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Keywords = ammonia-oxidizing bacterial communities

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13 pages, 926 KB  
Article
Determining the Minimum Mature Inoculum Requirement for Nitrification Efficiency and Enhanced Zootechnical Performance of Penaeus vannamei in BFT System
by Wilson Wasielesky, Lucélia Borges, Kiefer Menestrino, Mariana Holanda, Geraldo Fóes, Luís Poersch and Dariano Krummenauer
Aquac. J. 2026, 6(1), 6; https://doi.org/10.3390/aquacj6010006 - 28 Feb 2026
Viewed by 634
Abstract
The biofloc technology (BFT) system is widely used in aquaculture for the cultivation of Pacific white shrimp (Penaeus vannamei). While the practice of reusing percentages of water from previous crops to initiate the system is common, this study aimed to determine [...] Read more.
The biofloc technology (BFT) system is widely used in aquaculture for the cultivation of Pacific white shrimp (Penaeus vannamei). While the practice of reusing percentages of water from previous crops to initiate the system is common, this study aimed to determine the minimum inoculum of total suspended solids (TSS) required for the rapid stabilization of nitrogen compounds and the bacterial community. The experiment was conducted in 400 L experimental units stocked with juvenile P. vannamei. We compared six treatments with different initial inoculum concentrations: control (0 mg/L), 2.5 mg/L, 5 mg/L, 10 mg/L, 20 mg/L, and 40 mg/L. These concentrations corresponded to inoculations of 0%, 0.625%, 1.25%, 2.5%, 5%, and 10% of mature biofloc water with an initial TSS concentration of 400 mg/L. Treatments with an inoculum showed a more effective oxidation of ammonia and nitrite compared to the control. However, the 2.5 mg/L treatment differed significantly (p < 0.05) from the other inoculated treatments, exhibiting persistently high ammonia concentrations and a slower stabilization time. Survival rates in the 5, 10, 20, and 40 mg/L treatments were significantly higher (p < 0.05) than in the control and 2.5 mg/L treatments, remaining around 95%, while the latter had survival rates of 48.75% and 65.83%, respectively. The final biomass were as follows: control: 479.7 ± 30 g; 2.5 mg 628.1 ± 93.3 g; 5 mg 976.5 ± 128.1 g; 10 mg 850.3 ± 158.1 g; 20 mg 789.6 ± 122.7 g; 40 mg 856 ± 96.9 g. Final biomass and productivity were highest in the 5 mg/L treatment and did not differ significantly among the 10, 20, and 40 mg/L treatments. The results suggest that in a BFT system for P. vannamei, a minimum inoculum of 5 mg/L of TSS is sufficient to achieve high water quality and superior zootechnical performance. Full article
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19 pages, 5700 KB  
Article
Bacterial Community Structure and Environmental Adaptation in the Endorhizosphere and Rhizosphere Soils of Aeluropus sinensis from Saline Lands Across Coastal and Inland Regions of China
by Luoyan Zhang, Saiyu Han, Xiuxiu Guo, Lijie Wang, Yilin Fan, Xuejie Zhang and Shoujin Fan
Microorganisms 2026, 14(1), 165; https://doi.org/10.3390/microorganisms14010165 - 12 Jan 2026
Viewed by 638
Abstract
Bacterial communities in the rhizosphere and endorhizosphere of plants show distinct composition, function, and ecological roles during adaptation to diverse habitats. This study examines how rhizosphere and endophytic microbes associated with Aeluropus sinensis—a salt-excreting halophyte—contribute to its salt tolerance across saline-alkali environments. [...] Read more.
Bacterial communities in the rhizosphere and endorhizosphere of plants show distinct composition, function, and ecological roles during adaptation to diverse habitats. This study examines how rhizosphere and endophytic microbes associated with Aeluropus sinensis—a salt-excreting halophyte—contribute to its salt tolerance across saline-alkali environments. Microbial diversity and composition were analyzed via 16S rRNA gene amplicon sequencing. Soil physicochemical properties were measured to evaluate environmental effects. Linear regression assessed microbial–environment relationships, and co-occurrence networks identified key taxa and their adaptive strategies along environmental gradients. Soil salinity significantly affected rhizosphere bacterial diversity, with moderate levels increasing richness. Proteobacteria dominated both root and rhizosphere microbiomes across habitats. The endorhizosphere community strongly correlated with soil nutrients such as available phosphorus (AP) and total nitrogen (TN). Co-occurrence analysis reveals that chemoheterotrophic microbes in the A. sinensis rhizosphere employ distinct adaptive strategies across gradients, and ammonia-oxidizing bacteria (AOB) may support nitrogen cycling in the Yellow River Delta saline–alkaline ecosystem. This study underscores microbial adaptability in salt-tolerant grasses, demonstrating that comparing rhizosphere and endorhizosphere microbiomes in Poaceae under stress improves understanding of microbial functions in harsh environments. Full article
(This article belongs to the Special Issue Advances in Plant–Soil–Microbe Interactions)
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18 pages, 1213 KB  
Article
Contrasting Responses of N2O Mitigation to Different Nitrification Inhibitors in Tea Plantation Soils
by Wei Hua, Siyun Niu, Chenguang Zhao, Jie Wang, Xiangde Yang, Yuanzhi Shi and Kang Ni
Horticulturae 2025, 11(12), 1470; https://doi.org/10.3390/horticulturae11121470 - 5 Dec 2025
Viewed by 657
Abstract
Tea plantations are a hot-spot source of nitrous oxide (N2O) emissions in the agricultural system. Using nitrification inhibitors (NIs) is a promising way to mitigate agricultural N2O emissions and has been widely tested in many croplands. However, the efficiency [...] Read more.
