Arctic Strain Research Articles

Phosphate solubilizing ability of two ArcticAspergillus nigerstrains

Many filamentous fungi were isolated from the soils of Ny-A…lesund, Spitsbergen, Svalbard, and were screened in vitro for their phosphate solubilizing ability. Two strains of Aspergillus niger showed good tricalcium phosphate (TCP) solubilizing ability in Pikovskaya’s medium. The TCP solubilization index was calculated at varying levels of pH and temperatures. The ability of Aspergillus niger strain-1 to solubilize and release inorganic-P was 285µg ml-1, while Aspergillus niger strain-2 solubilized 262 µg ml-1 from 0.5% TCP after 7 days. This is the first report of TCP solubilization by Arctic strains that may serve as very good phosphate solubilizers in the form of biofertilizer. Kewords: Phosphate, Arctic, fungi, Aspergillus (Published: 15 June 2011) Citation: Polar Research 2011, 30 , 7283, DOI: 10.3402/polar.v30i0.7283

Nutrient requirements of polar Chlorella-like species

Eukaryotic micro-algae, well adapted to extremely low and varying temperatures, varying light intensities, as well as low availability of essential macronutrients and other resources, represent ideal producers in low-temperature biotechnological processes. In order to identify the nutrient requirements of six biotechnologically perspective Arctic and Antarctic soil Chlorella-like strains at various temperature and light regimes, the algae were cultivated in a unit for cross gradients of temperature (-4 to 24°C) and irradiance (5 to 65 µmol m-2 s-1), and at different nutrient treatments in each temperature-irradiance combination. The nutrient treatments included two different carbon (bicarbonate and carbonate concentrations of 1 and 5 mM) and nitrogen (nitrate concentrations of 50 amd 100 µM and ammonium concentrations 100 and 500 µM) forms at two different concentrations for each. Temperature and irradiance growth requirements were similar in the majority of strains reflecting thus comparable conditions in the original microhabitat, regardless of its geographic position. All studied strains tolerated low temperatures (1 to 5°C), but were able to grow even at temperatures above 20°C, thus, they were considered to be psychrotolerant. All experimental strains were able to grow at very low irradiances. Nutrient manipulation either did not affect the growth limits and optimum, or narrowed the growth optima; the response was strain-specific. Ammonium and nitrate additions resulted in decreased growth rates in all tested strains, with the exception of one strain in which growth stimulation was observed. The decrease in growth rate was probably due to nutrient oversaturation in the inhibited strains. Carbonate addition stimulated growth of all strains. Bicarbonate also increased the growth rate in all strains with one exception, in which bicarbonate inhibited growth, indicating thus carbon limitation during cultivation and different carbon uptake mechanisms.

Characterization of the pheromone gene family of an Antarctic and Arctic protozoan ciliate, Euplotes nobilii

Allelic genes encoding water-borne signal proteins (pheromones) were amplified and sequenced from the somatic (macronuclear) sub-chromosomic genome of Antarctic and Arctic strains of the marine ciliate, Euplotes nobilii. Their open reading frames appeared to be specific for polypeptide sequences of 83 to 94 amino acids identifiable with cytoplasmic pheromone precursors (pre-pro-pheromones), requiring two proteolytic steps to remove the pre- and pro-segments and secrete the mature pheromones. Differently from most of the macronuclear genes that have so far been characterized from Euplotes and other hypotrich ciliates, the 5′ and 3′ non-coding regions of all the seven E. nobilii pheromone genes are much longer than the coding regions (621 to 700 versus 214 to 285 nucleotides), and the 5′ regions in particular show nearly identical sequences across the whole set of pheromone genes. These structural peculiarities of the non-coding regions are likely due to the presence of intron sequences and provide presumptive evidence that they are site of basic, conserved activities in the mechanism that regulates the expression of the E. nobilii pheromone genes.

