Search Results (38)

Cyanobacteria inhabit ecosystems ranging from oligotrophic deserts to eutrophic lakes, yet it remains unclear whether distantly related species dominate in disparate habitats, share common genomic features, or show divergent specialization. Here, we established a comparative framework of Microcoleus vaginatus, the pioneer stabilizer of biocrusts, and Microcystis aeruginosa, a major cause of freshwater blooms worldwide. Our dataset comprises 504 high-quality cyanobacterial genomes, including 132 M. vaginatus, 148 M. aeruginosa, and 224 reference taxa, for analyses of genome architecture, functional repertoires, and genomic plasticity. Both focal lineages showed signatures of extensive horizontal gene transfer and shared a small set of conserved orthologous groups, annotated as FAD-dependent oxidoreductases, manganese efflux, and class II aldolases. Nevertheless, the two lineages followed distinct genomic strategies. M. vaginatus expands regulatory breadth and stress-resilience gene families, whereas M. aeruginosa shows evidence of genome streamlining and rapid nutrient exploitation. Notably, we hypothesize that aquatic M. vaginatus strains retain ancestral terrestrial genomic features while gradually acquiring potential aquatic-specific adaptations. Together, these results reveal a two-tier architecture associated with cyanobacterial dominance and provide a testable hypothesis for how cyanobacterial lineages may respond to global change pressures. Full article

Recent studies of understudied habitats, particularly caves, have revealed previously unrecognised cyanobacterial diversity. In this study, we used a metabarcoding approach to assess cyanobacterial communities in lampenflora developing in the most visited sections of Stopić Cave, Serbia. Two visually distinct lampenflora types were analysed: aerophytic lampenflora on exposed surfaces and submerged lampenflora within retained water, along with key environmental parameters. A wide range of Cyanobacteria was detected, including cave-adapted, rock-dwelling, atmophytic taxa from various habitats (deserts, thermal and saline environments), as well as species typically associated with freshwater and saline environments. Notably, many of the documented taxa have only recently been described. Dominant Cyanobacteria (>10%) included those assigned to Cyanothece aeruginosa, Loriellopsis cavernicola, Marileptolyngbya sina, Neochroococcus gongqingensis, Pseudocyanosarcina phycocyania, Scytonema hofmanii and Thainema salinarum, while representatives of the genera Chalicogloea, Crocosphaera, Dulcicalothrix, Gloeothece, Kovacikia, Timaviella, and Trichocoleus each contributed ≥1% of the community. In addition, Vampirovibrio chlorellavorus, a representative of Candidatus Melainabacteria, the non-photosynthetic relative of Cyanobacteria and an obligate parasite of Chlorella species, was detected in all aerophytic lampenflora. Full article

The Chiuchiu Pond (CCP) is an inland brackish water body in a pre-Andean scenery in the Atacama Desert, northern Chile. Presently unprotected, the CCP is attractive for tourism and a notable geosite for wildlife characterized by maintaining a fixed water level and chemical composition without surface inlets/outlets. This paper aims to characterize factors accounting for its perennial character by gathering climatic, hydrogeochemical, and morphometric information and microbiological and functional characterization. The CCP is an isolated U-shaped doline with a maximum depth of 17.5 m and vertical walls with more than 80% of soluble salts (halite and calcite) under arid conditions characterized by constant seasonal variation patterns. This is a unique case in that no similar conditions among reported wetlands or ponds have been found in the world. From our studies, it was characterized as an oligotrophic, lentic oligomictic, well-mixed water body, without thermal stratification, stable water level and hydrochemical composition, with water balance conditions from underground flows. Analysis of the microbial community revealed a core composition dominated by Proteobacteria (43.1%), Bacteroidetes (23.5%), and Cyanobacteria (10%). We provide a multidisciplinary contribution to justify urgent actions for the CCP’s conservation, representing a model for other unprotected coastal and inland wetlands in northern Chile and drylands elsewhere. Full article