Tea plantations are a hot-spot source of nitrous oxide (N2O) emissions in the agricultural system. Using nitrification inhibitors (NIs) is a promising way to mitigate agricultural N2O emissions and has been widely tested in many croplands. However, the efficiency of different NIs and whether there are soil-specific effects are still unclear in tea plantations with typical acidic soil conditions. This study evaluated the effects of three widely used NIs, i.e., dicyandiamide (DCD), 3,4-dimethylpyrazole phosphate (DMPP), and 2-chloro-6-(trichloromethyl) pyridine (Nitrapyrin), through a lab incubation trial, on the nitrification suppression, N2O emissions, and ammonia-oxidizing microbial communities in two tea plantation soils with contrasting physicochemical properties (pH and texture). During the 50-day incubation, the soil with a higher pH and coarse texture (TA) exhibited a four-times-higher apparent nitrification ratio (ANR) than the more acidic and clay soil (HZ). Nitrification inhibitor addition resulted in about a 60% and 80% reduction in the ANR in HZ and TA soils, respectively. During the entire incubation, ammonium sulfate (N) addition without NIs emitted N2O at 64.1 ± 1.2 and 61.5 ± 0.4 μg N kg−1 (mean ± standard deviation, and the same in the following text) in the HZ and TA soils, respectively. Compared with the N alone, the N2O mitigation efficiency of DCD, DMPP, and Nitrapyrin was 38.3% ± 0.4% (standard deviation), 33.8% ± 0.99%, and 36.5% ± 0.59% in the HZ soil and 94.1% ± 0.39%, 52.8% ± 1.05%, and 95.6% ± 0.65% in the TA soil, respectively. Nitrapyrin more effectively suppressed both ammonia-oxidizing archaeal (AOA) and ammonia-oxidizing bacterial (AOB) abundance, particularly in the acidic soil (HZ), where ammonia-oxidizing archaea dominate nitrification. These results revealed the pivotal role of soil properties in controlling NI efficiency and highlighted Nitrapyrin as a potential superior nitrification inhibitor for N2O mitigation under the tested conditions in this study. Full article
(This article belongs to the Special Issue Sustainable Soil Management for Tea Plantations)
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16 pages, 3003 KB  
Article
Effects of Light Irradiation Conditions on Nitrogen and Phosphorus Removal in Microalgae–Bacteria Biofilm Systems Treating Low-Carbon-to-Nitrogen Wastewater
by Zi Huang, Lei Hu, Qi Liu, Wentao Wang, Weijia Zhao, Tengyi Zhu and Qingan Meng
Water 2025, 17(23), 3426; https://doi.org/10.3390/w17233426 - 2 Dec 2025
Viewed by 1036
Abstract
The influence of light on nutrient removal in microalgae–bacteria biofilm systems containing polyphosphate-accumulating organisms (PAOs) remains unclear under low-carbon-to-nitrogen (C/N) ratio wastewater. This study investigated the effects of different light energy density (Es, 16.23–1101.61 J/gVSS) on the system performance and microbial community of [...] Read more.
