This study assessed the fungal community composition and its relationships with properties of surface soils in the Ny-Ålesund Region (Svalbard, High Arctic). A total of thirteen soil samples were collected and soil fungal community was analyzed by 454 pyrosequencing with fungi-specific primers targeting the rDNA internal transcribed spacer (ITS) region. The following eight soil properties were analyzed: pH, organic carbon (C), organic nitrogen (N), ammonium nitrogen (NH4+-N), silicate silicon (SiO42--Si), nitrite nitrogen (NO2--N), phosphate phosphorus (PO43--P), and nitrate nitrogen (NO3--N). A total of 57,952 reads belonging to 541 operational taxonomic units (OTUs) were found. of these OTUs, 343 belonged to Ascomycota, 100 to Basidiomycota, 31 to Chytridiomycota, 22 to Glomeromycota, 11 to Zygomycota, 10 to Rozellomycota, whereas 24 belonged to unknown fungi. The dominant orders were Helotiales, Verrucariales, Agaricales, Lecanorales, Chaetothyriales, Lecideales, and Capnodiales. The common genera (>eight soil samples) were Tetracladium, Mortierella, Fusarium, Cortinarius, and Atla. Distance-based redundancy analysis (db-rda) and analysis of similarities (ANOSIM) revealed that soil pH (p = 0.001) was the most significant factor in determining the soil fungal community composition. Members of Verrucariales were found to predominate in soils of pH 8–9, whereas Sordariales predominated in soils of pH 7–8 and Coniochaetales predominated in soils of pH 6–7. The results suggest the presence and distribution of diverse soil fungal communities in the High Arctic, which can provide reliable data for studying the ecological responses of soil fungal communities to climate changes in the Arctic.
Summary Ferulate 5‐hydroxylase (F5H) catalyses the hydroxylation of coniferyl alcohol and coniferaldehyde for the biosynthesis of syringyl (S) lignin in angiosperms. However, the coordinated effects of F5H with caffeic acid O ‐methyltransferase ( COMT ) on the metabolic flux towards S units are largely unknown. We concomitantly regulated F5H expression in COMT ‐down‐regulated transgenic switchgrass ( Panicum virgatum L.) lines and studied the coordination of F5H and COMT in lignin biosynthesis. Down‐regulation of F5H in COMT ‐ RNA i transgenic switchgrass plants further impeded S lignin biosynthesis and, consequently, increased guaiacyl (G) units and reduced 5‐ OH G units. Conversely, overexpression of F5H in COMT ‐ RNA i transgenic plants reduced G units and increased 5‐ OH units, whereas the deficiency of S lignin biosynthesis was partially compensated or fully restored, depending on the extent of COMT down‐regulation in switchgrass. Moreover, simultaneous regulation of F5H and COMT expression had different effects on cell wall digestibility of switchgrass without biomass loss. Our results indicate that up‐regulation and down‐regulation of F5H expression, respectively, have antagonistic and synergistic effects on the reduction in S lignin resulting from COMT suppression. The coordinated effects between lignin genes should be taken into account in future studies aimed at cell wall bioengineering.
BackgroundWith the growing demand for fossil fuels and the severe energy crisis, lignocellulose is widely regarded as a promising cost-effective renewable resource for ethanol production, and the use of lignocellulose residues as raw material is remarkable. Polar organisms have important value in scientific research and development for their novelty, uniqueness and diversity.ResultsIn this study, a fungus Aspergillus sydowii MS-19, with the potential for lignocellulose degradation was screened out and isolated from an Antarctic region. The growth profile of Aspergillus sydowii MS-19 was measured, revealing that Aspergillus sydowii MS-19 could utilize lignin as a sole carbon source. Its ability to synthesize low-temperature lignin peroxidase (Lip) and manganese peroxidase (Mnp) enzymes was verified, and the properties of these enzymes were also investigated. High-throughput sequencing was employed to identify and characterize the transcriptome of Aspergillus sydowii MS-19. Carbohydrate-Active Enzymes (CAZyme)-annotated genes in Aspergillus sydowii MS-19 were compared with those in the brown-rot fungus representative species, Postia placenta and Penicillium decumbens. There were 701CAZymes annotated in Aspergillus sydowii MS-19, including 17 cellulases and 19 feruloyl esterases related to lignocellulose-degradation. Remarkably, one sequence annotated as laccase was obtained, which can degrade lignin. Three peroxidase sequences sharing a similar structure with typical lignin peroxidase and manganese peroxidase were also found and annotated as haem-binding peroxidase, glutathione peroxidase and catalase-peroxidase.ConclusionsIn this study, the fungus Aspergillus sydowii MS-19 was isolated and shown to synthesize low-temperature lignin-degrading enzymes: lignin peroxidase (Lip) and manganese peroxidase (Mnp). These findings provide useful information to improve our understanding of low-temperature lignocellulosic enzyme production by polar microorganisms and to facilitate research and applications of the novel Antarctic Aspergillus sydowii strain MS-19 as a potential lignocellulosic enzyme source.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-017-1028-0) contains supplementary material, which is available to authorized users.
Genome-wide characterization of the Pohlia nutans transcriptome is essential for clarifying the role of stress-relevant genes in Antarctic moss adapting to the extreme polar environment. High-throughput Illumina sequencing was used to analyze the gene expression profile of P. nutans after cold treatment. A total of 93,488 unigenes, with an average length of 405 bp, were obtained. Gene annotation showed that 16,781 unigenes had significant similarity to known functional protein-coding genes, most of which were annotated using the GO, KOG and KEGG pathway databases. Global profiling of the differentially expressed genes revealed that 3,796 unigenes were significantly upregulated after cold treatment, while 1,405 unigenes were significantly downregulated. In addition, 816 receptor-like kinases and 1,309 transcription factors were identified from P. nutans. This overall survey of transcripts and stress-relevant genes can contribute to understanding the stress-resistance mechanism of Antarctic moss and will accelerate the practical exploitation of the genetic resources for this organism.
Natural red pigments have been widely used as food and cosmetics additives. However, due to toxic byproducts or allergen issues, it is still necessary to look for some other red pigment products. This study proposed combinatorial strategies to improve production of a new kind of red pigments from the fungus Geomyces WNF-15A, isolated from Antarctica. A high-production medium was developed by statistical experimental design, which was further simplified for industrial use by single-factor experiments. Strain breeding by atmospheric room temperature plasma mutagenesis generated a mutant, Geomyces sp. WNF-15A-M210, which increased production of red pigments by 24.4% and shortened culture phase by 33.3% comparing with the wild-type. The production of red pigments by this mutant favored a weak alkaline condition but required only mild dissolved oxygen tension. Control of initial pH 8.5 (process pH around 7.5) increased red pigments production by 19% comparing with natural condition. Precursor and inhibitor addition experiments indicated that the red pigments were synthesized by polyketide pathway, and feeding 6 mmol/L precursor of sodium acetate by three aliquots at days 3 to 5 improved biosynthesis of red pigments by 27%. Finally, the developed culture process was verified in a 5-L stirred tank bioreactor. The red pigments production of the pH regulation group reached 1.11-fold of the control and 1.95-fold of the precursor regulation group, respectively. This study provides high-production strain, optimized medium, and bioprocess for the possible industrial production of Antarctic Geomyces red pigments in future.
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