Freezing and desiccation injury resistance in the filamentous green alga Klebsormidium from the Antarctic, Arctic and Slovakia

The freezing and desiccation tolerance of 12 Klebsormidium strains, isolated from various habitats (aero- terrestrial, terrestrial, and hydro-terrestrial) from distinct geographical regions (Antarctic - South Shetlands, King George Island, Arctic - Ellesmere Island, Svalbard, Central Europe - Slovakia) were studied. Each strain was exposed to several freezing (�4 ◦ C, �40 ◦ C, �196 ◦ C) and desiccation (+4 ◦ Ca nd +20 ◦ C) regimes, simulating both natural and semi-natural freeze-thaw and desiccation cycles. The level of resistance (or the survival capacity) was evaluated by chlorophyll a content, viability, and chlorophyll fluorescence evaluations. No statistical differences (Kruskal-Wallis tests) between strains originat- ing from different regions were observed. All strains tested were highly resistant to both freezing and desiccation injuries. Freezing down to �196 ◦ C was the most harmful regime for all studied strains. Freezing at �4 ◦ C did not influence the sur- vival of studied strains. Further, freezing down to �40 ◦ C (at a speed of 4 ◦ C/min) was not fatal for most of the strains. RDA analysis showed that certain Antarctic and Arctic strains did not survive desiccation at +4 ◦ C; however, freezing at �40 ◦ C, as well as desiccation at +20 ◦ C was not fatal to them. On the other hand, other strains from the Antarctic, the Arctic, and Central Europe (Slovakia) survived desiccation at temperatures of +4 ◦ C, and freezing down to �40 ◦ C. It appears that

Classification of Hepatitis B Virus Genotype B into 2 Major Types Based on Characterization of a Novel Subgenotype in Arctic Indigenous Populations

Hepatitis B virus genotype B (HBV/B) has been classified into 5 subgenotypes. Except for Bj/B1 in Japan, the subgenotypes (Ba/B2-B5) have undergone recombination with HBV/C in the core promoter/precore/core genomic region. Phylogenetic analyses of complete sequences show that the Arctic strains belong to a novel subgenotype (HBV/B6) without the recombination, analogous to what is seen with Bj/B1. Comparison of 50 HBV/B6 carriers from the Arctic versus 50 Bj and 50 Ba age- and sex-matched carriers from Asia revealed that clinical characteristics of HBV/B6 carriers were similar to those of Bj/B1 carriers in Japan. The results suggest that HBV/B may be classified into nonrecombinant (Bj/B1 and B6) and recombinant (Ba/B2-B5) types.

Genetic Variation Among Penicillium crustosum Isolates from Arctic and other Ecological Niches

Penicillium crustosum is an important and panglobal contaminant of lipid- and protein-rich foods and feeds. Although it is infrequent in extremely cold environments, we isolated a high number of P. crustosum strains from Arctic coastal, but particularly, subglacial environments in Svalbard, Norway. P. crustosum is extremely consistent in its phenotypic properties, including morphology, physiology, and secondary metabolite production. However, some Arctic isolates differed from other Arctic and non-Arctic strains in their weak growth on creatine and in the production of the secondary metabolite andrastin A. In this study, we characterized genetic variability of P. crustosum strains originating from different Arctic and non-Arctic environments using amplified fragment length polymorphism (AFLP) and, in addition, M13 minisatellite fingerprinting and partial beta-tubulin gene sequencing. Most of the Arctic strains (85%) showed a relatively low variability and polymorphism level. They produced nine different AFLP genotypes grouped into two clusters in accordance with glacier origin and creatine utilization. The rest of the Arctic isolates and isolates from various non-Arctic environments displayed a much greater degree of genetic variability. It seems that in stressful glacial environment low microbial genetic variation is represented by only a few adapted genotypes that were not recovered from nonpolar environments.

Phylogenetic relationship and phenotypic comparison of Psychrobacter species isolated from polar oceans

To investigate the phylogenetic relationship and biogeography of bacterioplankton in polar oceans, four Psychrobacter strains, BSw10170, BSw20352, BSw20370, and BSw20461, isolated from seawater of the Beijing Sea, the Chukchi Sea, and the Prydz Bay, were characterized by 16S rDNA sequencing and physiological and biochemical testing. Results demonstrated that close relationships existed between the Arctic and Antarctic strains with sequence similarities higher than 97 %. These four Psychrobacter strains not only showed almost identical phenotypic characteristics among them, but also shared a lot of similarities with those related Psychrobacter species, indicating that psychrotolerance and halotolerance of Psychrobacter strains may be among the reasons for their bipolar, even global distribution in marine environments at the genus level.

