Wood-destroying soft rot fungi in the historic expedition huts of Antarctica

Three expedition huts in the Ross Sea region of Antarctica, built between 1901 and 1911 by Robert F. Scott and Ernest Shackleton, sheltered and stored the supplies for up to 48 men for 3 years during their explorations and scientific investigation in the South Pole region. The huts, built with wood taken to Antarctica by the early explorers, have deteriorated over the past decades. Although Antarctica has one of the coldest and driest environments on earth, microbes have colonized the wood and limited decay has occurred. Some wood in contact with the ground contained distinct microscopic cavities within secondary cell walls caused by soft rot fungi. Cadophora spp. could be cultured from decayed wood and other woods sampled from the huts and artifacts and were commonly associated with the soft rot attack. By using internal transcribed spacer sequences of ribosomal DNA and morphological characteristics, several species of Cadophora were identified, including C. malorum, C. luteo-olivacea, and C. fastigiata. Several previously undescribed Cadophora spp. also were found. At the Cape Evans and Cape Royds huts, Cadophora spp. commonly were isolated from wood in contact with the ground but were not always associated with soft rot decay. Pure cultures of Cadophora used in laboratory decay studies caused dark staining of all woods tested and extensive soft rot in Betula and Populus wood. The presence of Cadophora species, but only limited decay, suggests there is no immediate threat to the structural integrity of the huts. These fungi, however, are widely found in wood from the historic huts and have the capacity to cause extensive soft rot if conditions that are more conducive to decay become common.     

Endoglucanase-producing fungi isolated from Cape Evans historic expedition hut on Ross Island, Antarctica

Early explorers of Antarctica's Heroic Era erected wooden buildings and brought large quantities of supplies to survive in Antarctica. The introduction of wood and other organic materials provided nutrient sources for fungi that were indigenous to Antarctica or were brought in with the materials and adapted to the harsh conditions. Seventy-two isolates of filamentous fungi were cultured on selective media from interior structural wood of the Cape Evans historic hut and 27 of these screened positive for the ability to degrade carboxymethyl cellulose (CMC). Four non-CMC-degrading isolates were added to a group of 14 CMC-degrading isolates for further study, and endo-1, 4-beta-glucanase activity was demonstrated in the extracellular supernatant from all of these 18 isolates when grown at 4 degrees C, and also when they were grown at 15 degrees C. Isolates of Penicillium roquefortii and Cadophora malorum showed preference for growth at 15 degrees C rather than 25 degrees C or 4 degrees C indicating psychrotrophic characteristics. These results demonstrate that cellulolytic filamentous fungi found in Antarctica are capable of growth at cold temperatures and possess the ability to produce extracellular endo-1, 4-beta-glucanase when cultured at cold and temperate temperatures.     

Genetic diversity and dispersal of the moss Sarconeurum glaciale on Ross Island, East Antarctica

The extent of genetic variation and dispersal mechanisms were investigated over short distances of 1–100 m, and up to 3 km, by the random amplified polymorphic DNA (RAPD) technique, for the moss Sarconeurum glaciale , at three locations on Ross Island, Antarctica. At Arrival Heights, genetic variation occurred within single colonies, and the relationships between clumps indicated that they were dispersed down small, meltwater drainage channels by water. The genetic similarities between the colonies from Arrival Heights and others from Scott Base and Crater Hill, a few km away, together with the prevailing wind direction and absence of this moss in the intervening snow-covered area, suggested longer-distance dispersal by wind. Overall, the Ross Island samples appeared to form a single, polymorphic population that was distinct from another population at Canada Glacier, 110 km distant. Somatic mutation, rather than immigration of genetically different propagules from elsewhere, appeared to be the most probable cause of genetic variability in these haploid, vegetatively reproducing Antarctic moss populations. Initiation of recolonization of S. glaciale across a dirt track at Arrival Heights was also investigated by RAPDs, to investigate how regrowth of mosses in disturbed areas occurred in the extreme environment of Antarctica.     

