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The desiccation of the Aral Sea represents one of the largest human-made environmental regional disasters. The salt- and toxin-enriched dried-out basin provides a natural laboratory for studying ecosystem functioning and rhizosphere assembly under extreme anthropogenic conditions. Here, we investigated the prokaryotic rhizosphere communities of the native pioneer plant Suaeda acuminata (C.A.Mey.) Moq. in comparison to bulk soil across a gradient of desiccation (5, 10, and 40 years) by metagenome and amplicon sequencing combined with quantitative PCR (qPCR) analyses. The rhizosphere effect was evident due to significantly higher bacterial abundances but less diversity in the rhizosphere compared to bulk soil. Interestingly, in the highest salinity (5 years of desiccation), rhizosphere functions were mainly provided by archaeal communities. Along the desiccation gradient, we observed a significant change in the rhizosphere microbiota, which was reflected by (i) a decreasing archaeon-bacterium ratio, (ii) replacement of halophilic archaea by specific plant-associated bacteria, i.e.

BackgroundThe extraordinarily resistant bacteriumDeinococcus radioduranswithstands harsh environmental conditions present in outer space.Deinococcus radioduranswas exposed for 1 year outside the International Space Station within Tanpopo orbital mission to investigate microbial survival and space travel. In addition, a ground-based simulation experiment with conditions, mirroring those from low Earth orbit, was performed.MethodsWe monitoredDeinococcus radioduranscells during early stage of recovery after low Earth orbit exposure using electron microscopy tools. Furthermore, proteomic, transcriptomic and metabolomic analyses were performed to identify molecular mechanisms responsible for the survival ofDeinococcus radioduransin low Earth orbit.ResultsD. radioduranscells exposed to low Earth orbit conditions do not exhibit any morphological damage. However, an accumulation of numerous outer-membrane-associated vesicles was observed. On levels of proteins and transcripts, a multi-faceted response was detected to alleviate cell stress. The UvrABC endonuclease excision repair mechanism was triggered to cope with DNA damage. Defense against reactive oxygen species is mirrored by the increased abundance of catalases and is accompanied by the increased abundance of putrescine, which works as reactive oxygen species scavenging molecule. In addition, several proteins and mRNAs, responsible for regulatory and transporting functions showed increased abundances. The decrease in primary metabolites indicates alternations in the energy status, which is needed to repair damaged molecules.ConclusionLow Earth orbit induced molecular rearrangements trigger multiple components of metabolic stress response and regulatory networks in exposed microbial cells. Presented results show that the non-sporulating bacteriumDeinococcus radioduranssurvived long-term low Earth orbit exposure if wavelength below 200 nm are not present, which mirrors the UV spectrum of Mars, where CO2effectively provides a shield below 190 nm. These results should be considered in the context of planetary protection concerns and the development of new sterilization techniques for future space missions.

The ongoing COVID-19 pandemic has not only globally caused a high number of causalities, but is also an unprecedented challenge for scientists. False-positive virus detection tests not only aggravate the situation in the healthcare sector, but also provide ground for speculations. Previous studies have highlighted the importance of software choice and data interpretation in virome studies. We aimed to further expand theoretical and practical knowledge in bioinformatics-driven virome studies by focusing on short, virus-like DNA sequences in metagenomic data. Analyses of datasets obtained from different sample types (terrestrial, animal and human related samples) and origins showed that coronavirus-like sequences have existed in host-associated and environmental samples before the current COVID-19 pandemic. In the analyzed datasets, various Betacoronavirus-like sequences were detected that also included SARS-CoV-2 matches. Deepening analyses indicated that the detected sequences are not of viral origin and thus should not be considered in virome profiling approaches. Our study confirms the importance of parameter selection, especially in terms of read length, for reliable virome profiling. Natural environments are an important source of coronavirus-like nucleotide sequences that should be taken into account when virome datasets are analyzed and interpreted. We therefore suggest that processing parameters are carefully selected for SARS-CoV-2 profiling in host related as well as environmental samples in order to avoid incorrect identifications., Graphical abstract Unlabelled Image

