Evolution Of Microbial Communities Research Articles

Influence of Nitrogen Loading on the Performance of Partial Nitrification Processes and the Evolution of Microbial Communities

Stable and efficient partial nitrification reaction and nitrite accumulation are essential for the operation of partial nitrification-anaerobic ammonia oxidation process. This paper investigated the changes in the performance of a partial nitrification bioreactor during the domestication process. After 40 days of domestication, the partial nitrification reaction remained stable, the nitrite accumulation rate (NAR) increased significantly to 85.7%, and the NO2 --N/NH4 +-N ratio stabilized at 1.25 ± 0.04. Both diversity indices (Simpson and Shannon) and richness indices (Ace and Chao1) tend to decrease with domestication. Nitrosomonas as a typical ammonia oxidizing bacterium it increased its relative abundance in the reactor from 0.02 ± 0.007% at P1 to 11.6 ± 2.2% at P2, and at P3 stage the denitrifying functional bacteria norank_f_AKYH76, Dokdonella and unclassified_f_Comamonadaceae reached 33.4 ± 12.5%, 18.8 ± 1.8%, and 10.1 ± 1.3%, respectively, and the increase in the relative abundance of these functional species was also consistent with the accumulation of nitrite nitrogen in the reactor.

Microplastics in anoxic/aerobic membrane bioreactor (A/O-MBR): Characteristics, biofilms, degradation and carrier for antibiotic resistance genes

Wastewater treatment plants (WWTPs)are proposed as one of the ways for microplastics (MPs) to enter the water environment. MPs as the carrier of other pollutants, the inevitable aging process will change the characteristics and fate of MPs. Herein, the physicochemical property alteration, microbial community evolution and antibiotic resistance genes (ARGs) occurrence of the aged MPs surface were analyzed in A/O-MBR system. Remarkable alteration in MPs surface properties, which included the decrease in hydrophobicity and the increase in oxygen-containing functional groups, led to aging of MPs. Aging MPs are more likely to grow biofilms, which further increased the probability of microbial colonization. The genera Hydrogenophaga, Exiguobacterium, Enterobacter, Vibrio, Flavobacterium and Bacillus on MPs surface showed higher degradation potential. ARGs determination results indicated that MPs could enrich ARGs on their surface, and the relative abundance of β-lactam ARGs on different MPs surfaces was the highest. The above research results indicated that MPs in sewage treatment systems not only undergo aging, but also carry ARGs, causing further harm to the environment.

Evolution of microbial community and the volatilome of fresh-cut chili pepper during storage under different temperature conditions: Correlation of microbiota and volatile organic compounds

The effect of temperature conditions on the evolution of microbial communities and volatile organic compounds (VOCs) in fresh-cut chili peppers during storage was investigated. Results showed that Proteobacteria and Actinobacteriota were the dominant phyla in fresh-cut chili peppers. During storage, bacterial communities changed more dramatically than fungi. Different temperature conditions significantly affected the shift of bacteria at the genus level. At the beginning of storage, Rhodococcus, Pantoea, and Pseudomonas dominated the bacteria. However, on day 8, Pantoea and Enterobacter became the predominant genera at 5 °C and high temperatures (10, 15 °C, dynamic temperature), respectively. No significant variability in bacterial species was observed between different batches. Additionally, 140 VOCs were determined in fresh-cut chili peppers. Twenty-two VOCs were screened and could be recommended as potential spoilage markers. Based on Spearman's correlation analysis results, Enterobacter and Enterococcus were the most positive microorganisms correlated with spoilage markers.

Synergistic improvement of humus formation in compost residue by fenton-like and effective microorganism composite agents

Improving the humification of compost through a synergistic approach of biotic and abiotic methods is of great significance. This study employed a composite reagent, comprising Fenton-like agents and effective microorganisms (EM) to improve humification. This composite reagent increased humic-acid production by 37.44 %, reaching 39.82 g kg−1, surpassing the control group. The composite reagent synergistically promoted micromolecular fulvic acid and large humic acid production. Collaborative mechanism suggests that Fenton-like agents contributed to bulk residue decomposition and stimulated the evolution of microbial communities, whereas EMs promoted highly aromatic substance synthesis and adjusted the microbial community structure. Sequencing analysis indicates the Fenton-like agent initiated compost decomposition by Firmicutes, and EM reduced the abundance of Virgibacillus, Lentibacillus, and Alcanivorax. Applied as an organic fertilizer in Brassica chinensis L. plantations, the composite reagent considerably improved growth and photosynthetic pigment content. This composite reagent with biotic and abiotic components provides a learnable method for promoting humification.

