Abstract:

Abstract:[Objective] The purpose of this study was to investigate the growth characteristics of Graesiella sp. and the influence of pH and Mn²⁺ in acidic manganese-containing extreme water environments. [Methods] The purified algae was isolated from an acid mine drainage in a pyrite mine and identified by morphological observation and 18S rRNA gene sequencing. Firstly, we investigated the effects of pH and typical metal ion Mn²⁺ concentration on its growth characteristics. Then, with the determination of algae biomass, photosynthetic pigment, malondialdehyde (MDA), reduced glutathione (GSH) content and the specific vitalities of superoxide dismutase (SOD) and ascorbate peroxidase (APX), we analyzed the physiological response mechanism of the algae to Mn²⁺ stress.[Results] The isolated algae strain was identified and named as Graesiella sp. MA1. The medium pH had a significant effect on the growth of Graesiella sp. MA1, and its minimum initial tolerance pH was 3.5. When the initial pH was 3.5 and the concentration of Mn²⁺ was 5, 30 and 55 mg/L, the biomass of algal decreased with the increase of Mn²⁺ concentration. The Mn²⁺ concentration in experimental groups also decreased by 28.62%, 21.90% and 18.84%, respectively, and the pH value increased to 5.7, 5.6 and 5.4, respectively, while the pH value in control group was 9.1. After 24 days, the chlorophyll a/b value of algal decreased with the increase of Mn²⁺ concentration, while the contents of MDA and GSH, and the specific activities of SOD and APX increased significantly. The results showed that Graesiella sp. isolated and purified from acidic mine drainage could tolerate both low pH and Mn²⁺ in a certain concentration range. Under such extreme environment, the intracellular antioxidant system of Graesiella sp. could reduce membrane lipid peroxidation, and thus play an important role in tolerance of heavy metal ions and detoxification. [Conclusion] Graesiella sp. MA1 can tolerate low pH and heavy metal ions and generate alkalinity, thus this study provides a theoretical basis for in situ bioremediation of acidic mine drainage by using Graesiella sp..

Abstract:[Objective] The Mariana Trench is the deepest site on earth with diverse extreme conditions (e.g., ultra-high hydrostatic pressure, low temperature and lack of light). It contains abundant microbial resources. The aim of this study is to explore aquatic microbial morphological characteristics and to mine culturable bacterial resources from different depths of the Mariana Trench. [Methods] Seawaters of seven depths (2-8727 m) from the Mariana Trench were collected. Aquatic microbial morphological characteristics were observed by atomic force microscopy and scanning electron microscopy. Combined with enrichment culture by using tangential flow system and high pressure device, two kinds of conventional media (1/5×2216E and 1/30×2216E) and six kinds of selective media (made up of combinations of organic carbon and nitrogen) were used for isolation and cultivation of aquatic bacteria. [Results] Various aquatic bacteria with different sizes (130 nm-1.5 μm) were found at different depths, dominated by spherical or rod-shaped bacteria. Particle-associated bacteria were common in surface seawaters and free-living bacteria were common in deep seawaters. Belonging to 3 phyla, 31 genera and 56 species, a total of 365 strains were identified. Gammaproteobacteria dominated (accounting for 62.7% of the total isolates) and its relative abundance in deep waters was higher than that in shallow waters. Alteromonas (21.8%) and Sulfitobacter (19.1%) were the most abundant genera, dominated in shallow water samples. The diluted 2216E and amino acid medium were found to have a better selectivity to Sulfitobacter. The selectivity of glucose-mannose medium (GM) or taurine-glycolic acid medium (TG) to rare bacteria was better. Seven strains (five species) were potential novel bacteria. In addition, 70 0.22-μm-passable strains (22 genera) and 33 piezotolerant strains (8 genera) were isolated, respectively. [Conclusion] There were rich diversities of different trophic, 0.22-μm-passable and piezotolerant bacteria and their morphologies at different water depths of the Mariana Trench. This study provided unique resources of aquatic microorganisms to investigate their trophic types, high-pressure adaptation mechanisms and biogeochemical roles in the Mariana Trench.