The influence of light on nutrient removal in microalgae–bacteria biofilm systems containing polyphosphate-accumulating organisms (PAOs) remains unclear under low-carbon-to-nitrogen (C/N) ratio wastewater. This study investigated the effects of different light energy density (Es, 16.23–1101.61 J/gVSS) on the system performance and microbial community of a phototrophic simultaneous nitrification–denitrification phosphorus removal biofilm (P-SNDPRB) system treating wastewater with C/N ratios of 3.19–3.92. At Es below 367.22 J/gVSS, denitrification was the main nitrogen removal pathway, exceeding 82% total nitrogen removal. With increasing Es, nitrogen assimilation increased, while total nitrogen removal declined, remaining above 65%. Phosphorus removal was dependent on phosphorus-accumulating metabolism, achieving exceeding 90% phosphorus removal at Es below 367.22 J/gVSS. However, effluent phosphorus concentrations exceeded 0.5 mg/L at higher Es due to elevated glycogen-accumulating organism (GAO) activity and photoinhibition. Excessive light induced reactive oxygen species accumulation, inhibiting cellular activity and causing bacterial death in flocs. In contrast, the biofilm mitigated light stress, preserving the activity of PAOs, GAOs, ammonia-oxidizing bacteria, and nitrite-oxidizing bacteria across different Es levels. These findings demonstrate that P-SNDPRB systems exhibit resilience to fluctuating light conditions, enabling effective nutrient removal in low-C/N wastewater and offering insights into optimizing light management for microalgae-assisted treatment processes. Full article
(This article belongs to the Special Issue Environmental Fate and Transport of Organic Pollutants in Water)
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15 pages, 414 KB  
Review
Biotic and Abiotic Factors on Rhizosphere Microorganisms in Grassland Ecosystems
by Bademu Qiqige, Yuzhen Liu, Yu Tian, Li Liu, Weiwei Guo, Ping Wang, Dayou Zhou, Hui Wen, Qiuying Zhi, Yuxuan Wu, Xiaosheng Hu, Ming Li and Junsheng Li
Microorganisms 2025, 13(12), 2645; https://doi.org/10.3390/microorganisms13122645 - 21 Nov 2025
Cited by 1 | Viewed by 1812
Abstract
Rhizosphere microbiota, serving as pivotal drivers of multifunctionality in grassland ecosystems, are jointly shaped by the dual influences of biotic and abiotic factors. Among biotic components, plant functional types selectively modulate microbial communities through root exudate specificity, while soil fauna (e.g., nematodes and [...] Read more.
Rhizosphere microbiota, serving as pivotal drivers of multifunctionality in grassland ecosystems, are jointly shaped by the dual influences of biotic and abiotic factors. Among biotic components, plant functional types selectively modulate microbial communities through root exudate specificity, while soil fauna (e.g., nematodes and earthworms) drive microbial interaction networks via biophysical disturbances and trophic cascades. However, excessive nematode grazing suppresses the hyphal extension of arbuscular mycorrhizal fungi (AMF). Moderate grazing facilitates the proliferation of ammonia-oxidizing bacteria through fecal input, whereas intensive grazing induces topsoil compaction, leading to a dramatic 40–60% reduction in lipopolysaccharide content in Gram-negative bacteria. Long-term chemical fertilization significantly decreases the fungal-to-bacterial ratio, while organic amendments enhance microbial carbon use efficiency by activating extracellular enzymatic activities. Regarding abiotic factors, the stoichiometric characteristics of soil carbon, nitrogen, and phosphorus directly regulate microbial metabolic strategies. Hydrological dynamics influence microbial respiratory pathways through oxygen partial pressure shifts—drought stress inhibits mycelial network development. Future research should focus on predicting the emissions of gases such as N2O (ozone monomer) and optimizing nitrogen fertilizer management to significantly reduce greenhouse gas emissions at the source. The soil organic carbon storage in grassland ecosystems is extremely large. Effective prediction and management can make these soils become important carbon “sinks”, offsetting the carbon dioxide in the atmosphere. At the same time, transcriptomics and metabolic flux analysis should be combined with multi-omics technologies and in situ labeling methods to provide theoretical basis and technical support for developing mechanism-based and predictable grassland restoration and adaptive management strategies from both macroscopic and microscopic perspectives. Full article
(This article belongs to the Section Environmental Microbiology)
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19 pages, 3162 KB  
Article
Diversity and Functional Differences in Soil Bacterial Communities in Wind–Water Erosion Crisscross Region Driven by Microbial Agents
by Tao Kong, Tong Liu, Zhihui Gan, Xin Jin and Lin Xiao
Agronomy 2025, 15(7), 1734; https://doi.org/10.3390/agronomy15071734 - 18 Jul 2025
Cited by 5 | Viewed by 1417
Abstract
Soil erosion-prone areas require effective microbial treatments to improve soil bacterial communities and functional traits. Understanding the driving effects of different microbial interventions on soil ecology is essential for restoration efforts. Single and combined microbial treatments were applied to soil. Bacterial community structure [...] Read more.
