MikroMondo, a forthcoming science center in Austria, will be dedicated to the fascinating world of microorganisms, with a special focus on soil and its intricate biodiversity. Designed to promote soil literacy among the public, MikroMondo will feature cutting-edge exhibits, among them Europe's tallest Winogradsky column, live demonstrations of plant-microbe interactions (e.g., mycorrhization of pine seedlings in transparent soil columns), and engaging sound-producing slime molds. These exhibits aim to captivate visitors and highlight the vital role of microorganisms in soil ecosystems.The center will also offer interactive, hands-on activities tailored for school pupils, students, and educators, designed to deepen understanding of microbiological processes such as carbon and nutrient cycling, plant-microbe symbiosis, and soil microbial diversity. Activities will include guided microscopy sessions, microbial cultivation, the creation of Winogradsky columns, and decomposition and gas production experiments. MikroMondo’s innovative approach will inspire curiosity and enhance public appreciation of the hidden world beneath our feet, fostering a new generation of soil stewards and microbial enthusiasts.

BACKGROUND:In Europe, Pinus cembra forests cover subalpine and alpine areas and they are of high conservational and ecological relevance. These forests experience strong seasonality with alternating snow-free and snow covered periods. Although P. cembra is known for mycorrhization and mycorrhizae usually involve fungi, plants and bacteria, the community compositions of fungi and bacteria and their associations in (sub-)alpine P. cembra forests remain vastly understudied. Here, we studied the fungal and bacterial community compositions in three independent (sub-)alpine P. cembra forests and inferred their microbial associations using marker gene sequencing and network analysis. We asked about the effect of snow cover on microbial compositions and associations. In addition, we propose inferring microbial associations across a range of filtering criteria, based on which we infer well justified, concrete microbial associations with high potential for ecological relevance that are typical for P. cembra forests and depending on snow cover. RESULTS:The overall fungal and bacterial community structure was comparable with regards to both forest locations and snow cover. However, occurrence, abundance, and diversity patterns of several microbial taxa typical for P. cembra forests differed among snow-free and snow covered soils, e.g. Russula, Tetracladium and Phenoliphera. Moreover, network properties and microbial associations were influenced by snow cover. Here, we present concrete microbial associations on genus and species level that were repeatedly found across microbial networks, thereby confirming their ecological relevance. Most importantly, ectomycorrhizal fungi, such as Basidioascus, Pseudotomentella and Rhizopogon, as well as saprobic Mortierella changed their bacterial association partners depending on snow cover. CONCLUSION:This is the first study researching fungal-bacterial associations across several (sub-)alpine P. cembra forests. The poorly investigated influence of snow cover on soil fungi and bacteria, especially those mycorrhizing P. cembra roots, but also saprobic soil organisms, underlines the relevance of forest seasonality. Our findings highlight that the seasonal impact of snow cover has significant consequences for the ecology of the ecosystem, particularly in relation to mycorrhization and nutrient cycling. It is imperative to consider such effects for a comprehensive understanding of the functioning resilience and responsiveness of an ecosystem.

Background/Aims The European larch is a pioneer tree and a valuable economic resource in subalpine ecosystems, thus playing crucial roles to ecosystem services and human activities. However, their ectomycorrhizal fungal community remains unknown in high altitudinal natural habitats. Here, we explore the mycobiont diversity of Larix decidua var. decidua between naturally rejuvenated and adult trees, compare ectomycorrhizal colonization patterns in geographically disjunct areas within the Alps of South Tyrol, Italy, characterized by distinct climatic conditions, and explore turnover rates across various seasons. Methods Our approach combines morphotyping of mycorrhized root tips with molecular analysis. Particular effort was given to monitor both ectomycorrhizal host-specialist and -generalist fungi. Results Both adult and young trees show a 100% mycorrhization rate, with a total diversity of 68 ectomycorrhizal species. The ectomycorrhizal composition is dominated by typical host specialists of larch trees (e.g., Lactarius porninsis, Russula laricina, Suillus cavipes, S. grevillei, S. viscidus), which are widely distributed across sites. A rich diversity of host generalists was also detected. The composition of rare species within a habitat was comparatively consistent during one sampling campaign, but exhibited significant differences among individual sampling campaigns. The ectomycorrhizal compositions were only weakly correlated with distinct climatic conditions and tree ages. However, species richness and diversity, particularly of generalist fungi, was consistently higher in warmer, drier sites compared to cooler, more humid ones. Conclusions This study suggests potential mycobiont community shifts across climatic conditions with significant implications for the adaptability and resilience of subalpine forests in the face of climate change.

