Total Community Research Articles

Cyberbullying among University Students during the E-learning Transformation Era: The Role of the Student-Teacher Relationship and Virtual Classroom Community

Purpose: The current study assesses cyberbullying among university students and explores the role of the student-teacher relationship and virtual classroom community. Methods: A descriptive exploratory study on four randomly selected colleges at Damanhour University/Egypt. Participants were recruited conveniently using an equal allocation of 150 students/college (600 students). The European Cyberbullying Intervention Project Questionnaire (ECIPQ), Rovai's Classroom Community Scale (RCCS), and the Student Version of The Teacher-Student Relationship Inventory (S-STRI) were used for data collection. Results: Low cyber victimization was reported by 66.5% of the students, while 39.8% reported low cyberaggression behaviors. The highest percent reported average virtual class connectedness (77.3%), learning experience (70.3%), and overall virtual classroom community (80.8%). Besides, highly satisfying teacher relationships (82.3%); average (38.8%) and low (35.8%) instrumental help; low conflict (68.0%); and average total teacher-student relationship (70.5%). Regression analysis revealed that the increased scores of the total teacher-student relationship scale (<i>p</i><0.05) with its two domains [satisfaction and instrumental help (<i>p</i><0.01)] and the total classroom community scale (<i>p</i><0.05) with its domains [connectedness (<i>p</i><0.01) and learning experience (<i>p</i><0.05)] decreased the likelihood of cyber victimization and cyberaggression. However, perceived conflicting teacher relationships increased the likelihood of cyber victimization (<i>p</i><0.05) and cyberaggression (<i>p</i><0.01).Conclusion: Cyberbullying is a concern among university students, and the students’ perceived nature of their relationships with their teachers and sense of virtual classroom community play a pivotal role in shaping their involvement in cyberaggression and exposure to cyber victimization. Thus, developing mass media campaigns to enhance awareness about cyberbullying and cyber civility regulations is recommended.

Response of microalgae size-class structure to nutrients differences in northern Yellow Sea, China.

Marine phytoplankton size-class structure affects ecological functions and shellfish culture. We use high-throughput sequencing and size-fractioned grading techniques to identify and analyze responses of phytoplankton differences in environmental variables at Donggang, northern Yellow Sea (high inorganic nitrogen (DIN)) and Changhai (low DIN) for 2021. The main environmental variables that correlate with differences in the proportional contributions of pico-, nano-, and microphytoplankton to the total phytoplankton community are inorganic phosphorus (DIP), nitrite to inorganic nitrogen ratio (NO2/dissolved inorganic nitrogen (DIN)), and ammonia nitrogen to inorganic nitrogen ratio (NH4/DIN), respectively. DIN, which contributes most to environmental differences, mainly positively correlates with changes in picophytoplankton biomass in high DIN waters. Nitrite (NO2) correlates mostly with changes in the proportional contribution of microphytoplankton in high DIN waters and nanophytoplankton in low DIN waters, and negatively correlates with changes in the biomass and proportional representation of microphytoplankton in low DIN waters. For near-shore phosphorus-limited waters, an increase in DIN may increase total microalgal biomass, but proportions of microphytoplankton may not increase; for high DIN waters, an increase in DIP may increase proportions of microphytoplankton, while for low DIN waters, an increase in DIP may preferentially increase proportions of picophytoplankton and nanophytoplankton. Picophytoplankton contributed little to the growth of two commercially cultured filter-feeding shellfish, Ruditapes philippinarum and Mizuhopecten yessoensis.

Groundwater flow system and microbial dynamics of groundwater in a headwater catchment

