Psychrophilic Yeast Research Articles

Microbiological Characteristics of Bare Peat Circles on Flat-Topped Peat Mounds in the North of Western Siberia

A destructive peat horizon Tmd of bare peat circles on flat-topped peat mounds in the north of Western Siberia differs from peat horizons (T) of typical peat soils in its higher density, water content, and comminution of peat residues; lower microbial biomass; low mineralization and hydrolase activities; low physiological diversity of hydrolytic bacteria; and specific composition of the fungal complex with an uncharacteristically high proportion and quantity of psychrophilic yeasts Leucosporidium drummii. Specific respiration rate and hydrolase activity in the Tmd and T horizons are relatively close, which indicates that, in general, the metabolic activity of microorganisms decomposing the organic matter of peat and increasing the degree of peat decomposition remains unchanged in the soils of bare peat circles.

Expression patterns of molecular chaperone genes in Antarctic psychrophilic yeast, Glaciozyma antarctica PI12 in response to heat stress

Expression patterns of molecular chaperone genes in Antarctic psychrophilic yeast, Glaciozyma antarctica PI12 in response to heat stress

Toward a rapid method for the study of biodiversity in cold environments: the characterization of psychrophilic yeasts by MALDI-TOF mass spectrometry.

To investigate the potential of matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF/MS) as a platform to support biodiversity and phylogenetic studies of psychrophilic yeasts in cold environments, the technique was employed to rapidly characterize and distinguish three psychrophilic yeasts (Rhodotorula mucilaginosa, Naganishia vishniacii, and Dioszegia cryoxerica) from three mesophilic counterparts (Saccharomyces cerevisiae Cry Havoc, S. cerevisiae California V Ale, and S. pastorianus). A detailed workflow for providing reproducible mass spectral fingerprints of low molecular weight protein/peptide features specific to the organisms studied is presented. The potential of this approach as a tool in the study of biodiversity, systematics, and phylogeny of psychrophilic microorganisms is highlighted.

Correction to: A comparative transcriptomic analysis provides insights into the cold-adaptation mechanisms of a psychrophilic yeast, Glaciozyma antarctica PI12

Glaciozyma antarctica PI12, a psychrophilic yeast from Antarctica, grows well at low temperatures. However, it is not clear how it responds and adapts to cold and freeze stresses. Hence, this project was set out to determine the cold-adaptation strategies and mechanisms of G. antarctica PI12 using a transcriptomic analysis approach. G. antarctica PI12 cells, grown in rich medium at 12 °C, were exposed to freeze stress at 0 and − 12 °C for 6 h and 24 h. Their transcriptomes were sequenced and analyzed. A hundred and sixty-eight genes were differentially expressed. The yeast gene expression patterns were found to be dependent on the severity of the cold with more genes being differentially expressed at − 12 °C than at 0 °C. Glaciozyma antarctica PI12 was found to share some common adaptation strategies with other yeasts, Saccharomyces cerevisiae and Mrakia spp., but at the same time, found to have some of its own unique strategies and mechanisms. Among the unique mechanisms was the production of antifreeze protein to prevent ice-crystallization inside and outside the cell. In addition, several molecular chaperones, detoxifiers of reactive oxygen species (ROS), and transcription and translation genes were constitutively expressed in G. antarctica PI12 to enable the cells to endure the fluctuating freezing temperatures. Interestingly, G. antarctica PI12 used nitrite as an alternative terminal acceptor of electrons when the oxygen level was low to minimize disruption of energy production in the cell. These mechanisms coupled with several other common mechanisms ensured that G. antarctica PI12 adapted well to the cold temperatures.

Structural and functional insights into TRiC chaperonin from a psychrophilic yeast, Glaciozyma antarctica.

