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Permafrost acts as a potential pathogen reservoir. With accelerating climate change and intensifying permafrost degradation, the release of these pathogens poses significant threats to ecosystems and public health. However, the changes in pathogenic communities during permafrost degradation remain unclear. This study utilized quantitative PCR and Illumina high-throughput sequencing to analyze the composition and quantities of potential pathogenic bacteria in four types of permafrost soil on the northeast edge of the Qinghai-Tibet Plateau (QTP): sub-stable permafrost (SSP), transition permafrost (TP), unstable permafrost (UP), and extremely unstable permafrost (EUP). The results showed that during permafrost degradation, the quantity of potential pathogenic bacteria decreased from 7.8 × 10 6 to 3.1 × 10 6  copies/g. Both the Richness and Shannon indices initially declined from SSP, to TP, UP, and then began to rise when permafrost degraded to EUP. A total of 216 potential pathogenic bacterial species were identified, including 166 animal pathogens, 28 zoonotic pathogens, and 22 plant pathogens. The pathogenic community intergroup differences (ANOSIM), unique taxa, and dominant pathogen analysis indicated the significant changes in pathogenic communities during permafrost degradation. The potential pathogenic community was significantly influenced by non-pathogenic bacterial communities (Procrustes analysis), with soil moisture being the primary environmental factor, followed by TDS, soil organic carbon, and total nitrogen. SourceTracker2 analysis indicated that the majority of potential pathogenic bacteria in the soil originated from external sources, only a small portion coming from the permafrost itself. These findings suggest that a large number of pathogens were released into the environment while also preserving amount from external sources. It elucidates that each stage of permafrost degradation presents unique biosecurity risks. This study highlights the release and redistribution of pathogenic bacteria associated with the potential public health risks. It provides the crucial insights into the ecological dynamics of permafrost degradation, emphasizing the need for ongoing monitoring and proactive management strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Glaciers, which constitute the world's largest global freshwater reservoir, are also natural microbial repositories. The frequent pandemic in recent years underscored the potential biosafety risks associated with the release of microorganisms from the accelerated melting of glaciers due to global warming. However, the characteristics of pathogenic microorganisms in glaciers are not well understood. The glacier surface is the primary area where glacier melting occurs that is often the main subject of research on the dynamics of pathogenic microbial communities in efforts to assess glacier biosafety risks and devise preventive measures. In this study, high-throughput sequencing and quantitative polymerase chain reaction methods were employed in analyses of the composition and quantities of potential pathogenic bacteria on the surfaces of glaciers in the southeastern Tibetan Plateau. The study identified 441 potential pathogenic species ranging from 215 to 4.39 × 10 11 copies/g, with notable seasonal and environmental variations being found in the composition and quantity of potential pathogens. The highest level of diversity was observed in April and snow, while the highest quantities were observed in October and cryoconite. Host analysis revealed that >70 % of the species were pathogens affecting animals, with the highest proportion of zoonotic pathogens being observed in April. Analysis of aerosols and glacial meltwater dispersion suggested that these microbes originated from West Asia, primarily affecting the central and southern regions of China. Null model analysis indicated that the assembly of potential pathogenic microbial communities on glacier surfaces was largely governed by deterministic processes. In conclusion, potential pathogenic bacteria on glacier surfaces mainly originated from the snow and exhibited significant temporal and spatial variation patterns. These findings can be used to enhance researchers' ability to predict potential biosafety risks associated with pathogenic bacteria in glaciers and to prevent their negative impact on populations and ecological systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: New antibiotics are urgently needed in clinical treatment of superdrug-resistant bacteria. Nonribosomal peptides (NRPs) are a major source of antibiotics because they exhibit structural diversity, and unique antibacterial mechanisms and resistance. Analysis of gene clusters of S. agglomeratus 5-1-3 showed that Clusters 3, 6, 12, 21, and 28 were used to synthesize NRPs. Here, we examined secondary metabolites of S. agglomeratus 5-1-3 isolated from soils in the Qinghai-Tibet Plateau, China, for NRPs with antibacterial activity., Results: We isolated a total of 36 Streptomyces strains with distinct colony morphological characteristics from 7 soil samples. We screened 8 Streptomyces strains resistant to methicillin-resistant Staphylococcus aureus (MRSA). We then selected S. agglomeratus 5-1-3 for further study based on results of an antibacterial activity test. Here, we isolated three compounds from S. agglomeratus 5-1-3 and characterized their properties. The crude extract was extracted with ethyl acetate and purified with column chromatography and semipreparative high-performance liquid chromatography (HPLC). We characterized the three compounds using NMR analyses as echinomycin (1), 5,7,4'-trihydroxy-3.3',5'-trimethoxy flavone (2), and 2,6,2', 6'-tetramethoxy-4,4-bis(2,3-epoxy-1-hydroxypropyl)-biphenyl (3). We tested the antibacterial activity of pure compounds from strain 5-1-3 with the Oxford cup method. NRP echinomycin (1) showed excellent anti-MRSA activity with a minimum inhibitory concentration (MIC) of 2.0 μg/mL. Meanwhile, MIC of compound 2 and 3 was 128.0 μg/mL for both. In addition, 203 mg of echinomycin was isolated from 10 L of the crude extract broth of strain 5-1-3., Conclusion: In this study, S. agglomeratus 5-1-3 with strong resistance to MRSA was isolated from the soils in the Qinghai-Tibet Plateau. Strain 5-1-3 had a high yield of echinomycin (1) an NRP with a MIC of 2 μg/mL against MRSA. We propose that echinomycin derived from S. agglomeratus 5-1-3 may be a potent antibacterial agent for pharmaceutical use., (© 2023. The Author(s).)

