Исследование каталитической активности высокодисперсных порошков железа в синтезе Фишера-Тропша

Объектом данного исследования являлся высокодисперсный порошок железа, полученный методом электрического взрыва проводника, с последующим таблетированием под высоким давлением. Целью данной работы являлось изучение каталитической активности железного катализатора в синтезе Фишера-Тропша.The object of study is the superfine iron powder obtained by the method of electrical explosion with subsequent tableting with high pressure. The purpose of the work is to study of the catalytic activity iron catalyst in Fischer-Tropsch synthesi

Adaptions of Lichen Microbiota Functioning Under Persistent Exposure to Arsenic Contamination

Host-associated microbiota play an important role in the health and persistence of more complex organisms. In this study, metagenomic analyses were used to reveal microbial community adaptations in three lichen samples as a response to different arsenic concentrations at the sampling sites. Elevated arsenic concentrations at a former mining site expanded the spectrum and number of relevant functions in the lichen-associated microorganisms. Apparent changes affected the abundance of numerous detoxification-related genes, they were substantially enhanced in arsenic-polluted samples. Complementary quantifications of the arsenite S-adenosylmethionine methyltransferase (arsM) gene showed that its abundance is not strictly responding to the environmental arsenic concentrations. The analyzed samples contained rather low numbers of the arsM gene with a maximum of 202 gene copies μl-1 in total community DNA extracts. In addition, bacterial isolates were screened for the presence of arsM. Positive isolates were exposed to different As(III) and As(V) concentrations and tolerated up to 30 mM inorganic arsenic in fluid media, while no substantial biotransformations were observed. Obtained data deepens our understanding related to adaptions of whole microbial communities to adverse environmental conditions. Moreover, this study provides the first evidence that the integrity of bacteria in the lichen holobiont is maintained by acquisition of specific resistances

A novel assay for the detection of bioactive volatiles evaluated by screening of lichen-associated bacteria

Volatile organic compounds (VOCs) produced by microorganisms are known both for their effect on pathogens and their role as mediators in various interactions and communications. Previous studies have demonstrated the importance of VOCs for ecosystem functioning as well as their biotechnological potential, but screening for bioactive volatiles remained difficult. We have developed an efficient testing assay that is based on two multi-well plates, separated by a sealing silicone membrane, two tightening clamps, and variable growth media, or indicators. The experiment design as presented here is a novel and robust technique to identify positive as well as negative VOC effects on the growth of a target organism and to test for specific substances e.g. hydrogen cyanide which can be detected with a suitable indicator. While the first pre-screening assay is primarily based on indicator color change and visible growth diameter reduction, we also introduce an advanced and quantitatively precise experiment design. This adaptation involves qPCR-based quantification of viable target cells after concluding the treatment with VOCs. Therefore, we chose preselected active isolates and compared the partial 16S rRNA gene copy number of headspace-exposed E. coli with non-treated controls. Separately obtained headspace SPME and GC/MS-based profiles of selected bacterial isolates revealed the presence of specific and unique signatures which suggests divergent modes of action. The assay was evaluated by screening 100 isolates of lung lichen-associated bacteria. Approximately one quarter of the isolates showed VOC-based antibacterial and/or antifungal activity; mainly Pseudomonas and Stenotrophomonas species were identified as producers of bioactive volatiles

Understanding microbial multi-species symbioses

Lichens are commonly recognized as a symbiotic association of a fungus and chlorophyll containing partner, either green algae or cyanobacteria, or both. The fungus provides a suitable habitat for the partner, which provides photosynthetically fixed carbon as energy source for the system. The evolutionary result of the self-sustaining partnership is a unique joint structure, the lichen thallus, which is indispensable for fungal sexual reproduction. The classical view of a dual symbiosis has been challenged by recent microbiome research, which revealed host-specific bacterial microbiomes. The recent results about bacterial associations with lichens symbioses corroborate their notion as a multi-species symbiosis. Multi-omics approaches have provided evidence for functional contribution by the bacterial microbiome to the entire lichen meta-organism while various abiotic and biotic factors can additionally influence the bacterial community structure. Results of current research also suggest that neighboring ecological niches influence the composition of the lichen bacterial microbiome. Specificity and functions are here reviewed based on these recent findings, converging to a holistic view of bacterial roles in lichens. Finally we propose that the lichen thallus has also evolved to function as a smart harvester of bacterial symbionts. We suggest that lichens represent an ideal model to study multi-species symbiosis, using the recentily available omics tools and other cutting edge methods

