Alpine grasslands are vital in regulating carbon balance on the Qinghai-Tibetan Plateau (QTP) because of the large soil organic carbon (SOC) stocks, while persistent disturbance from the endemic small semifossorial herbivore, plateau pika (Ochotona curzoniae, hereafter pika), may break this balance. Pika affect the soil microclimate by creating a heterogeneous underlying surface, which is expected to alter soil microbial communities and eventually SOC stocks. However, our knowledge regarding the potential influence mechanism is still limited. Here, we investigated vegetation biomass, soil properties and soil microbes among 4 different surfaces (i.e., original vegetation, new pika pile, old pika pile and bare patch) of typical alpine grasslands to reveal soil microbial communities and the associated effect on SOC in response to pika bioturbation. Our results showed that pika bioturbation increased both bacterial and fungal diversity and their phyla abundance for SOC decomposition. Vegetation biomass, electrical conductivity and NH4+-N accounted for the variation in both bacterial and fungal community compositions and diversity. SOC stocks were 15-30% lower in pika piles and bare patches than in the original vegetation, which was mainly attributed to the reduced soil organic matter input from vegetation and the enhanced SOC consumption by soil microbial communities. Overall, we conclude that pika bioturbation altered the diversity and composition of soil microbial communities, which was associated with SOC loss and positive carbon feedback in alpine grasslands. Our findings provide insights into the role of small semifossorial herbivores in the carbon cycle of global grasslands.

The present world faces a new threat of ancient microbes and resistomes that are locked in the cryosphere and now releasing upon thawing due to climate change and anthropogenic activities. The cryosphere act as the best preserving place for these microbes and resistomes that stay alive for millions of years. Current reviews extensively discussed whether the resurrection of microbes and resistomes existing in these pristine environments is true or just a hype. Release of these ancient microorganisms and naked DNA is of great concern for society as these microbes can either cause infections directly or they can interact with contemporary microorganisms and affect their fitness, survival, and mutation rate. Moreover, the contemporary microorganisms may uptake the unlocked naked DNA, which might transform non-pathogenic microorganisms into deadly antibiotic-resistant microbes. Additionally, the resurrection of glacial microorganisms can cause adverse effects on ecosystems downstream. The release of glacial pathogens and naked DNA is real and can lead to fatal outbreaks; therefore, we must prepare ourselves for the possible reemergence of diseases caused by these microbes. This study provides a scientific base for the adoption of actions by international cooperation to develop preventive measures.

Permafrost regions play an important role in global carbon and nitrogen cycling, storing enormous amounts of organic carbon and preserving a delicate balance of nutrient dynamics. However, the increasing frequency and severity of wildfires in these regions pose significant challenges to the stability of these ecosystems. This review examines the effects of fire on chemical, biological, and physical properties of permafrost regions. The physical, chemical, and pedological properties of frozen soil are impacted by fires, leading to changes in soil structure, porosity, and hydrological functioning. The combustion of organic matter during fires releases carbon and nitrogen, contributing to greenhouse gas emissions and nutrient loss. Understanding the interactions between fire severity, ecosystem processes, and the implications for permafrost regions is crucial for predicting the impacts of wildfires and developing effective strategies for ecosystem protection and agricultural productivity in frozen soils. By synthesizing available knowledge and research findings, this review enhances our understanding of fire severity's implications for permafrost ecosystems and offers insights into effective fire management strategies.

Pigments are an essential part of everyday life on Earth with rapidly growing industrial and biomedical applications. Synthetic pigments account for a major portion of these pigments that in turn have deleterious effects on public health and environment. Such drawbacks of synthetic pigments have shifted the trend to use natural pigments that are considered as the best alternative to synthetic pigments due to their significant properties. Natural pigments from microorganisms are of great interest due to their broader applications in the pharmaceutical, food, and textile industry with increasing demand among the consumers opting for natural pigments. To fulfill the market demand of natural pigments new sources should be explored. Cold-adapted bacteria and fungi in the cryosphere produce a variety of pigments as a protective strategy against ecological stresses such as low temperature, oxidative stresses, and ultraviolet radiation making them a potential source for natural pigment production. This review highlights the protective strategies and pigment production by cold-adapted bacteria and fungi, their industrial and biomedical applications, condition optimization for maximum pigment extraction as well as the challenges facing in the exploitation of cryospheric microorganisms for pigment extraction that hopefully will provide valuable information, direction, and progress in forthcoming studies.