Soil erosion-prone areas require effective microbial treatments to improve soil bacterial communities and functional traits. Understanding the driving effects of different microbial interventions on soil ecology is essential for restoration efforts. Single and combined microbial treatments were applied to soil. Bacterial community structure was analyzed via 16S IRNA high-throughput sequencing, and functional groups were predicted using FAPROTAX. Soil microbial carbon, nitrogen, metabolic entropy, and enzymatic activity were assessed. Microbial Carbon and Metabolic Activity: The Arbuscular mycorrhizal fungi (AMF) and Bacillus mucilaginosus (BM) (AMF.BM) treatment exhibited the highest microbial carbon content and the lowest metabolic entropy. The microbial carbon-to-nitrogen ratio ranged from 1.27 to 3.69 across all treatments. Bacterial Community Composition: The dominant bacterial phyla included Firmicutes, Proteobacteria, Acidobacteria, Bacteroidetes, and Actinobacteria. Diversity and Richness: The AMF and Trichoderma harzianum (TH) (AMF.TH) treatment significantly reduced diversity, richness, and phylogenetic diversity indices, while the AMF.BM treatment showed a significantly higher richness index (p < 0.05). Relative Abundance of Firmicutes: Compared to the control, the AMF, TH.BM, and TH treatments decreased the relative abundance of Firmicutes, whereas the AMF.TH treatment increased their relative abundance. Environmental Correlations: Redundancy and correlation analyses revealed significant correlations between soil organic matter, magnesium content, and sucrase activity and several major bacterial genera. Functional Prediction: The AMF.BM treatment enhanced the relative abundance and evenness of bacterial ecological functions, primarily driving nitrification, aerobic ammonia oxidation, and ureolysis. Microbial treatments differentially influence soil bacterial communities and functions. The AMF.BM combination shows the greatest potential for ecological restoration in erosion-prone soils. Full article
(This article belongs to the Section Agroecology Innovation: Achieving System Resilience)
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22 pages, 5141 KB  
Article
Maifanstone Powder-Modified PE Filler for Enhanced MBBR Start-Up in Treating Marine RAS Wastewater
by Rubina Altaf, Tianyu Xiao, Kai Wang, Jianlin Guo, Qian Li, Jing Zou, Neemat Jaafarzadeh, Daoji Wu and Dezhao Liu
Water 2025, 17(13), 1888; https://doi.org/10.3390/w17131888 - 25 Jun 2025
Viewed by 1444
Abstract
The recirculating aquaculture system (RAS) has been rapidly adopted worldwide in recent years due to its high productivity, good stability, and good environmental controllability (and therefore friendliness to environment and ecology). Nevertheless, the effluent from seawater RAS contains a high level of ammonia [...] Read more.
The recirculating aquaculture system (RAS) has been rapidly adopted worldwide in recent years due to its high productivity, good stability, and good environmental controllability (and therefore friendliness to environment and ecology). Nevertheless, the effluent from seawater RAS contains a high level of ammonia nitrogen which is toxic to fish, so it is necessary to overcome the salinity conditions to achieve rapid and efficient nitrification for recycling. The moving bed biofilm reactor (MBBR) has been widely applied often by using PE fillers for efficient wastewater treatment. However, the start-up of MBBR in seawater environments has remained a challenge due to salinity stress and harsh inoculation conditions. This study investigated a new PE-filler surface modification method towards the enhanced start-up of mariculture MBBR by combining liquid-phase oxidation and maifanstone powder. The aim was to obtain a higher porous surface and roughness and a strong adsorption and alkalinity adjustment for the MBBR PE filler. The hydrophilic properties, surface morphology, and chemical structure of a raw polyethylene filler (an unmodified PE filler), liquid-phase oxidation modified filler (LO-PE), and liquid-phase oxidation combined with a coating of a maifanstone-powder-surface-modified filler (LO-SCPE) were first investigated and compared. The results showed that the contact angle was reduced to 45.5° after the optimal liquid-phase oxidation modification for LO-PE, 49.8% lower than that before modification, while SEM showed increased roughness and surface area by modification. Moreover, EDS presented the relative content of carbon (22.75%) and oxygen (42.36%) on the LO-SCPE surface with an O/C ratio of 186.10%, which is 177.7% higher than that of the unmodified filler. The start-up experiment on MBBRs treating simulated marine RAS wastewater (HRT = 24 h) showed that the start-up period was shortened by 10 days for LO-SCPE compared to the PE reactor, with better ammonia nitrogen removal observed for LO-SCPE (95.8%) than the PE reactor (91.7%). Meanwhile, the bacterial community composition showed that the LO-SCPE reactor had a more diverse and abundant AOB and NOB. The Nitrospira has a more significant impact on nitrification because it would directly oxidize NH4⁺-N to NO3⁻-N (comammox pathway) as mediated by AOB and NOB. Further, the LO-SCPE reactor showed a higher NH4+-N removal rate (>99%), less NO2-N accumulation, and a shorter adaption period than the PE reactor. Eventually, the NH4+-N concentrations of the three reactors (R1, R2, and R3) reached <0.1 mg/L within 3 days, and their NH4+-N removal efficiencies achieved 99.53%, 99.61%, and 99.69%, respectively, under ammonia shock load. Hence, the LO-SCPE media have a higher marine wastewater treatment efficiency. Full article
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18 pages, 8726 KB  
Article
Dynamic Response Mechanisms of Anammox Reactors Under Nitrogen-Loading Fluctuations: Nitrogen Removal Performance, Microbial Community Succession, and Metabolic Functions
by Xuemei Liu, Kai Wan, Chunqiao Xiao, Jingang Hu, Xiangyi Deng and Ruan Chi
Microorganisms 2025, 13(4), 899; https://doi.org/10.3390/microorganisms13040899 - 14 Apr 2025
Cited by 2 | Viewed by 1431
Abstract
The leachate from ion-adsorbed rare earth tailings poses challenges to the application of the anaerobic ammonium oxidation (anammox) process in this field due to its large fluctuations in ammonia nitrogen concentration (50–300 mg/L) and high flow rate (4000–10,000 m3/d). This study [...] Read more.
