Global warming due to climate change has substantial impact on high-altitude permafrost affected soils. This raises a serious concern that the microbial degradation of sequestered carbon can result in alteration of the biogeochemical cycles. Therefore, the characterization of permafrost affected soil microbiomes, especially of unexplored high-altitude, low oxygen arid region, is important for predicting their response to climate change. This study presents the first report of the bacterial diversity of permafrost-affected soils in the Changthang region of Ladakh. The relationship between soil pH, organic carbon, electrical conductivity, and available micronutrients with the microbial diversity was investigated. Amplicon sequencing of permafrost affected soil samples from Jukti and Tsokar showed that Proteobacteria and Actinobacteria were the dominant phyla in all samples. The genera Brevitalea, Chthoniobacter, Sphingomonas, Hydrogenispora, Clostridium, Gaiella, Gemmatimonas were relatively abundant in the Jukti samples whereas the genera Thiocapsa, Actinotalea, Syntrophotalea, Antracticibcterium, Luteolibacter, Nitrospirillum dominated the Tsokar sample. Correlation analyses highlighted the influence of soil geochemical parameters on the bacterial community structure. PCoA analyses showed that the bacterial beta diversity varied significantly between the sampling locations (PERMANOVA test (F-value: 2.3316; R2 = 0.466, p = 0.001) and similar results were also obtained while comparing genus abundance data using the ANOSIM test (R = 0.345, p = 0.007).

The impact of global climate change and human-induced nitrogen (N) deposition on winter weather patterns will have consequences for soil N cycling and greenhouse gas emissions in temperate deserts. Biological soil crusts (referred to as biocrusts) are crucial communities in soil and significant sources of nitrous oxide (N2O) emission in desert ecosystems and are sensitive to environmental changes. The contribution of bacteria and fungi to N2O production in drylands has been acknowledged. However, the effect of changes in snow cover and N deposition on the N2O production of different microbial groups of microorganisms is not yet clear. In this study, we examine the responses of fungi and bacteria mediated pathways involved in soil N2O production from biocrusts to longterm snow cover manipulation and N addition experiments in the Gurbantunggut Desert. These soils were incubated and subjected to biocide treatments (such as cycloheximide and streptomycin, and fungal and bacterial inhibitors), after which rates of potential nitrification and N2O production were measured. Compared with controls, snow removal treatments from bare sand, lichen crust and moss crust reduced background rates of N2O production by 29.41 %, 26.21 % and 20.49 %, respectively; N2O production rates were 1.53-fold higher in bare sand, 1.38-fold higher in lichen crust, and 1.56-fold higher in moss crust after N addition. The addition of streptomycin significantly reduced the potential nitrification rates of bare sand and biocrusts, indicating that bacteria may be important sources of NO3- production in biocrusts rather than fungi. Conversely, fungi were main sources of N2O production in biocrusts. Additionally, fungi also played a major role in N2O production in biocrusts after snow cover manipulation and N addition. Both snow cover manipulation and N addition treatment indirectly affected the N2O production in biocrusts by considerably affecting the content of substrate N and the abundance of microbial groups. Our research suggests that fungi are main contributors for denitrification in biocrusts, and that snow cover changes (removal snow and double snow) and N addition alter the contribution of biotic pathways responsible for N cycling.

Background:A shallow active layer of soil above the permafrost thaws during the summer months which promotes microbial growth and releases previously confined pathogens which result in bacterial epidemics in circumpolar regions. Furthermore, these permafrost sources harbor several antibiotic resistance genes (ARGs) which may disseminate and pose a challenge for pharmacologists worldwide.Aims:The authors examined the potential association between climate change-induced permafrost thawing, and the resulting release of antibiotic-resistant pathogens, as well as the potential impact this can have on global healthcare systems in the long run.Methodology:A cursory abstract screening was done to rule out any articles that did not have to do with viral pathogens caused by melting permafrost. Articles that were not available in English or that our institutions library did not have full-text access were weeded out by a secondary screen.Results:A comprehensive analysis of 13 relevant studies successfully revealed a wide variety of bacterial genera, including Staphylococcus spp., Pseudomonas spp., Acinetobacter spp., and Achromobacter spp., along with a total of 1043 antibiotic resistance genes (ARGs), with most pertaining to aminoglycosides and beta-lactams, offering resistance via diverse mechanisms such as efflux pumps and enzymatic modifications, within the permafrost isolates. Additionally, mobile genetic elements (MGEs) housing antibiotic resistance genes (ARGs) and virulence factor genes (VFGs), including plasmids and transposons, were also discovered.Conclusion:Permafrost thawing is an underrated healthcare challenge warranting the need for further articles to highlight it alongside concerted efforts for effective mitigation.