Abstract:Archaeoglobi is a class of thermophilic Archaea belonging to the Euryarchaeota, covering three genera:Archaeoglobus, Geoglobus and Ferroglobus. Archaeoglobus are all heterotrophic or chemolithotrophic sulfate reducers using sulfate, sulfite or thiosulfate as electron acceptors, with the formation of hydrogen sulfide as the end product. Geoglobus and Ferroglobus may reduce both nitrate and ferric irons. Archaeoglobi are strictly thermophilic anaerobes, which are widely distributed the natural environments and are dominant in some environments, such as oceans, terrestrial hydrothermal systems and terrain environments. Due to wide geographic distribution and diverse metabolic potential, and activity perform in metabolism of various elements, Archaeoglobi may play an important role in the global element cycle and has become a scenic spot for microbial ecology research. Members of Archaeoglobi phylogenetically close to methanogenic Euryarchaeota in their evolutionary history; on the other hand, fuctional genes of archaeal type Wood-Ljungdahl (WL) pathway are present in partial Archaeoglobi genomes, even the newest studies suggest that uncultured Archaeoglobi genomes contain complete mathanogensis pathway, these evidences provides new insights into the evolutionary transition from methanogenic archaea to sulfate-reducing bacterial. This review collected the information of the physiological, biochemical characteristics and genome analysis of eleven reported Archaeoglobi strains, summarized the metabolic characteristics of those isolated Archaeoglobi in terms of the aspects of chemolithoautotrophic, chemotherapeutic, sulfite reduction, acetogenesis, methanogenesis, and analyzed the potential metabolic functions of uncultured Archaeoglobi genomes based on the metagenomic information, which may provide theoretical guidance for the further isolation and cultivation of this kind of uncultured anaerobic microorganisms.

Abstract:Atribacteria is a new phylum covering the lineages of OP9 and JS1. Most of the members are uncultivated microorganisms, which are distributed widely in the natural environments and dominant in some environments, such as deep marine sediments, geothermal springs, and oil reservoirs. Studies based on genomic information indicate that Atribacteria are strictly anaerobic microorganisms and have the ability to degrade sugars, organic acids, and short chain n-alkanes, suggesting that they may play a key role in subsurface carbon cycling. However, due to the lack of representative pure culture strains, the physiological and biochemical functions of Atribacteria remain to be verified. In this paper, the discovery and development history of Atribacteria, and their environmental distribution and diversity were reviewed. The three proposed metabolic modes of Atribacteria were analyzed and future research directions in this field were also discussed.

Abstract:Ectoine[(S)-2-methyl-1,4,5,6-tetrahydropyrimidine-4-carboxylic acid] and its hydroxyectoine[(S,S)-2-methyl-5-hydroxy-1,4,5,6-tetrahydropyrimidine-4-carboxylic acid] play a crucial role in the salt adaptation mechanism in halophilic bacteria. The biosynthesis of ectoine is catalyzed by three enzymes:L-diaminobutyric acid aminotransferase (EctB), L-diaminobutyric acid acetyltransferase (EctA), and ectoine synthase (EctC). Using L-Aspartate-β-semialdehyde (ASA) as the substrate, L-2,4-diaminobutyrate (DABA), N-γ-Acetyl-L-2,4-diaminobutyrate (ADABA) and ectoine are biosynthesized successively. Hydroxyectoine is produced by the hydroxylation of ectoine with ectoine hydroxylase (EctD). In normal, the ectoine synthesis genes exist in the form of ectABC gene cluster, while the hydroxyectoine synthesis gene ectD exists alone. The functional expression of ectoine synthesis genes in microbe and genetically modified cash crops can improve their resistance to extreme conditions such as hyperosmotic stress, alkali stress, and drought. The expression of hydroxyectoine synthesis gene also can enhance the host's ability to resist heat and drought. The biological functions and potential applications of ectoines have become a frontier hotspot.

Abstract:As a common prokaryote in the deep subsurface biosphere, archaea are widely distributed in various marine sedimentary habitats and play important roles in the biogeochemical cycles. Due to the differences in physiological adaptabilities of different archaeal groups to environmental conditions, they constitute anaerobic microbial ecosystem and aerobic microbial ecosystem in coastal and open ocean sediments, respectively. In this paper, we compare the archaeal community structure in two different dimensions:nearshore and ocean, sediment and overlying water, and discuss the distribution, metabolism and environmental adaptation mechanism of common archaea (Thaumarchaeota, Bathyarchaeota, Thermoprofundales, Asgard, Woesearchaeota) in deep subsurface biosphere. We summary the research progresses of archaea in the deep subsurface biosphere. We also put forward several future research directions and key points of archaea for references.