Background: The bacterial mechanisms responsible for hydrogen peroxide (H 2 O 2 ) scavenging have been well-reported, yet little is known about how bacteria isolated from cold-environments respond to H 2 O 2 stress. Therefore, we investigated the transcriptional profiling of the Planomicrobium strain AX6 strain isolated from the cold-desert ecosystem in the Qaidam Basin, Qinghai-Tibet Plateau, China, in response to H 2 O 2 stress aiming to uncover the molecular mechanisms associated with H 2 O 2 scavenging potential., Methods: We investigated the H 2 O 2 -scavenging potential of the bacterial Planomicrobium strain AX6 isolated from the cold-desert ecosystem in the Qaidam Basin, Qinghai-Tibet Plateau, China. Furthermore, we used high-throughput RNA-sequencing to unravel the molecular aspects associated with the H 2 O 2 scavenging potential of the Planomicrobium strain AX6 isolate., Results: In total, 3,427 differentially expressed genes (DEGs) were identified in Planomicrobium strain AX6 isolate in response to 4 h of H 2 O 2 (1.5 mM) exposure. Besides, Kyoto Encyclopedia of Genes and Genomes pathway and Gene Ontology analyses revealed the down- and/or up-regulated pathways following H 2 O 2 treatment. Our study not only identified the H 2 O 2 scavenging capability of the strain nevertheless also a range of mechanisms to cope with the toxic effect of H 2 O 2 through genes involved in oxidative stress response. Compared to control, several genes coding for antioxidant proteins, including glutathione peroxidase (GSH-Px), Coproporphyrinogen III oxidase, and superoxide dismutase (SOD), were relatively up-regulated in Planomicrobium strain AX6, when exposed to H 2 O 2 ., Conclusions: Overall, the results suggest that the up-regulated genes responsible for antioxidant defense pathways serve as essential regulatory mechanisms for removing H 2 O 2 in Planomicrobium strain AX6. The DEGs identified here could provide a competitive advantage for the existence of Planomicrobium strain AX6 in H 2 O 2 -polluted environments., (© 2022. The Author(s).)

The Tibetan Plateau niche provides unprecedented opportunities to find microbes that are functional and commercial significance. The present study investigated the physiological and genomic characteristics of Planococcus halotolerans Y50 that was isolated from a petroleum-contaminated soil sample from the Qinghai-Tibet Plateau, and it displayed psychrotolerant, antiradiation, and oil-degraded characteristics. Whole genome sequencing indicated that strain Y50 has a 3.52 Mb genome and 44.7% G + C content, and it possesses 3377 CDSs. The presence of a wide range of UV damage repair genes uvrX and uvsE, DNA repair genes radA and recN, superoxide dismutase, peroxiredoxin and dioxygenase genes provided the genomic basis for the adaptation of the plateau environment polluted by petroleum. Related experiments also verified that the Y50 strain could degrade n-alkanes from C 11 -C 23 , and approximately 30% of the total petroleum at 25 °C within 7 days. Meanwhile, strain Y50 could withstand 5 × 10 3 J/m 2 UVC and 10 KGy gamma ray radiation, and it had strong antioxidant and high radical scavengers for superoxide anion, hydroxyl radical and DPPH. In addition, pan-genome analysis and horizontal gene transfers revealed that strains with different niches have obtained various genes through horizontal gene transfer in the process of evolution, and the more similar their geographical locations, the more similar their members are genetically and ecologically. In conclusion, P. halotolerans Y50 possesses high potential of applications in the bioremediation of alpine hydrocarbons contaminated environment., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Limited knowledge about the variation patterns of bacterial community composition in the sand and vegetative ecosystems confines our understanding regarding the contribution of the sand dune to desert areas. In this study, 454 pyrosequencing platforms were adopted to determine the community structure of bacteria and diversity of sand dunes in northeastern Qinghai-Tibet Plateau, China: 50 cm deep, rhizosphere, physical