Studies on TCP1-1 ring complex (TRiC) chaperonin have shown its indispensable role in folding cytosolic proteins in eukaryotes. In a psychrophilic organism, extreme cold temperature creates a low-energy environment that potentially causes protein denaturation with loss of activity. We hypothesized that TRiC may undergo evolution in terms of its structural molecular adaptation in order to facilitate protein folding in low-energy environment. To test this hypothesis, we isolated G. antarctica TRiC (GaTRiC) and found that the expression of GaTRiC mRNA in G. antarctica was consistently expressed at all temperatures indicating their importance in cell regulation. Moreover, we showed GaTRiC has the ability of a chaperonin whereby denatured luciferase can be folded to the functional stage in its presence. Structurally, three categories of residue substitutions were found in α, β, and δ subunits: (i) bulky/polar side chains to alanine or valine, (ii) charged residues to alanine, and (iii) isoleucine to valine that would be expected to increase intramolecular flexibility within the GaTRiC. The residue substitutions observed in the built structures possibly affect the hydrophobic, hydrogen bonds, and ionic and aromatic interactions which lead to an increase in structural flexibility. Our structural and functional analysis explains some possible structural features which may contribute to cold adaptation of the psychrophilic TRiC folding chamber.

Vishniacozyma ellesmerensis sp. nov., a psychrophilic yeast isolated from a retreating glacier in the Canadian High Arctic.

Two strains of a psychrophilic basidiomycetous yeast species belonging to the genus Vishniacozyma were isolated from sediments and soil at the front of a retreating glacier on northern Ellesmere Island in the Canadian Arctic. Analysis of the large subunit D1/D2 region and the internal transcribed spacer (ITS) regions of the rDNA indicated that these strains represented a novel species. The closest relatives of the novel species were Vishniacozyma globispora and V. dimennae, which exhibited sequence similarities of 82.2 and 81.6 %, respectively, to the ITS region of the novel species, and contained 61 and 57 nt substitutions, respectively, in the D1/D2 domain, in comparison with the novel species. Strains of the novel species were able to grow at sub-zero temperatures and in vitamin-free medium. These characteristics allow the strains to survive and grow in perennially cold, oligotrophic habitats in the Canadian High Arctic. The name Vishniacozyma ellesmerensis sp. nov. is proposed. The type strain is JCM 32573T (=UAMH 11973T=G3-4-8T) and the MycoBank number is MB825501.

Mrakia hoshinonis sp. nov., a novel psychrophilic yeast isolated from a retreating glacier on Ellesmere Island in the Canadian High Arctic.

Four strains isolated from sediment sampled at the front of a retreating glacier on northern Ellesmere Island in the Canadian high Arctic, namely JCM 32575T, JCM 32576, JCM 32577 and JCM 32578, belong to a novel psychrophilic basidiomycetous yeast species in the genus Mrakia. Molecular phylogenetic analysis indicated that these strains are most closely related to the type strains of Mrakia aquatica and Mrakianic combsii, but with 8-9 and 7-12 nt substitutions in ITS and in the D1/D2 domain of the LSU rRNA gene, respectively. The strains grew at sub-zero temperatures and in vitamin-free media, with lipase and cellulase highly active even at -3 °C. These characteristics likely allow this yeast species to grow and survive in extremely cold, oligotrophic environments, such as the fronts of retreating glaciers in the high Arctic. The name Mrakia hoshinonis sp. nov. is proposed, with type strain JCM 32575T (UAMH 11969) and MycoBank number MB 825484.

Utilization of sugars from wheat fermentatives with psychrophilic yeast under anaerobic conditions

Utilization of sugars from wheat fermentatives with psychrophilic yeast under anaerobic conditions

Metabolic profiling of Antarctic yeasts by proton nuclear magnetic resonance-based spectroscopy

The continent of Antarctica, as a combination of constantly low temperatures, strong winds, short summer season, and high solar radiation, is a highly extreme habitat suggesting appropriate conditions for growth of psychrophilic microorganisms. Five psychrophilic yeast strains were isolated from the samples taken from the region of the Bulgarian Base on Livingston Island, Antarctica: Cryptococcus laurentii AL65, Sporobolomyces salmonicolor AL36, Debaryomyces hansenii, Leucosporidium scotii and Rhodotorula glutinis, and their biomass yield and exopolysaccharides production were investigated. Best growth was observed for L. scotii and C. laurentii AL65, with 7.5 and 6.0 g/L biomass, respectively, and highest exopolysaccharide yield was established for L. scotii. Metabolic profiling revealed phylogenetically based diversity in the identified metabolic profiles. The proton nuclear magnetic resonance (1H NMR) spectroscopy analyses of compounds extracted from the biomass of the strains revealed significant differences in the metabolites between individual yeast strains in our investigation including: among the amino acids alanine, valine, threonine, leucine and tyrosine; some organic acids such as gamma-aminobutyric acid, acetic acid, formic acid and others. Glucose was identified in all investigated strains. The highest diversity of compounds was observed in D. hansenii strain, division Ascomycota. The main compounds in the metabolic profile of Basidiomycota strains were sugars. The statistical analysis revealed significant differences in the studied metabolites among the yeast strains. This result suggests that, together with 16S rRNA gene and enzyme gene analyses, metabolite profiling could be also used as a marker for a phylogenetic distance in fungi evolution.