Global warming leads to the melting of permafrost, affects changes in soil microbial community structures and related functions, and contributes to the soil carbon cycle in permafrost areas. Located at the southern edge of Eurasia's permafrost region, the Greater Khingan Mountains are very sensitive to climate change. Therefore, by analyzing the bacterial community structure, diversity characteristics, and driving factors of soil profiles (active surface layer, active deep layer, transition layer, and permafrost layer) in this discontinuous permafrost region, this research provides support for the study of the carbon cycling process in permafrost regions. The results show that the microbial diversity (Shannon index (4.81)) was the highest at 0-20 cm, and the Shannon index of the surface soil of the active layer was significantly higher than that of the other soil layers. Acidobacteria and Proteobacteria were the dominant bacteria in the active layer soil of the permafrost area, and Chloroflexi, Actinobacteria, and Firmicutes were the dominant bacteria in the permafrost layer. Chloroflexi made the greatest contribution to the bacterial community in the permafrost soil, and Bacteroidota made the greatest contribution to the bacterial community in the active surface soil. The structure, richness, and diversity of the soil bacterial community significantly differed between the active layer and the permafrost layer. The number of bacterial species was the highest in the active layer surface soil and the active layer bottom soil. The difference in the structure of the bacterial community in the permafrost soil was mainly caused by changes in electrical conductivity and soil-water content, while that in the active layer soil was mainly affected by pH and soil nutrient indices. Soil temperature, NO3--N, and pH had significant effects on the structure of the bacterial community. The active layer and permafrost soils were susceptible to environmental information processing and genetic information processing. Infectious disease: the number of bacterial species was significantly higher in the surface and permafrost layers than in the other layers of the soil. In conclusion, changes in the microbial community structure in soil profiles in discontinuous permafrost areas sensitive to climate change are the key to soil carbon cycle research.

Changing precipitation patterns and global warming have greatly changed winter snow cover, which can affect litter decomposition process by altering soil microenvironment or microbial biomass and activity. However, it remains unknown how and to what extent snow cover affects litter decomposition during winter and over longer periods of time. Here, we conducted a meta-analysis to synthesize litter decomposition studies under different levels of snow cover. Overall, deepened snow significantly enhanced litter decomposition rate and mass loss by 17% and 3%, respectively. Deepened snow enhanced litter carbon loss by 7% but did not impact the loss of litter nitrogen or phosphorus. Deepened snow increased soil temperature, decreased the frequency of freeze-thaw cycles, and stimulated microbial biomass carbon and bacterial biomass during winter, but had no effect on these parameters in summer. The promoting effect of deepened snow cover on litter decomposition in winter is mainly due to its positive effect on microbial decomposition by increasing soil temperature and reducing freezethaw cycles exceeded its negative effect on physical fragmentation of litter by reducing freeze-thaw cycles. Our findings indicate that the changes in winter snow cover under global change scenarios can greatly impact winter litter decomposition and the associated carbon cycling, which should be taken into consideration when assessing the global carbon budget in modeling.

The retreat of glaciers in Antarctica has increased in the last decades due to global climate change, influencing vegetation expansion, and soil physico-chemical and biological attributes. However, little is known about soil microbiology diversity in these periglacial landscapes. This study characterized and compared bacterial and fungal diversity using metabarcoding of soil samples from the Byers Peninsula, Maritime Antarctica. We identified bacterial and fungal communities by amplification of bacterial 16 S rRNA region V3-V4 and fungal internal transcribed spacer 1 (ITS1). We also applied 14C dating on soil organic matter (SOM) from six profiles. Physicochemical analyses and attributes associated with SOM were evaluated. A total of 14,048 bacterial ASVs were obtained, and almost all samples had 50% of their sequences assigned to Actinobacteriota and Proteobacteria. Regarding the fungal community, Mortierellomycota, Ascomycota and Basidiomycota were the main phyla from 1619 ASVs. We found that soil age was more relevant than the distance from the glacier, with the oldest soil profile (late Holocene soil profile) hosting the highest bacterial and fungal diversity. The microbial indices of the fungal community were correlated with nutrient availability, soil reactivity and SOM composition, whereas the bacterial community was not correlated with any soil attribute. The bacterial diversity, richness, and evenness varied according to presence of permafrost and moisture regime. The fungal community richness in the surface horizon was not related to altitude, permafrost, or moisture regime. The soil moisture regime was crucial for the structure, high diversity and richness of the microbial community, specially to the bacterial community. Further studies should examine the relationship between microbial communities and environmental factors to better predict changes in this terrestrial ecosystem.