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.

Asynchronous characteristics of Feammox and iron reduction from paddy soils in Southern China

Recently, the newly discovered anaerobic ammonium oxidation coupled with iron reduction (i.e., Feammox) has been proven to be a widespread nitrogen (N) loss pathway in ecosystems and has an essential contribution to gaseous N loss in paddy soil. However, the mechanism of iron-nitrogen coupling transformation and the role of iron-reducing bacteria (IRB) in Feammox were poorly understood. This study investigated the Feammox and iron reduction changes and microbial community evolution in a long-term anaerobic incubation by 15N isotope labeling combined with molecular biological techniques. The average rates of Feammox and iron reduction during the whole incubation were 0.25 ± 0.04 μg N g−1 d−1 and 40.58 ± 3.28 μg Fe g−1 d−1, respectively. High iron oxide content increased the Feammox rate, but decreased the proportion of Feammox–N2 in three Feammox pathways. RBG-13-54-9, Brevundimonas, and Pelomonas played a vital role in the evolution of microbial communities. The characteristics of asynchronous changes between Feammox and iron reduction were found through long-term incubation. IRB might not be the key species directly driving Feammox, and it is necessary to reevaluate the role of IRB in Feammox process.

The promotion of the atrazine degradation mechanism by humic acid in a soil microbial electrochemical system

The enhancing effects of anodes on the degradation of the organochlorine pesticide atrazine (ATR) in soil within microbial electrochemical systems (MES) have been extensively researched. However, the impact and underlying mechanisms of soil microbial electrochemical systems (MES) on ATR degradation, particularly under conditions involving the addition of humic acids (HAs), remain elusive. In this investigation, a soil MES supplemented with humic acids (HAs) was established to assess the promotional effects and mechanisms of HAs on ATR degradation, utilizing EEM-PARAFAC and SEM analyses. Results revealed that the maximum power density of the MES in soil increased by 150%, and the degradation efficiency of ATR improved by over 50% following the addition of HAs. Furthermore, HAs were found to facilitate efficient ATR degradation in the far-anode region by mediating extracellular electron transfer. The components identified as critical in promoting ATR degradation were Like-Protein and Like-Humic acid substances. Analysis of the microbial community structure indicated that the addition of HAs favored the evolution of the soil MES microbial community and the enrichment of electroactive microorganisms. In the ATR degradation process, the swift accumulation of Hydrocarbyl ATR (HYA) was identified as the primary cause for the rapid degradation of ATR in electron-rich conditions. Essentially, HA facilitates the reduction of ATR to HYA through mediated bonded electron transfer, thereby markedly enhancing the efficiency of ATR degradation.

Rare taxa as the microbial taxa more sensitive to environmental changes drive alterations of daqu microbial community structure and function

Microbial interactions and environmental conditions determine the evolution of microbial communities and their functions during Nongxiangxing daqu (daqu) fermentation. In this study, the sensitivity of rare microbial taxa, conditionally rare-abundant microbial taxa and abundant microbial taxa, to environmental changes, as well as the impact of their presence on the microbial community structure and function during daqu fermentation were elucidated by using high-throughput sequencing technology combined with environmental and volatile metabolites analysis. The results indicated that rare taxa, which were the predominant microbial taxa, were more heterogeneous during the daqu fermentation process. It is necessary to note that rare taxa were more sensitive to changing environmental conditions. The microbial molecular ecological network and within-module connectivity and among-module connectivity analysis showed that most of the key nodes (∼63% of operational taxonomic units) located in the networks determining microbial interactions belong to rare taxa. Furthermore, rare taxa were significantly associated with more volatile metabolites, and rare taxa were particularly important for the synthesis of pyrazines and alcohols. The present study demonstrated that rare taxa, as the microbial taxa more susceptible to environmental variation, drive alterations in the structure of microbial communities and their functions.

