Bioactive Metabolites From Acid-Tolerant Fungi in a Thai Mangrove Sediment

Abstract

Despite being potentially useful extremophile resources, there have been few reports on acid-tolerant fungi and their bioactive metabolites. Acidophilic/aciduric fungi (n = 237) were isolated from Thai mangrove sediments in an acidic medium. Using fungal identification technology (including morphologic observation, chemical screening, and sequence comparisons) all the isolates were identified and 41 representative isolates were selected for analysis of the phylogenetic relationships (ITS rDNA, β-tubulin, calmodulin, and actin gene sequences). There were seven genera identified – Penicillium; Aspergillus; Talaromyces; Cladosporium; Allophoma; Alternaria; and Trichoderma – in four taxonomic orders of the phylum Ascomycota, and Penicillium, Aspergillus, and Talaromyces were the dominant genera. Acidity tolerance was evaluated and 95% of the isolates could grow under extremely acidic conditions (pH 2). Six strains were classed as acidophilic fungi that cannot survive under pH 7, all of which had an extraordinarily close genetic relationship and belonged to the genus Talaromyces. This is the first report on the acidophilic characteristics of this genus. The antimicrobial, anti-tumor, and antiviral activities of the fermentation extracts were evaluated. Nearly three-quarters of the extracts showed cytotoxic activity, while less than a quarter showed antimicrobial or anti-H1N1 activity. The typical aciduric fungus Penicillium oxalicum OUCMDZ-5207 showed similar growth but completely different chemical diversity at pH 3 and 7. The metabolites of OUCMDZ-5207 that were obtained only at pH 3 were identified as tetrahydroauroglaucin (1), flavoglaucin (2), and auroglaucin (3), among which auroglaucin showed strong selective inhibition of A549 cells with an IC50 value of 5.67 μM. These results suggest that acid stress can activate silent gene clusters to expand the diversity of secondary metabolites, and the bioprospecting of aciduric/acidophilic microorganism resources in Thai mangrove sediments may lead to the discovery of compounds with potential medicinal applications.

Antimicrobial activity of actinomycetes isolated from mangrove soil in Tuban, East Java, Indonesia

“…Those microorganisms also have the potential to produce bioactive metabolites, which can be harnessed for industrial and medicinal purposes. Fungi isolated from mangrove soils were reported to produce industrial enzymes such as lipase, cellulase, protease, and pectinase and therapeutic compounds such as antimicrobials, antivirals, antioxidants, and anticancer (Gao et al 2021;Sopalun et al 2021). Meanwhile, bacterial strains isolated from mangrove soils produced antimicrobials, anti-inflammatory, and antioxidant compounds (Qureshi et al 2020;Rajan et al 2021).…”

Biological and physico-chemical properties of the soil in an acidified environment influenced by previous mining activities at the Šobov locality (Slovakia)

“…2017), an ultra-acidic soil environment might potentially offer new biotechnologically interesting fungi, especially in terms of enzyme production. Also, thermophilic fungi, particularly the species Talaromaces but also Aspergillus, Cladosporium and Trichoderma, can represent a rich source of industrially relevant enzymes at pH 2.0 (Gao et al, 2021;Thang et al, 2019). The effect of soil acidi cation showed that pH is an essential predictor for controlling the distribution of microbial communities, and fungal communities exhibit little response to soil acidity (Wang et al, 2022).…”

Membrane Lipids and Osmolytes in the Response of the Acidophilic Basidiomycete Phlebiopsis gigantea to Heat, Cold, and Osmotic Shocks

“…Such studies are also of interest for astrobiology, since fungi are the key organisms in the search for the limits of life on Earth and in the Universe and ecology—for the preservation of biocenoses despite abrupt climate changes and increased anthropogenic influence. Extremophiles are used for bioremediation and biofuel production and are also sources of new biologically active compounds and extremozymes [ 3 , 4 , 5 ].…”