A comparative transcriptomic analysis provides insights into the cold-adaptation mechanisms of a psychrophilic yeast, Glaciozyma antarctica PI12

A comparative transcriptomic analysis provides insights into the cold-adaptation mechanisms of a psychrophilic yeast, Glaciozyma antarctica PI12

(-)-Glaciantarcin, a New Dipeptide and Some Secondary Metabolites from the Psychrophilic Yeast Glaciozyma antarctica PI12

A new dipeptide, (-)-glaciantarcin (1) and three known compounds, cyclo(-Pro-Gly) (2), 1-(2-deoxypentofuranosyl)-5-methyl-2,4(1H,3H)-pyrimidinedione (3) and vidarabine (Ara-A) (4), were isolated from Glaciozyma antarctica PI12, a cold-adapted yeast. The chemical structures were elucidated by FT-IR, NMR and mass spectrometry. The cytotoxicity and antioxidant activities of compounds 1-4 were evaluated by using the MTT bioassay on MCF-7 (human breast cancer cell line), PC-3 (human prostate cancer cell line) and HEK-293 (normal human embryonic kidney cell line) and DPPH free radical scavenging activity, respectively. At concentration of 400 μM, all compounds showed the highest activity on MCF-7, with compound 1 at 65%, compound 2 (70%), compound 3 (66%) and compound 4 (58%) cell viability. All compounds exhibited weak antioxidant properties. To the best of our knowledge, this is the first report of compounds 1-4 from Glaciozyma antactica.

Taxonomy and richness of yeasts associated with angiosperms, bryophytes, and meltwater biofilms collected in the Antarctic Peninsula.

The interest in the diversity of yeasts in the Antarctic environment has increased in recent years, mainly because Antarctic microbiology is a recent science, and little is known about the biodiversity and genetic resources of the microorganisms that inhabit this ecosystem. This study aimed to determine the diversity of epiphytic yeasts in samples of Deschampsia antarctica, Colobanthus quitensis, and bryophytes, as well yeasts present in biofilms collected from Antarctic meltwater. Samples were collected in the summer of 2014 and 2015 during expeditions organized by the Brazilian Antarctic Program. A total of 310 yeasts were isolated, and 34 species were identified by sequencing the D1/D2 domains of the rDNA region belonging to 18 genera. The species Vishniacozyma victoriae and Mrakia gelida were the most abundant. Dioszegia antarctica and Leucosporidium creatinivorum were found only in plant substrates. Most psychrophilic yeasts were isolated from biofilms, including Glaciozyma antarctica, Glaciozyma martinii, Mrakia gelida, Mrakia frigida, Mrakia robertii, Phenoliferia glacialis, and Phenoliferia psychrophenolica, suggesting that the substrates examined in this study represented an interesting habitat for the isolation and characterization of epiphytic and non-epiphytic yeasts that colonize the Antarctic region.

Habitat-specificity and diversity of culturable cold-adapted yeasts of a cold-based glacier in the Tianshan Mountains, northwestern China.

Asian cold-based glacier yeasts with respect to their abundance, distribution, and taxonomy, in contrast to other continental cryosphere areas, have been little investigated. The present study reports the diversity and phylogeny of culturable cold-adapted yeasts in six cold habitats of the Glacier No.1 in the Tianshan Mountains (northwestern China). Of the total 591 yeast isolates, 401 were identified as basidiomycetous yeasts represented by 41 species of 15 genera, while 190 ascomycetous yeast isolates were assigned to the 8 species of 7 genera. The most prevalent species was Candida akabanensis with a 19.8% frequency of occurrence, followed by Vishniacozyma victoriae (16.4%) and Diutina rugosa (9.98%), of which V. victoriae was the only yeast species common to all six glacial habitats. Variability on the component and abundance of yeast taxa among glacial habitats primarily displayed in four dominant yeast genera, namely Candida, Vishniacozyma, Filobasidium, and Naganishia. However, network analysis illustrated that most of 32 rare yeast populations were habitat-specific, implying that the low-abundance yeast population was more easily influenced by the local habitat conditions (species sorting). Based on indicator species analyses, the subglacial habitat was characterized by psychrotolerant and/or psychrophilic yeast taxa.

