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- 4.1 Biologische Materialschädigung und Referenzorganismen (2)
- 4.2 Material-Mikrobiom Wechselwirkungen (2)
- 5 Werkstofftechnik (2)
- 5.4 Multimateriale Fertigungsprozesse (2)
- 1 Analytische Chemie; Referenzmaterialien (1)
- 1.7 Organische Spuren- und Lebensmittelanalytik (1)
A novel Gram-positive, aerobic, actinobacterial strain, CF6/1T, was isolated in 2007 during environmental screening of arid desert soil in the Sahara near to Ourba, Chad. The isolate was found to grow best in a temperature range of 20–37 °C and at pH 6.0–8.5 and showed no NaCl tolerance, forming black-coloured and nearly circular colonies on GYM agar. Chemotaxonomic and molecular characteristics determined for the isolate match those previously described for members of the genus Geodermatophilus. The DNA G + C content of the novel strain was determined to be 74.9 mol %. The peptidoglycan was found to contain meso-diaminopimelic acid as the diagnostic diamino acid. The main phospholipids were determined to be phosphatidylethanolamine, phosphatidylinositol, phosphatidylcholine, diphosphatidylglycerol and traces of phosphatidylglycerol; MK-9(H4) was identified as the dominant menaquinone and galactose as the diagnostic sugar. The major cellular fatty acids were found to be the branched-chain saturated acids iso-C16:0 and iso-C15:0, as well as C17:1ω8c. The 16S rRNA gene sequence shows 97.5–97.9 % sequence identity with the four validly named or at least effectively published members of the genus: Geodermatophilus obscurus (97.5 %), Geodermatophilus arenarius (97.7 %), Geodermatophilus ruber (97.9 %) and Geodermatophilus nigrescens (97.9 %). Based on the results from this polyphasic taxonomic analysis and DNA–DNA hybridizations with all type strains of the genus, we propose that strain CF6/1T represents a novel species, Geodermatophilus siccatus, with the type strain CF6/1T = DSM 45419T = CCUG 62765T = MTCC 11414T.
Ancient mariners knew that dust whipped up from deserts by strong winds travelled long distances, including over oceans. Satellite remote sensing revealed major dust sources across the Sahara. Indeed, the Bodélé Depression in the Republic of Chad has been called the dustiest place on earth. We analysed desert sand from various locations in Chad and dust that had blown to the Cape Verde Islands. High throughput sequencing techniques combined with classical microbiological methods showed that the samples contained a large variety of microbes well adapted to the harsh desert conditions. The most abundant bacterial groupings in four different phyla included: (a) Firmicutes—Bacillaceae, (b) Actinobacteria—Geodermatophilaceae, Nocardiodaceae and Solirubrobacteraceae, (c) Proteobacteria—Oxalobacteraceae, Rhizobiales and Sphingomonadaceae, and (d) Bacteroidetes—Cytophagaceae. Ascomycota was the overwhelmingly dominant fungal group followed by Basidiomycota and traces of Chytridiomycota, Microsporidia and Glomeromycota. Two freshwater algae (Trebouxiophyceae) were isolated. Most predominant taxa are widely distributed land inhabitants that are common in soil and on the surfaces of plants. Examples include Bradyrhizobium spp. that nodulate and fix nitrogen in Acacia species, the predominant trees of the Sahara as well as Herbaspirillum (Oxalobacteraceae), a group of chemoorganotrophic free-living soil inhabitants that fix nitrogen in association with Gramineae roots. Few pathogenic strains were found, suggesting that African dust is not a large threat to public health.
Three novel Gram-positive, aerobic, actinobacterial strains, CF5/2T, CF5/1 and CF7/1, were isolated in 2007 during environmental screening of arid desert soil in the Sahara desert, Chad. Results from riboprinting, MALDI-TOF protein spectra and 16S rRNA sequence analysis confirmed that all three strains belonged to the same species. Phylogenetic analysis of 16S rRNA sequences with the strains' closest relatives indicated that they represented a distinct species. The three novel strains also shared a number of physiological and biochemical characteristics distinct from previously named Geodermatophilus species. The novel strains' peptidoglycan contained meso-diaminopimelic acid; their main phospholipids were phosphatidylcholine, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol and a small amount of phosphatidylglycerol; MK-9(H4) was the dominant menaquinone. The major cellular fatty acids were the branched-chain saturated acids iso-C16:0 and iso-C15:0. Galactose was detected as diagnostic sugar. Based on these chemotaxonomic results, 16S rRNA gene sequence analysis and DNA–DNA hybridization between strain CF5/2T and the type strains of Geodermatophilus saharensis, Geodermatophilus arenarius, Geodermatophilus nigrescens, Geodermatophilus telluris and Geodermatophilus siccatus, the isolates CF5/2T, CF5/1 and CF7/1 are proposed to represent a novel species, Geodermatophilus tzadiensis, with type strain CF5/2T = DSM 45416 = MTCC 11411 and two reference strains, CF5/1 (DSM 45415) and CF7/1 (DSM 45420).