Comparison of treatment performance and microbial community evolution of typical dye wastewater by different combined processes

The degradation of typical dye wastewater is a focus of research in the printing and dyeing industry. In this study, a combined micro-electrolysis and microbial treatment method was established to treat refractory dye wastewater, and the pivotal factors in the microbial treatment were optimized. In the series and coupled modes, the removal rates of chroma reached 98.75% and 92.50%, and the removal rates of chemical oxygen demand (COD) reached 96.17% and 82.29%, respectively. The high-throughput sequencing results showed that the microbial communities in the microbial system varied at different treatment stages. From the culture stage to the domestication stage, the dominant phylum was Proteobacteria; however, the community abundance of microorganisms decreased. A combination of micro-electrolysis and biological methods can alter the characteristics of the microbial community, increase the number of dominant phyla, and increase the abundance of microorganisms. The degradation effect of the series mode and the overall strengthening effect of micro-electrolysis on the microorganisms were better than those of the coupled mode. In actual wastewater, the maximum removal rates of chroma, COD, total nitrogen (TN), ammonia nitrogen (NH3-N), and total phosphorus (TP) are 97.50%, 98.90%, 94.35%, 93.95%, and 91.17%, respectively. Three-dimensional fluorescence spectrum analysis showed that microbial processes could significantly degrade fluorescent components in wastewater, and methanogenic active enzymes in anaerobic processes could continue to react. The combined process can realize the efficient treatment of toxic dye wastewater by reducing the toxicity of wastewater and efficiently degrading organic matter, which has important guiding significance for the treatment of refractory dye wastewater.

Effect of sludge redistribution strategy on stability of partial nitrification-anammox process: Further exploration of the potential value of sludge

The stability of the two-stage partial nitrification-anammox (PN/A) system was compromised by the inappropriate conversion of insoluble organic matter. In response, a sludge redistribution strategy was implemented. Through the redistribution of PN sludge and anammox sludge in the two-stage PN/A system, a transition was made to the Anammox-single stage PN/A (A-PN/A) system. This specific functional reorganization, facilitated by the rapid reorganization of microbial communities, has the potential to significantly decrease the current risk of suppression. The results of the study showed that implementing the sludge redistribution strategy led to a substantial enhancement in the total nitrogen removal rate (TNRR) by 87.51%, accompanied by a significant improvement of 34.78% in the chemical oxygen demand removal rate (CRR). Additionally, this approach resulted in a remarkable two-thirds reduction in the aeration requirements. High-throughput sequencing revealed that the strategy enriched anammox and ammonia-oxidizing bacteria while limiting denitrifying bacteria, as confirmed by quantitative polymerase chain reaction analysis. Furthermore, the principal component analysis revealed that the location and duration of aeration had direct and indirect effects on functional gene expression and the evolution of microbial communities. This study emphasizes the potential benefits of restructuring microbial communities through a sludge redistribution strategy, especially in integrated systems that encounter challenges with suppression.

A novel sulfidogenic process via sulfur reduction to remove arsenate in acid mine drainage: Insights into the performance and microbial mechanisms