Abstract:[Objective] The aim of this study was to investigate the effect of Zn on the Fe(II)-driven denitrification and mineralization by a denitrifying bacterium, Pseudomonas stutzeri LS-2 under neutral anaerobic conditions. The result will extend our knowledge of microbial Fe(II)-driven denitrification and its environmental behavior under anaerobic conditions. [Methods] We designed the microbial driven Fe(II) oxidation with a series of Zn(II) concentration, detected the rates of Fe(II) oxidation and nitrate reduction, and characterized the mineralogy under different conditions.[Results] The activity of the Fe(II)-oxidizing denitrifying culture was affected by the presence of Zn. The results showed that the presence of Zn inhibited the rates of nitrate reduction and Fe(II) oxidation. A low inhibition was observed at initial concentrations of Zn(II) from 0.15 to 2 mmol/L. When Zn(II) was supplemented up to 4 mmol/L, the higher inhibition was observed. In addition, the minerals during nitrate-reducing Fe(II) oxidation can efficiently remove the supplemented Zn(II), including co-precipitation, sorption and isomorphous substitution. The nitrate-reducing Fe(II) oxidation resulted in the formation of a mixture of Fe(III) minerals in the presence of different Zn(II) concentrations. The use of low Zn(II) concentration cultures enhanced the formation of lepidocrocite, while the higher concentration resulted in the formation of franklinite. [Conclusion] The results clarified the effect of Zn on the nitrate-reducing Fe(II) oxidation process, including the rates of nitrate reduction and Fe(II) oxidation, and the mineral structure. These findings increase the understanding of the relationship between the heavy metals and the bacteria-driven Fe(II) oxidation and denitrification and provide scientific support for remediation of contaminated soils by heavy metals.

Abstract:[Objective] Microbial denitrification is the essential process to transform nitrate into nitrogen gas in estuarine environment. [Methods] In the present study, we investigated the diversity and distribution of the nirS-type and nirK-type denitrifying microbial communities in the surface sediments of the hypoxic zone near the Changjiang Estuary and in the East China Sea by Illumina MiSeq sequencing approach. [Results] A total of 346 nirS-type and 267 nirK-type Operational Taxonomic Units were detected. Environmental characteristics of sampling site and cluster analysis of nirS and nirK divided all Operational Taxonomic Units into hypoxic, southern and deep-water groups, and the samples from the deep-water group had the highest diversity of nirS functional genes. Furthermore, the dominant Operational Taxonomic Units phylogenetically formed several clusters, representing by Operational Taxonomic Units from distinct groups. All the dominant Operational Taxonomic Units were uncultured and some of them were first retrieved. Likewise, nirS gene was more adaptable to the hypoxic condition.[Conclusion] Our results indicate that widespread denitrifying microorganisms play a critical role in nitrogen cycle in the estuarine sediments.

Abstract:[Objective] The study aims to investigate the acetylene as electron acceptor anaerobic sulfur oxidation mediated by the chemoautotrophic sulfur oxidizing bacterium Halothiobacillus sp. LS2. [Methods] Cell growth was measured by dilution coating method, SO₄^2- and S₂O₃^2- in sulfur oxidation kinetics were measured by ion chromatograph, and gene expression was analyzed based on relative fluorescence quantitative method. [Results] Although strain LS2 obtained high maximum reaction rate V_max with O₂ as electron acceptor, its growth with acetylene as electron acceptor under anaerobic condition was twice that with O₂ as electron acceptor, and the expression of soxB gene was significantly higher than that with O₂ as electron acceptor. [Conclusion] These results indicated that strain LS2 can not only complete anaerobic sulfur oxidation with acetylene as electron acceptor, but also has higher productivity efficiency than aerobic sulfur oxidation. In this study, an anaerobic sulfur oxidation reaction using acetylene as electron acceptor was proposed for the first time, which is of positive significance to the sulfur biogeochemical cycle.

Abstract:[Objective] This study aimed to investigate the characteristics of microbial Fe(III) reduction under the condition of adding electron shuttles. [Methods] The effects of anthraquinone-2-sulfonic acid (AQS) and riboflavin on cell growth and Fe(II) concentration by a fermenting bacterium Clostridium butyricum LQ25 were investigated. [Results] The results showed that Fe(II) concentrations were significantly different under the series of electron shuttle concentrations, Fe(OH)₃ as electron acceptor and glucose as electron donor. The highest Fe(II) concentration under Fe(III)-reducing conditions by strain LQ25 was 12.95±0.08 mg/L at the AQS concentration of 0.5 mmol/L, which was 88% higher compared to the control without added AQS. When riboflavin was added as the electron shuttle, Fe(II) concentration was 11.06±0.04 mg/L at the riboflavin concentration of 100 mg/L, which was 61% higher compared to the control. The adding of electron shuttles could change the concentration of butyrate and acetic acid in fermentation products by strain LQ25, with the increasing of relative content of acetic acid. [Conclusion] The adding of electron shuttle AQS and riboflavin could significantly promote microbial Fe(III) reduction, which will provide the experimental evidence for the mechanism of extracellular electron transfer by fermentative Fe(III)-reducing bacteria.