The leachate from ion-adsorbed rare earth tailings poses challenges to the application of the anaerobic ammonium oxidation (anammox) process in this field due to its large fluctuations in ammonia nitrogen concentration (50–300 mg/L) and high flow rate (4000–10,000 m3/d). This study investigated the effects of nitrogen-loading rate (NLR) regulation on denitrification performance through reactor operation and elucidated the mechanisms of NLR impacts on anammox processes via microbial community analysis and metabolic profiling. The results revealed a nonlinear relationship between nitrogen loading and system performance. As NLR increased, both denitrification efficiency and anammox bacterial abundance (rising from 5.85% in phase P1 to 11.43% in P3) showed synchronous enhancement. However, excessive nitrogen loading (>3.68 kg/m3·d) or nitrogen starvation led to performance deterioration and reduced anammox bacterial abundance. Microbial communities adopted modular collaboration to counteract loading stress, with modularity indices of 0.563 and 0.545 observed in the inhibition phase (P2) and starvation phase (P4), respectively. Zi-Pi plot analysis demonstrated a significant increase in inter-module connectivity, indicating reinforced interspecies interactions among microorganisms to resist nitrogen-loading fluctuations. Full article
(This article belongs to the Special Issue Advances in Microbial Cell Factories, 3rd Edition)
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17 pages, 3193 KB  
Article
Effects of Biochar on Cadmium Availability, Nitrification and Microbial Communities in Soils with Varied pH Levels
by Wei Zhao, Xiaoxu Cao, Hong Pan, Yanhong Lou, Hui Wang, Quangang Yang and Yuping Zhuge
Microorganisms 2025, 13(4), 839; https://doi.org/10.3390/microorganisms13040839 - 7 Apr 2025
Cited by 6 | Viewed by 1809
Abstract
Cadmium (Cd) contamination poses severe threats to agricultural productivity and ecosystem health. Biochar has shown promise in immobilizing Cd and enhancing microbial functions, yet its pH-dependent mechanisms remain underexplored. This study aimed to elucidate pH-dependent variations in biochar-mediated cadmium (Cd) immobilization efficiency, nitrification [...] Read more.
Cadmium (Cd) contamination poses severe threats to agricultural productivity and ecosystem health. Biochar has shown promise in immobilizing Cd and enhancing microbial functions, yet its pH-dependent mechanisms remain underexplored. This study aimed to elucidate pH-dependent variations in biochar-mediated cadmium (Cd) immobilization efficiency, nitrification activity, and bacterial community diversity across soils of contrasting pH levels, with mechanistic insights into the synergistic interplay between biochar properties and soil pH. Real-time quantitative PCR (qPCR) and high-throughput sequencing were used to investigate the effects of a 1% (w/w) biochar amendment on ammonia-oxidizing microorganism abundance and microbial diversity in neutral Shandong soil (SD, pH 7.46) and acidic Yunnan soil (YN, pH 5.88). In neutral SD soil, available Cd decreased from 0.22 mg kg−1 (day 0) to 0.1 mg kg−1 (day 56) and stabilized, accompanied by insignificant changes in ammonia-oxidizing bacteria (AOB) abundance. However, nitrification activity was enhanced through the enrichment of Nitrospira (nitrite-oxidizing bacteria within Nitrospirales and Nitrospiraceae). In acidic YN soil, biochar reduced available Cd by 53.37% over 56 days, concurrent with a 34.28% increase in AOB amoA gene abundance (predominantly Nitrosomonadales), driving pH-dependent nitrification enhancement. These findings demonstrated that biochar efficacy was critically modulated by soil pH; the acidic soils require higher biochar dosages (>1% w/w, adjusted to local soil properties and agronomic conditions) for optimal Cd immobilization. Meanwhile, pH-specific nitrifier taxa (Nitrosomonadales in acidic vs. Nitrospira in neutral soils) underpinned biochar-induced nitrification dynamics. The study provided a mechanistic framework for tailoring biochar remediation strategies to soil pH gradients, emphasizing the synergistic regulation of Cd immobilization and microbial nitrogen cycling. Full article
(This article belongs to the Special Issue Microbial Processes in the Soil Environment)
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15 pages, 5449 KB  
Article
Spatial Heterogeneity of the Microbial Community in the Surface Sediments in the Okinawa Trough
by Ye Chen, Nengyou Wu, Cuiling Xu, Youzhi Xin, Jing Li, Xilin Zhang, Yucheng Zhou and Zhilei Sun
J. Mar. Sci. Eng. 2025, 13(4), 653; https://doi.org/10.3390/jmse13040653 - 25 Mar 2025
Cited by 2 | Viewed by 1471
Abstract
The Okinawa Trough (OT) has been a focus of scientific research for many years due to the presence of vibrant hydrothermal and cold seep activity within its narrow basin. However, the spatial distribution and environmental drivers of microbial communities in OT sediments remain [...] Read more.