This study investigates the long-term effects of catastrophic phosphate mining effluent contamination on the biocrust microbial community structure in sections of the ephemeral Ashalim Stream, Negev Desert, Israel. Microbial communities were characterized using next-generation sequencing of 16S rRNA gene fragments, conducted 1.5 and 5 years after the contamination event, across five stream strips. Samples from the nearby, uncontaminated Gmalim Stream served as controls. Biocrusts from Ashalim showed higher relative abundances of the phyla Actinobacteria and Firmicutes compared to Gmalim, whereas Chloroflexi were more prevalent in the controls. At the genus level, Blastococcus, Bacillus, Massilia, and Noviherbaspirillum were more abundant in the Ashalim strips, while Flavisolibacter, Segetibacter, and Rhodocytophaga were more abundant in the controls. Notably, genera within the Cyanobacteria phylum accounted for only 0.0–2.0% of sequences in Ashalim samples versus 2.5–20% in controls. The filamentous Leptolyngbya, Tychonema, and Trichocoleus genera were the most dominant cyanobacteria in all samples. The Nitrogen-fixing cyanobacterial genera Scytonema and Nostoc were consistently detected in Gmalim, but only in trace numbers in certain Ashalim sites. The results from both sampling campaigns support the hypothesis that phosphate effluent contamination had a profound impact on biocrust microbial community structure and function. In particular, the marked reduction in Cyanobacteria suggests a long-lasting disruption that may substantially hinder the natural ecosystem rehabilitation. Full article

The response of the desert cyanobacterium Chroococcidiopsis sp. CCMEE 010 was tested in Mars simulations to investigate the possibility of photosynthesis in near-surface protected niches. This cyanobacterium colonizes lithic niches enriched in far-red light (FRL) and depleted in visible light (VL) and is capable of far-red light photoacclimation (FaRLiP). Biofilms were grown under FRL and VL and exposed in a hydrated state to a low-pressure atmosphere, variable humidity, and UV irradiation, as occur on the Martian surface. VL biofilms showed a maximum quantum efficiency that dropped after 1 h, whereas a slow reduction occurred in FRL biofilms up to undetectable after 8 h, indicating that UV irradiation was the primary cause of photoinhibition. Post-exposure analyses showed that VL and FRL biofilms were dehydrated, suggesting that they entered a dried, dormant state and that top-layer cells shielded bottom-layer cells from UV radiation. After Mars simulations, the survivors (12% in VL biofilms and few cells in FRL biofilms) suggested that, during the evolution of Mars habitability, near-surface niches could have been colonized by phototrophs utilizing low-energy light. The biofilm UV resistance suggests that, during the loss of surface habitability on Mars, microbial life-forms might have survived surface conditions by taking refuge in near-surface protected niches. Full article

Biological soil crusts (BSCs) play a fundamental role in desert ecosystems by stabilizing soil, cycling nutrients, and retaining moisture. However, the assembly processes governing bacterial communities within BSCs remain largely unknown. This study aimed to reveal the spatiotemporal variations in the bacterial community diversity, co-occurrence patterns, and ecological assembly processes of BSCs and their underlying soils across different desert and seasonal conditions. We systematically analyzed the spatial differences in the bacterial diversity, co-occurrence networks, and community assembly processes of BSCs and their underlying soils using samples collected at various soil depths from different BSC types in different deserts. We discovered that BSC type and soil depth were the primary factors driving bacterial community assembly, while seasonal effects were weaker and more indirect, and mainly regulated community dynamics through changes in resource availability and environmental conditions. The underlying soils of moss- and lichen-BSCs exhibited higher bacterial diversity and richness than those of algae BSCs. In contrast, cyano-BSCs exhibited a lower diversity, but Cyanobacteria demonstrated the highest photosynthetic function. Among the different deserts, the community assembly of samples from the eastern Inner Mongolia deserts was largely influenced by environmental selection, whereas stochastic processes were more prominent in the central and western desert regions. A β-nearest taxon index (βNTI) analysis indicated that stochastic processes were dominant in surface BSC samples, while environmental selection played a stronger role in deeper layers. A co-occurrence network analysis revealed that surface BSC samples had a high degree of network connectivity, with those from moss- and lichen-BSCs being particularly high, and they also exhibited high modularity and local clustering that promoted the functional stability of the microbial communities. This study revealed the integrated effects of soil depth, BSC type, desert type, and resource availability on microbial community assembly in desert ecosystems. These findings provide a theoretical basis for the microbial management of BSCs and scientific insights to support restoration strategies in desert ecosystems. Full article

