Living strategy of cold-adapted fungi with the reference to several representative species

State of the Art in Hygienic Quality of Food Ice Worldwide: A Ten-Year Review

Ice consumption has widely increased over the last decade. Cases of ice contamination by various microorganisms (bacteria, viruses and fungi) have been documented in the literature. In this review, we summarize the findings of selected articles on the hygienic and sanitary quality of food ice from 1 January 2013 to 31 December 2023. A total of 14 articles found via the PubMed search engine during the study period were reviewed. From the comparison between the ice produced on an industrial scale and the ice produced on a local scale in food businesses, the latter was found to be more contaminated by microorganisms. The most detected bacteria included Escherichia coli, coliforms, Pseudomonas spp., Staphylococcus aureus; three studies evaluated the presence of Vibrio cholerae and Vibrio parahaemolyticus; two studies highlighted the presence of viruses (Rotavirus and Norovirus). Finally, two studies detected the presence of fungi (molds and yeasts). Almost all authors of the studies argued that ice contamination also depends on the hygienic-sanitary quality of the ice-making machines. The results show that the information currently available in the literature on the hygienic-sanitary quality of ice is incomplete and that future national and international scientific studies need to be carried out.

Endophytic fungi from Himalayan silver birch as potential source of plant growth enhancement and secondary metabolite production

Mountain biodiversity is under unparalleled pressure due to climate change, necessitating in-depth research on high-altitude plant's microbial associations which are crucial for plant survival under stress conditions. Realizing that high-altitude tree line species of Himalaya are completely unexplored with respect to the microbial association, the present study aimed to elucidate plant growth promoting and secondary metabolite producing potential of culturable endophytic fungi of Himalayan silver birch (Betula utilis D. Don). ITS region sequencing revealed that the fungal isolates belong to Penicillium species, Pezicula radicicola, and Paraconiothyrium archidendri. These endophytes were psychrotolerant in nature with the potential to produce extracellular lytic activities. The endophytes showed plant growth promoting (PGP) traits like phosphorus solubilization and production of siderophore, indole acetic acid (IAA), and ACC deaminase. The fungal extracts also exhibited antagonistic potential against bacterial pathogens. Furthermore, the fungal extracts were found to be a potential source of bioactive compounds including the host-specific compound-betulin. Inoculation with fungal suspension improved seed germination and biomass of soybean and maize crops under net house conditions. In vitro PGP traits of the endophytes, supported by net house experiments, indicated that fungal association may support the growth and survival of the host in extreme cold conditions.

Challenges and Approaches of Culturing the Unculturable Archaea

Since Carl Woese's discovery of archaea as a third domain of life, numerous archaeal species have been discovered, yet archaeal diversity is poorly characterized. Culturing archaea is complicated, but several queries about archaeal cell biology, evolution, physiology, and diversity need to be solved by culturing and culture-dependent techniques. Increasing interest in demand for innovative culturing methods has led to various technological and methodological advances. The current review explains frequent hurdles hindering uncultured archaea isolation and discusses features for more archaeal cultivation. This review also discusses successful strategies and available media for archaeal culturing, which might be helpful for future culturing practices.

Geographical Diversity of Proteomic Responses to Cold Stress in the Fungal Genus Pseudogymnoascus

In understanding stress response mechanisms in fungi, cold stress has received less attention than heat stress. However, cold stress has shown its importance in various research fields. The following study examined the cold stress response of six Pseudogymnoascus spp. isolated from various biogeographical regions through a proteomic approach. In total, 2541 proteins were identified with high confidence. Gene Ontology enrichment analysis showed diversity in the cold stress response pathways for all six Pseudogymnoascus spp. isolates, with metabolic and translation-related processes being prominent in most isolates. 25.6% of the proteins with an increase in relative abundance were increased by more than 3.0-fold. There was no link between the geographical origin of the isolates and the cold stress response of Pseudogymnoascus spp. However, one Antarctic isolate, sp3, showed a distinctive cold stress response profile involving increased flavin/riboflavin biosynthesis and methane metabolism. This Antarctic isolate (sp3) was also the only one that showed decreased phospholipid metabolism in cold stress conditions. This work will improve our understanding of the mechanisms of cold stress response and adaptation in psychrotolerant soil microfungi, with specific attention to the fungal genus Pseudogymnoascus.

