Changes In Microbial Communities Research Articles

Porewater microbiomes in buried wetland soils: Synergic effects of water chemistry and redox gradients associated with hydrological processes

Abstract Interstitial water or pore water occupies the space between soil particles and provides “hotspots” and “fluvial networks” for microbial activities in floodplain soil. However, to date, we know very little about the microorganisms living in pore water and how they respond to environmental changes. This study aimed to understand microbial distribution and assemblage in riparian pore waters, and how they respond to water chemistry and redox gradients associated with hydrological processes. We analysed the annual changes of porewater microbial communities from the east and west banks of the White Clay Creek, a site at the Christina River Basin – Critical Zone Observatory, Pennsylvania, USA. Microbial abundances were quantified by epifluorescence microscopy and detailed community structures were characterised by high‐throughput sequencing. Water chemistry and redox gradients were also monitored and recorded, and their interactions with porewater microbiomes were analysed using correlations and multivariate analyses. Abundance of microbial cells increased during summer and late autumn. Wetland porewater microbiomes mainly contained Acidobacteria, Bacteroidetes, Nitrospirae and Proteobacteria, and microbiome structures were easily distinguishable from those in the underlying hyporheic gravel layer. Seasonal dynamics of bacterial community structure in the east and west wetlands were distinct, responding to floodplain topography and associated hydrological/geochemical processes. Iron (Fe)‐cycling bacteria (mainly Gallionellaceae and Rhodoferax spp.) dominated the porewater microbiome, and their relative abundance was significantly higher in the east than the west wetland. Furthermore, Fe‐oxidising bacteria (Gallionellaceae) were negatively correlated with Fe‐reducing bacteria (Rhodoferax spp.) at the east wetland. Microbial abundances (cell density) in pore waters showed similar seasonal patterns across stream banks, but microbial community structure did not. Microbiome assembly in pore water is correlated with water chemistry and redox gradients primarily associated with local hydrological processes. As a consequence of their significance for carbon (C) mineralisation and Fe reduction at terrestrial–aquatic interfaces, microbiomes in riparian pore waters and associated microbial activity play an essential role in C and mineral dynamics. These findings will inform future studies of the response of freshwater ecosystems to hydrological dynamics influenced by global climate change.

Dynamic Changes of Environment and Gut Microbial Community of Litopenaeus vannamei in Greenhouse Farming and Potential Mechanism of Gut Microbial Community Construction

The aim of this study was to investigate the dynamic changes in the microbial communities of both the environment and gut of Litopenaeus vannamei, as well as to elucidate the mechanisms underlying microbial community assembly in greenhouse farming. 16S rDNA high-throughput sequencing and bioinformatics methods were used to carry out the research on the community structure of the microorganisms under greenhouse culture conditions in water, sediment, and gut microorganisms; correlations pertaining to environmental factors; the feasibility of using Source Tracker; and the mechanisms of community construction. The results show that the dominant microorganisms in water, sediment, and gut farming in a greenhouse environment varied and were subject to dynamic change. A variety of beneficial microbiota such as Bacillus were found in the gut, whereas a variety of microorganisms such as Marivita and Pseudomonas, which function as nitrogen and phosphorus removers, were present in water. Source Tracker and environmental correlation analyses showed that changes in the gut were associated with eutrophication indicators (total nitrogen, total phosphorus, ammonia nitrogen) and changes in environmental microorganisms (in water and sediment). The results of the community-building mechanism analysis show that stochastic processes determine the community-building directions of environmental and gut microorganisms. These findings will help us to understand the microbiota characteristics of shrimp ponds under greenhouse farming conditions, and the complex interactions between the shrimp gut and the environmental microbiota and environmental variables, as well as revealing the changing rules of the gut microbiota.