On the distribution of terrestrial invertebrates at Cape Bird, Ross Island, Antarctica

Terrestrial invertebrate distribution was surveyed over 12 km² of the ice-free area at Cape Bird, Ross Island, Antarctica. Gomphiocephalus hodgsoni (Collembola: Hypogastruridae), Stereotydeus mollis and Nanorchestes antarcticus (Acari: Prostigmata), Panagrolaimus davidi, Plectus sp. and Scottnema lindsayae (Nematoda), Tardigrada, Rotifera and Protozoa were all recorded. Invertebrates were found at 47 of 103 locations sampled. Logistic regression analysis suggested that the presence of mites and Collembola was strongly related to chlorophyll-a content of soil; but only Stereotydeus mollis and N. antarcticus were related to the presence of macroscopic vegetation, suggesting that current methods of assessing areas for protection may not adequately allow for invertebrate communities. Invertebrate communities were not dependent on ornithogenic carbon input. A better understanding of dispersal mechanisms is necessary to understand distributions of invertebrates in ice-free areas, particularly in light of potential habitat changes as a result of climate change.     

A New Decapod Trackway from the Upper Cretaceous, James Ross Island, Antarctica

A new trace fossil, Foersterichnus rossensis igen. nov. and isp. nov., is described from the Coniacian Hidden Lake Formation, James Ross Island, Antarctica. The trace fossil is a trackway comprising straight, or slightly curving, paired rows of elongate to tear-shaped impressions, parallel or slightly inclined to the long axis of the trackway. Foersterichnus is interpreted to be the trackway of a brachyuran decapod crustacean. It occurs in transgressive shallow marine deposits formed above the storm wave base in a shelf setting. Preservation of the trackway may have been linked to a rapid deoxygenation event during drowning that led to cessation of bioturbation allowing preservation of mixed layer trackways.     

Biodegradation of phenanthrene by indigenous microorganisms in soils from Livingstone Island, Antarctica

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) in soils has been linked to history of exposure to PAHs and prevailing environmental conditions. This work assessed the capacity of indigenous microorganisms in soils collected in Livingstone Island (South Shetlands Islands, Antarctica) with no history of pollution (∑PAHs: 0.14-1.47?ng?g(-1) dw) to degrade (14) C-phenanhthrene at 4, 12 and 22?°C. The study provides evidence of the presence of phenanthrene-degrading microorganisms in all studied soils. Generally, the percentage of (14) C-phenanhthrene mineralized increased with increasing temperature. The highest extent of (14) C-phenanhthrene mineralization (47.93%) was observed in the slurried system at 22?°C. This work supports findings of the presence of PAH-degrading microorganisms in uncontaminated soils and suggests the case is the same for uncontaminated Antarctic remote soils.     

Bacterial community along a historic lake sediment core of Ardley Island, west Antarctica

The bacterial community in a historic lake sediment core of Ardley Island, Antarctica, spanning approximately 1,600 years, was investigated by molecular approaches targeting the 16S rRNA gene fragments. The cell number in each 1 cm layer of the sediment core was deduced through semi-quantification of the 16S rRNA gene copies by quantitative competitive PCR (QC-PCR). It was found that the total bacterial numbers remained relatively stable along the entire 59 cm sediment core. Denaturing Gradient Gel Electrophoresis (DGGE) analysis and sequencing of PCR-amplified 16S rRNA gene fragments were performed to analyze the bacterial diversity over the entire column. Principle coordinates analysis suggested that the bacterial communities along the sediment core could be separated into three groups. There were obvious bacterial community shift among groups of 1–20 cm, 21–46 cm and 46–59 cm. Diversity indices indicated that the bacterial community in the 21–46 cm depth showed the highest species diversity and uniformity. The main bacterial groups in the sediments fell into 4 major lineages of the gram-negative bacteria: the α, γ and δ subdivision of Proteobacteria, the Cytophaga-Flavobacteria-Bacteroides, and some unknown sequences. The gram-positive bacteria Gemmatimonadetes, Firmicutes and Actinobacteria were also detected. The results demonstrated the presence of highly diverse bacterial community population in the Antarctic lake sediment core. And the possible influence of climate and penguin population change on the bacterial community shift along the sediment core was discussed.Shengkang Li and Xiang Xiao contributed equally to this paper     