Abstract:Under anaerobic conditions, microorganisms produce methane (CH₄) through anaerobic metabolism. The derived anaerobic digestion technology realizes energy recovery. The key step of CH₄ production is to stimulate the effective electron transfer between fermentation bacteria and methanogens. Electroactive microorganisms can replace the traditional hydrogen/formate to achieve direct interspecific electron transfer, with higher electron transfer efficiency. The addition of conductive materials promotes direct interspecific electron transfer and increase the yield of CH₄, which is a more effective way to enhance the electron transfer. Based on the development and mechanism of direct interspecific electron transfer, carbon-based and iron-based conductive materials that promote direct interspecific electron transfer are comprehensively reviewed. The structural characteristics, electron transfer mechanism, enhanced CH₄ production and intermediate consumption by these materials are systematically summarized. This review aims to provides reference for the research of conductive materials promoting direct interspecific electron transfer, and to explore the possible research direction in future.

Abstract:Autotrophic microorganisms can use inorganic carbon as a carbon source to synthesize their own nutrients, which have strong environmental adaptability and play an important role in the carbon fixation of the soil in the karst area rich in calcium and alkali. This review focuses on the process of autotrophic carbon fixation driven by soil microorganisms, the carbon fixing functional microorganisms in karst soils, and the molecular mechanisms of soil microbial autotrophic carbon fixation and their eco-environmental effects in karst area. The key scientific problems to be solved are also proposed. It provides a reference for further study and understanding the carbon sequestration process and its mechanisms driven by autotrophic microorganisms in the soil ecosystem of karst areas, improving the carbon sequestration potential of soil in karst areas, developing the protection and restoration strategies of karst ecological environment, and coping with the risk of soil degradation caused by climate change and human activities.

Abstract:[Objective] This study aims to investigate the effects of cell density and Fe(II) concentrations on the kinetics and secondary minerals during nitrate reduction and Fe(II) oxidation by Acidovorax sp. strain BoFeN1 under anoxic condition. [Methods] The anaerobic culture system containing strain BoFeN1, nitrate and Fe(II) was set up; the concentrations of nitrate, nitrite, acetate, Fe(II) were determined with the use of ion chromatography and microplate reader; and the mineralogy and morphology of the secondary minerals were characterized by using XRD and SEM. [Results] In the system of microbially-mediated nitrate (NO₃^-) reduction coupled with Fe(II) oxidation, high cell density substantially promoted nitrate reduction and Fe(II) oxidation. With low cell density, the Fe(II) oxidation reaction rate and extent of reaction declined for the high concentrations of Fe(II), while no obvious effect was observed in the high cell density. The higher crystallinity of secondary minerals was generated and inhibited the nitrate reduction to some extent. In the system of microbially-mediated nitrite (NO₂^-) reduction coupled with Fe(II) oxidation, the high cell density and Fe(II) concentration promoted the nitrite reduction, but the Fe(II) oxidation had a strong inhibitory effect on the microbial reduction of nitrite, and the types and crystallinity of secondary minerals were mainly affected by the concentration of Fe(II). [Conclusion] Biological denitrification is the main process controlling nitrate reduction; nitrite reduction was contributed by both of the biological and chemical denitrification; biological and chemical denitrification are the main reasons for Fe(II) oxidation and secondary mineral formation in the nitrate system; but chemical denitrification is the main reason for Fe(II) oxidation and secondary mineral formation in the nitrite system. This study can provide basic data and theoretical support for the coupling reactions of iron and nitrogen mediated by anaerobic microorganisms.

Abstract:Nitrous oxide (N₂O) is a potent greenhouse gas which generates approximately 300-fold powerful greenhouse effect than carbon dioxide (CO₂) and is one of the main compounds that causing ozone-depletion in stratospheric. Nitrification and denitrification of microorganism is the most important path for N₂O production. It has long been considered that denitrification only occurred in prokaryote until in 1970's two Japanese scientists found that fungi like Fusarium oxysporum also had the ability to denitrifying. Unlike bacterial denitrification (bDNF), N₂O is the end-product of fungal denitrification process (fDNF) due to the lack of nitrous oxide reductase (nosZ). It means that fDNF usually produce more N₂O than bDNF. Recent studies have proved that fDNF contributed over 50% of the total N₂O emission in soil and 70% in high permeable sediments thus it shouldn't be neglect. In this review, we elucidated the species composition, denitrification mechanism, measurements and N₂O-contribution of fDNF base on the current studies. At last, we discussed some problems remain to be solved on the research of fDNF and suggest prospects for future studies.

Abstract:Sulfur is an essential component of all creatures and one of indispensable nutrient elements for living organisms. Sulfur-redox microorganisms are numerous, widely distributed, and have diverse metabolic pathways, while the balance between sulfur compounds depends on various sulfur-transforming reactions and metabolism pathways in the microbial metabolism network. In addition, the sulfur cycle is closely related to the carbon and nitrogen cycles and plays a vital role in the earth's ecological cycle. In this review, we summarize current research progress of the microbial sulfur-cycling network, including the involved microorganisms, biochemical pathways, their environmental implications, and industrial applications, etc., which helps to understand the sulfur cycle existing in the natural and artificial ecological environment and provides a solid theoretical basis and application solutions for controlling the increase and decrease of sulfur in industrial and agricultural production.