The Cytotoxic Properties of Extreme Fungi's Bioactive Components-An Updated Metabolic and Omics Overview

Fungi are the most diverse living organisms on planet Earth, where their ubiquitous presence in various ecosystems offers vast potential for the research and discovery of new, naturally occurring medicinal products. Concerning human health, cancer remains one of the leading causes of mortality. While extensive research is being conducted on treatments and their efficacy in various stages of cancer, finding cytotoxic drugs that target tumor cells with no/less toxicity toward normal tissue is a significant challenge. In addition, traditional cancer treatments continue to suffer from chemical resistance. Fortunately, the cytotoxic properties of several natural products derived from various microorganisms, including fungi, are now well-established. The current review aims to extract and consolidate the findings of various scientific studies that identified fungi-derived bioactive metabolites with antitumor (anticancer) properties. The antitumor secondary metabolites identified from extremophilic and extremotolerant fungi are grouped according to their biological activity and type. It became evident that the significance of these compounds, with their medicinal properties and their potential application in cancer treatment, is tremendous. Furthermore, the utilization of omics tools, analysis, and genome mining technology to identify the novel metabolites for targeted treatments is discussed. Through this review, we tried to accentuate the invaluable importance of fungi grown in extreme environments and the necessity of innovative research in discovering naturally occurring bioactive compounds for the development of novel cancer treatments.

Exploring Differences in Culturable Fungal Diversity Using Standard Freezing Incubation-A Case Study in the Limestones of Lemos Pantheon (Portugal)

In this study, we explored the biodiversity and abundance of culturable fungi in four samples associated with different biodeterioration outlines collected from the Lemos Pantheon, a limestone-built artwork in Portugal. We compared the results from prolonged standard freezing with those previously obtained from fresh samples to analyze differences in the obtained community and assess the effectiveness of the standard freezing incubation protocol in uncovering a different segment of culturable fungal diversity. Our results showed a slight decrease in culturable diversity, but over 70% of the obtained isolates were not present in the previously studied fresh samples. We also identified a high number of potential new species with this procedure. Moreover, the use of a wide variety of selective culture media positively influenced the diversity of the cultivable fungi obtained in this study. These findings highlight the importance of developing new protocols under varying conditions to accurately characterize the culturable fraction in a given sample. The identification and study of these communities and their possible contribution to the biodeterioration process is crucial knowledge for formulating effective conservation and restoration plans to prevent further damage to valuable cultural heritage assets.

The Unusual Dominance of the Yeast Genus Glaciozyma in the Deeper Layer in an Antarctic Permafrost Core (Adélie Cove, Northern Victoria Land) Is Driven by Elemental Composition

Rock glaciers are relatively common in Antarctic permafrost areas and could be considered postglacial cryogenic landforms. Although the extensive presence of rock glaciers, their chemical–physical and biotic composition remain scarce. Chemical–physical parameters and fungal community (by sequencing the ITS2 rDNA, Illumina MiSeq) parameters of a permafrost core were studied. The permafrost core, reaching a depth of 6.10 m, was divided into five units based on ice content. The five units (U1–U5) of the permafrost core exhibited several significant (p < 0.05) differences in terms of chemical and physical characteristics, and significant (p < 0.05) higher values of Ca, K, Li, Mg, Mn, S, and Sr were found in U5. Yeasts dominated on filamentous fungi in all the units of the permafrost core; additionally, Ascomycota was the prevalent phylum among filamentous forms, while Basidiomycota was the dominant phylum among yeasts. Surprisingly, in U5 the amplicon sequence variants (ASVs) assigned to the yeast genus Glaciozyma represented about two-thirds of the total reads. This result may be considered extremely rare in Antarctic yeast diversity, especially in permafrost habitats. Based on of the chemical–physical composition of the units, the dominance of Glaciozyma in the deepest unit was correlated with the elemental composition of the core.