Desert dust seeds distant lands and waters
with minerals as well as micro-organisms raising the
question of whether this ancient phenomenon also
spreads pathogens across the globe. Severe dust
storms require strong winds blowing over land-masses
that are largely devoid of vegetation, effectively
limiting the scope for winds to raise pathogens into
the air. Nevertheless, changing patterns of land-use,
often driven by belligerency, result in refugees
spreading to areas that were previously deemed barely
habitable. With the help of the International Committee
of the Red Cross, a number of sand/dust samples
were collected from the Republic of Chad, some near
refugee camps, others further removed from human
influence. In parallel studies, we documented the
micro-organisms present in these samples and used a
number of the isolates here to test the effect of
environmental constraints on their ability to survive
intercontinental flight. We also added traditional
pathogens to the palette of microbes and tested the
effects of UV irradiation, desiccation and temperature
on survival of both bacteria and fungi. A clear trend
was obvious—those microbes that are coloured or able
to form conidia or spores (in other words, those that
are native to deserts) were well able to resist the
imposed stresses. On the other hand, most pathogens
were more sensitive to stresses than the environmental
isolates. Toxin production in two species of Aspergillus
was also investigated. Short-term desiccation
(simulating environmental conditions during intercontinental
travel) of sand amended with fungal spores
containing sterigmatocystin leads to increased mycotoxin
contents, but significant mycotoxin production
was only possible under growth-permissive conditions,
e.g. at higher humidity. It thus seems likely that an ever-decreasing fraction of the initial pathogen load
survives as the dust recedes from its desert source and
that those organisms that land on other continents are
highly enriched in desert dwellers.
A novel Gram-positive, aerobic, actinobacterial strain, CF5/5, was isolated from soil in the Sahara desert, Chad. It grew best at 20–35 °C and at pH 6.0–8.0 and with 0–4 % (w/v) NaCl, forming black-colored colonies. Chemotaxonomic and molecular characteristics of the isolate matched those described for members of the genus Geodermatophilus. The DNA G + C content was 75.9 mol%. The peptidoglycan contained meso-diaminopimelic acid; galactose and xylose were detected as diagnostic sugars. The main phospholipids were diphosphatidylglycerol, phosphatidylcholine, and phosphatidylinositol; MK-9(H4) was the dominant menaquinone. The major cellular fatty acids were: iso-C16:0 and iso-C15:0. The 16S rRNA gene showed 95.6–98.3 % sequence similarity with the other named members of the genus Geodermatophilus. Based on the polyphasic taxonomy data, the isolate is proposed to represent a novel species, Geodermatophilus saharensis with the type strain CF5/5T = DSM 45423 = CCUG 62813 = MTCC 11416.
Microbiological studies on the intercontinental transport of dust are confounded by the difficulty of obtaining sufficient material for analysis. Axenic samples of dust collected at high altitudes or historic specimens in museums are often so small and precious that the material can only be sacrificed when positive results are assured. With this in mind, we evaluated current methods and developed new ones in an attempt to catalogue all microbes present in small dust or sand samples. The methods used included classical microbiological approaches in which sand extracts were plated out on a variety of different media, polymerase chain reaction (PCR)-based amplification of 16S/18S rRNA sequences followed by construction of clone libraries, PCR amplification of 16S rRNA sequences followed by high-throughput sequencing (HtS) of the products and direct HtS of DNA extracted from the sand. A representative sand sample collected at Bahaï Wadi in the desert of the Republic of Chad was used. HtS with or without amplification showed the most promise and can be performed on ≤100 ng DNA. Since living microbes are often required, current best practices would involve geochemical and microscopic characterisation of the sample, followed by DNA isolation and direct HtS. Once the microbial content of the sample has been deciphered, growth conditions (including media) can be tailored to isolate the micro-organisms of interest.