Permafrost region stores 1014-1035 Pg (1 Pg=10(15) g) carbon (C) in the upper 3 m of soils, approximately twice of the atmosphere C pool. Over the past few decades, climate warming has caused substantial permafrost thaw. Consequently, a proportion of permafrost C becomes available for microbial utilization and can be decomposed as carbon dioxide (CO2) and methane (CH4) into the atmosphere, thus triggering potential C-climate feedback. However, the magnitude of this feedback remains highly uncertain, partly due to limited understanding of the formation and stabilization mechanisms of permafrost organic C. As an important component of soil stable C pool, microbial necromass C could make up more than 50% of soil organic carbon (SOC). Therefore, our knowledge of spatial distributions and key drivers of microbial necromass C in permafrost deposits is crucial for accurately predicting permafrost C dynamics under the context of global warming. Based on large-scale permafrost sampling along a similar to 1000 km transect on the Tibetan Plateau and biomarker analysis of amino sugars, we determined microbial necromass C content in permafrost deposits across 24 sampling sites. We then compared the contribution of microbial necromass C to SOC between permafrost deposits and active layer. To investigate key determinants of microbial necromass C content in permafrost deposits, we obtained climatic factors (e.g., mean annual temperature, mean annual precipitation) and measured soil variables (e.g., active layer thickness, soil moisture, soil texture), as well as microbial properties (e.g., fungal and bacterial biomass on the basis of phospholipid fatty acids analysis). Our results showed that total microbial necromass C, fungal and bacterial necromass C content in permafrost deposits increased from the west to the east of the study area. The average content of microbial necromass C in permafrost deposits was 2741.0 +/- 815.3 (values were reported as mean +/- standard error) mg kg(-1), and its contribution to SOC was 13.2%+/- 1.1%. The fungal necromass C and its contribution to SOC were significantly higher than that of bacterial necromass C. Our results also indicated that the contribution of fungal necromass C to SOC in the permafrost deposits was significantly lower than that in the active layer, however, there were no significant differences in the contribution of bacterial necromass C to SOC between these two layers. Regression analyses showed that total microbial necromass C, fungal and bacterial necromass C content in permafrost deposits increased with mean annual precipitation, soil moisture and their corresponding microbial biomasses, but decreased with mean annual temperature and active layer thickness. Structural equation modeling analyses further revealed that soil moisture and microbial biomass were the direct drivers of microbial necromass C content in permafrost deposits, and climatic factors indirectly affected microbial necromass C content. Overall, this study offers the first attempt to analyze the spatial distribution and dominant drivers of permafrost microbial necromass C on the Tibetan Plateau. The contribution of microbial necromass C to SOC observed in permafrost deposits was lower than those reported in temperate and global grassland soils. Moreover, the key factors of microbial necromass C detected in permafrost deposits were distinct from those reported in other ecosystems, where plant C input and mineral protection are dominant factors affecting soil microbial necromass C content. These findings illustrate the unique characteristics of C formation and accumulation in permafrost soils, suggesting that C formation processes and mechanisms obtained in other ecosystems cannot be simply generalized to permafrost ecosystems. More importantly, despite the relatively lower contribution of microbial necromass C to SOC, microbial necromass C is a non-negligible source of permafrost C, and its dynamics may affect the positive feedback between permafrost C cycle and climate warming.