The Okinawa Trough (OT) has been a focus of scientific research for many years due to the presence of vibrant hydrothermal and cold seep activity within its narrow basin. However, the spatial distribution and environmental drivers of microbial communities in OT sediments remain poorly understood. The present study aims to address this knowledge gap by investigating microbial diversity and abundance at ten different sampling sites in a transitional zone between hydrothermal vents and cold seeps in the OT. The microbial community at two sampling sites (G08 and G09) in close proximity to hydrothermal vents showed a high degree of similarity. However, lower bacterial and archaeal abundances were found in these sites. The archaeal groups, classified as Hydrothermarchaeota and Thermoplasmata, showed a comparatively higher relative abundance at these sites. In addition, ammonia-oxidizing archaea (AOA), from the family Nitrosopumilaceae, were found to have a higher relative abundance in the OT surface sediments at sampling sites G03, G04, G05, G06, and G07. This result suggests that ammonia oxidation may be actively occurring in these areas. Furthermore, Methylomirabilaceae, which are responsible for methane oxidation coupled with nitrite reduction, dominated three sampling sites (G07, G08, and G09), implying that N-DAMO may play an important role in mitigating methane emissions. Using the FAPROTAX database, we found that predicted prokaryotic microbial functional groups involved in methyl-reducing methanogenesis and hydrogenotrophic methanogenesis were most abundant at sites G08 and G09. At sampling sites G01 and G02, functional groups such as hydrocarbon degradation, methanotrophy, methanol oxidation, denitrification, sulfate respiration, and sulfur oxidation were more abundant. Nitrogen content is the most important environmental factor determining the bacterial and archaeal communities in the OT surface sediments. These results expand our knowledge of the spatial distribution of microbial communities in the transitional zone between hydrothermal vents and cold seeps in the OT. Full article
(This article belongs to the Special Issue Research Progress on Deep-Sea Organisms)
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24 pages, 3799 KB  
Article
Impacts of Land Use on Soil Nitrogen-Cycling Microbial Communities: Insights from Community Structure, Functional Gene Abundance, and Network Complexity
by Junnan Ding and Shaopeng Yu
Life 2025, 15(3), 466; https://doi.org/10.3390/life15030466 - 14 Mar 2025
Cited by 14 | Viewed by 4068
Abstract
This study investigates the effects of different land-use types (forest, arable land, and wetland) on key soil properties, microbial communities, and nitrogen cycling in the Lesser Khingan Mountains. The results revealed that forest (FL) and wetland (WL) soils had significantly higher soil organic [...] Read more.
This study investigates the effects of different land-use types (forest, arable land, and wetland) on key soil properties, microbial communities, and nitrogen cycling in the Lesser Khingan Mountains. The results revealed that forest (FL) and wetland (WL) soils had significantly higher soil organic matter (SOM) content compared with arable land (AL), with total phosphorus (TP) being highest in FL and available nitrogen (AN) significantly higher in WL. In terms of enzyme activity, AL and WL showed reduced activities of ammonia monooxygenase (AMO), β-D-glucosidase (β-G), and β-cellobiosidase (CBH), while exhibiting increased N-acetyl-β-D-glucosaminidase (NAG) activity, highlighting the impact of land use on nitrogen dynamics. WL also exhibited significantly higher microbial diversity and evenness compared with FL and AL. The dominant bacterial phyla included Actinobacteriota, Proteobacteria, and Acidobacteriota, with Acidobacteriota being most abundant in FL and Proteobacteria most abundant in WL. Network analysis showed that AL had the most complex and connected microbial network, while FL and WL had simpler but more stable networks, suggesting the influence of land use on microbial community interactions. Regarding nitrogen cycling genes, AOA-amoA was most abundant in AL, while AOB-amoA was significantly enriched in FL, reflecting the influence of land use on ammonia oxidation. These findings highlight how land-use types significantly affect soil properties, microbial community structures, and nitrogen cycling, offering valuable insights for sustainable land management. Full article
(This article belongs to the Special Issue Carbon and Nitrogen Cycles in Terrestrial Ecosystems)
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21 pages, 3794 KB  
Article
Effects of Moisture Content Gradient on Alfalfa Silage Quality, Odor, and Bacterial Community Revealed by Electronic Nose and GC–MS
by Yichao Liu, Zhijun Wang, Lin Sun, Yuhan Zhang, Muqier Zhao, Junfeng Hao, Mingjian Liu, Gentu Ge, Yushan Jia and Shuai Du
Microorganisms 2025, 13(2), 381; https://doi.org/10.3390/microorganisms13020381 - 9 Feb 2025
Cited by 14 | Viewed by 3198
Abstract
Better quality and odor of silage and normal microbial fermentation metabolism are mostly dependent on an appropriate moisture content. The purpose of this study was to determine the effects of different moisture content gradients (50, 60, 70, and 80%) on the bacterial community, [...] Read more.