Abstract:Oxygen minimum zones (OMZs) are characterized with special hydrodynamic and vertical oxygen profiles and are the main areas of nitrogen loss through fascinating biogeochemical reactions. The presence of OMZs affects the abundance, diversity, distribution, and respiration of plankton. There are some extensive reaction in OMZs, such as denitrification, anammox, anaerobic oxidation of methane, and cryptic anaerobic sulfide oxidation, which are the key parts of the ocean material cycle. Under the influence of human activities and global warming, the area of the OMZs is also expanding. The changes of the ocean hypoxic environment can be determined by microbial diversity and the stability of the community structure, so it is necessary to understand the diversity level of the area. With limited understanding of the biogeochemical cycle and microbial diversity in OMZs, the comprehensive discussion on the biogeochemical, microbiological and ecological features of OMZs remains to be rare. Particularly, there are still many gap knowledge on the microbial activity, community structure stability and metabolic network in these hypoxic environments of the world's ocean. This paper summarized the distribution and biogeochemical features of these marine hypoxic environments, and particularly discussed nutrient cycling processes and microbial communities in OMZs. Finally, it identified the current information gap and pointed out the future research directions in these interesting ocean habitats.

Abstract:As the important part of earth's critical zone, groundwater system provides special habitat environment and complex conditions for microorganisms, which further evolves complicated biogeochemical processes. In the last decades, with the developing and inter-crossing of new technologies and multi-discipline, important progresses have been obtained in the fields of microbial functional communities and biogeochemical cycle in groundwater. This review mainly describes the ecological niche of functional microbial communities, introduces the new findings in microbially-mediated geochemical cycling, microbial remediation and numerical simulation of the biogeochemical processes in groundwater system, including the discovery of new species, the coupling of various element cycles, and the latest technology of in-situ remediation of contaminated groundwater. This work also prospects the related future research direction including the microbial "dark matters" and "dark processes", bioremediation, medical geology, and multidisciplinary integration in groundwater system.

Abstract:[Objective] A SRB strain Desulfotomaculum reducens ZTS1 isolated from enrichment from coal mine water was used to anaerobically degrade Yunnan Zhaotong lignite, and the physicochemical properties of which before and after degradation with SRB strain were analyzed. [Methods] Mineral components, organic functional groups, surface morphology, pore structure changes of lignite minerals before and after anaerobic degradation with SRB were studied by proximate and ultimate analysis, X-ray diffraction, Fourier transform infared spectromotry, Scanning electron microscopy and low temperature liquid nitrogen adsorption method. [Results] After anaerobic degradation by D. reducens ZTS1, the ash and volatiles of lignite decreased slightly, the contents of carbon, nitrogen and sulfur decreased, while the content of oxygen increased. The sodium thiosulfate disappeared in the residual coal. FT-IR results showed that the methyl and methylene groups on the long chain hydrocarbon of lignite increased, while the free hydroxyl group decreased. With the increase of coal surface roughness, the pore size of small pore and the specific surface area of pore size Increases.[Conclusion] D. reducens ZTS1 can anaerobically degrade Zhaotong lignite, and change the physicochemical properties of the coal.

Abstract:[Objective] The urease-producing fungus was screened from the sediment of mangrove in Luoyuan Bay. Study the best tolerance concentration of strains to La(Ⅲ), and use the urease-producing properties of the strains to induce mineralization and recovery of La(Ⅲ). It was expected to provide strain resources and application technology references for resource recovery of rare earth ions La(Ⅲ). [Methods] The urease-producing and La-resistant strains were isolated, screened and purified from the mangrove sediment of Luoyuan Bay, and identification was made through ITS rDNA gene sequence analysis. Meanwhile, the mechanisms of recover La(Ⅲ) were discussed by XRD, SEM-Mapping and FT-IR analysis. [Results] A urease-producing and high-concentration La(Ⅲ)-tolerant fungus was obtained by isolation and purification, which was identified as Fusarium oxysporum-FZU-07. Strain FZU-07 has a strong ability to recovery of La(Ⅲ), and the maximum La(Ⅲ) tolerance concentration is 400 mg/L. The recovery efficiency of strain FZU-07 for La(Ⅲ) adsorption was 46.19%, and the recovery efficiency could be increased to 99.16% under the condition of induced mineralization. FT-IR and SEM-Mapping analysis showed that the functional group of amido, hydroxyl, carbonyl and phosphate on the cell surface played a principal role to adsorption of La(Ⅲ). XRD and SEM-Mapping analysis showed that induction of mineralization is through the urease-producing characteristics of the strain, which decomposes urea to produce carbonic acid, and combines with calcium ions to form vaterite crystal (calcium carbonate). La(Ⅲ) was removed via incorporation into the lattice of calcium carbonate particles and formed mixed crystal. [Conclusion] The strain FZU-07 was identified as Fusarium oxysporum, with urease-producing properties and strong ability to induce mineralization and recovery of La(Ⅲ). The results indicate that the microbial induced calcium carbonate precipitation method is a feasible and eco-friendly technology for the recovering rare earth ions.