Assemblage characteristics and diet of fish in the shallow coastal waters of James Ross Island,Antarctica

Polar Biology - This study presents data on fish assemblage structure for the relatively pristine and understudied Antarctic coastal zone (5–25 m). A total of 545 Notothenioidei and...     

Diet of the south polar skua Catharacta maccormicki at Cape Bird,Ross Island,Antarctica

Regurgitated pellets and fecal samples from south polar skuas Catharacta maccormicki breeding on Ross Island were analyzed for diet items. Adult penguin feathers were found in 79% of all the pellets and 42% of the fecal samples. Evidence of fish was found in 26% of the pellets and 39% of the fecal samples. The amount of refuse in the diet of skuas on Ross Island was directly related to the distance from McMurdo Station.     

Pyocin-mediated antagonistic interactions in Pseudomonas spp. isolated in James Ross Island,Antarctica

Interactions within bacterial communities are frequently mediated by the production of antimicrobial agents. Despite the increasing interest in research of new antimicrobials, studies describing antagonistic interactions among cold-adapted microorganisms are still rare. Our study assessed the antimicrobial interactions of 36 Antarctic Pseudomonas spp. and described the genetic background of these interactions in selected strains. The overall bacteriocinogeny was greater compared to mesophilic Pseudomonas non-aeruginosa species. R-type tailocins were detected on transmission electron micrographs in 16 strains (44.4%); phylogenetic analysis of the corresponding gene clusters revealed that the P. prosekii CCM 8878 tailocin was related to the Rp3 group, whereas the tailocin in Pseudomonas sp. CCM 8880 to the Rp4 group. Soluble antimicrobials were produced by eight strains (22.-2%); gene mining found pyocin L homologues in the genomes of P. prosekii CCM 8881 and CCM 8879 and pyocin S9-like homologues in P. prosekii CCM 8881 and Pseudomonas sp. CCM 8880. Analysis of secretomes confirmed the production of all S- and L-type pyocin genes. Our results suggest that bacteriocin-based inhibition plays an important role in interactions among Antarctic soil bacteria, and these native, cold-adapted microorganisms could be a promising source of new antimicrobials.     

Usnea lichen community biomass estimation on volcanic mesas, James Ross Island, Antarctica

Ground macrolichens dominated by several species of fruticose Usnea spp. with foliose Leptogium puberulum constitute an important component of the terrestrial ecosystem of James Ross Island. Long-term monitoring of lichen communities in respect to their reaction to ongoing climatic changes in this part of Antarctica became a research task for scientists in recent years. The non-destructive estimation of lichen biomass provides data necessary for the management and protection of Antarctica. We have developed and tested the methodology of non-destructive estimation of biomass of fruticose Usnea species, which predominate in the ice-free tertiary basalt outcrop areas on James Ross Island. In 38 experimental squares (non-destructive measurements), the density and height of lichen thalli were measured and digital photography with ground cover evaluation was performed. Lichen biomass was harvested from 14 experimental squares and analysed for dry mass, chlorophyll a, b content, and thalli surface area (TSA). Predictive linear models were constructed from available non-destructively measured variables with the aim to maximize predictive accuracy for the destructively measured attributes. A total of 82.3?% of variability in the TSA values was explained (87.5?% for biomass determination). Cross-validated prediction error for lichen TSA estimation was 423?cm² (11.5?% of the average TSA). In the case of lichen dry mass determination, cross-validated prediction error was 4.53?g?m^?2 (7.3?% of the average dry mass). This study proves that macrolichens in maritime Antarctica can be monitored non-destructively by simple field methods combining digital photography and measurements of lichen thalli in botanical squares.     