Black soldier fly-based bioconversion of biosolids: Microbial community dynamics and fate of antibiotic resistance genes

Biosolids as by-products of wastewater treatment can contain a large spectrum of pathogens and antibiotic resistance genes (ARGs). Insect-based bioconversion using black soldier fly larvae (BSFL) is an emerging technology that has shown to reduce significant amounts of biosolids quickly and produce larvae biomass containing low heavy metal concentrations. However, to the best of our knowledge, this is the first study investigating the transfer of pathogens and ARGs from biosolids into the process' end-products, BSFL and frass. We hypothesized that BSF-based bioconversion can decrease the abundance of pathogenic bacteria and ARGs in biosolids. In this study, we performed BSFL feeding trials with biosolids blended or not blended with wheat bran, and wheat bran alone as a low bioburden diet (control). We conducted 16S rRNA amplicon sequencing to monitor changes of the BSFL-associated microbial community and the fate of biosolids-associated pathogens. A diverse set of ARGs (ermB, intl1, sul1, tetA, tetQ, tetW, and blaCTX-M-32) were quantified by qPCR and were linked to changes in substrate- and BSFL-associated microbiomes. BSF-based bioconversion of biosolids-containing substrates led to a significant reduction of the microbial diversity, the abundance of several pathogenic bacteria and the investigated ARGs (< 99 %). Feeding with a high bioburden biosolid diet resulted in a higher microbial diversity, and the accumulation of pathogenic bacteria and ARGs in the BSFL. Results of this study demonstrated that BSF-based bioconversion can be a suitable waste management technology to (1) reduce significant amounts of biosolids and (2) reduce the presence of pathogens and ARGs. However, the resulting larvae biomass would need to undergo further post-treatment to reduce the pathogenic load to allow them as animal feed.

Response signatures of intestinal microbiota and gene transcription of the pearl gentian grouper to Vibrio harveyi infection

Vibrio harveyi causes high mortality and severely limits grouper culture. The gut microbiota is an important biological barrier against pathogen invasion. In this study, we investigated dynamic changes in the intestinal microbial community, gene transcription and immune responses signatures of pearl gentian grouper (Epinephelus fuscoguttatus♂ × Epinephelus lanceolatus♀) at 0, 3 and 7 days (referred to as d0, d3 and d7 groups, respectively) after infection with V. harveyi. The results demonstrated that the d7 treatment reduced the gut microbial diversity and increased the proportion of Proteobacteria and Cyanobacteria. Notably, several putative pathogenic genera (Sphingomonas and Bacteroides) proliferated, while putative probiotic genera (Rhodococcus and Lactobacillus) reduced, and these changes in intestinal bacteria might be correlated to the alterations of host immune-related molecules. The d3 and d7 treatments also altered the histomorphology and gene transcription profiles mainly associated with immune function in intestine, such as ‘MAPK signaling pathway’, ‘Apoptosis’ and ‘Toll-like receptor (TLR) signaling pathway’. Furthermore, d3 group induced a homeostatic dysregulation of the antioxidant system, cytokines and TLR signaling, with a tendency to gradually return to a normal state in d7 group, along with the apoptosis process. The pathogenic infection suppressed the expression of JNK pathway and enhanced the ERK pathway. In conclusion, the dysbiosis of the intestinal bacterial communities caused by the immune changes that occurred during V. harveyi infection disrupted the intestine health in the pearl gentian grouper. These results provided a comprehensive understandings of the immune defense mechanisms in fish and valuable references to develop disease control strategies in grouper aquaculture.

Bile Acid Diarrhea

Diarrhea is a very common gastrointestinal symptom, and the presence of higher concentrations of bile acid in the colon leads to bile acid diarrhea (BAD). In BAD patients, a portion of bile from the small intestine that is normally controlled by enterohepatic circulation is present at a high concentration in the lumen of the large intestine, resulting in increased motility and secretion of the large intestine. The prevalence of BAD is estimated to be 1-2% of the general population, and it comprises one-third of the instances of diarrhea-predominant irritable bowel syndrome. The clinical symptoms of BAD include chronic diarrhea, increased frequency of defecation, urgency to defecate, fecal incontinence, and cramping abdominal pain. The pathophysiology of BAD has not yet been fully elucidated. However, recent studies have reported increased intestinal permeability, shortened intestinal transit time, and changes in the intestinal microbial community to be the possible causes of BAD. Although fecal and serum bile acid tests are widely used for diagnosis, new test methods that are non-invasive, inexpensive, and have high sensitivity and specificity are needed at various institutions to facilitate the diagnosis. The selenium homo-tauro-cholic acid (SeHCAT) test is the gold standard for BAD diagnosis and severity assessment. The validation of several other serum markers, such as 7-hydroxy-4-cholesten-3-one (serum 7αC4) and the fibroblast growth factor 19 (FGF19) for use in clinical practice is ongoing. Although bile acid sequestrants are the mainstay of treatment, the development of drugs that are more effective and have better compliance is required. Farnesoid X receptor (FXR) agonists are showing promising results.