Background: With increasing numbers of interplanetary missions, there is a need to establish robust protocols to ensure the protection of extraterrestrial planets being visited from contamination by terrestrial life forms. The current study is the first report comparing the commercial resupply vehicle (CRV) microbiome with the International Space Station (ISS) microbiome to understand the risks of contamination, thus serving as a model system for future planetary missions. Results: Samples obtained from the internal surfaces and ground support equipment of three CRV missions were subjected to various molecular techniques for microbial diversity analysis. In total, 24 samples were collected with eight defined locations from each CRV mission prior to launch. In general, the internal surfaces of vehicles were clean, with an order of magnitude fewer microbes compared to ground support equipment. The first CRV mission had a larger microbial population than subsequent CRV missions, which were clean as compared to the initial CRV locations sampled. Cultivation assays showed the presence of Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes and members of Ascomycota and Basidiomycota. As expected, shotgun metagenome analyses revealed the presence of more microbial taxa compared to cultivation-based assays. The internal surface locations of the CRV microbiome reportedly showed the presence of microorganisms capable of tolerating ultraviolet radiation (e.g. Bacillus firmus) and clustered separately from the ISS microbiome. Conclusions: The metagenome sequence comparison of the CRV microbiome with the ISS microbiome revealed significant differences showing that CRV microbiomes were a negligible part of the ISS environmental microbiome. These findings suggest that the maintenance protocols in cleaning CRV surfaces are highly effective in controlling the contaminating microbial population during cargo transfer to the ISS via the CRV route.

[Background] The ongoing COVID-19 pandemic has not only globally caused a high number of causalities, but is also an unprecedented challenge for scientists. False-positive virus detection tests not only aggravate the situation in the healthcare sector, but also provide ground for conspiracy theorists. Previous studies have highlighted the importance of software choice and data interpretation in virome studies. We aimed to further expand theoretical and practical knowledge in virome studies by focusing on short, virus-like DNA sequences in metagenomic data., [Results] Exemplarily, analyses of metagenomic data from the dried-out Aral Sea basin in Uzbekistan showed that Coronavirus-like sequences have existed in environmental samples before the current COVID-19 crisis. In the analyzed environmental datasets, diverse Betacoronavirus-like sequences were detected, which also included SARS-CoV-2 matches. Moreover, the data sets harbored regions that show complementarity to PCR primers that are currently in use for virus detection and origin tracing., [Conclusions] Our study confirms the importance of parameter selection, especially in terms of read length, for reliable virome profiling. Natural environments are an important source of Coronavirus-like nucleotide sequences that should be taken into account when virome datasets are analyzed and interpreted. Moreover, the identified test primer binding sites in metagenomic data might play an important role for the development of reliable test systems and origin tracing.

The International Space Station (ISS) is a unique habitat for humans and microorganisms. Here, we report the results of the ISS experiment EXTREMOPHILES, including the analysis of microbial communities from several areas aboard at three time points. We assess microbial diversity, distribution, functional capacity and resistance profile using a combination of cultivation-independent analyses (amplicon and shot-gun sequencing) and cultivation-dependent analyses (physiological and genetic characterization of microbial isolates, antibiotic resistance tests, co-incubation experiments). We show that the ISS microbial communities are highly similar to those present in ground-based confined indoor environments and are subject to fluctuations, although a core microbiome persists over time and locations. The genomic and physiological features selected by ISS conditions do not appear to be directly relevant to human health, although adaptations towards biofilm formation and surface interactions were observed. Our results do not raise direct reason for concern with respect to crew health, but indicate a potential threat towards material integrity in moist areas., The International Space Station is a unique habitat for humans and microbes. Here, Mora et al. analyze microbial communities from several areas aboard, finding similarities with those of ground-based indoor environments, as well as adaptations towards biofilm formation but not necessarily relevant to human health.

The International Space Station (ISS) is a unique, completely confined habitat for the human crew and co-inhabiting microorganisms. Here, we report on the results of the ISS experiment “EXTREMOPHILES”. We aimed to exploit the microbial information obtained from three surface and air sampling events aboard the International Space Station during increments 51 and 52 (2017) with respect to: i) microbial sources, diversity and distribution within the ISS, ii) functional capacity of microbiome and microbial isolates, iii) extremotolerance and antibiotics-resistance (compared to ground controls), and iv) microbial behavior towards ISS-relevant materials such as biofilm formation, or potential for degradation. We used wipe samples and analyzed them by amplicon and metagenomics sequencing, cultivation, comparative physiological studies, antibiotic resistance tests, genome analysis of isolates and co-incubation experiments with ISS-relevant materials. The major findings were: i) the ISS microbiome profile is highly similar to ground-based confined indoor environments, ii) the ISS microbiome is subject to fluctuations and indicative for the (functional) location, although a core microbiome was present over time and independent from location, iii) the ISS selects for microorganisms adapted to the extreme environment, but does not necessarily induce genomic and physiological changes which might be relevant for human health, iv) cleanrooms and cargo seems to be a minor source of microbial contamination aboard, and v) microorganisms can attach to and grow on ISS-relevant materials. Biofilm formation might be a threat for spacecraft materials with the potential to induce instrument malfunctioning with consequences for mission success. We conclude that our data do not raise direct reason for concern with respect to crew health, but indicate a potential threat towards biofilm formation and material integrity in moist areas.