Basidium formation of Rhizopogon roseolus with Pinus thunbergii in agar medium

The edible ectomycorrhizal (ECM) mushroom Rhizopogon roseolus usually develops basidium and basidiospores in the gleba of its basidiomata. Here, we report a novel production of basidia in laboratory cultures of the edible ECM mushroom. The basidium with sterigma was observed on the old mantle structure (> six months) of the ECM between R. roseolus and Pinus thunbergii in a modified Melin-Norkrans medium that was subjected to a temperature shock from 25 °C to 4 °C. The basidia were cylindrical to clavate, with prominent sterigmata and no basidiospores. The absence of basidiospores might indicate partial development of the basidium structure as a response to environmental stress and incomplete life cycle of R. roseolus. In addition, branched cystidia were evident in two or three clavate-to-ovoid cells. This study suggests the possibility of obtaining the primary mycelium of R. roseolus from pure cultures and may be an alternative genetic source for cultivation purposes. Further observations are required to induce basidiosporogenesis of R. roseolus basidia in an agar medium focusing on manipulation of temperature.

The First Comprehensive Biodiversity Study of Culturable Fungal Communities Inhabiting Cryoconite Holes in the Werenskiold Glacier on Spitsbergen (Svalbard Archipelago, Arctic)

Cryoconite holes on glacier surfaces are a source of cold-adapted microorganisms, but little is known about their fungal inhabitants. Here, we provide the first report of distinctive fungal communities in cryoconite holes in the Werenskiold Glacier on Spitsbergen (Svalbard Archipelago, Arctic). Due to a combination of two incubation temperatures (7 °C and 24 ± 0.5 °C) and two media during isolation (PDA, YPG), as well as classical and molecular identification approaches, we were able to identify 23 different fungi (21 species and 2 unassigned species). Most of the fungi cultured from cryoconite sediment were ascomycetous filamentous micromycetes. However, four representatives of macromycetes were also identified (Bjerkandera adusta, Holwaya mucida, Orbiliaceae sp., and Trametes versicolor). Some of the described fungi possess biotechnological potential (Aspergillus pseudoglaucus, A. sydowii, Penicillium expansum, P. velutinum, B. adusta, and T. versicolor), thus, we propose the Arctic region as a source of new strains for industrial applications. In addition, two phytopathogenic representatives were present (P. sumatraense, Botrytis cinerea), as well as one potentially harmful to humans (Cladosporium cladosporioides). To the best of our knowledge, we are the first to report the occurrence of A. pseudoglaucus, C. allicinum, C. ramotenellum, P. sumatraense, P. velutinum, P. cumulodentata, B. adusta, and T. versicolor in polar regions. In all likelihood, two unassigned fungus species (Orbiliaceae and Dothideomycetes spp.) might also be newly described in such environments. Additionally, due to experimenting with 10 sampling sites located at different latitudes, we were able to conclude that the number of fungal spores decreases as one moves down the glacier. Considering the prevalence and endangerment of glacial environments worldwide, such findings suggest their potential as reservoirs of fungal diversity, which should not be overlooked.

Microbial diversity and associated metabolic potential in the supraglacial habitat of a fast-retreating glacier: a case study of Patsio glacier, North-western Himalaya

In the present study, we investigated the microbial community composition and their associated metabolic potentials using the 16S rRNA gene (V3-V4) and ITS (ITS1) amplicon sequencing approach in the Patsio glacier. The bacterial community composition was mainly dominated by Bacteroidota (18%-38% of total reads) and Cyanobacteria (9%-30%), along with a rare Candidate phylum Patescibacteria. Ferruginibacter (13%) and Polaromonas (8%) were the most dominant genera identified across the samples known to have potential ecological roles in colonization, driving the functioning of supraglacial habitats. The prevalence of metabolic genes associated with nitrogen, carbon and sulfur cycling processes was identified in the present study. The fungal diversity was dominated by members of unclassified phyla, followed by Ascomycota (up to 6%) and Basidiomycota (up to 4%), in terms of its relative abundance. The relative abundance of Fusarium and Didymella (8%-14%) was higher among the high altitude, cryoconite samples (P1-P5), while Rhodotorula (12%-29%) dominated in the glacial ice debris samples (P6-P8). Thus, our study provides significant insights into dynamics of microbial communities and its potential ecological roles in the changing climate.