crusts, and biological crusts representing sand and vegetative ecosystems, respectively. The findings revealed significant variation in bacterial diversities and the structure of communities in the sand and vegetative ecosystems. The dominant bacterial phyla of sand and vegetative ecosystems were Firmicutes (47%), Actinobacteria (21%), Proteobacteria (16%), and Bacteroidetes (13%), while Lactococcus (50%) was found to be the dominant genus. Furthermore, samples with high alpha-diversity indices (Chao 1 and Shannon) for the vegetative ecosystem have the lowest modularity index and the largest number of biomarkers, with some exceptions. Redundancy analysis exhibited that environmental factors could explain 72% (phyla) and 67% (genera) of the bacterial communities, with EC, TC, and TOC being the major driving factors. This study expands our understanding of bacterial community composition in the desert ecosystem. The findings suggest that variations in the sand and vegetative ecosystems, such as those predicted by environmental factors, may reduce the abundance and diversity of bacteria, a response that likely affects the provision of key ecosystem processes by desert regions., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A bacterial strain, designated Y40 T , was isolated from sandy soil sampled on the Qinghai-Tibet Plateau. A polyphasic study confirmed the affiliation of the strain with the genus Mesobacillus . Strain Y40 T was found to be an aerobic, Gram-stain-positive, motile and rod-shaped bacterium. The strain grew at 10-42 °C, pH 6-9 and with 0-2 % (w/v) NaCl. The diagnostic amino acid was meso -diaminopimeilic acid. MK7 was predominant menaquinone, and iso-C 15:0 , iso-C 17:1 ω10 c and anteiso-C 15:0 were the major fatty acids. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified lipid. The DNA G+C content was 40.6 mol%. Based on he results of 16S rRNA gene sequence analysis, strain Y40 T was phylogenetically closely related to Mesobacillus zeae JJ-247 T and Mesobacillus foraminis CV53 T , with similarities of 98.0 and 97.7 %, respectively. The average nucleotide identity (ANIb) values between strain Y40 T and Mesobacillus zeae JJ-247 T and Mesobacillus foraminis CV53 T were 69.9 and 70.0 %, respectively. Based on the morphological, physiological, and chemotaxonomic data, it is proposed that strain Y40 T (=CICC 24459 T =JCM 32794 T ) should be classified into the genus Mesobacillus as Mesobacillus harenae sp. nov.

Strain Y74 T was an isolate from the sandy soil in the town of Huatugou, Qinghai-Tibet Plateau, China. An analysis of this strain's phenotypic, chemotaxonomic, and genomic characteristics established the relationship of the isolate with the genus Planococcus. Strain Y74 T was able to grow between 4 and 42°C (with an optimum temperature of 28°C) at pH values of 6-8.5 and in 0%-7% (w/v) NaCl. The dominant quinones were MK-8 and MK-7. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, and an unknown phospholipid. The majority of the fatty acid content was anteiso-C 15:0 (28.8%) followed by C 16:1 ω7c alcohol (20.9%) and iso-C 14:0 (13.4%). The 16S rRNA gene sequence similarity analysis demonstrated a stable branch formed by strain Y74 T and Planococcus halotolerans SCU63 T (99.66%). The digital DNA-DNA hybridization between these two strains was 57.2%. The G + C content in the DNA of Y74 T was 44.5 mol%. In addition, the morphological, physiological, and chemotaxonomic pattern clearly differentiated the isolates from their known relatives. In conclusion, the strain Y74 T (=JCM 32826 T  = CICC24461 T ) represents a novel member of the genus Planococcus, for which the name Planococcus antioxidans sp. nov. is proposed. Strain Y74 T was found to have potent antioxidant activity via its hydrogen peroxide tolerance and its 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. The DPPH radical-scavenging activity was determined to be 40.2 ± 0.7%. The genomic analysis indicated that six peroxidases genes, one superoxide dismutase gene, and one dprA (DNA-protecting protein) are present in the genome of Y74 T ., (© 2020 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.)