Biological sulfidogenic processes based on sulfate-reducing bacteria (SRB) are not suitable for arsenic (As)-containing acid mine drainage (AMD) treatment because of the formation of the mobile thioarsenite during sulfate reduction. In contrast, biological sulfidogenic processes based on sulfur-reducing bacteria (S0RB) produce sulfide without pH increase, which could achieve more effective As removal than the SRB-based process. However, the reduction ability and toxicity tolerance of S0RB to As remains mysterious, which may substantially affect the practical applicability of this process when treating arsenate (As(V))-containing AMD. Thus, this study aims to develop a biological sulfur reduction process driven by S0RB, and explore its long-term performance on As(V) removal and microbial community evolution. Operating under moderately acidic conditions (pH=4.0), the presence of 10 mg/L As(V) significantly suppressed the activity of S0RB, leading to the failure of As(V) removal. Surprisingly, a drop in pH to 3.0 enhanced the tolerance of S0RB to As toxicity, allowing for efficient sulfide production (396±102 mg S/L) through sulfur reduction. Consequently, effective and stable removal of As(V) (99.9 %) was achieved, even though the sulfidogenic bacteria were exposed to high levels of As(V) (42 mg/L) in long-term trials. Spectral and spectroscopic analysis showed that As-bearing sulfide minerals were present in the bioreactor. Remarkably, the presence of As(V) induced notable changes in the microbial community composition, with Desulfurella and Clostridium identified as predominate sulfur reducers. The qPCR result further revealed an increase in the concentration of functional genes related to As transport (asrA and arsB) in the bioreactor sludge as the pH decreased from 4.0 to 3.0. This suggests the involvement of microorganisms carrying asrA and arsB in an As transport process. Furthermore, metagenomic binning demonstrated that Desulfurella contained essential genes associated with sulfur reduction and As transportation, indicating its genetic potential for sulfide production and As tolerance. In summary, this study underscores the effectiveness of the biological sulfur reduction process driven by S0RB in treating As(V)-contaminated AMD. It offers insights into the role of S0RB in remediating As contamination and provides valuable knowledge for practical applications.

Carbonate microbialites and chemotrophic microbes: Insights from caves from south‐east China

ABSTRACTChemosynthetic microorganisms facilitate microbialite development in many caves throughout the world. In Youqin Cave and Tian'e Cave, located in the Carboniferous–Triassic carbonates on the South China Block, five Quaternary speleothems (stalagmite, stalactite and cave pearl) that are 2.3 to 11.0 cm long were examined for their petrographic, geochemical and microbiological features to reveal how chemotrophs contribute to microbialite growth. In the speleothems, millimetre‐sized stromatolites, thrombolites and calcified microbial mats are characterized by alternating light, calcitic microlaminae and dark, clay and organic‐rich calcite microlaminae. Filamentous (reticulate, smooth, nodular and helical), coccoid and bacilliform microbes, originally carried into the caves from surface soils, are more common in the dark microlaminae/clots than in the light microlaminae. 16S rRNA gene sequencing shows that the biotas in the microbialites are dominated by chemoorganotrophic heterotrophic bacteria, including primarily Sphingomonas, Crossiella and Acinetobacter, and rare Archaea. Diverse metabolic pathways of these prokaryotes, including ureolysis, denitrification and nitrite ammonification, contributed to increases in localized pH and/or dissolved inorganic carbon in these microenvironments, prompting carbonate precipitation. Development of the cave microbialites was probably controlled by the evolution of the cave microbial community as environmental conditions changed. Microbialite growth was probably mediated by the microorganisms that flourished on the speleothem surfaces during periods of low drip water rates and slow calcite precipitation. The change from microstromatolites to microthrombolites was probably linked to a decrease in cell populations in the microbial communities. These cave microbialites provide clear insights regarding the biogenicity and growth mechanisms of chemosynthetic microbialites. Given their association with chemolithotrophic activities that can date back to the Meso‐Archean, cave microbialites provide insights into the biogenicity and growth mechanisms of chemosynthesis‐based microbialites throughout geological history.

Effects of running time on biological activated carbon filters: water purification performance and microbial community evolution.

Ozone-biologically activated carbon (BAC) filtration is an advanced treatment process that can be applied to remove recalcitrant organic micro-pollutants in drinking water treatment plants (DWTPs). In this study, we continuously monitored a new and an old BAC filter in a DWTP for 1year to compare their water purification performance and microbial community evolution. The results revealed that, compared with the new filter, the use of the old BAC filter facilitated a slightly lower rate of dissolved organic carbon (DOC) removal. In the case of the new BAC filter, we recorded general increases in the biomass and microbial diversity of the biofilm with a prolongation of operating time, with the biomass stabilizing after 7months. For both new and old BAC filters, Proteobacteria and Acidobacteria were the dominant bacterial phyla. At the genus level, the microbial community gradually shifted over the course of operation from a predominance of Herminiimonas and Hydrogenophaga to one predominated by Bradyrhizbium, Bryobacter, Hyphomicrobium, and Pedomicrobium, with Bradyrhizobium being established as the most abundant genus in the old BAC filter. Regarding spatial distribution, we detected reductions in the biomass and number of operational taxonomic units with increasing biofilm depth, whereas there was a corresponding increase in microbial diversity. However, compared with the effects of time, the influence of depth on the composition of the biofilm microbial community was considerably smaller. Furthermore, co-occurrence network analysis revealed that the microbial community network of the new filter after 11months of operation was the most tightly connected, although its modular coefficient was the lowest of those assessed. We speculate that the positive and negative interactions within the network may be attributable to symbiotic or competitive relationships among species. Moreover, there may have been a significant negative interaction between SWB02 and Acidovorax, plausibly associated with a competition for substrates.