Proline-Specific Fungal Peptidases: Genomic Analysis and Identification of Secreted DPP4 in Alkaliphilic and Alkalitolerant Fungi

Proline-specific peptidases (PSP) play a crucial role in the processing of fungal toxins, pheromones, and intracellular signaling. They are of particular interest to biotechnology, as they are able to hydrolyze proline-rich oligopeptides that give a bitter taste to food and can also cause an autoimmune celiac disease. We performed in silico analysis of PSP homologs in the genomes of 42 species of higher fungi which showed the presence of PSP homologs characteristic of various kingdoms of living organisms and belonging to different families of peptidases, including homologs of dipeptidyl peptidase 4 (DPP4) and prolyl aminopeptidase 1 found in almost all the studied fungal species. Homologs of proliniminopeptidases from the S33 family absent in humans were also found. Several studied homologs are characteristic of certain taxonomic groups of fungi. Phylogenetic analysis suggests a duplication of ancestral DPP4 into transmembrane and secreted versions, which predate the split of ascomycete and basidiomycete lineages. Comparative biochemical analysis of DPP4 in alkaliphilic and alkali-tolerant strains of fungi showed that, notwithstanding some individual features of these enzymes, in both cases, the studied DPP4 are active and stable under alkaline conditions and at high salt concentrations, which makes them viable candidates for biotechnology and bioengineering.

Genomic characterization of three marine fungi, including Emericellopsis atlantica sp. nov. with signatures of a generalist lifestyle and marine biomass degradation

Marine fungi remain poorly covered in global genome sequencing campaigns; the 1000 fungal genomes (1KFG) project attempts to shed light on the diversity, ecology and potential industrial use of overlooked and poorly resolved fungal taxa. This study characterizes the genomes of three marine fungi: Emericellopsis sp. TS7, wood-associated Amylocarpus encephaloides and algae-associated Calycina marina. These species were genome sequenced to study their genomic features, biosynthetic potential and phylogenetic placement using multilocus data. Amylocarpus encephaloides and C. marina were placed in the Helotiaceae and Pezizellaceae (Helotiales), respectively, based on a 15-gene phylogenetic analysis. These two genomes had fewer biosynthetic gene clusters (BGCs) and carbohydrate active enzymes (CAZymes) than Emericellopsis sp. TS7 isolate. Emericellopsis sp. TS7 (Hypocreales, Ascomycota) was isolated from the sponge Stelletta normani. A six-gene phylogenetic analysis placed the isolate in the marine Emericellopsis clade and morphological examination confirmed that the isolate represents a new species, which is described here as E. atlantica. Analysis of its CAZyme repertoire and a culturing experiment on three marine and one terrestrial substrates indicated that E. atlantica is a psychrotrophic generalist fungus that is able to degrade several types of marine biomass. FungiSMASH analysis revealed the presence of 35 BGCs including, eight non-ribosomal peptide synthases (NRPSs), six NRPS-like, six polyketide synthases, nine terpenes and six hybrid, mixed or other clusters. Of these BGCs, only five were homologous with characterized BGCs. The presence of unknown BGCs sets and large CAZyme repertoire set stage for further investigations of E. atlantica. The Pezizellaceae genome and the genome of the monotypic Amylocarpus genus represent the first published genomes of filamentous fungi that are restricted in their occurrence to the marine habitat and form thus a valuable resource for the community that can be used in studying ecological adaptions of fungi using comparative genomics.