Behaviours of methane metabolism and community dynamics of methane anaerobic oxidation microbes on carbonate rocks with long-term cultivation in cold seep environment

The anaerobic oxidation of methane (AOM) and sulfate reduction processes in cold seep environments can control methane emission sources and thus mitigate the pressure of increasing global greenhouse gas concentrations. The surfaces of carbonate rocks in cold seep host an abundance of microorganisms that participate in AOM reactions. Investigating the metabolism and conversion of methane by these microbes is instrumental in advancing the exploration and utilization of deep-sea methane energy. Previous studies primarily focused on in-situ investigations of microbial communities on carbonate rocks in cold seep environments, while the dynamic balance of carbonate mineralization caused by microbial community changes and the characteristics of methane consumption in carbonate samples remains unclear. In this study, we used methane as the sole carbon source, enriched and cultured carbonate samples under high pressure, and monitored the community dynamics regularly. The results demonstrated that methane consumption and metabolic pathways played a crucial role in influencing community succession and carbonate mineralization. AOM processes, coupled with sulfate reduction and nitrate reduction, which are dominated by ANME-2c, facilitate the precipitation of calcium carbonate. Conversely, the acetate production process, dominated by ANME-1, may hinder the efficiency of calcium carbonate mineralization. Additionally, the impact of bacterial groups in the enrichment process, through the production of extracellular enzymes, organic acid pathways, and the expression of carbonic anhydrase pathways on carbonate mineralization, should not be disregarded. These findings highlight the significance of diverse pathway methane metabolism in the dynamics of methane consumption, deep-sea microbial communities, carbonate kinetics, and marine biological carbon sequestration processes.

Changes in microbial composition explain the contrasting responses of glucose and lignin decomposition to soil acidification in an alpine grassland

Soil acidification often suppresses microbial growth and activities, resulting in a negative impact on soil organic carbon (C) decomposition. While the detrimental effects of acidification on soil and plant properties have been extensively studied, less attention has been paid on the shifts in soil microbial communities and their influences of the decomposition of organic C with different chemical complexities. Taking advantage of an acid addition experiment in a Tibetan alpine meadow, here we examined the response of soil microbial communities to soil acidification and microbial effect on the decomposition of organic C with different chemical complexities (i.e., glucose and lignin, representing labile and recalcitrant C respectively). We found that soil acidification had no impact on microbial respiration and microbial abundance even though it decreased bacterial diversity significantly. Soil acidification increased the relative abundance of some microbial taxa, like Alphaproteobacteria and Acidobacteriia in bacteria increased by 36 %, 284 %, and Eurotiomycetes, Sordariomycetes and Leotiomycetes in fungi increased by 145 %, 279 % and 12.7-fold, but decreased the relative abundance of Acidimicrobiia by 33 % in highest acid addition treatment. Changes in microbial communities (bacterial and fungal community composition, the diversity of bacterial community and the ratio of fungi to bacteria) are significantly related to the decomposition of glucose and lignin. More specifically, soil acidification decreased the decomposition of glucose but increased the decomposition of lignin, indicating a trade-off between the decomposition of labile and recalcitrant soil organic C under soil acidification. Overall, shifts in microbial communities under soil acidification might be accompanied by an increased ability to break down more recalcitrant C. This trade-off between the decomposition of labile and recalcitrant C may change soil C quality under future acid deposition scenarios.