Abstract:Geological sequestration is the process that injects carbon dioxide (CO₂) captured from an industrial or energy-related source into deep subsurface rock formations for long-term storage, which is one of the viable and feasible means to reduce greenhouse gas emission and sequester CO₂ permanently. Injecting massive amounts of CO₂ into the deep geological formations may cause significant changes to subsurface that abundant microbiota use as habitats, and hence influence microbial activity and microbial structure. Thus, geological sequestration of CO₂ will directly or indirectly affect the subsurface biogeochemical processes. When exposed to short-or long-term stresses by super-critical phase CO₂(scCO₂), adaptive evolution of the deep subsurface microorganisms may influence the fate and transport of the sequestered CO₂. This review focuses on the latest progress in the domestic and international studies and the current understandings about the scCO₂-water-microbe-mineral interactions in the subsurface environments impacted by CO₂ geological sequestration. In addition, this paper also includes a discussion about the potential to enhance CO₂ stabilization and transformation to the value-added products by the deep subsurface microorganisms.

Abstract:[Objective] To reveal the diversity of bacterial communities on the surface of lithium ores and weathering products on the ground. [Methods] We performed high-throughput sequencing for the amplification of bacterial 16S rRNA fragments, and analyzed the composition, diversity and functional properties of bacterial communities on the terrestrial surface of different lithium ores and their weathering products.[Results] The bacterial community diversity on the surface of pegmatite-type lithium ores and its weathering products in Nanyangshan, Lushi, Henan Province was different from that on the granite-type lithium ores in Yichun, Jiangxi Province. The OTUs of Nanyangshan pegmatite ores and weathering products, Yichun granite ores surface and weathering products (NK-1, NK-1F, YK-1, YK-1F, YK-2, YK-2F, YK-3) were 1010, 540, 835, 828, 1117, 974 and 604, respectively. The difference was significantly related to the different mineral composition. Both mines had their own dominant microorganisms at the phylum level, and Actinobacteria and Proteobacteria were their dominant phyla. At the same time, there were significant differences in the composition of microbial communities in the two mines (P<0.05), and the differences in weathering product samples from different mines were particularly significant (P<0.001). At the genus level, the relative abundance of pegmatite ore NK-1 dominant genera (greater than 5%) was Sphingomonas, Massilia; weathered product NK-1F was Paenibacillus, Bacillus, Massilia. The dominant genera of the weathered ore YK-1F was Blastococcus, Candidatus-Solibacter, Noviherbaspirillum, Burkholderia-Caballeronia-Paraburkholderia, YK-2 was unidentified-Chloroplast, while the granite ores YK-2F and YK-3 were Kitasatospora, Massilia 1174-901-12 and Methylobacterium, respectively. The functional annotations of ore and weathered material samples from different mines all involved six metabolic pathways, including metabolism, genetic information processing, and environmental information processing. [Conclusion] 16S rRNA high-throughput sequencing revealed that there were differences in bacterial diversity of lithium ores and its weathering products in different mines, each with unique dominant groups. The differences in bacterial composition, diversity and functional properties between samples closely associated with the mineral composition, weathering degree, and the geographical location. The revealed potential relationships between the elemental geochemical functions of the dominant microbial groups and the surface weathering of lithium-containing minerals provides new data for studies on the microbial ecological distribution and development of microbial resources.

Abstract:Karst soil is an important part of karst ecosystem, and its parent material, carbonate rock, can successively evolve into black calcareous soil, brown calcareous soil, yellow calcareous soil and red calcareous soil under the comprehensive effect of climate, topography, time and biology. [Objective] To better understand the response of soil bacterial community to calcareous soil at different succession stages, which can provide the basic references for rocky desertification control and soil erosion control in karst area. [Methods] The contents of SOC, TN and TP, and the abundance and diversity of culturable bacteria in calcareous soils (black, brown, yellow and red) were determined. [Results] The contents of soil SOC and TN at different succession stages were in the order of black calcareous soil > brown calcareous soil > yellow calcareous soil > red calcareous soil. The content of TP was highest in black calcareous soil and lowest in red calcareous soil. A total of 144 strains of bacteria were isolated and purified, and R2A medium was the suitable medium. Then, the bacterial strains were classified into Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. Pseudomonas, Cupriavidus and Bacillus were the dominant genera of culturable bacteria. At the genus level, the most strains were isolated from the black calcareous soil, and the dominant genera such as Arenimonas, Thermomonas, Achromobacter and Brevibacillus appeared. In the early succession stages, a large number of bacteria involved in carbon, nitrogen and phosphorus cycling appeared. [Conclusion] Based on the characteristics of parent material carbonate rock, black calcareous soil rich in organic matter is formed under the action of bacteria participating in carbon, nitrogen and phosphorus cycle. The physicochemical properties and culturable bacterial diversity of karst limestone soil decreased with the increase of leaching degree of limestone soil.