Besides surface water systems, groundwater also provides a habitat for prokaryotes. The prokaryotes inhabiting groundwater are affected by the environment that they grow in. Owing to the environmental specificity, some prokaryotic community constituents might thus provide information on local subsurface growth conditions as well as advective transport processes in case of rapid dislocation. In this study, we investigated the spatiotemporal distribution of prokaryotic communities in groundwater and spring water to examine the relationship between the groundwater flow system and prokaryotic dynamics. We sampled and monitored the water in a mountainous forested catchment in Kawamata Town, Fukushima Prefecture, Japan. Seven piezometers and a spring located across a ridge, hillslope, and valley were monitored. Prokaryotic information, such as density estimated by total direct counting, community constituents and diversity using the next-generation sequencing methods, physicochemical parameters, general water quality, and groundwater mean residence time using sulfur hexafluoride (SF6) were analyzed. Our results showed that the mean residence time of groundwater and spring water ranged from less than 1 year to 30 years. The prokaryotic density ranged from 5.37 × 103cells/mL to 2.01 × 106cells/mL (n = 60). As the mean residence time increased, the density of prokaryotes in the shallow subsurface also increased, whereas that of the prokaryotes in the deep subsurface decreased. The contribution of deep groundwater to the examined groundwater is inferred using the groundwater residence time and prokaryotic information, including density and specific constituents. The stable water isotopes did not suggest the deep groundwater contribution to the groundwater at the ridge in the high-rainfall period; however, the SiO2 concentration indicated that. Elucidating the prokaryotic information along with existing hydrological tracers may enable a better understanding of groundwater flow processes.

Biodiversity and Potential Activity of Microorganisms in Underground Gas Storage Horizons

The share of molecular hydrogen as a source of “green energy” is currently significantly increasing. It is proposed to use existing underground natural gas storage facilities to store large volumes of hydrogen. In Russia, depleted oil and gas fields (DOGFs) and deep aquifers are used for natural gas storage. The purpose of this work was to determine microbial diversity in DOGF and deep aquifers by cultural and 16S rRNA gene-based approaches and the effect of H2 on the growth of microorganisms from the underground gas storage (UGS) horizons. The composition of the microbial community inhabiting the formation water of the Peschano–Umetskoe depleted oil and gas reservoir was typical for microbial communities of oil reservoirs and included bacteria of the phyla Bacillota (Dethiosulfatibacter, Defluviitalea, Acetobacterium, Syntrophobotulus), Actinobacteriota (Dietzia, Rhodococcus), Spirochaetota (Sphaerochaeta), Pseudomonadota (Shewanella), and Bacteroidota (Petrimonas), together with methanogenic archaea of the phylum Euryarchaeota (Methanobacterium). In some formation water samples, the share of methanogens of the genus Methanobacterium reached 61.6% of the total community; these hydrogen-utilizing organisms may contribute to the formation of methane in the reservoirs used for the storage of molecular hydrogen. Microbial communities of UGSs located in aquifers were less diverse and abundant. Cultivable hydrogenotrophic sulfate-reducing, homoacetogenic, and methanogenic prokaryotes were retrieved from the studied aquifers and from the DOGF used for gas storage. Microorganisms present in the condensation and reservoir waters of the UGS facilities can influence the composition of the water and gas phase, and affect the host rocks and borehole equipment.

Assemblages of Trichoptera larvae on water moss in the middle reaches of the Yenisei River (Siberia, Russia).

This study provides first data on species composition of trichopterans inhabiting water moss, Fontinalis antipyretica Hedw., in the middle reaches of the Yenisei River. Analysis of Trichoptera larvae collected from samples of water moss in tail waters of the Krasnoyarsk Hydroelectric Plant in 2008-2021 revealed nine species of the order, which belonged to four families. Among them, six species belonging to the Limnephilidae family have not been mentioned in previous studies of the Yenisei invertebrates. Images of species are provided. One species, Apatania crymophyla McLachlan, was the most dense in all samples of water moss. The densities of A. crymophyla in samples of water moss in 2021 ranged within 1.2-7.0 thousand individuals / kg f.w. Other representatives of the order occurred in samples of water moss sporadically or consistently but in very low densities, which did not allow reliable quantification of their abundances. Consequently, numerous large clumps of water moss in the fast-flowing waters of the Yenisei favor an abundance of Trichoptera larvae, providing these insects refuge, food, and material for their cases. However, the reasons for the predominance of one species, A. crymophyla, are to be elucidated in further studies. The present study suggests that the contributions of Trichoptera and the total invertebrate community inhabiting water moss to biomass and energy budgets in the Yenisei have been usually underestimated before now. Hence, seasonal trends of species composition and abundance of invertebrates associated with water moss in the Yenisei River, including comparison with the entire zoobenthic community, are to be studied in the future.

