Fungal endophytes from arid areas of Andalusia: high potential sources for antifungal and antitumoral agents

Abstract

Native plant communities from arid areas present distinctive characteristics to survive in extreme conditions. The large number of poorly studied endemic plants represents a unique potential source for the discovery of novel fungal symbionts as well as host-specific endophytes not yet described. The addition of adsorptive polymeric resins in fungal fermentations has been seen to promote the production of new secondary metabolites and is a tool used consistently to generate new compounds with potential biological activities. A total of 349 fungal strains isolated from 63 selected plant species from arid ecosystems located in the southeast of the Iberian Peninsula, were characterized morphologically as well as based on their ITS/28S ribosomal gene sequences. The fungal community isolated was distributed among 19 orders including Basidiomycetes and Ascomycetes, being Pleosporales the most abundant order. In total, 107 different genera were identified being Neocamarosporium the genus most frequently isolated from these plants, followed by Preussia and Alternaria. Strains were grown in four different media in presence and absence of selected resins to promote chemical diversity generation of new secondary metabolites. Fermentation extracts were evaluated, looking for new antifungal activities against plant and human fungal pathogens, as well as, cytotoxic activities against the human liver cancer cell line HepG2. From the 349 isolates tested, 126 (36%) exhibited significant bioactivities including 58 strains with exclusive antifungal properties and 33 strains with exclusive activity against the HepG2 hepatocellular carcinoma cell line. After LCMS analysis, 68 known bioactive secondary metabolites could be identified as produced by 96 strains, and 12 likely unknown compounds were found in a subset of 14 fungal endophytes. The chemical profiles of the differential expression of induced activities were compared. As proof of concept, ten active secondary metabolites only produced in the presence of resins were purified and identified. The structures of three of these compounds were new and herein are elucidated.

Diversity and bioactivities of fungal endophytes from Distylium chinense, a rare waterlogging tolerant plant endemic to the Three Gorges Reservoir

“…Endophytic fungi in plants are microorganisms that parasitize symbiotically in the internal tissues during the whole or part of their life cycles of the hosts without causing apparent pathogenic symptoms [1], but may turn pathogenic during host senescence [2]. Accumulated evidence has confirmed that plant endophytes from special orextreme environment has many effects on host ecological adaptability [3][4][5]. It is well known that the concurrence of endophytes may accelerate plant growth and increase the survival rate of biotic or abioticstresses, such as plant diseases, pests, drought, salinity and extreme temperatures [6][7][8][9].…”

Anti-Staphylococcal Potential of Fusarium Sp: Fungal Endophyte Isolated From Rauwolfia Serpentina

“…Alignment gaps were taken as missing characters. Bootstrap analysis (1000 bootstrap) was executed to deduce the consensus tree for the demonstration of evolutionary relationship (Kapoor and Saxena, 2014;González-Menéndez et al, 2018).…”

Extending the Metabolite Diversity of the Endophyte Dimorphosporicola tragani

“…In a recent work with 349 fungal endophytes, we studied the effect of the addition of adsorptive polymeric resins based on styrene-divinylbenzene matrix during fungal fermentations to increase the production titers of some SMs and the chemical diversity of the molecules produced by these fungi [15]. In the same way, the addition of several epigenetic modifiers belonging to both classes of DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, in a subset of diverse endophytic fungi was shown to promote the induction of secondary metabolite pathways, otherwise silent under standard culture conditions [16].…”

“…In the framework of our natural product screening programme targeted at discovering new antimicrobial compounds, we applied an OSMAC approach that included the use of adsorptive polymeric resins in fermentations of a large set of fungal endophytes isolated from plants collected in arid areas of Andalusia. As a result of this screening, we observed the production of antimicrobial activities from the extracts of Dimorphosporicola tragani CF-090383, when only grown in presence of styrene-divinylbenzene resins [15]. For this reason, we decided to perform an in depth study of this fungal endophyte and assess the effect of multiple nutritional conditions and the addition of metabolic effectors on the bioactive secondary metabolite diversity.…”