Abstract:[Objective] To explore the diversity and community compositions of onshore soil and plant endophytic fungi in the soil zones at different exposure periods and their response to continuous lake desiccation in the Aral Sea. [Methods] Soil samples were collected from farshore (exposed before 1970) towards the present shoreline in the Aral Sea, followed by geochemistry and mineralogy analysis. At the same time, soil samples and dominant aboveground plants from different onshore soil zones were collected, and their fungal diversity were analyzed by ITS gene high-throughput sequencing. The fungal response to lake desiccation (such as salinity, mineralogy and plant species) were explored. [Results] The results showed that the continuously exposed lake bed formed an increasing gradient of total soluble salts:E48 (exposed before 1970, total soluble salts (in abbr. TSS):0.5±0.5 g/L);E38 (exposed before 1980, TSS:0.4±0.2 g/L);E28 (exposed before 1990, TSS:23.3±2.1 g/L);E18 (exposed before 2000, TSS:23.7±7.5 g/L);E9 (exposed before 2009, TSS:71.3±6.1 g/L);E1 (exposed in 2017, TSS:62.9±10.7 g/L); E0 (the present shoreline in 2018, TSS:69.9±8.3 g/L). These soil zones were inhabited by different plants:Haloxylon ammodendron were dominated in the E38 and E28 zones; Chenopodium album were dominated in the E28, E19 and E9 zones; and no visible plants were found in the E1 and E0 zones. In addition, the mineralogical composition varied among different soil zones:the contents of clay mineral and evaporites generally increased from farshore towards the present shoreline of the Aral Sea, while the content of carbonates gradually decreased. The dominant fungal communities (>5%) in the studied soil samples were Eurotiomycetes, Sordariomycetes, Leotiomycetes, Dothideomycetes, Ustilaginomycotina and Agaricomycetes, and were clustered by plant species richness. While a large number of unknown fugal species (>97.8%) were dominated in the endophytic fungal communities, and were clustered by plant species. Linear regression showed that the fungal community differences in the soil sample from different onshore soil zones had a significant (R²=0.32, P<0.05) correlation with the exposure time difference, whereas there was no significant correlation with the difference in total soluble salts. In addition, there was no significant difference between the plant endophytic fungal community difference and exposure time distance and total soluble salts difference. Mantel test showed that fungal communities in different soil zones had significant (P<0.05) correlations with plant species richness and dolomite, calcite, microcline and gypsum. Among them, plant species richness and calcite were the most important factors influencing on soil fungal communities. There was a significant (P<0.05) correlation between the plant endophytic fungal community and calcite. [Conclusion] The community compositions of soil fungi and plant endophytic fungi in different Aral Sea soil zones show temporal and spatial variations, which could be ascribed to plant species (richness) and specific mineral compositions, but not significantly correlated with total soluble salts.

Abstract:[Objective] In this study, the main goal was to explore the spatial heterogeneity and driving factors of soil microbial populations from Chlorobi phylum in different vegetation zones from the middle reach of Xilin River Basin. [Methods] We selected the typical riparian vegetation zones along the landward direction from the riverbed center (BC) without vegetation zone to the river terrace. These vegetation zones included Juncellus serotinus-dominated marsh plant communities from riverbed side (BS), Juncus effusus-dominated marsh meadow plant communities from low floodplain (LF), Potentilla anserina-dominated meadow plant communities from high floodplain (HF), Leymus chinensis grassland on the river terrace (LT) and Stipa grandis grassland on a slope in the hilly zone (HT). Meanwhile, we collected 0-10 cm soil samples and analyzed the spatial distribution characteristics, abundance and composition of soil Chlorobi communities based on 16S rRNA gene high-throughput sequencing. To explore the environmental factors driving the spatial heterogeneity of soil microbial communities from Chlorobi phylum, we detected the soil physiochemical factors.[Results] Nine populations from the orders Chlorobiales and Ignavibacteriales were detected at genus level. The highest relative abundance of Chlorobiales1, Chlorobiales2, Chlorobiales6, Ignavibacteriales7 and Ignavibacteriales9 were less than 0.40%, while those of the other four populations from order Ignavibacteriales ranged from 0.54% to 1.06%. The relative abundances of both Chlorobiales1 and Chlorobiales2 in HF, LT and HT were higher than those in BS (P<0.05). The abundance of Chlorobiales1 was significantly positively correlated with pH and total organic carbon content (P<0.01), while that of Chlorobiales2 was significantly positively correlated with the content of clay and silt particles (P<0.01). The relative abundances of Chlorobiales6 and Ignavibacteriales8 in BS were higher than those of the other vegetation zones (P<0.05). Their abundances were significantly positively correlated with ammonia nitrogen content (P<0.01). Variation partitioning analysis (VPA) showed that soil water content accounted for 65.7% of the spatial variation of microbial communities from Chlorobi phylum. [Conclusion] In the Xilin River Basin, the populations of Chlorobi communities from different vegetation zones demonstrated obvious spatial heterogeneity. Water content was the main driving factor of the spatial heterogeneity of the soil microbial communities from Chlorobi phylum in different vegetation zones.