Microorganisms are major constituents of the total biomass in permafrost regions, whose underlain soils are frozen for at least two consecutive years. To understand potential microbial responses to climate change, here we examined microbial community compositions and functional capacities across four soil depths in an Alaska tundra site. We showed that a 5-year warming treatment increased soil thaw depth by 25.7% (p = .011) within the deep organic layer (15-25 cm). Concurrently, warming reduced 37% of bacterial abundance and 64% of fungal abundances in the deep organic layer, while it did not affect microbial abundance in other soil layers (i.e., 0-5, 5-15, and 45-55 cm). Warming treatment altered fungal community composition and microbial functional structure (p < .050), but not bacterial community composition. Using a functional gene array, we found that the relative abundances of a variety of carbon (C)-decomposing, iron-reducing, and sulphate-reducing genes in the deep organic layer were decreased, which was not observed by the shotgun sequencing-based metagenomics analysis of those samples. To explain the reduced metabolic capacities, we found that warming treatment elicited higher deterministic environmental filtering, which could be linked to water-saturated time, soil moisture, and soil thaw duration. In contrast, plant factors showed little influence on microbial communities in subsurface soils below 15 cm, despite a 25.2% higher (p < .05) aboveground plant biomass by warming treatment. Collectively, we demonstrate that microbial metabolic capacities in subsurface soils are reduced, probably arising from enhanced thaw by warming.

The world is concerned about the emergence of pathogens and the occurrence and spread of antibiotic resistance among pathogens. Drug development requires time to combat these issues. Consequently, drug development from natural sources is unavoidable. Cryosphere represents a gigantic source of microbes that could be the bioprospecting source of natural products with unique scaffolds as molecules or drug templates. This review focuses on the novel source of drug discovery and cryospheric environments as a potential source for microbial metabolites having potential medicinal applications. Furthermore, the problems encountered in discovering metabolites from cold-adapted microbes and their resolutions are discussed. By adopting modern practical approaches, the discovery of bioactive compounds might fulfill the demand for new drug development.

Permafrost thaw could induce substantial carbon (C) emissions to the atmosphere, and thus trigger a positive feedback to climate warming. As the engine of biogeochemical cycling, soil microorganisms exert a critical role in mediating the direction and strength of permafrost C-climate feedback. However, our understanding about the impacts of thermokarst (abrupt permafrost thaw) on microbial structure and function remains limited. Here we employed metagenomic sequencing to analyze changes in topsoil (0-15 cm) microbial communities and functional genes along a permafrost thaw sequence (1, 10, and 16 years since permafrost collapse) on the Tibetan Plateau. By combining laboratory incubation and a two-pool model, we then explored changes in soil labile and stable C decomposition along the thaw sequence. Our results showed that topsoil microbial alpha-diversity decreased, while the community structure and functional gene abundance did not exhibit any significant change at the early stage of collapse (1 year since collapse) relative to non-collapsed control. However, as the time since the collapse increased, both the topsoil microbial community structure and functional genes differed from the control. Abundances of functional genes involved in labile C degradation decreased while those for stable C degradation increased at the late stage of collapse (16 years since collapse), largely driven by changes in substrate properties along the thaw sequence. Accordingly, faster stable C decomposition occurred at the late stage of collapse compared to the control, which was associated with the increase in relative abundance of functional genes for stable C degradation. These results suggest that upland thermokarst alters microbial structure and function, particularly enhances soil stable C decomposition by modulating microbial functional genes, which could reinforce a warmer climate over the decadal timescale.