Studies performed in North America, Africa, and South America have led to the isolation of four new species of Kastovskya, a filamentous cyanobacterial genus that before this manuscript had only one species, Kastovskya adunca from Chile. Kastovskya nitens and K. viridissima were isolated from soils on San Nicolas Island, K. sahariensis was isolated from hypolithic habitats from the Sahara Desert in Algeria, and K. circularithylacoides was isolated from hypolithic habitats in Chile. The molecular analyses are corroborated by morphological data, morphometric analysis, and ecological and biogeographical considerations for robust polyphasic descriptions of all taxa. The peculiar transatlantic distribution of this genus bears similarity to other taxa in recently published studies and is in agreement with a hypothesis suggesting that cyanobacteria in Africa may disperse to the Americas on dust particles during windstorms. This work is unusual in that species in a single rare cyanobacterial genus with a disjunct distribution are described simultaneously from three continents. The 16S rRNA gene analyses performed for this study also revealed that another recent genus, Arizonema, is clearly a later synonym of Symplocastrum. This issue is resolved here with the collapsing of the type species Arizonema commune into Symplocastrum flechtnerae. Full article

Desert strains of the genus Chroococcidiopsis are among the most desiccation-resistant cyanobacteria capable of anhydrobiosis. The accumulation of two sugars, sucrose and trehalose, facilitates the entrance of anhydrobiotes into a reversible state of dormancy by stabilizing cellular components upon water removal. This study aimed to evaluate, at the atomistic level, the role of trehalose in desiccation resistance by using as a model system the 30S ribosomal subunit of the desert cyanobacterium Chroococcidiopsis sp. 029. Molecular dynamic simulations provided atomistic evidence regarding its protective role on the 30S molecular structure. Trehalose forms an enveloping shell around the ribosomal subunit and stabilizes the structures through a network of direct interactions. The simulation confirmed that trehalose actively interacts with the 30S ribosomal subunit and that, by replacing water molecules, it ensures ribosomal structural integrity during desiccation, thus enabling protein synthesis to be carried out upon rehydration. Full article

Afforestation is a widely used method of controlling desertification globally as it significantly impacts the soil quality, microbial community structure, and function. Investigating the effects of various artificial vegetation restoration models on soil microbial communities is crucial in understanding the mechanisms involved in combating desertification. However, research on this topic in arid, desertified regions is limited. In this study, we collected soil samples from two types of artificial forests (single species and mixed species) and bare desert soils in desertified areas of Northwest China to explore the impact of afforestation on soil nutrients, the microbial community composition, network relationships, and carbohydrate degradation abilities using metagenomic sequencing techniques. Our findings indicate that afforestation significantly enhances the soil moisture, total carbon, available phosphorus, and total nitrogen levels. The soil under mixed-species forests exhibited significantly higher levels of total carbon, total phosphorus, available phosphorus, and total nitrogen than that under single-species forests. Following afforestation, the populations of Pseudomonadota, Acidobacteriota, and Cyanobacteria increased significantly, whereas Actinomycetota decreased markedly. In single-species forests, Pseudomonadota and Bacillota were enriched, whereas Chloroflexota, Planctomycetota, and Acidobacteriota were more prevalent in mixed-species plantations. Afforestation increases the complexity and stability of microbial community networks. Afforestation enhances microbial metabolic activity, particularly increasing the abundance of carbon degradation functional genes in forest soils compared to bare desert soils. Mixed-species plantations outperform single-species forests in enhancing carbohydrate metabolism, amino acid metabolism, and the biodegradation and metabolism of xenobiotics. The abundance of functional genes associated with the degradation of starch, cellulose, hemicellulose, chitin, and pectin in mixed-species forests was significantly greater than in single-species plantations. Our study shows that mixed-species afforestation effectively improves the soil quality, enhances the stability of soil microbial communities, and bolsters the carbon cycle in arid regions prone to desertification. The reciprocal relationship between microorganisms and plants may serve as an intrinsic mechanism by which mixed-species afforestation more effectively controls desertification. Full article