Bio-Drying of Municipal Wastewater Sludge: Effects of High Temperature, Low Moisture Content and Volatile Compounds on the Microbial Community

This study examined microbiological processes during the bio-drying of municipal wastewater sludge (WS) from the waste treatment facilities of the Moscow region (Russia). In just 21 days of bio-drying, the moisture content of the mixture of WS and wood chips decreased by 19.7%. It was found that members of the genus Bacillus were the main organic matter destructors. In the period from 7 to 14 days, the rates of organic matter mineralization and moisture loss were the highest, and bacteria of the genus Bacillus dominated, accounting for 43.5 to 84.6% of the bacterial community with a total number of 1.20 (±0.09) × 106 to 6.70 (±0.44) × 105 gene copies µg−1. The maximum number of Amaricoccus was (15.7% of the total bacterial community) in the middle of bio-drying. There was an active accumulation of nitrate nitrogen due to the oxidation of nitrogen-containing substances during the same period of time. Bacteria of the genera Sphingobacterium, Brevundimonas, Brucella, Achromobacter and fungi of the genus Fusarium dominated in the biofilter, which removed volatile compounds from the waste air by 90%. The obtained results allow to model the further intensification of bio-drying, as well as its efficiency and safety.

Accelerated dissipation, soil microbial toxicity and dispersal of antimicrobial resistance in soils repeatedly exposed to tiamulin, tilmicosin and sulfamethoxazole

The application of manures leads to the contamination of agricultural soils with veterinary antibiotics (VAs). These might exert toxicity on the soil microbiota and threaten environmental quality, and public health. We obtained mechanistic insights about the impact of three VAs, namely, sulfamethoxazole (SMX), tiamulin (TIA) and tilmicosin (TLM), on the abundance of key soil microbial groups, antibiotic resistance genes (ARGs) and class I integron integrases (intl1). In a microcosm study, we repeatedly treated two soils (differing in pH and VA dissipation capacity) with the studied VAs, either directly or via fortified manure. This application scheme resulted in accelerated dissipation of TIA, but not of SMX, and accumulation of TLM. Potential nitrification rates (PNR), and the abundance of ammonia-oxidizing microorganism (AOM) were reduced by SMX and TIA, but not by TLM. VAs strongly impacted the total prokaryotic and AOM communities, whereas manure addition was the main determinant of the fungal and protist communities. SMX stimulated sulfonamide resistance, while manure stimulated ARGs and horizontal gene transfer. Correlations identified opportunistic pathogens like Clostridia, Burkholderia-Caballeronia-Paraburkholderia, and Nocardioides as potential ARG reservoirs in soil. Our results provide unprecedented evidence about the effects of understudied VAs on soil microbiota and highlight risks posed by VA-contaminated manures. Environmental implicationThe dispersal of veterinary antibiotics (VAs) through soil manuring enhances antimicrobial resistance (AMR) development and poses a threat to the environment and the public health. We provide insights about the impact of selected VAs on their: (i) microbially-mediated dissipation in soil; (ii) ecotoxicity on the soil microbial communities; (iii) capacity to stimulate AMR. Our results (i) demonstrate the effects of VAs and their application-mode on the bacterial, fungal, and protistan communities, and on the soil ammonia oxidizers; (ii) describe natural attenuation processes against VA dispersal, (iii) depict potential soil microbial AMR reservoirs, essential for the development of risk assessment strategies.

Total and arbuscular mycorrhizal fungal communities in the first 3 years after the collapse of the Fundão Dam: are we on the ecosystem recovery pathway?

After the collapse of Fundão Dam in Mariana‐MG, Brazil, the discharge of iron ore mining waste into the Doce River watershed negatively impacted the landscape. Monitoring the composition and species richness of soil microbiota may be useful bioindicators of ecosystem recovery. This study aimed to compare soil chemical properties, total fungal species, and arbuscular mycorrhizal fungi (AMF) in sites unaffected and affected by mining tailings in the first 3 years after the collapse of Fundão Dam. Soil and root samples were collected in dry and rainy seasons over 3 years in unaffected (adjacent forest and pasture) and affected areas (REC1, REC2, and PASTrec) by mine tailings. Changes in soil chemical properties over the sampling period were measured by routine chemical analyses. Total fungi in the soil was determined by high‐throughput sequencing. AMF community was evaluated using spore number, root colonization, and denaturing gradient gel electrophoresis. Affected sites had higher ranges of pH and lower soil organic matter than unaffected sites. Revegetation had a positive effect on soil fungal community. Increased similarity in AMF DGGE analysis was observed in the two sampling sites over time. A high similarity of total fungi and AMF was observed between REC and pasture areas, suggesting that revegetation strategy employed may be heading towards a pasture condition. Thus, post‐disturbance analysis of this study was important to evaluate of ecosystem recovery affected by the rupture of iron ore mining dam and demonstrated that the soil microbiota was a sensitive bioindicator in this long path of ecosystem recovery.