A novel Gram-positive, multiloculated thalli-forming, aerobic, actinobacterial strain, CF9/1/1T, was isolated in 2007 during environmental screening for xerophilic fungi in arid desert soil from the Sahara desert, Chad. The isolate grew best at a temperature range of 20–35 °C and at pH 6.0–8.5 and with 0–4% (w/v) NaCl, forming black-coloured and irregular colonies on GYM agar. Chemotaxonomic and molecular characteristics of the isolate matched those described for members of the genus Geodermatophilus. The DNA G+C content of the novel strain was 75.4 mol%. The peptidoglycan contained meso-diaminopimelic acid as a diagnostic diamino acid. The main phospholipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, a not yet structurally identified aminophospholipid and a small amount of phosphatidylglycerol; MK-9(H4) was identified as the dominant menaquinone and galactose was a diagnostic sugar. The major cellular fatty acids were branched-chain saturated acids: iso-C16:0 and iso-C15:0. The 16S rRNA gene sequence of the isolate showed 94.697.0% sequence similarities with those of five members of the genus: Geodermatophilus ruber DSM 45317T (94.6%), Geodermatophilus obscurus DSM 43160T (94.8%), Geodermatophilus siccatus DSM 45419T (96.2%), Geodermatophilus nigrescens DSM 45408T (96.7%) and Geodermatophilus arenarius DSM 45418T (97.0%). Based on the evidence from this polyphasic taxonomic study, a novel species, Geodermatophilus telluris sp. nov., is proposed; the type strain is CF9/1/1T (=DSM 45421T=CCUG 62764T).
Life at the atmosphere-lithosphere boundary is an ancient terrestrial niche that is sparsely covered by thin subaerial biofilms. The microbial inhabitants of these biofilms (a) have adapted to all types of terrestrial/subaerial stresses (e.g., desiccation, extreme temperatures, low nutrient availability, intense solar radiation), (b) interact with minerals that serve as both a dwelling and a source of mineral nutrients, and (c) provoke weathering of rocks and soil formation. Subaerial communities comprise heterotrophic and phototrophic microorganisms that support each other's lifestyle. Major lineages of eubacteria associated with the early colonization of land (e.g., Actinobacteria, Cyanobacteria) are present in these habitats along with eukaryotes such as microscopic green algae and ascomycetous fungi. The subaerial biofilm inhabitants have adapted to desiccation, solar radiation, and other environmental challenges by developing protective, melanized cell walls, assuming microcolonial architectures and symbiotic lifestyles. How these changes occurred, their significance in soil formation, and their potential as markers of climate change are discussed below.
Worldwide, abandoned coal mines release substantial amounts of methane, which is largely of biogenic origin. The aim of this study was to understand the microbial processes involved in mine-gas formation. Therefore, coal and timber samples and anaerobic enrichments from two abandoned coal mines in Germany were subjected to DGGE analyses and quantitative PCR. The primers used were specific for Bacteria, Archaea, Fungi, and the key functional genes for sulfate reduction (dsrA) and methanogenesis (mcrA). A broad spectrum of facultative anaerobic bacteria and acetogens belonging to all five groups (α-ε) of the Proteobacteria, as well as the Bacteroidetes, Tenericutes, Actinobacteria, Chlorobi and Chloroflexi were detected. Archaea were represented by acetoclastic Methanosarcinales and Crenarchaeota with an unknown metabolism. Fungi formed thick biofilms particularly on timber, and were identified as typical wood degraders belonging to the Ascomycetes and Basidiomycetes. The community analysis as well as the environmental conditions and the metabolites detected in a previous study are consistent with the following scenario of methane release: Weathering of coal and timber is initiated by wood-degrading Fungi and Bacteria under a suboxic atmosphere. In the lower, oxygen-depleted layers Fungi and Bacteria perform incomplete oxidation and release reduced substrates which can be channeled into methanogenesis. Acetate appeared to be the main precursor of the biogenic methane in the investigated coal mines.
A novel Gram-positive, aerobic, actinobacterial strain, CF5/4T, was isolated in 2007 during an environmental screening of arid desert soil in Ouré Cassoni, Chad. The isolate grew best in a temperature range of 2840 °C and at pH 6.0-8.5, with 0-1 % (w/v) NaCl, forming brown-coloured and nearly circular colonies on GYM agar. Chemotaxonomic and molecular characteristics of the isolate matched those described for members of the genus Geodermatophilus. The DNA G + C content of the novel strain was 75.9 mol %. The peptidoglycan contained meso-diaminopimelic acid as diagnostic diaminoacid. The main phospholipids were phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, diphosphatidylglycerol and a small amount of phosphatidylglycerol; MK-9(H4) was identified as the dominant menaquinone and galactose as diagnostic sugar. The major cellular fatty acids were branched-chain saturated acids: iso-C15:0 and iso-C16:0. The 16S rRNA gene showed 96.298.3 % sequence identity with the three members of the genus Geodermatophilus: G. obscurus (96.2 %), G. ruber (96.5 %), and G. nigrescens (98.3 %). Based on the chemotaxonomic results, 16S rRNA gene sequence analysis and DNA–DNA hybridization with the type strain of G. nigrescens, the isolate is proposed to represent a novel species, Geodermatophilus arenarius (type strain CF5/4T = DSM 45418T = MTCC 11413T = CCUG 62763T).