Molecular epidemiology of rabies virus isolates from South Korea

A molecular epidemiological study was performed on 13 Korean virus isolates, which were collected from wild and domestic animals diagnosed as rabid between 1998 and 2004. Seven samples were from domestic animals such as dogs and cattle infected by rabid raccoon dogs ( Nyctereutes procyonoides koreensis), and the rest of the six samples were from raccoon dogs in the wild. The study was carried out based on the comparison of nucleotide and amino acid sequences of nucleoprotein (N) and glycoprotein (G) coding regions and nucleotide sequence of the G-L intergenic (Ψ) non-coding region of the isolates. The similarities of nucleotide and amino acid sequence were at least 97.8 and 98.5%, respectively, between all Korean isolates. Phylogenetic analyses of the isolate showed that they formed a monophyletic group closely related to the Arctic strains but distant from other Asian strains, including Chinese strains. The fact that the raccoon dog is the main epidemic carrier of rabies in Korea and the results of these studies supported the conclusion of previous studies (Kuzmin et al.) that the raccoon dogs take part in the circulation of rabies virus within their natural territories in the Far East. The Korean isolates can be divided into two subgroups. All the topology of the most likelihood tree of Korean isolates using nucleotide and amino acid sequences of N, G and G-L region reflected not the species but the year of isolation and geographical location of the virus isolates. This study presents the detailed description of the molecular epidemiology of rabies virus in Korea.

Growth inhibition of rhizobia isolated from arctic legumes (Astragalus and Oxytropis spp.) and sainfoin (Onobrychis viciifolia) by sainfoin seed diffusates

Cold-adapted arctic rhizobia (from Astragalus and Oxytropis species) were used in nodulation studies and field inoculation trials with a temperate forage legume, sainfoin (Onobrychis viciifolia), since they have the potential to improve symbiotic nitrogen fixation at low temperatures. A major concern in legume inoculation is the toxicity of seed and root tannins to rhizobia. We studied the effects of sainfoin seed diffusates on the growth of 47 arctic and 2 sainfoin strains of rhizobia. Growth of all tested strains on yeast-extract mannitol agar plate was inhibited to various degrees by sainfoin seed diffusates. There was no correlation between the zone of inhibition and the symbiotic effectiveness of each strain on sainfoin. However, growth inhibition was totally reversed by the addition of iron as Fe-EDTA in the agar medium. In liquid medium without iron, growth inhibition of an arctic strain was 94% after 4-day growth. With the addition of 100 µM Fe-EDTA, inhibition was only 5%, and with 100 µM Fe-citrate, 76 %. These results underline the importance of evaluating the toxicity effect under normal rhizospheric conditions.

Volatile Organic Compounds from Arctic Bacteria of the Cytophaga‐Flavobacterium‐Bacteroides Group: A Retrobiosynthetic Approach in Chemotaxonomic Investigations

Volatile organic compounds emitted by different marine arctic strains of the Cytophaga-Flavobacterium-Bacteroides group were investigated by using a modified closed-loop stripping apparatus (CLSA). Seven of nine strains emitted volatiles, dominated by methyl ketones, in specific patterns. The methyl ketones were aliphatic saturated, or unsaturated, and comprised 12 to 18 C-atoms, sometimes with terminal Me branches. They were identified by GC/MS, retention-index calculations, derivatization with dimethyl disulfide for C=C bond location, and GC/FTIR to elucidate their uniform (Z)-configuration. The proposed structures of all methyl ketones were subsequently confirmed by synthesis, while the absolute configuration of chiral volatiles was elucidated by stereoselective synthesis. From retrobiosynthetic considerations, it was found that strain ARK10267 uses mainly valine, and strain ARK10063 mainly isoleucine for formation of starters for the ketone biosynthesis, which is correlated to fatty acid biosynthesis. Four strains (ARK10223, ARK10044, ARK10141, and ARK10146) use leucine. These separations are supported by phylogenetic affiliations based on 16S rRNA. Strain ARK10255b, in the course of this study found to be not a member of the Cytophaga-Flavobacterium-Bacteroides phylum, did not emit aliphatic ketones of medium chain length, but methionine-derived 4-(methylsulfanyl)butan-2-one and corresponding 4-(methylsulfanyl)butan-2-ol. Most of the compounds described have not been reported previously from nature.

Molecular and antigenic characterization of rabies viruses from Iran identifies variants with distinct epidemiological origins.

A molecular epidemiological study of 48 recent rabies isolates recovered from cases reported throughout Iran identified three distinct viral variants, the evolutionary origins of which were identified by phylogenetic comparison with rabies viruses originating from Europe and Asia. Members of group 1 (15 isolates) were recovered from the northern half of the country only, while those of group 2 (31 isolates) were widely dispersed; both groups clustered within the widely disseminated cosmopolitan lineage. The two isolates of group 3 were detected in the northeastern tip of the country only and belonged to the Arctic strain. Rapid variant discrimination tools, employing restriction fragment length polymorphisms applied to amplified fragments of the viral genome, were devised whilst antigenic characterization of representative viruses identified a small panel of monoclonal antibodies that were also discriminatory. The future application of such methods should provide valuable epidemiological information on rabies incidence in Iran.