Seasonal assembly of skin microbiota driven by neutral and selective processes in the greater horseshoe bat.

Skin microbiota play an important role in protecting bat hosts from the fungal pathogen Pseudogymnoascus destructans, which has caused dramatic bat population declines and extinctions. Recent studies have provided insights into the bacterial communities of bat skin, but variation in skin bacterial community structure in the context of the seasonal dynamics of fungal invasion, as well as the processes that drive such variation, remain largely unexplored. In this study, we characterized bat skin microbiota over the course of the bat hibernation and active season stages and used a neutral model of community ecology to determine the relative roles of neutral and selective processes in driving microbial community variation. Our results showed significant seasonal shifts in skin community structure, as well as less diverse microbiota in hibernation than in the active season. Skin microbiota were influenced by the environmental bacterial reservoir. During both the hibernation and active season stages, more than 78% of ASVs in bat skin microbiota were consistent with neutral distribution, implying that neutral processes, that is, dispersal or ecological drift contributing the most to shifts in skin microbiota. In addition, the neutral model showed that some ASVs were actively selected by the bats from the environmental bacterial reservoir, accounting for approximately 20% and 31% of the total community during hibernation and active season stages, respectively. Overall, this research provides insights into the assemblage of bat-associated bacterial communities and will aid in the development of conservation strategies against fungal disease.

Nitrogen removal performance and mechanism of low-carbon sewage by airlift internal loop sequencing batch bio-microcapsule reactor

In this study, bio-microcapsules (PSCF) embedded with corncobs, zero-valent iron (ZVI) and Acinetobacter pittii SY9 were prepared, and the airlift internal loop sequencing batch reactor (AILP-SBR) was constructed with PSCF as filler. Results showed that the TN removal ratios of AILP-SBR were affected by HRT, C/N ratio and NH4+-N concentration, the NH4+-N, TN and COD removal efficiency of AILP-SBR reached 97.46 ± 2.18%, 90.67 ± 3.53% and 76 ± 7.43%, respectively under appropriate conditions (HRT of 10–12 h, C/N of 2–3, the influent COD concentration of 162.75 ± 16.02 mg/L, influent NH4+-N of 50 ± 0.92 mg/L, and pH of 7.00 ± 0.02), and the maximum first-order rate constant of TN removal was 0.2563 h−1. Moreover, carbon and total Fe (TFe) release characteristics, enzyme activity, functional genes and microbial community structure were used to explore the mechanisms of PSCF to enhance nitrogen removal. These results indicated that PSCF could release 98.15 mg COD/g and 1.15 mg/g TFe, provide electron donors for denitrification, and improve enzyme activity of nitrogen conversion. In addition, the addition of zero-valent iron (ZVI) could promote the abundance of nitrogen removal genes and functional bacteria in the AILP-SBR. In AILP-SBR, the dominant genera for nitrogen removal included Acinetobacter (10.57%), Dechloromonas (4.09%) and Hydrogenophaga (4.09%).

Quantifying drift-selection balance usingan agent-based biofilm model ofidentical heterotrophs under low-nutrient conditions.

Both deterministic and stochastic forces shape biofilm communities, but thebalance between those forces is variable. Quantifying the balance is both desirable and challenging. For example, drift-driven failure, astochastic force, can be thought of as an organism experiencing 'bad luck' and manipulating 'luck' as a factor in real-world systems is difficult. We used an agent-based model to manipulate luck by controlling seed cevalues governing random number generation. We determined which organism among identical competitors experienced the greatest drift-driven failure, gave it a deterministic growth advantage and re-ran the simulation with the same seed. This enabled quantifying the growth advantage required to overcome drift, e.g. a 50% chance to thrive may require a 10-20% improved growth rate. Further, we found that crowding intensity affected that balance. At moderate spacings, there were wide ranges where neither drift nor selection dominated. Those ranges shrank at extreme spacings; close and loose crowding, respectively, favoured drift and selection. We explain how these results may partially illuminate two conundrums: the fact that a stably operating wastewater treatment plant's microbial community can vary greatly over time and the difference between equivalent and total community size in neutral community assembly models.