Better quality and odor of silage and normal microbial fermentation metabolism are mostly dependent on an appropriate moisture content. The purpose of this study was to determine the effects of different moisture content gradients (50, 60, 70, and 80%) on the bacterial community, odor, and quality of alfalfa silage at 60 days by using gas chromatography–mass spectrometry (GC–MS) and electronic nose, with six replicates per group. The results showed that there were significant differences in odor response intensity among all groups, among which the 80% group had the strongest reaction to terpenoids, sulfides, and nitrogen oxides. Similarly, the different volatile organic compounds (VOCs) were mainly terpenoids, alcohols, and ketones, such as pine, camphor, and menthol (e.g., carlin and levomenthol). The dominant bacterium was Enterococcus with higher fiber, pH, and ammonia nitrogen (NH3-N) content but poorer quality and odor (p < 0.05). The differential VOCs in the 60% group were mainly heterocyclics, esters, and phenols with fruity, floral, and sweet odors such as 2-butylthiophene and acorone. Pediococcus and Lactiplantibacillus were the dominant bacteria, with higher crude protein (CP), water-soluble carbohydrates (WSC), and lactic acid (LA) contents, as well as better quality and odor (p < 0.05). The biosynthesis of terpenoids and steroids, biosynthesis of secondary metabolites, and biosynthesis of phenylpropanoids were the main metabolic pathways of differential VOCs. In conclusion, regulating moisture content can alter bacterial community and metabolites, which will encourage fermentation and enhance alfalfa silage quality and odor. Full article
(This article belongs to the Section Microbial Biotechnology)
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20 pages, 2730 KB  
Article
Network of Nitrifying Bacteria in Aquarium Biofilters: An Unfaltering Cooperation Between Comammox Nitrospira and Ammonia-Oxidizing Archaea
by Martyna Godzieba, Piotr Hliwa and Slawomir Ciesielski
Water 2025, 17(1), 52; https://doi.org/10.3390/w17010052 - 28 Dec 2024
Cited by 11 | Viewed by 8147
Abstract
Nitrification plays a crucial role in aquatic ecosystems and in the biofilters used in fish farms. Despite their importance, the role of canonical nitrifiers, comammox bacteria, and archaea has not yet been sufficiently investigated. The aim of this study was to characterize the [...] Read more.
Nitrification plays a crucial role in aquatic ecosystems and in the biofilters used in fish farms. Despite their importance, the role of canonical nitrifiers, comammox bacteria, and archaea has not yet been sufficiently investigated. The aim of this study was to characterize the microbiome of the external canister biofilter in a freshwater fish aquarium, with particular focus on the role of comammox Nitrospira and their competition with other nitrifiers. To achieve this, a comprehensive approach combining metagenome sequencing and co-occurrence network analysis was used to study the interactions between microorganisms in portable biofilter. The fish were subjected to a changing feeding regime that affected the ecological relationships and abundance of different microbial taxa. The results showed the presence of two types of nitrifiers in the biofilter: comammox Nitrospira and ammonia-oxidizing archaea (AOA). Five comammox Nitrospira genomes were reconstructed, with comammox clade B being the most abundant with an average abundance of 7.8 ± 0.4%. In addition, two families of archaea were identified: Nitrosopumilaceae and Nitrososphaeraceae, with an average abundance of 4.3 ± 0.4%. Heterotrophs were also abundant in the bacterial community, particularly in the genera Actinomycetota, Planctomycetota, and Pseudomonadota. Network analysis indicated competitive interactions between comammox and heterotrophs, whereas no competition was observed between comammox and AOA. The predominance of comammox Nitrospira, and AOA over canonical nitrifiers emphasizes their better adaptation to oligotrophic environments. This study highlights the importance of competition within the biofilter microbiome and the role of ecological interaction networks, which can contribute to the optimization of water purification systems in RASs. Full article
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20 pages, 4777 KB  
Article
The Application of Kitchen Waste Changed the Community Structure and Composition of AOA and AOB by Affecting the pH and Soil Organic Carbon of Red Soil
by Donghui Zhang, Wen Chen, Changtao Wen, Zheng Hou, Keqin Wang and Yali Song
Agronomy 2024, 14(12), 3053; https://doi.org/10.3390/agronomy14123053 - 20 Dec 2024
Cited by 2 | Viewed by 1985
Abstract
To investigate the effects of kitchen waste on the chemical properties of acidic red soil and the community structure of ammonia–oxidizing archaea (AOA) and ammonia–oxidizing bacteria (AOB), a study was conducted in the flue–cured tobacco farmland ecosystem of the Erlongtan small watershed in [...] Read more.