Bipolar distribution of the cyst-forming dinoflagellate Polarella glacialis

Morphological investigations of motile cells and cysts of a small dinoflagellate (strain CCMP 2088) isolated from Canadian Arctic waters were carried out under both light and scanning electron microscopy. This species strongly resembled Polarella glacialis (strain CCMP 1383), which up to now was known only from Antarctic sea ice. The photosynthetic pigment composition of strain CCMP 2088 is typical of dinoflagellates, with peridinin as a major accessory pigment. Phylogenetic relationships between the two strains and other dinoflagellate species were inferred from SSU nrDNA using Neighbour Joining and weighted parsimony analyses. Our results showed that strain CCMP 2088 and P. glacialis (strain CCMP 1383) grouped in the same clade (Suessiales clade), showing high similarity values (0.99%). Morphological and molecular data support the assignment of the Arctic strain to P. glacialis. The free-living Gymnodinium simplex and the two P. glacialis strains have a basal position in the Suessiales clade, as compared to Symbiodinium spp.

The isolation and characterisation of a cold-adapted metallo-alkaline phosphatase from the Arctic psychrophile strain PA-43

The isolation and characterisation of a cold-adapted metallo-alkaline phosphatase from the Arctic psychrophile strain PA-43

EVOLUTIONARY RELATIONSHIPS OF CULTIVATED ANTARCTIC OSCILLATORIANS (CYANOBACTERIA)

The evolutionary relationships of cultivated psychrophilic and psychrotolerant polar oscillatorians were examined, based on small subunit rDNA sequences. Psychrophilic oscillatorians from the Antarctic were affiliated in one well‐supported clade, which also includes two Arctic strains. Two of the Antarctic psychrophiles contain an 11‐nucleotide insertion that is identical to, and previously only described in, an Arctic oscillatorian. The psychrotolerant phenotype, conversely, has arisen multiple times in the cyanobacterial lineage, and psychrotolerant strains are sometimes most closely related to organisms of temperate latitudes. These findings support the hypothesis that oscillatorians in both polar regions originated from more temperate species. Furthermore, morphological designations of these filamentous cyanobacteria often do not have phylogenetic significance.

Induction of cold active acid phosphomonoesterase activity at low temperature in psychrotrophic ectomycorrhizal Hebeloma spp.

Hebeloma strains of arctic and temperature origin, grown at 22° or 6°, were assayed for wall-bound and extracellular acid phosphomonoesterase (pNPPase) across a temperature range 2-37°. Only when grown at 6° was a cold active extracellular pNPPase induced in all the arctic strains and most of the temperature strains tested. Such enzymes are suggested to be a adaptation to low soil temperatures, and are discussed in the context of ectomycorrhizal access to soil PO4− monoesters at low temperature.

Utilization of organic nitrogen by ectomycorrhizal fungi ( Hebeloma spp.) of arctic and temperate origin

Arctic and temperate strains of Hebeloma spp. were grown in axenic culture on glutamic acid, alanine, lysine and NH4+ as sole sources of nitrogen (N), with excess carbon (C) or deficient C (supplied as glucose). Their ability to utilize seed protein as a natural N source was also assessed. All strains tested had the capacity to assimilate amino acids and generally utilized alanine and glutamic acid more readily than NH4+. Some strains were able to utilize amino C when starved of glucose C, and could mineralize amino-N to NH3-N. Arctic strains, in particular, appeared to be pre-adapted to the utilization of seed protein N and glutamic acid N, which is often liberated in high concentrations after soil freezing. The results are discussed in relation to their possible ecological importance.

The effect of temperature and inorganic phosphorus supply on growth and acid phosphatase production in arctic and temperate strains of ectomycorrhizal Hebeloma spp. in axenic culture

Acid phosphatase production by 12 Hebeloma strains was usually derepressed when inorganic phosphorus in the growth medium was limited, but appeared to be constitutive in some strains. At low temperatures (≤ 12°) arctic strains produced more extracellular and wall-bound acid phosphatase, yet grew more slowly than the temperate strains. We suggest that low growth rates in arctic strains may be a physiological response to cold whereby resources are diverted into carbohydrate accumulation for cryoprotection. At near freezing temperatures, increased extracellular phosphatase production may compensate for a loss of enzyme activity at low temperature and serve to hydrolyse organic phosphorus in frozen soil over winter.