Analyzing the antagonistic potential of the lichen microbiome against pathogens by bridging metagenomic with culture studies

Naturally occurring antagonists towards pathogens play an important role to avoid pathogen outbreaks in ecosystems, and they can be applied as biocontrol agents for crops. Lichens present long-living symbiotic systems continuously exposed to pathogens. To analyze the antagonistic potential in lichens, we studied the bacterial community active against model bacteria and fungi by an integrative approach combining isolate screening, omics techniques and high resolution mass spectrometry. The highly diverse microbiome of the lung lichen (Lobaria pulmonaria (L.) Hoffm.) included an abundant antagonistic community dominated by Stenotrophomonas, Pseudomonas and Burkholderia. While antagonists represent 24.5% of the isolates, they were identified with only 7% in the metagenome; which means that they were overrepresented in the culturable fraction. Isolates of the dominant antagonistic genus Stenotrophomonas produced spermidine as main bioactive component. Moreover, spermidine-related genes, especially for the transport, were identified in the metagenome. The majority of hits identified belonged to Alphaproteobacteria, while Stenotrophomonas-specific spermidine synthases were not present in the dataset. Evidence for plant growth promoting effects was found for lichen-associated strains of Stenotrophomonas. Linking of metagenomic and culture data was possible but showed partly contradictory results, which required a comparative assessment. However, we have shown that lichens are important reservoirs for antagonistic bacteria, which open broad possibilities for biotechnological applications

Deciphering functional diversification within the lichen microbiota by meta-omics

Abstract Background Recent evidence of specific bacterial communities extended the traditional concept of fungal-algal lichen symbioses by a further organismal kingdom. Although functional roles were already assigned to dominant members of the highly diversified microbiota, a substantial fraction of the ubiquitous colonizers remained unexplored. We employed a multi-omics approach to further characterize functional guilds in an unconventional model system. Results The general community structure of the lichen-associated microbiota was shown to be highly similar irrespective of the employed omics approach. Five highly abundant bacterial orders—Sphingomonadales, Rhodospirillales, Myxococcales, Chthoniobacterales, and Sphingobacteriales—harbor functions that are of substantial importance for the holobiome. Identified functions range from the provision of vitamins and cofactors to the degradation of phenolic compounds like phenylpropanoid, xylenols, and cresols. Conclusions Functions that facilitate the persistence of Lobaria pulmonaria under unfavorable conditions were present in previously overlooked fractions of the microbiota. So far, unrecognized groups like Chthoniobacterales (Verrucomicrobia) emerged as functional protectors in the lichen microbiome. By combining multi-omics and imaging techniques, we highlight previously overlooked participants in the complex microenvironment of the lichens

The cancer stem cell subtype determines immune infiltration of glioblastoma

Immune cell infiltration varies widely between different glioblastomas (GBMs). The underlying mechanism, however, remains unknown. Here we show that TGF-beta regulates proliferation, migration, and tumorigenicity of mesenchymal GBM cancer stem cells (CSCs) in vivo and in vitro. In contrast, proneural GBM CSCs resisted TGF-beta due to TGFR2 deficiency. In vivo, a substantially increased infiltration of immune cells was observed in mesenchymal GBMs, while immune infiltrates were rare in proneural GBMs. On a functional level, proneural CSC lines caused a significantly stronger TGF-beta-dependent suppression of NKG2D expression on CD8(+) T and NK cells in vitro providing a mechanistic explanation for the reduced immune infiltration of proneural GBMs. Thus, the molecular subtype of CSCs TGF-beta-dependently contributes to the degree of immune infiltration