Endolithic micro-environments of rock are unique, ranging from high mountains and deep-sea floors to deserts and the Arctic and Antarctic regions colonized by high diversity of microbes. Endolithic microorganisms survive the extreme environmental conditions of rock pores and fissures with their survival strategies. In addition, the bulk rock provides mineral nutrients and protects the inhabitants from drastic ecological stresses from changes in the local conditions. Thus, endolithic microbes are at pivotal interface between geology and biology that offers a model system for unique microbial ecology, astrobiology, and geomicrobiology. This review provides comprehensive information on the diversity of endolithic microbial communities in cold, arid, aquatic, and terrestrial ecosystems and their survival strategies under ecological stresses. Furthermore, rock architecture for the colonization of endoliths, their biochemical functions and potential applications are discussed. It is clear that integrating modern molecular methods with physical and chemical analytical instrumentation will further advance our knowledge about endolithic microbial ecology, diversity, unique adaptive mechanisms, ecological functioning, and biochemical processes that shape the past, current, and future biosphere.

Warming in the Arctic accelerates top-soil decomposition and deep-soil permafrost thaw. This may lead to an increase in plant-available nutrients throughout the active layer soil and near the permafrost thaw front. For nitrogen (N) limited high arctic plants, increased N availability may enhance growth and alter community composition, importantly affecting the ecosystem carbon balance. However, the extent to which plants can take advantage of this newly available N may be constrained by the following three factors: vertical distribution of N within the soil profile, timing of N-release, and competition with other plants and microorganisms. Therefore, we investigated species- and depth-specific plant N uptake in a high arctic tundra, northeastern Greenland. Using stable isotopic labelling (N-15-NH4+), we simulated autumn N-release at three depths within the active layer: top (10 cm), mid (45 cm) and deep-soil near the permafrost thaw front (90 cm). We measured plant species-specific N uptake immediately after N-release (autumn) and after 1 year, and assessed depth-specific microbial N uptake and resource partitioning between above- and below-ground plant parts, microorganisms and soil. We found that high arctic plants actively foraged for N past the peak growing season, notably the graminoidKobresia myosuroides. While most plant species (Carex rupestris,Dryas octopetala,K. myosuroides) preferred top-soil N, the shrubSalix arcticaalso effectively acquired N from deeper soil layers. All plants were able to obtain N from the permafrost thaw front, both in autumn and during the following growing season, demonstrating the importance of permafrost-released N as a new N source for arctic plants. Finally, microbial N uptake markedly declined with depth, hence, plant access to deep-soil N pools is a competitive strength. In conclusion, plant species-specific competitive advantages with respect to both time- and depth-specific N-release may dictate short- and long-term plant community changes in the Arctic and consequently, larger-scale climate feedbacks.

The freezing-thawing cycle is a basic feature of a frozen soil ecosystem, and it affects the growth of alpine vegetation both directly and indirectly. As the climate changes, the freezing-thawing mode, along with its impact on frozen soil ecosystems, also changes. In this research, the freezing-thawing cycle of the Nagqu River Basin in the Qinghai-Tibet Plateau was studied. Vegetation growth characteristics and microbial abundance were analyzed under different freezing-thawing modes. The direct and indirect effects of the freezing-thawing cycle mode on alpine vegetation in the Nagqu River Basin are presented, and the changing trends and hazards of the freezing-thawing cycle mode due to climate change are discussed. The results highlight two major findings. First, the freezing-thawing cycle in the Nagqu River Basin has a high-frequency mode (HFM) and a low-frequency mode (LFM). With the influence of climate change, the LFM is gradually shifting to the HFM. Second, the alpine vegetation biomass in the HFM is lower than that in the LFM. Frequent freezing-thawing cycles reduce root cell activity and can even lead to root cell death. On the other hand, frequent freezing-thawing cycles increase microbial (Bradyrhizobium, Mesorhizobium, and Pseudomonas) death, weaken symbiotic nitrogen fixation and the disease resistance of vegetation, accelerate soil nutrient loss, reduce the soil water holding capacity and soil moisture, and hinder root growth. This study provides a complete response mechanism of alpine vegetation to the freezing-thawing cycle frequency while providing a theoretical basis for studying the change direction and impact on the frozen soil ecosystem due to climate change.