Clostridia are anaerobic spore-forming bacteria, which degrade carbohydrates to butyric acid, carbon dioxide, hydrogen and other compounds. These bacteria are commonly found in feces of ruminants, from where they can enter to udders and milk via manure or fodder. This study was done to find a sustainable sanitation method to control the resistant clostridial spores as they are difficult to control in the food processing industry. Clostridia spoil cheeses and other dairy products, and thereby increase the carbon footprint of products and cause economical losses in the dairy industry. The efficacy of two organic peroxides, peracetic acid (PAA) and performic acid (PFA) was tested against 30 clostridia strains isolated from cattle slurry, silage, or spoiled cheeses. PAA, at a concentration of 220 mg L&minus, 1, only eliminated 6/30 clostridia strains, whereas PFA totally eliminated 26/30 clostridia strains at a concentration of 120 mg L&minus, 1. PFA therefore seems to be a more potent disinfectant than the more commonly used PAA. PFA is an effective disinfectant against Clostridium tyrobutyricum and other resistant clostridia at 120 mg L&minus, 1 for 5&ndash, 10 min contact time at room temperature.

The gut microbiome is strongly interwoven with human health. Conventional gut microbiome analysis generally involves 16S rRNA gene targeting next generation sequencing (NGS) of stool microbial communities, and correlation of results with clinical parameters. However, some microorganisms may not be alive at the time of sampling, and thus their impact on the human health is potentially less significant. As conventional NGS methods do not differentiate between viable and dead microbial components, retrieved results provide only limited information.Propidium monoazide (PMA) is frequently used in food safety monitoring and other disciplines to discriminate living from dead cells. PMA binds to free DNA and masks it for subsequent procedures. In this article we show the impact of PMA on the results of 16S rRNA gene-targeting NGS from human stool samples and validate the optimal applicable concentration to achieve a reliable detection of the living microbial communities.Fresh stool samples were treated with a concentration series of zero to 300 μM PMA, and were subsequently subjected to amplicon-based NGS. The results indicate that a substantial proportion of the human microbial community is not intact at the time of sampling. PMA treatment significantly reduced the diversity and richness of the sample depending on the concentration and impacted the relative abundance of certain important microorganisms (e.g. Akkermansia, Bacteroides). Overall, we found that a concentration of 100 μM PMA was sufficient to quench signals from disrupted microbial cells.The optimized protocol proposed here can be easily implemented in classical microbiome analyses, and helps to retrieve an improved and less blurry picture of the microbial community composition by excluding signals from background DNA.

Human-associated archaea remain understudied in the field of microbiome research, although in particular methanogenic archaea were found to be regular commensals of the human gut, where they represent keystone species in metabolic processes. Knowledge on the abundance and diversity of human-associated archaea is extremely limited, and little is known about their function(s), their overall role in human health, or their association with parts of the human body other than the gastrointestinal tract and oral cavity. Currently, methodological issues impede the full assessment of the human archaeome, as bacteria-targeting protocols are unsuitable for characterization of the full spectrum of Archaea. The goal of this study was to establish conservative protocols based on specifically archaea-targeting, PCR-based methods to retrieve first insights into the archaeomes of the human gastrointestinal tract, lung, nose, and skin. Detection of Archaea was highly dependent on primer selection and the sequence processing pipeline used. Our results enabled us to retrieve a novel picture of the human archaeome, as we found for the first time Methanobacterium and Woesearchaeota (DPANN superphylum) to be associated with the human gastrointestinal tract and the human lung, respectively. Similar to bacteria, human-associated archaeal communities were found to group biogeographically, forming (i) the thaumarchaeal skin landscape, (ii) the (methano)euryarchaeal gastrointestinal tract, (iii) a mixed skin-gastrointestinal tract landscape for the nose, and (iv) a woesearchaeal lung landscape. On the basis of the protocols we used, we were able to detect unexpectedly high diversity of archaea associated with different body parts., IMPORTANCE In summary, our study highlights the importance of the primers and NGS data processing pipeline used to study the human archaeome. We were able to establish protocols that revealed the presence of previously undetected Archaea in all of the tissue samples investigated and to detect biogeographic patterns of the human archaeome in the gastrointestinal tract, on the skin, and for the first time in the respiratory tract, i.e., the nose and lungs. Our results are a solid basis for further investigation of the human archaeome and, in the long term, discovery of the potential role of archaea in human health and disease.