The different responses of planktonic bacteria and archaea to water temperature maintain the stability of their community diversity in dammed rivers

BackgroundPlanktonic bacteria and archaea play a key role in river nutrient biogeochemical cycling; however, their respective community assembly and how to maintain their diversity are not well known in dammed rivers. Therefore, a seasonal survey of planktonic bacterial and archaeal community compositions and related environmental factors was conducted in 16 cascade reservoirs and corresponding river waters on the Wujiang River and the Pearl River in southwest China to understand the above mechanisms.ResultsDeterministic processes dominated bacterial and archaeal community assembly. The structural equation models showed that water temperature can directly or indirectly affect the microbial diversity. Interestingly, planktonic bacterial diversity increased with increasing water temperature, while archaea showed the opposite trend; the overall diversity of bacteria and archaea was no significant changes with changeable water temperature. Abundant microbes had a stronger distance–decay relationship than middle and rare ones, and the relationship was stronger in winter and spring than in summer and autumn.ConclusionsPlanktonic bacteria and archaea in dammed rivers had different biogeographic distributions, and water temperature was a key controlling factor. The different responses of planktonic bacterial and archaeal diversity to water temperature could be due to their different phylogenetic diversity. This ultimately maintained the stability of total microbial community diversity. This study reveals the different responses of planktonic bacteria and archaea to water temperature and perfects the theoretical framework for planktonic microbial biogeography in dammed rivers.

Metagenomic Profile of Endophytic Bacteria in Acacia mearnsii.

Acacia mearnsii is one of the invasive plants belonging to the Mimosaceae family. The family is known to be able to symbiosis with some endophytic nitrogen-fixing soil bacteria. Such ability will significantly contribute to plant growth and development by influencing nutrient uptake and stress tolerance and thus to improve soil conditions for a better and more fertile. Comprehensive identification of bacterial population dynamic in that zone should elucidate symbiosis mechanism that in turn can be used for soil improvement. Metagenomic-based profiling are now commonly used in studying whole total microbial communities in nature. Sampling of the root was collected from A. mearnsii young trees grown in Alahan Panjang at 60 and 120 days after transplanting, sterilized and stored at -80°C in a falcon tube before being subjected to metagenome analysis. The dynamics of growth and diversity of endophytic microbes were checked through amplicon sequence of the 16S rRNA gene in the V3-V4 region using Next Generation Sequencing (NGS) platform. Data analysis was performed using the QIIME2 application. The metagenomics analysis of endophytic bacteria on root A. mearnsii elucidates that the Proteobacteria is a dominant phyla in A. mearnsii root and analysis at the genera level shows that most of the Proteobacteria is dominated by the Bradyrhizobium which increase significantly during early growth phase.

Research progress in calculating net community production of marine ecosystem by remote sensing

Net community production (NCP) is defined as the difference between gross primary production (GPP) and total community respiration (R). NCP indicates the balance between the production and consumption of community organic carbon, therefore making it a key parameter for evaluating the efficiency of carbon sequestration using the biological pump (BP). It is difficult to quantify NCP directly via satellite, because there are complex processes in community production and respiration. We reviewed previous research on satellite-based NCP and classified the methods into two primary categories: empirical methods and semi-analytical methods. The former category was established based on numerical relationships between NCP and satellite-based proxies, while the latter was developed by utilizing mechanistic analysis to establish quantitative expressions linking NCP to such proxies. Although satellite-based calculations of NCP have been attempted, they still suffer from significant uncertainties. Future research should focus on the precise calculation of satellite-based NCP by investigating the underlying processes and mechanisms that regulate NCP, developing regional models, and increasing the resolution of satellite sensors, as well as applying satellite lidar and coordinated multi-sensor observation technology.

Evolution of fungal and non-fungal eukaryotic communities in response to thermophilic co-composting of various nitrogen-rich green feedstocks.