Microbial community evolution and individual-based model validation of biofilms in single-stage partial nitrification/anammox system

In this study, matrix degradation, microbial community development, and distribution using an individual-based model during biofilm formation on carriers at varying depths within a single-stage partial nitrification/anammox system were simulated. The findings from the application of individual-based model fitting, fluorescence in situ hybridization, and high-throughput sequencing reveal the presence of aerobic bacteria, specifically ammonia-oxidizing bacteria, as discrete particles within the outer layer of the carrier. Facultative anaerobic bacteria exemplified by anaerobic ammonia-oxidizing bacteria, are observed as aggregates within the middle layer. Conversely, anaerobic bacteria, represented by denitrifiers, are enveloped by extracellular polymeric substances within the inner layer. The present study extends the application of individual-based model to the formation of polyurethane-supported biofilms and presents valuable avenues for the design and advancement of pragmatic engineering carriers.

Detecting horizontal gene transfer with metagenomics co-barcoding sequencing.

Horizontal gene transfer (HGT) is the process through which genetic information is transferred between different genomes and that played a crucial role in bacterial evolution. HGT can enable bacteria to rapidly acquire antibiotic resistance and bacteria that have acquired resistance is spreading within the microbiome. Conventional methods of characterizing HGT patterns include short-read metagenomic sequencing (short-reads mNGS), long-read sequencing, and single-cell sequencing. These approaches present several limitations, such as short-read fragments, high amounts of input DNA, and sequencing costs, respectively. Here, we attempt to circumvent present limitations to detect HGT by developing a metagenomics co-barcode sequencing workflow (MECOS) and applying it to the human and mouse gut microbiomes. In addition to that, we have over 10-fold increased contig length compared to short-reads mNGS; we also obtained exceeding 30 million paired reads with co-barcode information. Applying the novel bioinformatic pipeline, we integrated this co-barcoding information and the context information from long reads, and observed over 50-fold HGT events after we corrected the potential wrong HGT events. Specifically, we detected approximately 3,000 HGT blocks in individual samples, encompassing ~6,000 genes and ~100 taxonomic groups, including loci conferring tetracycline resistance through ribosomal protection. MECOS provides a valuable tool for investigating HGT and advance our understanding on the evolution of natural microbial communities within hosts.IMPORTANCEIn this study, to better identify horizontal gene transfer (HGT) in individual samples, we introduce a new co-barcoding sequencing system called metagenomics co-barcoding sequencing (MECOS), which has three significant improvements: (i) long DNA fragment extraction, (ii) a special transposome insertion, (iii) hybridization of DNA to barcode beads, and (4) an integrated bioinformatic pipeline. Using our approach, we have over 10-fold increased contig length compared to short-reads mNGS, and observed over 50-fold HGT events after we corrected the potential wrong HGT events. Our results indicate the presence of approximately 3,000 HGT blocks, involving roughly 6,000 genes and 100 taxonomic groups in individual samples. Notably, these HGT events are predominantly enriched in genes that confer tetracycline resistance via ribosomal protection. MECOS is a useful tool for investigating HGT and the evolution of natural microbial communities within hosts, thereby advancing our understanding of microbial ecology and evolution.

