ORCID Profile
0000-0002-4847-6492
Current Organisation
University of Waikato
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Publisher: Wiley
Date: 03-2009
DOI: 10.1111/J.1462-2920.2009.01859.X
Abstract: Tramway Ridge, located near the summit of Mount Erebus in Antarctica, is probably the most remote geothermal soil habitat on Earth. Steam fumaroles maintain moist, hot soil environments creating extreme local physicochemical differentials. In this study a culture-independent approach combining automated rRNA intergenic spacer analysis (ARISA) and a 16S rRNA gene library was used to characterize soil microbial (Bacterial and Archaeal) ersity along intense physicochemical gradients. Statistical analysis of ARISA data showed a clear delineation between bacterial community structure at sites close to fumaroles and all other sites. Temperature and pH were identified as the primary drivers of this demarcation. A clone library constructed from a high-temperature site led to the identification of 18 novel bacterial operational taxonomic units (OTUs). All 16S rRNA gene sequences were deep branching and distantly (85-93%) related to other environmental clones. Five of the signatures branched with an unknown group between candidate ision OP10 and Chloroflexi. Within this clade, sequence similarity was low, suggesting it contains several yet-to-be described bacterial groups. Five archaeal OTUs were obtained and exhibited high levels of sequence similarity (95-97%) with Crenarchaeota sourced from deep-subsurface environments on two distant continents. The novel bacterial assemblage coupled with the unique archaeal affinities reinvigorates the hypotheses that Tramway Ridge organisms are relics of archaic microbial lineages specifically adapted to survive in this harsh environment and that this site may provide a portal to the deep-subsurface biosphere.
Publisher: Wiley
Date: 13-05-2004
Publisher: Elsevier BV
Date: 2022
Publisher: Springer Science and Business Media LLC
Date: 15-02-2019
DOI: 10.1038/S42003-018-0274-5
Abstract: Abiotic and biotic factors control ecosystem bio ersity, but their relative contributions remain unclear. The ultraoligotrophic ecosystem of the Antarctic Dry Valleys, a simple yet highly heterogeneous ecosystem, is a natural laboratory well-suited for resolving the abiotic and biotic controls of community structure. We undertook a multidisciplinary investigation to capture ecologically relevant biotic and abiotic attributes of more than 500 sites in the Dry Valleys, encompassing observed landscape heterogeneities across more than 200 km 2 . Using richness of autotrophic and heterotrophic taxa as a proxy for functional complexity, we linked measured variables in a parsimonious yet comprehensive structural equation model that explained significant variations in biological complexity and identified landscape-scale and fine-scale abiotic factors as the primary drivers of ersity. However, the inclusion of linkages among functional groups was essential for constructing the best-fitting model. Our findings support the notion that biotic interactions make crucial contributions even in an extremely simple ecosystem.
Publisher: Microbiology Society
Date: 12-2015
Abstract: An aerobic, thermophilic and cellulolytic bacterium, designated strain WKT50.2 T , was isolated from geothermal soil at Waikite, New Zealand. Strain WKT50.2 T grew at 53–76 °C and at pH 5.9–8.2. The DNA G+C content was 58.4 mol%. The major fatty acids were 12-methyl C 18 : 0 and C 18 : 0 . Polar lipids were all linked to long-chain 1,2-diols, and comprised 2-acylalkyldiol-1- O -phosphoinositol (diolPI), 2-acylalkyldiol-1- O -phosphoacylmannoside (diolP-acylMan), 2-acylalkyldiol-1- O -phosphoinositol acylmannoside (diolPI-acylMan) and 2-acylalkyldiol-1- O -phosphoinositol mannoside (diolPI-Man). Strain WKT50.2 T utilized a range of cellulosic substrates, alcohols and organic acids for growth, but was unable to utilize monosaccharides. Robust growth of WKT50.2 T was observed on protein derivatives. WKT50.2 T was sensitive to icillin, chlor henicol, kanamycin, neomycin, polymyxin B, streptomycin and vancomycin. Metronidazole, lasalocid A and trimethoprim stimulated growth. Phylogenetic analysis of 16S rRNA gene sequences showed that WKT50.2 T belonged to the class Thermomicrobia within the phylum Chloroflexi , and was most closely related to Thermorudis peleae KI4 T (99.6% similarity). DNA–DNA hybridization between WKT50.2 T and Thermorudis peleae DSM 27169 T was 18.0%. Physiological and biochemical tests confirmed the phenotypic and genotypic differentiation of strain WKT50.2 T from Thermorudis peleae KI4 T and other members of the Thermomicrobia . On the basis of its phylogenetic position and phenotypic characteristics, we propose that strain WKT50.2 T represents a novel species, for which the name Thermorudis pharmacophila sp. nov. is proposed, with the type strain WKT50.2 T ( = DSM 26011 T = ICMP 20042 T ). Emended descriptions of Thermomicrobium roseum , Thermomicrobium carboxidum , Thermorudis peleae and Sphaerobacter thermophilus are also proposed, and include the description of a novel respiratory quinone, MK-8 2,3-epoxide (23%), in Thermomicrobium roseum .