Under the background of climate change, freeze-thaw patterns tend to be turbulent: ecosystem function processes and their mutual feedback mechanisms with microorganisms in sensitive areas around the world are currently a hot topic of research. We studied changes of soil properties in alpine wetlands located in arid areas of Central Asia during the seasonal freeze-thaw period (which included an initial freezing period, a deep freezing period, and a thawing period), and analyzed changes in soil bacterial community diversity, structure, network in different stages with the help of high-throughput sequencing technology. The results showed that the alpha diversity of the soil bacterial community showed a continuous decreasing trend during the seasonal freeze-thaw period. The relative abundance of dominant bacterial groups (Proteobacteria (39.04%-41.28%) and Bacteroidota (14.61%-20.12%)) did not change significantly during the freeze-thaw period. At the genus level, different genera belonging to the same phylum dominated in different stages, or there were clusters of genera belonging to different phylum. For example, g_Ellin6067, g_unclassified_f_Geobacteraceae, g_unclassified_f_Gemmatimonadaceae coexisted in the same cluster, belonging to Proteobacteria, Desulfobacterota and Gemmatimonadota respectively, and their abundance increased significantly during the freezing period. This adaptive freeze-thaw phylogenetic model suggests a heterogeneous stress resistance of bacteria during the freeze-thaw period. In addition, network analysis showed that, although the bacterial network was affected to some extent by environmental changes during the initial freezing period and its recovery in the thawing period lagged behind, the network complexity and stability did not change much as a whole. Our results prove that soil bacterial communities in alpine wetlands are highly resistant and adaptive to seasonal freeze-thaw conditions. As far as we know, compared with short-term freeze-thaw cycles research, this is the first study examining the influence of seasonal freeze-thaw on soil bacterial communities in alpine wetlands. Overall, our findings provide a solid base for further investigations of biogeochemical cycle processes under future climate change.

Bacteria in the genus Arthrobacter have been found in extreme environments, e.g. glaciers, brine and mural paintings. Here, we report the discovery of a novel pink-coloured bacterium, strain QL17(T), capable of producing an extracellular water-soluble blue pigment. The bacterium was isolated from the soil of the East Rongbuk Glacier of Mt. Everest, China. 16S rRNA gene sequence analysis showed that strain QL17(T) was most closely related to the species Arthrobacter bussei KR32 (T). However, compared to A.bussei KR32(T) and the next closest relatives, the new species demonstrates considerable phylogenetic distance at the whole-genome level, with an average nucleotide identity of <85 % and inferred DNA-DNA hybridization of <30 %. Polyphasic taxonomy results support our conclusion that strain QL17(T) represents a novel species of the genus Arthrobacter. Strain QL17(T) had the highest tolerance to hydrogen peroxide at 400 mM. Whole-genome sequencing of strain QL17(T) revealed the presence of numer-ous cold-adaptation, antioxidation and UV resistance-associated genes, which are related to adaptation to the extreme envi-ronment of Mt. Everest. Results of this study characterized a novel psychrotolerant Arthrobacter species, for which the name Arthrobacter antioxidans sp. nov. is proposed. The type strain is QL17(T) (GDMCC 1.2948(T)=JCM 35246(T)).

High latitude regions are experiencing considerable winter climate change, and reduced snowpack will likely affect soil microbial communities and their function, ultimately altering microbial-mediated biogeochemical cycles. However, the current knowledge on the responses of soil microorganisms to snow cover changes in permafrost ecosystems remains limited. Here, we conducted a 2-year (six periods) snow manipulation experi-ment comprising ambient snow and snow removal treatments with three replications of each treatment to explore the immediate and legacy effects of snow removal on soil bacterial community and enzyme activity in secondary Betala platyphylla forests in the permafrost region of the Daxing'an Mountains. Generally, bacterial community diversity was not particularly sensitive to the snow removal. Seasonal fluctuations in the relative abundance of dominated bacterial taxa were observed, but snow removal merely exerted a significant impact on the bacterial community structure during the snow melting period and early vegetation growing season within two consecutive years, with a reduction in the relative abundance of Chloroflexi and an increase in the relative abundance of Actinobacteria, and no evidence of cross-season legacy effects was found. Moreover, snow removal significantly altered the soil enzyme activities in the snow stabilization period and snow melting period, with an increase in soil acid phosphatase (ACP) activity of snow melting period and a decrease in polyphenol oxidase (PPO) activity of snow stabilization period as well as beta-glucosidase (BG) activity of snow stabilization period and snow melting period, but this effect did not persist into the vegetation growing periods. The seasonal variations in bacterial community and enzyme activity were mostly driven by changes in soil nutrient availability. Overall, our results suggest that soil bacterial communities have rather high resilience and rapid adaptability to snow cover changes in the forest ecosystems in the cold region of the Daxing'an Mountains.