Antioxidant enzyme activity of filamentous fungi isolated from Livingston Island, Maritime Antarctica

From 18 soil samples taken in the vicinity of the permanent Bulgarian Antarctic base “St. Kliment Ohridski” (62°38′29″S, 60°21′53″W) on Livingston Island, 109 filamentous fungi were isolated on selective media. The most widespread fungal species were members of the genera Cladosporium, Geomyces, Penicillium and Aspergillus. Other species, already recorded in Antarctic environment, were also isolated: Lecanicillium muscarium, Epicoccum nigrum and Alternaria alternata. Thirty strains demonstrating good growth were screened for antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) that play an important role in the defense of aerobic organisms against oxidative stress, by converting reactive oxygen species into nontoxic molecules. Six of them showed high enzyme activity. The tested strains produced SOD with statistically significant higher activity at 15°C than at 30°C suggesting that this enzyme is cold-active. Such SOD could be useful in medicine and cosmetics. The best producer of cold-active SOD, Aspergillus glaucus 363, cultivated in bioreactors, demonstrated optimal growth temperature at 25°C and maximum enzyme activities at 25 and 30°C for SOD and CAT, respectively. The electrophoretical analysis showed that the fungus possesses Cu/Zn-SOD.     

Fishes of the eastern Ross Sea,Antarctica

Antarctic fishes were sampled with 41 midwater and 6 benthic trawls during the 1999–2000 austral summer in the eastern Ross Sea. The oceanic pelagic assemblage (0–1,000 m) contained Electrona antarctica, Gymnoscopelus opisthopterus, Bathylagus antarcticus, Cyclothone kobayashii and Notolepis coatsi. These were replaced over the shelf by notothenioids, primarily Pleuragramma antarcticum. Pelagic biomass was low and concentrated below 500 m. The demersal assemblage was characteristic of East Antarctica and included seven species each of Artedidraconidae, Bathydraconidae and Channichthyidae, ten species of Nototheniidae, and three species each of Rajidae and Zoarcidae. Common species were Trematomus eulepidotus (36.5%), T. scotti (32.0%), Prionodraco evansii (4.9%), T. loennbergii (4.7%) and Chaenodraco wilsoni (4.3%). Diversity indices were highest for tows from 450 to 517 m (H=1.90–2.35). Benthic biomass ranged from 0.7 to 3.5 t km^–2. It was generally higher in tows from 450 to 517 m (0.9–2.0 t km^–2) although the highest biomass occurred at an inner-shelf station (238 m) due to large catches of T. eulepidotus, T. scotti and P. evansii.     

Broadscale patterns in the distribution of aquatic and terrestrial vegetation at three ice-free regions on Ross Island,Antarctica

Distribution patterns are presented for selected aquatic algae, and terrestrial algae, mosses and lichens, at three large, coastal ice-free regions on Ross Island. Each region is unique in certain aspects of its vegetation. The variation in areal and quantitative occurrence of different components of the vegetation in diverse ponds and streams, and over exposed ground surfaces, is related to the levels of marine salts in the environment, fertilisation by birds, water availability, substratum type and degree of exposure. A comparison is made with other antarctic, coastal, ice-free regions where similar broadscale patterns have been recognised.     

Enumeration of Thermophilic Heterotrophs in Geothermally Heated Soils from Mount Erebus, Ross Island, Antarctica

Soil samples with temperatures up to 64°C were collected from Mount Erebus, an active volcano located on Ross Island, Antarctica. Acridine orange direct counts and most probable number counts of soil samples stored at 4°C for 2 months showed a wide variation in the number of thermophilic microorganisms in different soils. Organisms similar to Clostridium thermohydrosulfuricum, Bacillus schlegelii, and Bacillus acidocaldarius, as well as neutrophilic Bacillus strains, were isolated.