Gene expression patterns of Glaciozyma antarctica PI12 in response to cold, and freeze stress

Psychrophilic yeast, Glaciozyma antarctica PI12 was isolated from the sea ice in the Southern Ocean. Several recent studies have revealed some of the strategies employed by G. antarctica PI12 to grow and survive at low temperatures, but those information are still limited. Hence this project was carried out to sequence the whole transcriptome to generate additional information on the cold-adaptation strategies of G. antarctica PI12. The yeast grown optimally in Saccharomyces cerevisiae minimal medium at 12 °C was subsequently exposed to cold-shock at 0 °C and freeze-shock at −12 °C for 6 h and 24 h. RNA from those cells were extracted, sequenced, and analyzed. Interestingly, the results showed that G. antarctica PI12 remained metabolically active at −12 °C. Two hundred and five genes were differentially expressed in the cells. Among them, 107 genes were upregulated while 98 genes were downregulated. In the first 6 h after the cells were exposed to cold- and freeze-shocks, CCR4-NOT (carbon catabolite repressed 4 - negative on TATA-less) core subunit cdc36, DNA repair protein Rad8, Elongation factor 1-gamma, 26s proteosome subunit 45, and Homocitrate synthase genes were commonly upregulated to perform several immediate and important tasks to ensure the cells survived. Apart from that, there were also genes upregulated and downregulated uniquely at 6 h and 24 h to facilitate the cells to adjust to the new temperatures. After overcoming the stress of the cold- and freeze-shocks for 24 h, the cells acclimatized to those temperatures and became metabolically active again, and the cell cycles related genes were up-regulated.

Gene isolation and prediction of the corresponding three-dimensional structure of subtilisin from the psychrophilic yeast, Glaciozyma antarctica PI12

Gene isolation and prediction of the corresponding three-dimensional structure of subtilisin from the psychrophilic yeast, Glaciozyma antarctica PI12

Mrakia gelida in brewing process: An innovative production of low alcohol beer using a psychrophilic yeast strain

Due to the increasing consumer demand, the production of low alcoholic and non alcoholic beer is the new goal of the present brewing producers. Although the beer with reduced alcohol content is currently obtained by physical methods, the use of non-Saccharomyces yeast, with low fermentations capacities, may represent an interesting biological approach.In this study the ethanol content and the volatile profile of a beer obtained using the basidiomycetous psychrophilic yeast strain Mrakia gelida DBVPG 5952 was compared with that produced by a commercial starter for low alcohol beers, Saccharomycodes ludwigii WSL17.The two beers were characterized by a low alcohol content (1.40% and 1.32% v/v) and by a low diacetyl production (5.04 and 5.20 μg/L). However, the organoleptic characteristics of the beer obtained using M. gelida are more appreciated by the panelists, in comparison to the analogous produced with the commercial strain of S. ludwigii.

Cold active β‐1,3‐glucanase from Antarctic Yeast, Glaciozyma antarctica PI12

Glaciozyma antarctica is a psychrophilic yeast that was isolated from the surface of Antarctic sea ice. A key adaptation of psychrophilic microorganisms is to synthesize cold‐active enzymes for survival at low temperatures. In this study, the full‐length cDNA encoding Exo‐β‐glucanase (GaExg55) from G. antarctica PI12 was amplified by reverse‐transcription polymerase chain reaction (RT‐PCR). The cDNA encoded a 480‐residue polypeptide with a putative signal peptide of 20 residues. Subsequently, the novel GaExg55 was expressed in E. coli and purified with nickel affinity chromatography as an approximately 55 kDa protein. The biochemical characterization of purified recombinant GaExg55 (rGaExg55) revealed typical cold‐active enzyme characteristics, such as maximal activity at 20 °C and pH 8.0. The Km and Vmax values of the enzyme using laminarin as the substrate were 10.04 mg mL−1 and 14.12 U mg−1, respectively. An analysis of the three‐dimensional structure of the enzyme was carried out using MODELLER9v16 and compared with homologous mesophilic exo‐β‐1,3‐glucanase. The results of the comparative structural study revealed that the psychrophilic GaExg55 contains longer loops, fewer hydrogen bonds and salt bridges, and a higher total solvent‐accessible surface area which enhanced the protein flexibility for high catalytic efficiency at low temperatures.Support or Funding InformationThis research was supported by a research grant from the Ministry of Science Technology and Innovation (MOSTI), Malaysia under the research grants 10‐05‐16‐MB002 and 02‐05‐20‐SF0007.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Unravelling the adaptation strategies employed by Glaciozyma antarctica PI12 on Antarctic sea ice

