Screening of endophytic fungi from Antarctic mosses: Potential production for L-asparaginase free of glutaminase and urease activity.

Studies involving endophytic fungi aim to identify organisms inhabiting extreme and relatively unexplored environments, as these fungi possess unique characteristics and uncommon biochemical pathways that enable them to produce compounds with biotechnological potential. Among various enzymes, L-Asparaginase is employed in the treatment of Acute Lymphoblastic Leukemia. In this study, we identified endophytic fungi from Sanionia uncinata and Polytrichastrum alpinum collected on King George Island in Antarctica. The fungi were categorized into morphological groups based on their characteristics, molecularly identified, and assessed for L-Asparaginase (L-ASNase) enzyme production. Subsequently, production optimization was conducted. A total of 161 endophytes were isolated from 504 moss gametophytes, with 107 originating from P. alpinum and 54 from S. uncinata. These isolates were categorized into 31 morphotypes. Fungi exhibiting high enzyme production were identified molecularly. Among them, nine identified isolates belonged to the genera Aspergillus, Collariella, Diaporthe, Epicoccum, Peroneutypa, Xylaria, and Trametes. Three of these isolates were identified at the species level through multigene phylogeny, namely Epicoccum nigrum, Collariella virescens, and Peroneutypa scoparia. All 31 fungi were subjected to solid media testing for L-ASNase enzyme production, with 22 isolates demonstrating production capability, and 13 of them produced L-ASNase free from Urease and Glutaminase. The isolates displaying solid media production underwent further testing in liquid media, all of which exhibited enzyme production ranging from 0.75 to 1.29 U g-1. Notably, the three fungi identified at the species level were the highest producers of the enzyme (1.29, 1.17, and 1.13 U g-1). The production of these fungi was optimized using the Taguchi method, resulting in production values ranging from 0.687 to 2.461 U g-1. In conclusion, our findings indicate that Antarctic moss endophytic fungi exhibit significant potential for the production of the anti-leukemic enzyme L-ASNase.

Impact of the Temperature in Endophytic Ascomycota Isolated from Antarctic Hair-Grass.

Antarctica is one of the most inhospitable continents on the planet, with lichens and mosses being the most common terrestrial organisms in ice-free areas. Antarctica is represented by only two species of Angiosperms, Deschampsia antarctica Desv. (Poaceae) and Colobanthus quitensis (Kunth) Bartl. (Caryophyllaceae). In this study, we characterized fungi isolated from the fresh leaves of this grass species. The fungi were isolated from four individual plants from Half Moon Island (246 leaf fragments investigated), and seven from King George Island-Keller Peninsula (with 111 leaf fragments investigated) Antarctica. Neoascochyta paspali, Septoriella elongata, Pyrenophora cf. chaetomioides and Alternaria sp. were associated with the plant and identified through analysis of the sequences of the internal transcribed spacer region (ITS) of the rDNA and nuclear ribosomal large subunit rRNA gene (LSU) as well as through macro and micro-morphological characteristics. The isolates showed higher growth rate ranging from 10 to 20 °C. An interesting result was that the aforementioned fungi are already recognized as both plant pathogens and endophytic fungi. The results demonstrate that D. antarctica is an interesting fungal source. Those species might provide important information about the relationship on the endemic Antarctic biota.

Morphological and Molecular Characterization of Three Endolichenic Isolates of Xylaria (Xylariaceae), from Cladonia curta Ahti & Marcelli (Cladoniaceae).

Endophyte biology is a branch of science that contributes to the understanding of the diversity and ecology of microorganisms that live inside plants, fungi, and lichen. Considering that the diversity of endolichenic fungi is little explored, and its phylogenetic relationship with other lifestyles (endophytism and saprotrophism) is still to be explored in detail, this paper presents data on axenic cultures and phylogenetic relationships of three endolichenic fungi, isolated in laboratory. Cladonia curta Ahti & Marcelli, a species of lichen described in Brazil, is distributed at three sites in the Southeast of the country, in mesophilous forests and the Cerrado. Initial hyphal growth of Xylaria spp. on C. curta podetia started four days after inoculation and continued for the next 13 days until the hyphae completely covered the podetia. Stromata formation and differentiation was observed, occurring approximately after one year of isolation and consecutive subculture of lineages. Phylogenetic analyses indicate lineages of endolichenic fungi in the genus Xylaria, even as the morphological characteristics of the colonies and anamorphous stromata confirm this classification. Our preliminary results provide evidence that these endolichenic fungi are closely related to endophytic fungi, suggesting that the associations are not purely incidental. Further studies, especially phylogenetic analyses using robust multi-locus datasets, are needed to accept or reject the hypothesis that endolichenic fungi isolated from Xylaria spp. and X. berteri are conspecific.

Distribution of aerophilous diatom communities associated with terrestrial green macroalgae in the South Shetland Islands, Maritime Antarctica.

The establishment of diatom communities depends on environmental factors such as the type of substrate and geographic conditions that influence the dispersal processes of these organisms. The main goal of this study was to evaluate the similarity between diatom communities associated with the macroalgae Prasiola crispa (Lightfoot) Kützing in relation to spatial distance from six sampled sites located in the South Shetland Islands, Maritime Antarctica. The diatom flora associated with Prasiola crispa was represented by 23 species distributed in 15 genera. Pinnularia australoschoenfelderi Zidarova, Kopalová & Van de Vijver, Luticola austroatlantica Van de Vijver, Kopalová, S.A.Spaulding & Esposito, Luticola amoena Van der Vijver, Kopalová, Zidarova & Levkov, Pinnularia austroshetlandica (Carlson) Cleve-Euler and Psammothidium papilio (D.E. Kellogg et al.) Kopalová & Zidarova were the most abundant species in our samples, together they represented 68% of the total number of individuals collected. There was great similarity and abundance of the diatom communites among the sampled points, which resulted in the absence of a linear relationship pattern with distance between sampling points. We conclude that distance was not a factor of differentiation of Antarctic diatom communities associated with terrestrial green macroalgae. This suggests that Antarctic environments may have unique characteristics with homogeneous abiotic factors, at least in relation to this substrate.

In situ methane and nitrous oxide fluxes in soil from a transect in Hennequin Point, King George Island, Antarctic.

The study aimed at to determine the magnitude of the methane (CH(4)) and nitrous oxide (N(2)O) flux rates in soils at Hennequin Point, King George Island, Antarctic, under different slope positions, vegetal covers and presence of skuas, as well as to evaluate the main soil and climate factors that are involved with the flux of such gases. In situ gas sampling (closed chamber method) was performed in four sites along a transect involving a skua nesting field in a moraine with 5% and 100% of surface covered by vegetal, and two poor-drained soils in the toeslope (a bare alluvium soil and a poor-drained moss field with 100% soil cover). Flux rates ranged from -0.86±0.45 to 2.75±1.52 µg N(2)O-N m(-2) h(-1) and -12.26±3.05 to 1.42±1.31 µg CH(4)-C m(-2) h(-1). The soil totally covered by vegetal in the skua field had the largest CH(4) influx rates. However, this benefic effect was counterbalanced by the greatest N(2)O efflux rates from this soil, resulting in the largest contribution to the global warming potential among the soils evaluated. Flux rates were closely related to soil temperature, but no significant relation was observed with mineral N contents and water-filled pore space. In turn, accumulated CH(4) and N(2)O emissions were closely related to the total N and total organic C stocks in the soil. Net CH(4) influx predominated even in the poor-drained soils, suggesting that the coarse soil texture avoided critical anaerobic conditions. No significant changes in flux rates were observed for sampling time along the day.