Abstract:Mollisol soil is one of the soil types with high content of organic matter and fertility, climate change will significantly change the structure and potential interactions of mollisol soils microbial communities. [Objective] This study is aimed to explore the microbial community structure and succession characteristics of mollisol soils under increasing hydrothermal conditions. [Methods] Based on a soil transplantation expriment, 16S rRNA high-throughput sequencing was used to analyze the bacterial community structure of mollisol soils (in-situ, warming1 and warming2); CoNet was used to construct the microbial co-occurrence networks and identify the hub microbes, structural equation models and correlation analysis were used to explore the direct and indirect relationships between soil properties, microbial co-occurrence networks, and diversity under the increasing precipitation and temperature conditions. [Results] We found that mollisol soils were dominated by Verrucomicrobia, Proteobacteria, Acidobacteria, and Actinobacteria. Soil transplantation simulating climate change altered the patterns of microbial co-occurrence network with increased negative edge percentage and different network sizes. Climatic factors affected the taxonomic diversity directly and indirectly from altering the microbial interactions. The strengthen of negative interactions in communities directly induced the loss of soil organic carbon. [Conclusion] The increasing hydrothermal conditions will significantly change the microbial community co-occurrence network of mollisol soils, and the response of network hub microbes will be more sensitive.

Abstract:[Objective] In this paper, our main goal was to clarify the spatial heterogeneity and environmental driver of Verrucomicrobial populations from different landscape components in Xilin River basin. [Methods] Based on the difference of habitat and microtopography, we selected the landscape components of aquatic riverbed center, riverbed edge and oxbow lakebed, hygric low floodplain and high floodplain, xeric low terrace and high terrace. Then we employed 16S rRNA gene high-throughput sequencing to study the landscape heterogeneity of soil Verrucomicrobial populations from different landscape components. We also explored environmental variables driving landscape heterogeneity of soil Verrucomicrobial populations combining with environmental variables (e.g. soil moisture). [Results] Spatial distribution of Verrucomicrobial populations showed convergent characteristics within landscape components and divergent characteristics between landscape components. The members of Chthoniobacter from Spartobacteria class and Prosthecobacter from Verrucomicrobiae class were mainly distributed in the aquatic riverbed center (RC), showing significant positive correlation with sand particle (P<0.05). Those of Opitutae class were mainly distributed in hygric floodplain, showing positive correlation with pH (P<0.05 or P>0.05). DA101_soil_group members of Spartobacteria class were mainly distributed in the xeric terrace, showing significant positive correlation with salinity and nutrients (P<0.01). Variation partitioning analyses of single, two groups and three groups of environmental variables showed that moisture, salinity and pH explained 24.7% & 21.4%, 24.3% & 22.7% and 23.1% & 20.8% of landscape heterogeneity of Verrucomicrobial populations, respectively. [Conclusion] Verrucomicrobial populations demonstrated landscape heterogeneity in Xilin River basin. Members of Chthoniobacter and Prosthecobacter were indicators of the riverbed center landscape component, DA101_soil_group was the indicator of the terrace landscape components. The combination of moisture, salinity with pH co-drove the landscape heterogeneity of Verrucomicrobial populations.

Abstract:In all earth ecosystems, the coastal zone is one of the most active areas in multiple biogeochemical cycles. As the major driver of natural biogeochemical cycles, microbial community in coastal ecosystems is of vital importance to the material transformation and energy flow in this critical zone. In this review, we summarized the responses and feedbacks of microbial community to the circumstances of climate change and anthropogenic disturbance in typical coastal areas, such as coastal wetlands, offshore waters, seagrass meadows and kelp forests. It was mainly elucidated around microbes-involved carbon and nitrogen cycles, and greenhouse gases emission to reveal the microbial mechanisms on coastal ecosystem functioning and maintenance. Finally, some preliminary prospects are provided for the future studies of microbial ecology in the coastal zones.