Amendments affect the community assembly and co-occurrence network of microorganisms in Cd and Pb tailings of the Eucalyptus camaldulensis rhizosphere

Mining tailings containing large amounts of Pb and Cd cause severe regional ecosystem pollution. Soil microorganisms play a regulatory role in the restoration of degraded ecosystems. The remediation of heavy metal-contaminated tailings with amendments and economically valuable Eucalyptus camaldulensis is a research hotspot due to its cost-effectiveness and sustainability. However, the succession and co-occurrence patterns of these microbial communities in this context remain unclear. Tailing samples of five kinds of Cd and Pb were collected in E. camaldulensis restoration models. Physicochemical properties, the proportions of different Cd and Pb forms, microbial community structure, and the co-occurrence network of rhizosphere tailings during different restoration process (organic bacterial manure, organic manure, inorganic fertilizer, bacterial agent) were considered. Organic and organic bacterial manures significantly increased pH, cation exchange capacity, and the proportion of residual Pb. Still, there was a significant decrease in the proportion of reducible Pb. The changes in microbial communities were related to physicochemical properties and the types of amendments. Organic and organic bacterium manures decreased the relative abundance of oligotrophic groups and increased the relative abundance of syntrophic groups. Inorganic fertilizers and bacterial agents decreased the relative abundance of saprophytic fungi. B. subtilis would play a better role in the environment improved by organic manure, increasing the relative abundance of beneficial microorganism and reducing the relative abundance of pathogenic microorganism. pH, cation exchange capacity, and the proportion of different forms of Pb were the main factors affecting the bacterial and fungi variation. All four amendments transformed the main critical groups of the microbial network structure from acidophilus and pathogenic microorganisms to beneficial microorganisms. Heavy metal-resistant microorganisms, stress-resistant microorganisms, beneficial microorganisms that promote nutrient cycling, and copiotrophic groups have become critical to building stable rhizosphere microbial communities. The topological properties and stability of the rhizosphere co-occurrence network were also enhanced. Adding organic and organic bacterium manures combined with E. camaldulensis to repair Cd and Pb tailings improved (1) pH and cation exchange capacity, (2) reduced the biological toxicity of Pb, (3) enhanced the stability of microbial networks, and (4) improved ecological network relationships. These positive changes are conducive to the restoration of the ecological functions of tailings.

Mechanisms of microbial coexistence in a patchy ecosystem: Differences in ecological niche overlap and species fitness between rhythmic and non-rhythmic species

Resource patchiness caused by external events breaks the continuity and homogeneity of resource distribution in the original ecosystem. For local organisms, this leads to drastic changes in the availability of resources, breaks down the co-existence of species, and reshuffles the local ecosystem. West Lake is a freshwater lake with resource patchiness caused by multiple exogenous disturbances that has strong environmental heterogeneity that prevents clear observation of seasonal changes in the microbial communities. Despite this, the emergence of rhythmic species in response to irregular changes in the environment has been helpful for observing microbial communities dynamics in patchy ecosystems. We investigated the ecological mechanisms of seasonal changes in microbial communities in West Lake by screening rhythmic species based on the ecological niche and modern coexistence theories. The results showed that rhythmic species were the dominant factors in microbial community changes and the effects of most environmental factors on the microbial community were indirectly realised through the rhythmic species. Random forest analyses showed that seasonal changes in the microbial community were similarly predicted by the rhythmic species. In addition, we incorporated species interactions and community phylogenetic patterns into stepwise multiple regression analyses, the results of which indicate that ecological niches and species fitness may drive the coexistence of these subcommunities. Thus, this study extends our understanding of seasonal changes in microbial communities and provides new ways for observing seasonal changes in microbial communities, especially in ecosystems with resource patches. Our study also show that combining community phylogenies with co-occurrence networks based on ecological niches and modern coexistence theory can further help us understand the ecological mechanisms of interspecies coexistence.