Potential of Rhizobium and Bradyrhizobium species as plant growth promoting rhizobacteria on non-legumes: Effect on radishes (Raphanus sativus L.)

Bradyrhizobia and rhizobia are symbiotic bacterial partners forming nitrogen fixing nodules on legumes. These bacteria share characteristics with plant growth promoting rhizobacteria (PGPR). Nodule inducing bacteria, like other PGPR, are capable of colonizing the roots of non-legumes and produce phytohormones, siderophores and HCN. They also exhibit antagonistic effects towards many plant pathogenic fungi. The potential of nodule inducing bacteria to function as PGPR, was examined by using radish as a model plant. Three percent of the 266 strains tested were found to be cyanogens, while a majority (83%) produced siderophores. Fifty eight percent of the strains produced indole 3-acetic acid (IAA) and 54% solubilized phosphorus. Some of the bacterial species examined were found to have a deleterious effect while others were neutral or displayed a stimulatory effect on radishes. Bradyrizobium japonicum strain Soy 213 was found to have the highest stimulatory effect (60%), and an arctic strain (N44) was the most deleterious, causing a 44% reduction in radish dry matter yield. A second plant inoculation test, performed in growth cabinets, revealed that only strain Tal 629 of B. japonicum significantly increased (15%) the dry matter yield of radish. This indicates that specific bradyrhizobia have the potential to be used as PGPR on non-legumes.

Temperature adaptation in strains of the amphi-equatorial green alga Urospora penicilliformis (Acrosiphoniales): biogeographical implications

The temperature requirements for growth and the upper survival temperatures (UST's) of the amiphi-equatorial green alga Urospora penicilliformis collected from several localities within its distribution area between 1986 and 1991 were determined. Ecotypic variation, both with regard to growth ranges and optima and to survival temperatures, was demonstrated. In the polar strains of U. penicilliformis, temperature growth ranges were narrower and the growth optima and UST's were at lower temperatures compared to cold-temperate strains. In particular, the polar strains grew between 0 and 15°C with optimal growth at 0 or 5°C, whereas the cold-temperate isolates grew between 0 and (15) 20°C with almost equal growth rates or a growth optimum between 5 and 15°C. The Arctic strains survived 23 to 24°C, and the Antarctic isolate only 19°C, while the UST's of the cold-temperate isolates were between (24) 25 to 26°C. The data strongly indicate that a cold water history of ca. 3 million yr in the Arctic can be sufficient for changes in the temperature growth ranges and optima as well as for small changes of UST as shown in the Arctic populations of U. penicilliformis. For stronger reduction of upper survival temperatures, longer time periods are necessary as exemplified in the isolate from Antarctica, where low temperatures have existed for at least 14 million yr. The significantly lower UST of the Antarctic strain, points to an early contact of the alga with the cold water of the Antarctic region and may indicate an origin of U. penicilliformis in the Southern Hemisphere. The UST's of the cold-temperate isolates (24 to 26°C) would have allowed a migration across the equator during Pleistocene lowerings of the seawater temperatures in the tropics. Growth, however, would not have been possible during the passage across the equator due to the narrow temperature-growth window. The nature of the geographical boundaries and the control of seasonal development of U. penicilliformis by the temperature conditions in the various geographical regions are discussed in relation to the present local temperature regime.

Temperature ecotypes and biogeography of Acrosiphoniales (Chlorophyta) with Arctic-Antarctic disjunct and Arctic/cold-temperature distributions

The temperature requirements for growth and the upper survival temperatures (USTs) of the Antarctic-Arctic disjunct green alga Acrosiphonia arcta and of the Arctic/cold-temperature A. sonderi (Acrosiphoniales) from several localities within their distribution areas were determined. Ecotypic variation with regard to growth optima as well as survival temperatures was demonstrated in both species. While cold-temperature strains had relatively high or optimal growth rates at 15°C, polar isolates had very low rates at this temperature and showed growth optima between 0 and 10°C. The UST of the polar isolates of A. arcta is 22°C, i.e. slightly lower than those of the cold-temperate strains at 23–25°C. The cold-temperate isolate of A. sonderi survived 25°C, whereas Arctic strains had USTs of 22–24°C. The data indicate that changes in growth responses to temperature as well as small changes in UST can be achieved in relatively short time periods of exposure to low temperatures (3 million years) as exemplified in ...