Thermophilic composting is a promising soil and waste management approach involving diverse micro and macro-organisms, including eukaryotes. Due to sub-optimal amounts of nutrients in manure, supplemental feedstock materials such as Lantana camara, and Tithonia diversifolia twigs are used in composting. These materials have, however, been reported to have antimicrobial activity in in-vitro experiments. Furthermore, the phytochemical analysis has shown differences in their complexities, thus possibly requiring various periods to break down. Therefore, it is necessary to understand these materials' influence on the biological and physical-chemical stability of compost. Most compost microbiome studies have been bacterial-centric, leaving out eukaryotes despite their critical role in the environment. Here, the influence of different green feedstock on the fungal and non-fungal eukaryotic community structure in a thermophilic compost environment was examined. Total community fungal and non-fungal eukaryotic DNA was recovered from triplicate compost samples of four experimental regimes. Sequencing for fungal ITS and non-fungal eukaryotes; 18S rDNA was done under the Illumina Miseq platform, and bioinformatics analysis was done using Divisive Amplicon Denoising Algorithm version 2 workflow in R version 4.1. Samples of mixed compost and composting day 84 recorded significantly (P<0.05) higher overall fungal populations, while Lantana-based compost and composting day 84 revealed the highest fungal community diversity. Non-fungal eukaryotic richness was significantly (P< 0.05) more abundant in Tithonia-based compost and composting day 21. The most diverse non-fungal eukaryotic biome was in the Tithonia-based compost and composting day 84. Sordariomycetes and Holozoa were the most contributors to the fungal and non-fungal community interactions in the compost environment, respectively. The findings of this study unravel the inherent influence of diverse composting materials and days on the eukaryotic community structure and compost's biological and chemical stability.

Online-based English Reading Learning Model in the New Normal Era (Post-Pandemic Covid-19)

This article is part of research entitled "Online-based Student English Learning Models in Facing Curriculum Changes in the New Normal Era." This research was conducted to see and identify online-based reading learning models for students. The research method is a descriptive qualitative method using a questionnaire and the final assignment of the Project course (Lesson Plan and Instruction). The number of samples used was 52 students who took the Project course (Lesson Plan and Instruction). Of the 52 students, 7 students chose to teach the reading skill. Data analysis includes observation, open coding, and axial coding. The results reveal that the media used by students in learning reading skills is divided into online media 57.14% (4 students) and 42.85% offline (3 students) in learning reading skills. Applications used by students in learning reading are divided into Zoom, face-to-face/ offline, Quizzes, PPT, and YouTube. The learning methods that students apply in learning reading are Communicative Language Teaching (14.28%), Guided Discovery Learning (14.28%), Audio Lingual Method (14.28%), Suggestopedia (14.28%), Discovery Learning (14.28%), Total Physical Response (14.28%) and Community Language Learning (14.28%). The topics presented included: Comparison; Narrative text; Personal Letters; Description, and Notice.

Effects of Cropping Systems on Soil Physicochemical Properties and Abundances and Spatial Distributions of Nitrogen-Cycling Bacteria

Soil nitrogen (N) is a common limiting factor where soil N-cycling is a key component of agroecosystems. Soil N transformation processes are largely mediated by microbes, and understanding bacteria involvement in soil N-cycling in agricultural systems has both agronomic and environmental importance. This 2 yr field-scale study examined the abundances and spatial distributions of the total bacterial community (16S rRNA), bacteria involved in nitrification (amoA) and denitrification (narG, nirK, and nosZ), and soil physicochemical properties of winter wheat (Triticum aestivum L.)–soybean (Glycine max L.) double-crop with 2–3 weeks of spring grazing (WGS) and without grazing (WS) and tall fescue (Festuca arundinacea (L.) Schreb.) pasture (TF) managed to near-natural conditions with similar grazing. The TF soil had a significantly higher abundance of 16S rRNA, amoA, narG, nirK, and nosZ genes than the WS and WGS soils, which had similar levels between themselves. Soil organic matter (OM) and soil pH had stronger effects on the N-cycling bacteria gene abundance. All bacterial gene concentrations and soil pH showed nonrandom distribution patterns with a 141–186 m range autocorrelation. These results indicate that biological N transformation processes are more important in natural agricultural systems and the abundance of N-cycling bacteria can be manipulated by field-scale management strategies.

Enrichment of rare methanogenic Archaea shows their important ecological role in natural high-CO2 terrestrial subsurface environments.