Indoor environments, where people spend most of their time, are characterized by a specific microbial community, the indoor microbiome. Most indoor environments are connected to the natural environment by high ventilation, but some habitats are more confined: intensive care units, operating rooms, cleanrooms and the international space station (ISS) are extraordinary living and working areas for humans, with a limited exchange with the environment. The purposes for confinement are different: a patient has to be protected from infections (intensive care unit, operating room), product quality has to be assured (cleanrooms), or confinement is necessary due to extreme, health-threatening outer conditions, as on the ISS. The ISS represents the most secluded man-made habitat, constantly inhabited by humans since November 2000 – and, inevitably, also by microorganisms. All of these man-made confined habitats need to be microbiologically monitored and controlled, by e.g., microbial cleaning and disinfection. However, these measures apply constant selective pressures, which support microbes with resistance capacities against antibiotics or chemical and physical stresses and thus facilitate the rise of survival specialists and multi-resistant strains. In this article, we summarize the available data on the microbiome of aforementioned confined habitats. By comparing the different operating, maintenance and monitoring procedures as well as microbial communities therein, we emphasize the importance to properly understand the effects of confinement on the microbial diversity, the possible risks represented by some of these microorganisms and by the evolution of (antibiotic) resistances in such environments – and the need to reassess the current hygiene standards.

Background The International Space Station (ISS) represents a unique biotope for the human crew but also for introduced microorganisms. Microbes experience selective pressures such as microgravity, desiccation, poor nutrient-availability due to cleaning, and an increased radiation level. We hypothesized that the microbial community inside the ISS is modified by adapting to these stresses. For this reason, we analyzed 8–12 years old dust samples from Russian ISS modules with major focus on the long-time surviving portion of the microbial community. We consequently assessed the cultivable microbiota of these samples in order to analyze their extremotolerant potential against desiccation, heat-shock, and clinically relevant antibiotics. In addition, we studied the bacterial and archaeal communities from the stored Russian dust samples via molecular methods (next-generation sequencing, NGS) and compared our new data with previously derived information from the US American ISS dust microbiome. Results We cultivated and identified in total 85 bacterial, non-pathogenic isolates (17 different species) and 1 fungal isolate from the 8–12 year old dust samples collected in the Russian segment of the ISS. Most of these isolates exhibited robust resistance against heat-shock and clinically relevant antibiotics. Microbial 16S rRNA gene and archaeal 16S rRNA gene targeting Next Generation Sequencing showed signatures of human-associated microorganisms (Corynebacterium, Staphylococcus, Coprococcus etc.), but also specifically adapted extremotolerant microorganisms. Besides bacteria, the detection of archaeal signatures in higher abundance was striking. Conclusions Our findings reveal (i) the occurrence of living, hardy microorganisms in archived Russian ISS dust samples, (ii) a profound resistance capacity of ISS microorganisms against environmental stresses, and (iii) the presence of archaeal signatures on board. In addition, we found indications that the microbial community in the Russian segment dust samples was different to recently reported US American ISS microbiota. Electronic supplementary material The online version of this article (doi:10.1186/s40168-016-0217-7) contains supplementary material, which is available to authorized users.

To date, the behavior of hyperthermophilic microorganisms in their biotope has been studied only to a limited degree; this is especially true for motility. One reason for this lack of knowledge is the requirement for high-temperature microscopy—combined, in most cases, with the need for observations under strictly anaerobic conditions—for such studies. We have developed a custom-made, low-budget device that, for the first time, allows analyses in temperature gradients up to 40°C over a distance of just 2 cm (a biotope-relevant distance) with heating rates up to ∼5°C/s. Our temperature gradient-forming device can convert any upright light microscope into one that works at temperatures as high as 110°C. Data obtained by use of this apparatus show how very well hyperthermophiles are adapted to their biotope: they can react within seconds to elevated temperatures by starting motility—even after 9 months of storage in the cold. Using the temperature gradient-forming device, we determined the temperature ranges for swimming, and the swimming speeds, of 15 selected species of the genus Thermococcus within a few months, related these findings to the presence of cell surface appendages, and obtained the first evidence for thermotaxis in Archaea .