A bacterial strain, designated GEM5 T , was isolated from sand soil samples from the Qinghai-Tibet Plateau. The polyphasic study confirmed the affiliation of the isolate with the genus Massilia . GEM5 T had Gram-stain-negative, non-spore-forming and rod-shaped cells and grew at 4-30 °C, pH 6-8 and with 0-2 % (w/v) NaCl. Its cell wall contained ribose. Q8 was the predominant respiratory quinone, and summed feature 3 (C 16 : 1 ω6 c /ω7 c ) and C 16 : 0 were the major components of the fatty acids. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified phospholipid, an unidentified aminolipid and four unidentified lipids. The DNA G+C content was 65.1 mol%. The phylogenetic analysis based on the 16S rRNA gene showed a stable clade being formed by GEM5 T , Massilia timonae CCUG 45783 T (97.94 %) and Massilia oculi CCUG 43427A T (97.58 %). The average nucleotide identity (ANIb) values between GEM5 T and M. timonae CCUG 45783 T , M.oculi CCUG 43427A T were 91.3 and 91.7 %, respectively. On the basis of the morphological, physiological and chemotaxonomic pattern, it was proposed that strain GEM5 T (=JCM 32744 T =CICC 24458 T ) should be classified as representing a member of the genus Massilia with the name Massilia arenae sp. nov.

The Qinghai-Tibet Plateau glaciers are an important carrier of mercury (Hg). With global warming, Hg enters into the downstream ecosystem in the melt waters, threatening human health and ecosystem security in the region. Methylmercury (MeHg), which has higher toxicity than Hg itself, is converted from inorganic Hg. However, little is known about the process of Hg methylation and, in particular, microbial Hg methylation in high altitude mountain glaciers. We combined Hg speciation measurements and metagenomic analysis of 6 sample types from the terminus of Laohugou No.12 glacier to elucidate potential microbially mediated Hg methylation. We found higher Hg concentrations in supraglacial cryoconite (SC) and dusty layer (DL) samples which contain considerable debris and dust. In addition, MeHg concentrations were highest in some of these SC and DL samples. Bacterial hgcA Hg methylation genes were present in all samples except supraglacial ice but were of highest abundance in SC and DL. This suggested that microbial Hg methylation is most likely to occur in SC and DL. There were 8 phyla of potential Hg methylation microorganisms, but 37% of the sequences could not be classified into any known genus. Most of the hgcA sequences were closely related to sequences from previously reported Hg methylating genera within the Deltaproteobacteria and Firmicutes, but the common Hg methylating Methanomicrobia were absent in glacial samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A novel actinobacterial strain, designated Z022 T , isolated from a soil sample collected from Dangxiong in Tibet Autonomous Region (PR China), was determined by polyphasic taxonomic approach. The organism had chemotaxonomic and morphological properties consistent with its classification in the genus Streptomyces. Strain Z022 T showed high similarity value to Streptomyces lucensis NBRC 13056 T (98.87 %) and S. achromogenes subsp . achromogenes NBRC 12735 T (98.68 %) based on the 16S rRNA gene phylogenetic tree. The genomic DNA G+C content of strain Z022 T based on the genome sequence was 72.16 mol%. DNA-DNA relatedness values between strain Z022 T and strain Streptomyces lucensis NBRC 13056 T was 23.7±1.3 % and significantly lower than 70 %. Chemotaxonomic data revealed that strain Z022 T possessed MK-9(H 8 ) and MK-9(H 6 ) as the predominant menaquinone, ll-diaminopimelic acid as the diagnostic diamino acid, and galactose, glucose, xylose and ribose as whole cell sugars. Diphosphatidylglycerol (DPG) and phosphatidylethanolamine (PE) were the predominant polar lipids; anteiso-C 15 : 0 , iso-C 16 : 0 , and anteiso-C 17 : 0 were the major fatty acids. On the basis of these genotypic and phenotypic data, it is proposed that isolate Z022 T (=JCM 31053 T =CGMCC 4.7273 T ) should be classified in the genus Streptomyces as Streptomyces dangxiongensis sp. nov.

This study investigates the biodegradation of crude oil by a mixed culture of bacteria isolated from the Qinghai-Tibet plateau using gas chromatography-mass spectrometer (GC-MS) and the gravimetric method. The results showed that a mixed culture has a stronger ability to degrade hydrocarbon than pure cultures. Once both Nocardia soli Y48 and Rhodococcus erythropolis YF28-1 (8) were present in a culture, the culture demonstrated the highest crude oil removal efficiency of almost 100% after 10 days of incubation at 20 °C. Moreover, further analysis of the degradation mechanisms used by the above strains, which revealed utilization of different n-alkane substrates, indicated the diversity of evolution and variations in different strains, as well as the importance of multiple metabolic mechanisms for alkane degradation. Therefore, it is concluded that a mixed culture of Y48 and YF28-1 (8) strains can provide a more effective method for bioremediation of hydrocarbon-contaminated soil in permafrost regions.