Long-term stability of underground CO2 storage is partially affected by microbial activity but our knowledge of these effects is limited, mainly due to a lack of sites. A consistently high flux of mantle-derived CO2 makes the Eger Rift in the Czech Republic a natural analogue to underground CO2 storage. The Eger Rift is a seismically active region and H2 is produced abiotically during earthquakes, providing energy to indigenous microbial communities. To investigate the response of a microbial ecosystem to high levels of CO2 and H2, we enriched microorganisms from samples from a 239.5 m long drill core from the Eger Rift. Microbial abundance, diversity and community structure were assessed using qPCR and 16S rRNA gene sequencing. Enrichment cultures were set up with minimal mineral media and H2/CO2 headspace to simulate a seismically active period with elevated H2. Methane headspace concentrations in the enrichments indicated that active methanogens were almost exclusively restricted to enrichment cultures from Miocene lacustrine deposits (50-60 m), for which we observed the most significant growth. Taxonomic assessment showed microbial communities in these enrichments to be less diverse than those with little or no growth. Active enrichments were especially abundant in methanogens of the taxa Methanobacterium and Methanosphaerula. Concurrent to the emergence of methanogenic archaea, we also observed sulfate reducers with the metabolic ability to utilize H2 and CO2, specifically the genus Desulfosporosinus, which were able to outcompete methanogens in several enrichments. Low microbial abundance and a diverse non-CO2 driven microbial community, similar to that in drill core samples, also reflect the inactivity in these cultures. Significant growth of sulfate reducing and methanogenic microbial taxa, which make up only a small fraction of the total microbial community, emphasize the need to account for rare biosphere taxa when assessing the metabolic potential of microbial subsurface populations. The observation that CO2 and H2-utilizing microorganisms could only be enriched from a narrow depth interval suggests that factors such as sediment heterogeneity may also be important. This study provides new insight on subsurface microbes under the influence of high CO2 concentrations, similar to those found in CCS sites.

Distribution and survival strategies of endemic and cosmopolitan diazotrophs in the Arctic Ocean

Dinitrogen (N2) fixation is the major source of reactive nitrogen in the ocean and has been considered to occur specifically in low-latitude oligotrophic oceans. Recent studies have shown that N2 fixation also occurs in the polar regions and thus is a global process, although the physiological and ecological characteristics of polar diazotrophs are not yet known. Here, we successfully reconstructed diazotroph genomes, including that of cyanobacterium UCYN-A (Candidatus ‘Atelocyanobacterium thalassa’), from metagenome data corresponding to 111 samples isolated from the Arctic Ocean. These diazotrophs were highly abundant in the Arctic Ocean (max., 1.28% of the total microbial community), suggesting that they have important roles in the Arctic ecosystem and biogeochemical cycles. Further, we show that diazotrophs within genera Arcobacter, Psychromonas, and Oceanobacter are prevalent in the <0.2 µm fraction in the Arctic Ocean, indicating that current methods cannot capture their N2 fixation. Diazotrophs in the Arctic Ocean were either Arctic-endemic or cosmopolitan species from their global distribution patterns. Arctic-endemic diazotrophs, including Arctic UCYN-A, were similar to low-latitude-endemic and cosmopolitan diazotrophs in genome-wide function, however, they had unique gene sets (e.g., diverse aromatics degradation genes), suggesting adaptations to Arctic-specific conditions. Cosmopolitan diazotrophs were generally non-cyanobacteria and commonly had the gene that encodes the cold-inducible RNA chaperone, which presumably makes their survival possible even in deep, cold waters of global ocean and polar surface waters. This study shows global distribution pattern of diazotrophs with their genomes and provides clues to answering the question of how diazotrophs can inhabit polar waters.

Gut microbial communities of hybridising pygmy angelfishes reflect species boundaries

Hybridisation and introgression of eukaryotic genomes can generate new species or subsume existing ones, with direct and indirect consequences for biodiversity. An understudied component of these evolutionary forces is their potentially rapid effect on host gut microbiomes, and whether these pliable microcosms may serve as early biological indicators of speciation. We address this hypothesis in a field study of angelfishes (genus Centropyge), which have one of the highest prevalence of hybridisation within coral reef fish. In our study region of the Eastern Indian Ocean, the parent fish species and their hybrids cohabit and display no differences in their diet, behaviour, and reproduction, often interbreeding in mixed harems. Despite this ecological overlap, we show that microbiomes of the parent species are significantly different from each other in form and function based on total community composition, supporting the division of parents into distinct species, despite the confounding effects of introgression acting to homogenize parent species identity at other molecular markers. The microbiome of hybrid individuals, on the other hand, are not significantly different to each of the parents, instead harbouring an intermediate community composition. These findings suggest that shifts in gut microbiomes may be an early indicator of speciation in hybridising species.