Publisher: Microbiology Society
Date: 12-2007
Abstract: An unidentified obligately anaerobic, fastidious, Gram-positive, non-motile, non-spore-forming, non-fermentative coccoid-shaped bacterium (designated strain GPC 589 T ) was isolated from the rumen fluid of a sheep. The major fatty acid constituents ( %) were C 16 : 0 (29.2 %), C 18 : 0 (40.7 %) and an unidentified compound (19.7 %) with an equivalent chain-length of 13.523. The G+C content of the DNA was 34 mol%. The organism was strongly ureolytic and generated ATP through the hydrolysis of urea. Comparative 16S rRNA gene sequence analysis demonstrated that strain GPC 589 T was far removed, phylogenetically, from the ruminococci and related Gram-positive anaerobic cocci but exhibited a phylogenetic association with Clostridium rRNA cluster XIVa [as defined by Collins, M. D., Lawson, P. A., Willems, A., Cordoba, J. J., Fernandez-Garayzabal, J., Garcia, P., Cai, J., Hippe, H. & Farrow, J. A. E. (1994). Int J Syst Bacteriol 44 , 812–826]. Sequence ergence values of 12.5 % or more were observed between strain GPC 589 T and all other recognized species within this and related rRNA clostridial clusters. Phylogenetic analysis showed that strain GPC 589 T represents a new genus within cluster XIVa. On the basis of both phylogenetic and phenotypic evidence, it is proposed that strain GPC 589 T should be classified as representing a new genus and novel species, Howardella ureilytica gen. nov., sp. nov. The type strain is strain GPC 589 T (=DSM 15118 T =JCM 13267 T ).
Publisher: Wiley
Date: 28-03-2008
DOI: 10.1111/J.1462-2920.2008.01593.X
Abstract: Biotic communities and ecosystem dynamics in terrestrial Antarctica are limited by an array of extreme conditions including low temperatures, moisture and organic matter availability, high salinity, and a paucity of bio ersity to facilitate key ecological processes. Recent studies have discovered that the prokaryotic communities in these extreme systems are highly erse with patchy distributions. Investigating the physical and biological controls over the distribution and activity of microbial bio ersity in Victoria Land is essential to understanding ecological functioning in this region. Currently, little information on the distribution, structure and activity of soil communities anywhere in Victoria Land are available, and their sensitivity to potential climate change remains largely unknown. We investigated soil microbial communities from low- and high-productivity habitats in an isolated Antarctic location to determine how the soil environment impacts microbial community composition and structure. The microbial communities in Luther Vale, Northern Victoria Land were analysed using bacterial 16S rRNA gene clone libraries and were related to soil geochemical parameters and classical morphological analysis of soil metazoan invertebrate communities. A total of 323 16S rRNA gene sequences analysed from four soils spanning a productivity gradient indicated a high ersity (Shannon-Weaver values > 3) of phylotypes within the clone libraries and distinct differences in community structure between the two soil productivity habitats linked to water and nutrient availability. In particular, members of the Deinococcus/Thermus lineage were found exclusively in the drier, low-productivity soils, while Gammaproteobacteria of the genus Xanthomonas were found exclusively in high-productivity soils. However, rarefaction curves indicated that these microbial habitats remain under-s led. Our results add to the recent literature suggesting that there is a higher bio ersity within Antarctic soils than previously expected.
No related grants have been discovered for Ian McDonald.