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Strain CP2CT was isolated from biological soil crusts in the Colorado Plateau, USA. The isolate was aerobic, facultatively fermentative, Gram-negative, non-motile and red-pigmented (due to the presence of carotenoids), but did not contain bacteriochlorophyll a. The strain tested positive for catalase, oxidase and urease and was negative for lysine and ornithine decarboxylases and arginine dihydrolase. The major fatty acids present were C(18 : 1)omega7c and C(16 : 0). It had a high DNA G+C content of 75 mol%. Comparisons of 16S rRNA gene sequences identified bacteriochlorophyll a-producing strains of Paracraurococcus ruber (94.9 %), Craurococcus roseus (92.2 %) and Roseococcus thiosulfatophilus (92.3 %), as well...
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Archaea are common and abundant members of biological soil crust communities across large-scale biogeographic provinces of arid North America. Regardless of microbial community development, archaeal populations averaged 2 � 107 16S rRNA gene copies per gram of soil, representing around 5% of the prokaryotic (total calculated bacterial and archaeal) numbers assessed by quantitative-PCR. In contrast, archaeal diversity, determined by denaturing gradient gel electrophoresis fingerprinting and clone libraries of 16S rRNA genes, was very restricted. Only six different phylotypes (all Crenarchaea) were detected, three of which were very dominant. Some phylotypes were widespread, while others were typical of Southern desert...
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We characterized, at millimeter resolution, bacterial biomass, diversity, and vertical stratification of biological soil crusts in arid lands from the Colorado Plateau. Microscopic counts, extractable DNA, and plate counts of viable aerobic copiotrophs (VAC) revealed that the top centimeter of crusted soils contained atypically large bacterial populations, tenfold larger than those in uncrusted, deeper soils. The plate counts were not always consistent with more direct estimates of microbial biomass. Bacterial populations peaked at the immediate subsurface (1-2 mm) in light-appearing, young crusts, and at the surface (0-1 mm) in well-developed, dark crusts, which corresponds to the location of cyanobacterial populations....
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Global change caused by anthropogenic activities may significantly modify the abundance, structure, and function of biological soil crusts. The components of global change can be grouped into (1) those that impact discreet sites but are occurring on a global scale, such as land-use change and invasive species, and (2) those that alter atmospheric chemistry resulting in changes in CO2 concentration, UV radiation, temperature, and precipitation (Vitousek 1994). In this chapter we will examine how landuse change, invasive species, elevated atmospheric CO2, increased UV radiation, and climate change may affect biological soil crusts and the ecosystems which they inhabit. Published in Biological Soil Crusts: Structure,...
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Photosynthetic microbes, particularly cyanobacteria, that bore into carbonates are ancient biological players in various geologic phenomena such as the destruction of biogenic carbonates and coastal limestones, the reworking of carbonate sands and the cementation of microbialites. Their signatures are important tools for paleoenvironmental reconstruction, and they play a significant role in marine aquaculture. In spite of their geologic, environmental and economic importance, the mechanism by which they are able to excavate calcareous and calcophosphatic mineral substrates remains unknown. Excavation by acidulation, commonly thought to be a possible mechanism, constitutes nothing less than an apparent paradox, in...
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