was observed within SEVT. Four new taxa within the predominately saprotrophic order Pezizales, were observed. This finding may represent an example of ecosystem specificity. A large number of Preussia, Nigrospora and Guignardia species were also observed. Fungal specificity was found to be occurring between several species of Guignardia and G. salicifolia. 6 novel pure compounds were isolated from a Preussia sp. Three of these showed significant antimicrobial activity against MRSA and C. albicans. The results of this study indicate that SEVT harbour a vast storehouse of novel and medicinally significant endophytic fungi.