Cold-active catalase from the psychrotolerant fungus Penicillium griseofulvum

Cold-active catalase (CAT) elicits great interest because of its vast prospective at the medical, commercial, and biotechnological levels. The study paper reports the production of cold-active CAT by the strain Penicillium griseofulvum P29 isolated from Antarctic soil. Improved enzyme production was achieved by optimization of medium and culture conditions. Maximum CAT was demonstrated under low glucose content (2%), 10% inoculum size, temperature 20°C, and dissolved oxygen concentration (DO) 40%. An effective laboratory technology based on changing the oxidative stress level through an increase of DO in the bioreactor was developed. The used strategy resulted in a 1.7- and 1.4-fold enhanced total enzyme activity and maximum enzyme productivity. The enzyme was purified and characterized. P. griseofulvum P29 CAT was most active at approximately 20°C and pH 6.0. Its thermostability was in the range between 5°C and 40°C.

Greater Mouse-Eared Bats (Myotis myotis) Hibernating in the Nietoperek Bat Reserve (Poland) as a Vector of Airborne Culturable Fungi

Bats can contribute to an increase of aeromycota in underground ecosystems and might be a vector/reservoir of microorganisms; however, there is no information about the number and species composition of fungi around hibernating bats. One of the most common species in Europe with direct human contact is the greater mouse-eared bat (Myotis myotis). The goal of our research was the first report of the airborne fungi present in the close vicinity of hibernating M. myotis in the Nietoperek bat reserve (Western Poland) by the use of culture-based techniques and genetic and phenotypic identifications. Aerobiological investigations of mycobiota under hibernating bats were performed on two culture media (PDA and YPG) and at two incubation temperatures (7 and 24 ± 0.5 °C). Overall, we detected 32 fungal species from three phyla (Ascomycota, Basidiomycota, and Zygomycota) and 12 genera. The application of YPG medium and the higher incubation temperature showed higher numbers of isolated fungal species and CFU. Penicillium spp. were dominant in the study, with spores found outside the underground hibernation site from 51.9% to 86.3% and from 56.7% to 100% inside the bat reserve. Penicillium chrysogenum was the most frequently isolated species, then Absidia glauca, Aspergillus fumigatus, A. tubingensis, Mortierella polycephala, Naganishia diffluens, and Rhodotorula mucilaginosa. Temperature, relative humidity, and the abundance of bats correlated positively with the concentration of airborne fungal propagules, between fungal species diversity, and the concentration of aeromycota, but the number of fungal species did not positively correlate with the number of bats. The air in the underground site was more contaminated by fungi than the air outside; however, the concentration of aeromycota does not pose a threat for human health. Nevertheless, hibernating bats contribute to an increase in the aeromycota and as a vector/reservoir of microscopic fungi, including those that may cause allergies and infections in mammals, and should be monitored.

Metagenomic insights into the fungal assemblages of the northwest Himalayan cold desert

Psychrophilic fungi are a critical biotic component in cold deserts that serves a central role in nutrient recycling and biogeochemical cycles. Despite their ecological significance, culture-independent studies on psychrophilic mycobiome are limited. In the present study, the fungal diversity patterns across the Drass, an Indian cold desert in the Himalaya, were indexed by targeted amplicon pyrosequencing (ITS). In the Drass dataset, Ascomycota was represented by 92 genera, while 22 genera represented Basidiomycota. The most abundant genus was Conocybe (20.46%). Most of the identified genera were reported in the literature to be prolific extracellular hydrolytic enzyme producers. To identify whether the Drass fungal assemblages share similarities to other cold deserts, these were further compared to Antarctic and Arctic cold deserts. Comparative analysis across the three cold deserts indicated the dominance of Dikarya (Ascomycota and Basidiomycota). The observed alpha diversity, Shannon index as well as Pielou's evenness was highest in the Antarctic followed by Drass and Arctic datasets. The genera Malassezia, Preussia, Pseudogymnoascus, Cadophora, Geopora, Monodictys, Tetracladium, Titaea, Mortierella, and Cladosporium were common to all the cold deserts. Furthermore, Conocybe was represented predominantly in Drass. Interestingly, the genus Conocybe has not been previously reported from any other studies on Antarctic or Arctic biomes. To the best of our knowledge, this is the first fungal metagenome study in Drass soil. Our analysis shows that despite the similarities of low temperature among the cold deserts, a significant differential abundance of fungal communities prevails in the global cold deserts.