Unique worldwide, nitrate/iodine deposits (NIDs) are located along a 700 km geological belt in the Atacama Desert, Chile. They serve as the primary source of mineral ores for the extraction of iodine, sodium, and potassium nitrates. NIDs have been relatively underexplored from a biological perspective. To address this, we collected sixteen soil samples from abandoned mines in Oficinas Pissis and Savona for chemical, mineralogical, and metagenomic analyses. The soils primarily consisted of halite and darapskite, with only one sample being predominantly composed of thenardite. Deliquescence and water activity measurements yielded values ranging from 0.02% to 0.40% and 0.47 to 0.62, respectively. To investigate the presence, identification, relative abundance, and diversity of microbial life in NID soils, we employed MiSeq high-throughput sequencing and bioinformatic tools. The dominant phyla observed were Firmicutes and Proteobacteria, with Actinobacteria and Cyanobacteria being predominant in two soil samples. Furthermore, we detected nitrate/perchlorate-reducing bacterial activity in enriched cultures from the soil samples. This study sheds light on the resilience of microbial life in the Atacama Desert NIDs, providing compelling evidence for its existence and offering insight into factors that could facilitate it within this unique environment. Full article

Lichens are some of the most unique fungi and are naturally encountered as symbiotic biological organisms that usually consist of fungal partners (mycobionts) and photosynthetic organisms (green algae and cyanobacteria). Due to their distinctive growth environments, including hot deserts, rocky coasts, Arctic tundra, toxic slag piles, etc., they produce a variety of biologically meaningful and structurally novel secondary metabolites to resist external environmental stresses. The endofungi that live in and coevolve with lichens can also generate abundant secondary metabolites with novel structures, diverse skeletons, and intriguing bioactivities due to their mutualistic symbiosis with hosts, and they have been considered as strategically significant medicinal microresources for the discovery of pharmaceutical lead compounds in the medicinal industry. They are also of great importance in the fundamental research field of natural product chemistry. In this work, we conducted a comprehensive review and systematic evaluation of the secondary metabolites of endolichenic fungi regarding their origin, distribution, structural characteristics, and biological activity, as well as recent advances in their medicinal applications, by summarizing research achievements since 2015. Moreover, the current research status and future research trends regarding their chemical components are discussed and predicted. A systematic review covering the fundamental chemical research advances and pharmaceutical potential of the secondary metabolites from endolichenic fungi is urgently required to facilitate our better understanding, and this review could also serve as a critical reference to provide valuable insights for the future research and promotion of natural products from endolichenic fungi. Full article

Land use practices and climate change have driven substantial soil degradation across global drylands, impacting ecosystem functions and human livelihoods. Biological soil crusts, a common feature of dryland ecosystems, are under extensive exploration for their potential to restore the stability and fertility of degraded soils through the development of inoculants. However, stressful abiotic conditions often result in the failure of inoculation-based restoration in the field and may hinder the long-term success of biocrust restoration efforts. Taking an assisted migration approach, we cultivated biocrust inocula sourced from multiple hot-adapted sites (Mojave and Sonoran Deserts) in an outdoor facility at a cool desert site (Colorado Plateau). In addition to cultivating inoculum from each site, we created an inoculum mixture of biocrust from the Mojave Desert, Sonoran Desert, and Colorado Plateau. We then applied two habitat amelioration treatments to the cultivation site (growth substrate and shading) to enhance soil stability and water availability and reduce UV stress. Using marker gene sequencing, we found that the cultivated mixed inoculum comprised both local- and hot-adapted cyanobacteria at the end of cultivation but had similar cyanobacterial richness as each unmixed inoculum. All cultivated inocula had more cyanobacterial 16S rRNA gene copies and higher cyanobacterial richness when cultivated with a growth substrate and shade. Our work shows that it is possible to field cultivate biocrust inocula sourced from different deserts, but that community composition shifts toward that of the cultivation site unless habitat amelioration is employed. Future assessments of the function of a mixed inoculum in restoration and its resilience in the face of abiotic stressors are needed to determine the relative benefit of assisted migration compared to the challenges and risks of this approach. Full article