Impact of NaCl on physicochemical properties, microbial community, and pathogen surveillance in the Chinese traditional fermented broad bean (Vicia faba L.) paste

Doubanjiang (DBJ), a mixed fermented broad bean (Vicia faba L.) and red pepper (Capsicum annuum L.) condiment used worldwide, is known for its high-salt content (∼20g/100g). Industry demands sodium reduction in DBJs. In this study, we investigated the physicochemical properties, microbial community changes, and pathogen surveillance in DBJ samples with varying salt contents (10g/100g, 15g/100g, 20g/100g and 25g/100g). Our findings revealed that these samples could be categorized into two groups: low-salt (10g/100g) and high-salt samples (15–25g/100g). In low-salt samples, Lactobacillus emerged as the predominant bacteria, exhibiting higher antioxidant activity. The most concentrated organic acids were γ-aminobutyric acid and lactic acid. Conversely, Staphylococcus dominated the bacteria composition in high-salt samples. Human pathogenicity such as Proteus mirabilis, Escherichia coli, and Klebsiella pneumoniae were discovered in both low- and high-salt samples. Higher abundance of antimicrobial resistances was observed in high-salt samples while slightly increased biogenic amine content in low-salt samples. This knowledge provides insights into impact of NaCl on fermented broad bean (Vicia faba L.) paste.

Variations and Interseasonal Changes in the Gut Microbial Communities of Seven Wild Fish Species in a Natural Lake with Limited Water Exchange during the Closed Fishing Season.

The gut microbiota of fish is crucial for their growth, development, nutrient uptake, physiological balance, and disease resistance. Yet our knowledge of these microbial communities in wild fish populations in their natural ecosystems is insufficient. This study systematically examined the gut microbial communities of seven wild fish species in Chaohu Lake, a fishing-restricted area with minimal water turnover, across four seasons. We found significant variations in gut microbial community structures among species. Additionally, we observed significant seasonal and regional variations in the gut microbial communities. The Chaohu Lake fish gut microbial communities were predominantly composed of the phyla Firmicutes, Proteobacteria(Gamma), Proteobacteria(Alpha), Actinobacteriota, and Cyanobacteria. At the genus level, Aeromonas, Cetobacterium, Clostridium sensu stricto 1, Romboutsia, and Pseudomonas emerged as the most prevalent. A co-occurrence network analysis revealed that C. auratus, C. carpio, and C. brachygnathus possessed more complex and robust gut microbial networks than H. molitrix, C. alburnus, C. ectenes taihuensis, and A. nobilis. Certain microbial groups, such as Clostridium sensu stricto 1, Romboutsia, and Pseudomonas, were both dominant and keystone in the fish gut microbial network. Our study offers a new approach for studying the wild fish gut microbiota in natural, controlled environments. It offers an in-depth understanding of gut microbial communities in wild fish living in stable, limited water exchange natural environments.

Unveiling the influence of microaeration and sludge recirculation on enhancement of pharmaceutical removal and microbial community change of the novel anaerobic baffled biofilm - membrane bioreactor in treating building wastewater

This research aims to conduct a comparative investigation of the role played by microaeration and sludge recirculation in the novel anaerobic baffled biofilm-membrane bioreactor (AnBB-MBR) for enhancing pharmaceutical removal from building wastewater. Three AnBB-MBRs — R1: AnBB-MBR, R2: AnBB-MBR with microaeration and R3: AnBB-MBR with microaeration and sludge recirculation — were operated simultaneously to remove Ciprofloxacin (CIP), Caffeine (CAF), Sulfamethoxazole (SMX) and Diclofenac (DCF) from real building wastewater at the hydraulic retention time (HRT) of 30 h for 115 days. From the removal profiles of the targeted pharmaceuticals in the AnBB-MBRs, it was found that the fixed-film compartment (C1) could significantly reduce the targeted pharmaceuticals. The remaining pharmaceuticals were further removed with the microaeration compartment. R2 exhibited the utmost removal efficiency for CIP (78.0 %) and DCF (40.8 %), while SMX was removed most successfully by R3 (microaeration with sludge recirculation) at 91.3 %, followed by microaeration in R2 (88.5 %). For CAF, it was easily removed by all AnBB-MBR systems (>90 %). The removal mechanisms indicate that the microaeration in R2 facilitated the adsorption of CIP onto microaerobic biomass, while the enhanced biodegradation of CAF, SMX and DCF was confirmed by batch biotransformation kinetics and the adsorption isotherms of the targeted pharmaceuticals. The microbial groups involved in biodegradation of the targeted compounds under microaeration were identified as nitrogen removal microbials (Nitrosomonas, Nitrospira, Thiobacillus, and Denitratisoma) and methanotrophs (Methylosarcina, Methylocaldum, and Methylocystis). Overall, explication of the integration of AnBB-MBR with microaeration (R2) confirmed it as a prospective technology for pharmaceutical removal from building wastewater due to its energy-efficient approach characterized by minimal aeration supply.