Intra- and inter-cores fungal diversity suggests interconnection of different habitats in an Antarctic frozen lake (Boulder Clay, Northern Victoria Land)

A perennially frozen lake at Boulder Clay site (Victoria Land, Antarctica), characterized by the presence of frost mounds, have been selected as an in situ model for ecological studies. Different samples of permafrost, glacier ice and brines have been studied as a unique habitat system. An additional sample of brines (collected in another frozen lake close to the previous one) was also considered. Alpha- and beta-diversity of fungal communities showed both intra- and inter-cores significant (p < 0.05) differences, which suggest the presence of interconnection among the habitats. Therefore, the layers of frost mound and the deep glacier could be interconnected while the brines could probably be considered as an open habitat system not interconnected with each other. Moreover, the absence of similarity between the lake ice and the underlying permafrost suggested that the lake is perennially frozen based. The predominance of positive significant (p < 0.05) co-occurrences among some fungal taxa allowed to postulate the existence of an ecological equilibrium in the habitats systems. The positive significant (p < 0.05) correlation between salt concentration, total organic carbon and pH, and some fungal taxa suggests that a few abiotic parameters could drive fungal diversity inside these ecological niches.

Production, characterization and biological activities of exopolysaccharides from a new cold-adapted yeast: Rhodotorula mucilaginosa sp. GUMS16

Lately, it has been proved that yeast exopolysaccharides (EPS) are potentially applicable biopolymers, a fact that has led to incremental needs for their assessment. The current study is based on the biochemical and molecular level identification of the novel cold-adapted yeast Rhodotorula mucilaginosa sp. GUMS16. Possible antioxidant and antiproliferative activities, as well as extraction and characterization of the GUMS16-produced EPS, were assessed during the course of this study. The results indicated that the strain of GUMS16 is a cold-adapted yeast with growth capability at 4 °C and an approximate EPS production yield of 28.5 g/L which are characterized as highly branched beta-D-glucan having glucose and mannose residues (85:15 mol%, respectively) with an average molecular weight of 84 kDa. In comparison to hyaluronic acid, DPPH, and OH, the scavenging activity attributed to the GUMS16-produced EPS was higher alongside being dose-dependent. The biocompatibility profile of the EPS was well-recognized based on its zero-cytotoxicity rate on a normal cell model. Collectively, the favorable properties of the EPS accentuate their potential as biocompatible compound suitable for subsequent pharmaceutical and industrial applications.

Microbial Ecology from the Himalayan Cryosphere Perspective

Cold-adapted microorganisms represent a large fraction of biomass on Earth because of the dominance of low-temperature environments. Extreme cold environments are mainly dependent on microbial activities because this climate restricts higher plants and animals. Himalaya is one of the most important cold environments on Earth as it shares climatic similarities with the polar regions. It includes a wide range of ecosystems, from temperate to extreme cold, distributed along the higher altitudes. These regions are characterized as stressful environments because of the heavy exposure to harmful rays, scarcity of nutrition, and freezing conditions. The microorganisms that colonize these regions are recognized as cold-tolerant (psychrotolerants) or/and cold-loving (psychrophiles) microorganisms. These microorganisms possess several structural and functional adaptations in order to perform normal life processes under the stressful low-temperature environments. Their biological activities maintain the nutrient flux in the environment and contribute to the global biogeochemical cycles. Limited culture-dependent and culture-independent studies have revealed their diversity in community structure and functional potential. Apart from the ecological importance, these microorganisms have been recognized as source of cold-active enzymes and novel bioactive compounds of industrial and biotechnological importance. Being an important part of the cryosphere, Himalaya needs to be explored at different dimensions related to the life of the inhabiting extremophiles. The present review discusses the distinct facts associated with microbial ecology from the Himalayan cryosphere perspective.