Glaciozyma antarctica PI12, is a psychrophilic yeast isolated from Antarctic sea. In this work, Expressed Sequence Tags (EST) from cells exposed to three different temperatures; 15 °C, 0 °C and −12 °C were generated to identify genes associated with cold adaptation. A total of 5376 clones from each library were randomly picked and sequenced. Comparative analyses from the resulting ESTs in each condition identified several groups of genes required for cold adaptation. Additionally, 319 unique transcripts that encoded uncharacterised functions were identified in the −12 °C library and are currently unique to G. antarctica. Gene expression analysis using RT-qPCR revealed two of the unknown genes to be up-regulated at −12 °C compared to 0 °C and 15 °C. These findings further contribute to the collective knowledge into G. antarctica cold adaptation and as a resource for understanding the ecological and physiological tolerance of psychrophilic microbes in general.

Biochemical and structural characterization of a novel cold-active esterase-like protein from the psychrophilic yeast Glaciozyma antarctica.

Dienelactone hydrolase, an α/β hydrolase enzyme, catalyzes the hydrolysis of dienelactone to maleylacetate, an intermediate for the Krebs cycle. Genome sequencing of the psychrophilic yeast, Glaciozyma antarctica predicted a putative open reading frame (ORF) for dienelactone hydrolase (GaDlh) with 52% sequence similarity to that from Coniophora puteana. Phylogenetic tree analysis showed that GaDlh is closely related to other reported dienelactone hydrolases, and distantly related to other α/β hydrolases. Structural prediction using MODELLER 9.14 showed that GaDlh has the same α/β hydrolase fold as other dienelactone hydrolases and esterase/lipase enzymes, with a catalytic triad consisting of Cys-His-Asp and a G-x-C-x-G-G motif. Based on the predicted structure, GaDlh exhibits several characteristics of cold-adapted proteins such as glycine clustering in the binding pocket, reduced protein core hydrophobicity, and the absence of proline residues in loops. The putative ORF was amplified, cloned, and overexpressed in an Escherichia coli expression system. The recombinant protein was overexpressed as soluble proteins and was purified via Ni-NTA affinity chromatography. Biochemical characterization of GaDlh revealed that it has an optimal temperature at 10°C and that it retained almost 90% of its residual activity when incubated for 90min at 10°C. The optimal pH was at pH 8.0 and it was stable between pH 5-9 when incubated for 60min (more than 50% residual activity). Its Km value was 256μM and its catalytic efficiency was 81.7s-1. To our knowledge, this is the first report describing a novel cold-active dienelactone hydrolase-like protein.

Cold active pectinase, amylase and protease production by yeast isolates obtained from environmental samples.

The present study was performed to screen for psychrophilic yeasts that are able to secrete cold active enzymes. Yeast isolates were obtained from environmental samples from northern Turkey and examined for enzyme production at low temperatures. The isolates which were capable of cold active enzyme production on plates were identified by molecular identification techniques. It has been found that the isolates belonged to three genera of yeasts, i.e., Rhodosporidiobolus, Cystofilobasidium and Yamadazyma. The isolates were then fermented in different media at 15°C and the pectinase, amylase and protease activities were determined in the range of 0.76-1.73, 0.5-1.57 and 2.11-10.53U/mL, respectively. Maximum enzyme activities were found in Yamadazyma isolates for all three enzymes. To the best of our knowledge, cold active pectinase, amylase and protease production by Yamadazyma spp. were investigated for the first time in the present study. Besides, this is the first report which indicates cold active amylase production by Cystofilobasidium capitatum and pectinase production by Rhodosporidiobolus colostri. Yeast isolates obtained in this study may have potential for industrial cold active enzyme production.