The Canine Gut Health: The Impact of a New Feed Supplement on Microbiota Composition.

This study aimed to determine the impact of a novel formulation of a supplement composed of the natural ingredients, bromelain, quercetin, and Lentinula edodes, on the gut microbiota of healthy adult dogs. Adult healthy female dogs were administered either a placebo (CTR, n = 15) or the supplement (TRT, n = 15) over 28 days. Stool samples were collected for 16S rRNA sequencing before supplement administration (T0), at completion of supplement administration (T28), and one week after the end of supplement administration (T35) to characterize changes in the gut microbial communities. QIIME was used to determine both alpha- and beta-diversity, and ANCOM-BC was used to identify differences in taxonomic abundances before and after supplementation. We found a significant decrease in overall diversity in the CTR group but no significant differences in overall diversity in the TRT group over time. Furthermore, we found differences in the abundance of several taxa in both the CTR and TRT groups, but differences in the abundance of beneficial bacteria were more pronounced in the TRT group. Specifically, we found increases in the abundance of sequences belonging to the genera Bifidobacterium, Lactobacillus, and Pediococcus at T28 in the TRT group with significant increases in Bifidobacterium and Lactobacillus persisting at T35 when compared to T0. Importantly, members of these genera are considered important for their anti-inflammatory properties, vital for fostering a balanced and robust gut microbiota in dogs. The results of our study show the potential of our supplement to selectively enhance specific beneficial bacterial taxa, offering a targeted approach to modulating the gut microbiome without causing disruptions to the overall equilibrium.

Untargeted metabolomics to study changes in soil microbial community in response to tillage practices

Soil microbes are the main drivers of nutrient turnover in agro-ecosystems. The series of biochemical processes involved by these microorganisms are inseparable from the regulation of metabolites in the root-zone soils. Therefore, understanding the evolution of microbial communities driven by root-zone soil metabolites will help optimize agricultural management practices. Based on a field experiment, we explore the changes in soil properties, microbes, and metabolites under three tillage practices such as no-tillage with straw mulching (NTS), rotary tillage, and plough tillage with straw returning (RTS and PTS) based on untargeted metabolomics. We found that NTS helped to enhance nutrient contents and enzyme activities in the 0–20 cm soil layer. Specifically, compared with RTS and PTS, NTS increased grain yield by 6.4 % and 8.5 %, and SOC by 13.3 % and 5.7 %, respectively, but decreased pH by 2.8 % and 1.1 %. In addition, compared with NTS, RTS and PTS decreased the fungal richness by 16.5 % and 8.1 %, and decreased the fungal shannon index by 16.4 % and 9.2 %. However, tillage practices did not result in substantial differences in the alpha diversity of bacterial community. Both bacterial and fungal community composition were substantially affected by tillage practices and they were both significantly correlated with soil metabolites. In the symbiotic networks, NTS significantly increased the abundance of microorganisms with high connectivity, while RTS significantly increased the concentration of metabolites with high connectivity. Amino acids, as the main drivers, were significantly and positively associated with bacterial and fungal community composition, mainly enriched in the metabolic pathways of D − glutamine and D − glutamate metabolism and arginine and proline metabolism, and correlated with soil properties negatively and carbohydrates positively, directly or indirectly affecting soil microbial community composition. Our findings would provide new insight into metabolomics for the in-depth understanding of the metabolic mechanism for soil microbial community changes in dryland wheat fields under different tillage practices.