Ice-binding proteins from the fungus Antarctomyces psychrotrophicus possibly originate from two different bacteria through horizontal gene transfer

Various microbes, including fungi and bacteria, that live in cold environments produce ice-binding proteins (IBPs) that protect them from freezing. Ascomycota and Basidiomycota are two major phyla of fungi, and Antarctomyces psychrotrophicus is currently designated as the sole ascomycete that produces IBP (AnpIBP). However, its complete amino acid sequence, ice-binding property, and evolutionary history have not yet been clarified. Here, we determined the peptide sequences of three new AnpIBP isoforms by total cDNA analysis and compared them with those of other microbial IBPs. The AnpIBP isoforms and ascomycete-putative IBPs were found to be phylogenetically close to the bacterial ones but far from the basidiomycete ones, which is supported by the higher sequence identities to bacterial IBPs than basidiomycete IBPs, although ascomycetes are phylogenetically distant from bacteria. In addition, two of the isoforms of AnpIBP share low sequence identity and are not close in the phylogenetic tree. It is hence presumable that these two AnpIBP isoforms were independently acquired from different bacteria through horizontal gene transfer (HGT), which implies that ascomycetes and bacteria frequently exchange their IBP genes. The non-colligative freezing-point depression ability of AnpIBP was not very high, whereas it exhibited significant abilities of ice recrystallization inhibition, ice shaping, and cryo-protection against freeze-thaw cycles even at submicromolar concentrations. These results suggest that HGT is crucial for the cold-adaptive evolution of ascomycetes, and their IBPs offer freeze resistance to organisms to enable them to inhabit the icy environments of Antarctica. DATABASES: Nucleotide sequence data are available in the DDBJ database under the accession numbers LC378707, LC378707, LC378707 for AnpIBP1a, AnpIBP1b, AnpIBP2, respectively.

Heterologous expression, purification and characterization of a highly thermolabile endoxylanase from the Antarctic fungus Cladosporium sp

Numerous endoxylanases from mesophilic fungi have been purified and characterized. However, endoxylanases from cold-adapted fungi, especially those from Antarctica, have been less studied. In this work, a cDNA from the Antarctic fungus Cladosporium sp. with similarity to endoxylanases from glycosyl hydrolase family 10, was cloned and expressed in Pichia pastoris. The pure recombinant enzyme (named XynA) showed optimal activity on xylan at 50 °C and pH 6-7. The enzyme releases xylooligosaccharides but not xylose, indicating that XynA is a classical endoxylanase. The enzyme was most active on xylans with high content of arabinose (rye arabinoylan and wheat arabinoxylan) than on xylans with low content of arabinose (oat spelts xylan, birchwood xylan and beechwood xylan). Finally, XynA showed a very low thermostability. After 20-30 min of incubation at 40 °C, the enzyme was completely inactivated, suggesting that XynA would be the most thermolabile endoxylanase described so far in filamentous fungi. This is one of the few reports describing the heterologous expression and characterization of a xylanase from a fungus isolated from Antarctica.

Optimisation and characterisation of the orange pigment produced by a cold adapted strain of Penicillium sp. (GBPI_P155) isolated from mountain ecosystem

With globalisation and growing health risks of synthetic colourants, search for pigments from natural sources has increased owing to their non-toxic nature. The present study highlights the bioprospection of natural pigment from a cold adapted fungal strain of Penicillium sp. (GBPI_P155), isolated from soil of Indian Himalayan region. The fungus produced insoluble and orange-coloured pigment in liquid medium with maximum production recorded in potato dextrose (PD) broth at 15°C and 3 pH, while maximum biomass was produced at 25°C and pH 3. While examining the effect of different mineral salts, and carbon and nitrogen sources on pigment production, maximum accumulation of pigment was recorded in PD broth supplemented with 2% maltose. Following production, extraction of pigment was performed using chloroform and characterised partially by UV/vis (λmax at 495 nm and a shoulder peak at 530 nm) and Fourier Transform Infrared (FT-IR) spectroscopy. Thin layer chromatography of chloroform extract resulted in separation of pigment in three fractions with Rf values 0.911, 0.852 and 0.808, which were further analysed using Liquid Chromatography Mass Spectrometry (LC/MS). The overall approach resulted in identification of pigment as a mixture of different derivatives of carotenoids. The extracted pigment also possessed antimicrobial activity against Gram-positive and Gram-negative bacteria and actinobacteria.