Fervidobacterium pennivorans subsp. keratinolyticus subsp. nov. strain T was isolated from a terrestrial, high-altitude hot spring in Tajikistan. This strain is an obligate anaerobic rod and their cells occur singly, in pairs, or as short chains under the optimal growth conditions of a temperature of 65 °C and pH 6.5, with peptone, glucose, and galactose as the preferred substrates. The minimum generation time of this strain is 150 min. Strain T can efficiently degrade feather keratin at 65–75 °C; this unusual feature is also exhibited by a few other members of the Fervidobacterium genus. The total genome size of this bacterial strain is 2,002,515 base pairs, with a C + G content of 39.0%. The maximum digital DNA–DNA hybridization (dDDH) value of 76.9% was observed on comparing the genome of this strain with that of Fervidobacterium pennivorans type strain DSM9078. This study describes the physiological and genomic properties of strain T, with an emphasis on its keratinolytic power and differences from other members of the genus Fervidobacterium.

Drought-induced changes in plant traits are well-studied, e.g. building smaller and thicker leaves, reducing stomatal density or increasing root uptake. However, the extent to which these changes depend on plant-soil interactions remains unclear. Mutualistic soil microbes like arbuscular mycorrhizal fungi (AMF) and Rhizobium are known to enhance plant productivity, water and nutrient uptake and stress tolerance. Therefore, alterations in soil microbial loads are expected to affect not only plant productivity but also plant responses to drought through changing plant traits. In this study, we investigated the effects of plant-soil interactions on the productivity and traits of red clover (Trifolium pratense L.) under repeated drought. We conducted a pot experiment with two treatments: water treatment (wet versus drought) and microbial reduction by soil steam sterilization (native versus sterilized soil). We found that plants in native soil showed lower productivity and plant traits associated with slow-growing strategies (i.e. small and coarse leaves, lower stomatal density and higher root mass). However, the reduction of soil microbial load by soil steam sterilization increased plant productivity under wet conditions and led to plant traits associated with fast-growing strategies. Drought in sterilized soil decreased productivity, promoted earlier wilting and resulted in the development of plant traits associated with a more slow-growing strategy. Furthermore, roots became longer and thinner and rhizobial nodulation decreased, demonstrating the reduction of mutualists. Hence, our results show that soil microbes trigger plant traits, which suggests that they play an important role in plant responses to drought, in maintaining plant productivity and in prolonging plant vitality.

Background and Aims Pinus cembra represent a typical and important tree species growing in European subalpine and alpine habitats. The ectomycorrhizal (ECM) fungal communities associated to this tree under natural conditions are largely unknown. Methods In this study, we investigated the ECM fungal abundance and composition at four high-altitude sites (two northern-exposed and two southern-exposed habitats) in South Tyrol (Italy), and included also two different age classes of P. cembra. The ECM partners were characterized morphologically, and identified by rDNA ITS sequence analysis. Results The degree of mycorrhization in adult P. cembra was typically 100% in these natural habitats, with a total species diversity of 20 ECM species. The four high-altitude sites were similar concerning their species richness and mycobiont diversity, but they differed significantly in ECM species composition. Young P. cembra had a mycorrhization degree of 100% and a total of 10 species were observed. All mycorrhizal partners of naturally regenerated young P. cembra were only detected in one specific location, with the exception of Cenococcum sp. and Amphinema sp. which were detected at two sites. Young trees harbour a distinct ectomycorrhizal fungal diversity, which is clearly lower than the diversity detected in adult P. cembra trees. The P. cembra bolete (Suillus plorans) is the most important symbiotic partner of P. cembra at Southern Tyrolean high-altitude sites and is known for its strict, species-specific host association. Conclusions The ectomycorrhizal fungal community composition strongly depends on geographic region and on the slope exposure (north or south) of the site.

Due to their small size, microorganisms directly experience only a tiny portion of the environmental heterogeneity manifested in the soil. The microscale variations in soil properties constrain the distribution of fungi and bacteria, and the extent to which they can interact with each other, thereby directly influencing their behavior and ecological roles. Thus, to obtain a realistic understanding of bacterial–fungal interactions, the spatiotemporal complexity of their microenvironments must be accounted for. The objective of this review is to further raise awareness of this important aspect and to discuss an overview of possible methodologies, some of easier applicability than others, that can be implemented in the experimental design in this field of research. The experimental design can be rationalized in three different scales, namely reconstructing the physicochemical complexity of the soil matrix, identifying and locating fungi and bacteria to depict their physical interactions, and, lastly, analyzing their molecular environment to describe their activity. In the long term, only relevant experimental data at the cell-to-cell level can provide the base for any solid theory or model that may serve for accurate functional prediction at the ecosystem level. The way to this level of application is still long, but we should all start small.

This atlas aims to provide an overview of the picocyanobacteria cultures hold by the CNR-IRSA collection. These are monoclonal strains mostly of the genera Synechococcus and Cyanobium. These strains were mainly isolated from lakes of different trophic status around the globe and, so far, they are not available in other collections of algae and (pico)cyanobacteria. Here we summarise the main characteristics of these strains, including some previously published data, and offer most of the strains as material available for research to every scientists upon request.