To investigate the effects of kitchen waste on the chemical properties of acidic red soil and the community structure of ammonia–oxidizing archaea (AOA) and ammonia–oxidizing bacteria (AOB), a study was conducted in the flue–cured tobacco farmland ecosystem of the Erlongtan small watershed in central Yunnan. Eight fertilization methods were applied: no fertilization control CK, single application of chemical fertilizer T1 (1 t·hm−2), kitchen waste combined with a chemical fertilizer (T2:12 t·hm−2 + 1 t·hm−2, T3:15 t·hm−2 + 1 t·hm−2, T4:18 t·hm−2 + 1 t·hm−2), and single application of kitchen waste (T5:12 t·hm−2, T6:15 t·hm−2, T7:18 t·hm−2). The numbers twelve, fifteen, and eighteen in brackets represent the amount of food waste applied, and one represents the amount of chemical fertilizer applied. The study evaluated the effects of kitchen waste on soil chemical properties, the community structure and composition of AOA and AOB, and the relationship between soil chemical properties and these microbial communities in acidic red soil. The results showed that: (1) single application of kitchen waste (T5, T6, T7) effectively improved soil nutrient status (SOC increased by 15.79–217.24%; TN increased by 1.53–92.99%; NH4+–N increased by 18.19–520.74%; NO3–N) increased by 15.54–750.61%), and alleviated acidification. (2) Temporal variations had a more significant effect on the community structure of AOA and AOB than different treatments. The dominant phyla of AOA were Thaumarchaeota, Crenarchaeot. The dominant phylum of AOB was Proteobacteria, and the dominant genera were Nitrosospira and norank_Bacteri. (3) The number of AOA co–occurrence network nodes were equivalent to that of AOB, but AOB had more connection edges, indicating a more complex interaction network. In contrast, AOA exhibited higher modularity, reflecting tighter internal connections and greater stability. The AOA co–occurrence network showed stronger performance during the maturity and fallow stages, while AOB interactions were most active during the topping stage. (4) AOA demonstrated a strong correlation with soil chemical properties during the topping and maturity stages, whereas AOB showed a stronger correlation at the rosette and fallow stages. Among soil chemical factors, pH and SOC were identified as the primary drivers influencing AOA and AOB community abundance and structural differentiation. In conclusion, kitchen waste application enhances the nutrient content of acidic red soil and influences the niche differentiation of AOA and AOB, thereby affecting nitrogen recycling. This approach represents an environmentally friendly and sustainable fertilization method. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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17 pages, 4420 KB  
Article
Metagenomic Analysis Revealing the Impact of Water Contents on the Composition of Soil Microbial Communities and the Distribution of Major Ecological Functional Genes in Poyang Lake Wetland Soil
by Yuxin Long, Xiaomei Zhang, Xuan Peng, Huilin Yang, Haiyan Ni, Long Zou and Zhong’er Long
Microorganisms 2024, 12(12), 2569; https://doi.org/10.3390/microorganisms12122569 - 13 Dec 2024
Cited by 1 | Viewed by 2421
Abstract
Poyang Lake is the largest freshwater lake in China, which boasts unique hydrological conditions and rich biodiversity. In this study, metagenomics technology was used to sequence the microbial genome of soil samples S1 (sedimentary), S2 (semi-submerged), and S3 (arid) with different water content [...] Read more.
Poyang Lake is the largest freshwater lake in China, which boasts unique hydrological conditions and rich biodiversity. In this study, metagenomics technology was used to sequence the microbial genome of soil samples S1 (sedimentary), S2 (semi-submerged), and S3 (arid) with different water content from the Poyang Lake wetland; the results indicate that the three samples have different physicochemical characteristics and their microbial community structure and functional gene distribution are also different, resulting in separate ecological functions. The abundance of typical ANME archaea Candidatus Menthanoperedens and the high abundance of mcrA in S1 mutually demonstrate prominent roles in the methane anaerobic oxidation pathway during the methane cycle. In S2, the advantageous bacterial genus Nitrospira with ammonia oxidation function is validated by a large number of nitrification functional genes (amoA, hao, nxrA), manifesting in that it plays a monumental role in nitrification in the nitrogen cycle. In S3, the dominant bacterial genus Nocardioides confirms a multitude of antibiotic resistance genes, indicating their crucial role in resistance and their emphatic research value for microbial resistance issues. The results above have preliminarily proved the role of soil microbial communities as indicators predicting wetland ecological functions, which will help to better develop plans for restoring ecological balance and addressing climate change. Full article
(This article belongs to the Section Environmental Microbiology)
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