Short-Term Simulated Warming Changes the Beta Diversity of Bacteria in Taiga Forests’ Permafrost by Altering the Composition of Dominant Bacterial Phyla

Permafrost is widely degraded in the context of global warming. The spatial distribution of soil microbes in these cold habitats has received a lot of attention. However, knowledge on the changes in permafrost microbial communities following permafrost thaw is still limited. We used permafrost soil from a taiga forest for indoor experiments using pristine soil as a control (CK, −2 °C), simulating warming for 15 days at temperatures of 0 °C (T1), 2 °C (T2), and 4 °C (T3). Amplicons of the hypervariable V4 region of the bacterial 16S rRNA gene were sequenced to identify bacterial communities present in the soils of pristine and warming treatments. Warming increased the average relative abundance of Proteobacteria (5.71%) and decreased that of Actinobacteriota (7.82%). The Beta diversity changed (p = 0.001) and significantly correlated with the pH, microbial biomass carbon (MBC), and available potassium (AK) of the soil (p &lt; 0.05). Warming further increased the Alpha diversity (Simpson index), changing the functional pathways of the bacterial communities, whereby secondary functional pathways produced significant correlations with bacterial phyla (p &lt; 0.05). Combined, the results indicated that short-term warming altered the Beta diversity of soil bacteria in a taiga forest’s permafrost soil by decreasing the abundance of Actinobacteria and increasing that of Ascomycetes, while pH, MBC, and AK were identified as the soil factors influencing the structure and diversity of the bacterial communities.

Environmental temperature variations drive the changes of microbial communities to affect Baijiu flavor quality: Case study of Qingxiangxing Baijiu

Environmental temperature is a crucial factor that affects the fermentation quality of Baijiu. In this study, Illumina Miseq sequencingd, Two-dimensional gas chromatography coupled to mass spectrometry (GC × GC-MS), and physicochemical analyses were employed to investigate the microbial communities, flavor compounds, and physicochemical properties during fermentation at different ambient temperatures (10 ± 2 °C in the lower environmental temperature (LT) group and 22 ± 2 °C in the higher environmental temperature (HT) group). The findings demonstrated an augmentation in microbial diversity, ecological network complexity, and utilization of raw materials by microorganisms in HT group. Sensory analysis showed that sensory properties of Baijiu produced by the HT group had a better overall performance. The Baijiu in the HT group exhibited higher quality in terms of sweetness, fruity and floral, whereas the Baijiu in the LT group displayed a greater degree of unpleasant pungency and acidity. 24 flavor compounds were identified with the Variable Importance in Projection (VIP) > 1, and they were the main factors contributing to the differences in Baijiu flavors at two environmental temperatures. Correlation analysis showed that ambient temperature influenced microbial interactions and their correlation with metabolites. This difference showed the quality change of Baijiu driven by different temperatures. These results provide solid data support for optimizing the Baijiu fermentation process under different seasonal temperatures.

Effects of sulfur nanoparticles on rhizosphere microbial community changes in oilseed rape plantation soil under mercury stress

In the present study, experiments were conducted to assess the influence of nanoscale sulfur in the microbial community structure of metallophytes in Hg-contaminated rhizosphere soil for planting rapeseed. The results showed that the richness and diversity of the rhizobacteria community decreased significantly under Hg stress, but increased slightly after SNPs addition, with a reduction in the loss of Hg-sensitive microorganisms. Moreover, all changes in the relative abundances of the top ten phyla influenced by Hg treatment were reverted when subjected to Hg + SNPs treatment, except for Myxococcota and Bacteroidota. Similarly, the top five genera, whose relative abundance decreased the most under Hg alone compared to CK, increased by 19.05%–54.66% under Hg + SNPs treatment compared with Hg alone. Furthermore, the relative abundance of Sphingomonas, as one of the dominant genera for both CK and Hg + SNPs treatment, was actively correlated with plant growth. Rhizobacteria, like Pedobacter and Massilia, were significantly decreased under Hg + SNPs and were positively linked to Hg accumulation in plants. This study suggested that SNPs could create a healthier soil microecological environment by reversing the effect of Hg on the relative abundance of microorganisms, thereby assisting microorganisms to remediate heavy metal-contaminated soil and reduce the stress of heavy metals on plants.