The desert, which covers around one-third of Earth’s continental surface, is defined as the harshest terrestrial environment and comprises a highly extensive biome of the terrestrial ecosystem. Microorganisms are key drivers that maintain the integrity of desert terrestrial ecosystems. Over the past few decades, desertification has increased owing to changes in rainfall patterns and global warming, characterized by land degradation, loss of microbial diversity (biocrust diversity), and multifunctionality with time. Soil stabilization is a geotechnical modality that improves the physiochemical properties of the soil. Biological modality is an emerging method that attracts the scientific community for soil stabilization. Enriching the soil with microorganisms such as some bacteria geniuses (Cystobacter, Archangium, Polyangium, Myxococcus, Stigmatella and Sorangium, Bacillus, Acinetobacter, Proteus, Micrococcus, and Pseudom) or Cyanobacteria (Oscillatoria pseudogeminata, Chroococcus minutus, Phormidium Tenue, and Nostoc species), and Lichens (Collema sps., Stellarangia sps., and Buellia species) might contribute to stabilizing the soil and mitigating desertification. In this timeline review article, we summarize the biological method of soil stabilization, especially focusing on the role of microorganisms in soil stabilization in the desert. Full article

Xerophytes in desert improve their fitness under stress through the development of stems and branches. However, little is known about changes in the structure and function of endophytic microorganisms in response to interactions between desert plants and their environment. In this study, we analyzed the lignification indices of young and mature branches during their development in a typical desert xerophyte, Nitraria tangutorum, and combined 16S and ITS high-throughput sequencing techniques to draw the following conclusions. Nitraria tangutorum accumulated more lignin, cellulose, and hemicellulose content during lignification. In addition, the number of OTUs and diversity of endophytic bacteria and fungi were reduced. Both endophytic bacteria and fungi were governed by stochastic processes during the development of stems and branches of Nitraria tangutorum and were significantly affected by lignification indices. Meanwhile, the development of stems and branches increased the relative abundance of Cyanobacteria and Ascomycota, and the dominant bacterial genera were mostly positively correlated with the lignification indices. In addition, stem and branch lignification reduced endophytic microbial interactions in the relationship between the endophytic bacterial and fungal networks of Nitraria tangutorum. Functional prediction analysis further revealed that lignification of Nitraria tangutorum branches changed the metabolic function of endophytic bacteria. The results of this study indicate that plant endophytic microorganisms play an important role in resisting and adapting to adversity and provide support for related studies on microbial ecology in desert areas. Full article

Desert is one of the harshest environments on the planet, characterized by exposure to daily fluctuations of extreme conditions (such as high temperature, low nitrogen, low water, high salt, etc.). However, some cyanobacteria are able to live and flourish in such conditions, form communities, and facilitate survival of other organisms. Therefore, to ensure survival, desert cyanobacteria must develop sophisticated and comprehensive adaptation strategies to enhance their tolerance to multiple simultaneous stresses. In this review, we discuss the metabolic pathways used by desert cyanobacteria to adapt to extreme arid conditions. In particular, we focus on the extracellular polysaccharides and compatible solutes biosynthesis pathways and their evolution and special features. We also discuss the role of desert cyanobacteria in the improvement of soil properties and their ecological and environmental impact on soil communities. Finally, we summarize recent achievements in the application of desert cyanobacteria to prevent soil erosion and desertification. Full article