Co-migration behavior of toluene coupled with trichloroethylene and the response of the pristine groundwater ecosystems – A mesoscale indoor experiment

Experimental scale and sampling precision are the main factors limiting the accuracy of migration and transformation assessments of complex petroleum-based contaminants in groundwater. In this study, a mesoscale indoor aquifer device with high environmental fidelity and monitoring accuracy was constructed, in which dissolved toluene and trichloroethylene were used as typical contaminants in a 1.5-year contaminant migration experiment. The process was divided into five stages, namely, pristine, injection, accumulation, decrease, and recovery, and characteristics such as differences in contaminant migration, the responsiveness of environmental factors, and changes in microbial communities were investigated. The results demonstrated that the mutual dissolution properties of the contaminants increased the spread of the plume and confirmed that toluene possessed greater mobility and natural attenuation than trichloroethylene. Attenuation of the contaminant plume proceeded through aerobic degradation, nitrate reduction, and sulfate reduction phases, accompanied by negative feedback from characteristic ion concentrations, dissolved oxygen content, the oxidation-reduction potential and microbial community structure of the groundwater. This research evaluated the migration and transformation characteristics of typical petroleum-based pollutants, revealed the response mechanism of the ecosystem to pollutant, provided a theoretical basis for predicting pollutant migration and formulating control strategies.

Response of Soil Physicochemical Properties and Microbial Community Composition in Larix olgensis Plantations to Disturbance by a Large Outbreak of Bark Beetle

Forests are affected by a wide range of disturbances globally, resulting in the decline or death of large areas of them. There is a lack of comparative studies on how soil properties change in forests that die under the influence of disturbances, especially considering different levels of disturbance. For this study, we took Larix olgensis—a major plantation forest species in northeast China—as the research object, one in which a large outbreak of bark beetle led to large-scale forest death, and set up fixed sample plots characterized by different disturbance intensities. We investigated the responses of soil physicochemical properties and microbial community compositions to different disturbance intensities through the determination of soil nutrient indices and high-throughput sequencing. The results show that there were significant differences (p &lt; 0.05) in the effects of different disturbance intensities on soil physicochemical properties, where the soil moisture content, total nitrogen, total carbon, and total phosphorus in the control group were significantly higher than those in the disturbed groups. The soil pH was highest under low-intensity disturbance and the soil total potassium content was highest under high-intensity disturbance. At different disturbance intensities, the highest soil moisture content was found in the high-intensity group. Proteobacteria, Actinobacteria, Verrucomicrobia, Acidobacteria, Candidatus_Rokubacteria, Chloroflexi, Gemmatimonadetes, and Thaumarchaeota were the dominant populations with higher abundances; meanwhile, the relative abundance of Bacteroidetes, Tenericutes, and a tentatively unclassified fungus differed significantly (p &lt; 0.05) across disturbance intensities. Among the dominant microbial populations, Acidobacteria showed a significant negative correlation with soil pH and a significant positive correlation with total potassium content, Thaumarchaeota showed significant positive correlations with soil moisture content and total nitrogen content, and Firmicutes and Gemmatimonadetes showed significant negative correlations with total carbon content in the soil. Furthermore, soil total nitrogen content was the key factor driving changes in microbial communities. The results of this study provide a scientific basis for the study of the long-term effects of tree mortality caused by insect pests on soil microbial communities and their response mechanisms, which is of great theoretical value for the establishment of scientific and effective methods for woodland restoration.

Agricultural and urban practices are correlated to changes in the resistome of riverine systems

The objective of this study was to comprehensively characterise the resistome, the collective set of antimicrobial resistance genes in a given environment, of two rivers, from their source to discharge into the sea, as these flow through areas of different land use. Our findings reveal significant differences in the riverine resistome composition in areas of different land uses, with increased abundance and diversity of AMR in downstream agricultural and urban locations, with the resistome in urban areas more similar to the resistome in wastewater. The changes in resistome were accompanied by changes in microbial communities, with a reduction in microbial diversity in downstream agricultural and urban affected areas, driven mostly by increased relative abundance in the phyla, Bacteroidetes and Proteobacteria. These results provide insight into how pollution associated with agricultural and urban activities affects microbial communities and influences AMR in aquatic water bodies. These results add valuable insights to form effective strategies for mitigating and preserving aquatic ecosystems. Overall, our study highlights the critical role of the environment in the development and dissemination of AMR and underscores the importance of adopting a One Health approach to address this global public health threat.