Microbial responses to elevated temperature: Evaluating bentonite mineralogy and copper canister corrosion within the long-term stability of deep geological repositories of nuclear waste

Deep Geological Repositories (DGRs) consist of radioactive waste contained in corrosion-resistant canisters, surrounded by compacted bentonite clay, and buried few hundred meters in a stable geological formation. The effects of bentonite microbial communities on the long-term stability of the repository should be assessed. This study explores the impact of harsh conditions (60 °C, highly-compacted bentonite, low water activity), and acetate:lactate:sulfate addition, on the evolution of microbial communities, and their effect on the bentonite mineralogy, and corrosion of copper material under anoxic conditions. No bentonite illitization was observed in the treatments, confirming its mineralogical stability as an effective barrier for future DGR. Anoxic incubation at 60 °C reduced the microbial diversity, with Pseudomonas as the dominant genus. Culture-dependent methods showed survival and viability at 60 °C of moderate-thermophilic aerobic bacterial isolates (e.g., Aeribacillus). Despite the low presence of sulfate-reducing bacteria in the bentonite blocks, we proved their survival at 30 °C but not at 60 °C. Copper disk's surface remained visually unaltered. However, in the acetate:lactate:sulfate-treated samples, sulfide/sulfate signals were detected, along with microbial-related compounds. These findings offer new insights into the impact of high temperatures (60 °C) on the biogeochemical processes at the compacted bentonite/Cu canister interface post-repository closure.

Pollutant accumulation and microbial community evolution in rain gardens with different drainage types at field scale

Rain gardens play a key role in urban non-point source pollution control. The drainage type affects the infiltration processes of runoff pollutants. The soil properties and microbial community structures were studied to reveal the stability of the ecosystem in rain gardens with different drainage types under long-term operation. The results showed that the soil water content and total organic carbon in the drained rain gardens were always higher than that of the infiltrated ones. With the increase in running time, the contents of heavy metals in rain gardens showed significant accumulation phenomena, especially the contents of Zn and Pb in drained rain gardens were higher than that in infiltrated ones. The accumulation of pollutants resulted in lower microbial diversity in drained rain gardens than in infiltrated rain gardens, but the microbial community structures were the same in all rain gardens. The effects of drainage type on microbial community evolution were not significant, only the accumulation of heavy metals led to changes in the abundance of dominant microorganisms. There were differences in the soil environment of rain gardens with different drainage types. The long-term operation of rain gardens led to fluctuations in the soil ecosystem, while the internal micro-ecosystems of the drained rain gardens were in unstable states.

Rapid start-up sulfur-driven autotrophic denitrification granular process: Extracellular electron transfer pathways and microbial community evolution

Sulfur-driven autotrophic denitrification (SAD) granular process has significant advantages in treating low-carbon/nitrogen wastewater; however, the slow growth rate of sulfur-oxidizing bacteria (SOB) results in a prolonged start-up duration. In this study, the thiosulfate-driven autotrophic denitrification (TAD) was successfully initiated by inoculating anaerobic granular sludge on Day 7. Additionally, the electron donor was successfully transferred to the cheaper elemental sulfur from Day 32 to Day 54 at the nitrogen loading rate of 176.2 g N m−3 d-1. During long term experiment, the granules maintained compact structures with the α-helix/(β-sheet + random coil) of 29.5–40.1 %. Extracellular electron transfer (EET) pathway shifted from indirect to direct when electron donors were switched thiosulfate to elemental sulfur. Microbial analysis suggested that thiosulfate improved EET involving enzymes activity. Thiobacillus and Sulfurimonas were dominant in TAD, whereas Longilinea was enriched in elemental sulfur-driven autotrophic denitrification. Overall, this strategy achieved in-situ enrichment of SOB in granules, thereby shortening start-up process.

Microbial community evolution in the biofilm attached to sponge carriers in pulp mill effluent treatment

This study investigates the evolution of the biofilm matrix responsible for treating effluent from a pulp mill and identifies the microbial community by 16S rRNA gene sequencing. In addition, a biocarrier promising a functional structure with better specific features for biofilm formation than traditional polyurethane carriers was explored. The average removal efficiencies were 43.7% for chemical oxygen demand (COD) and 62.7% for biochemical oxygen demand (BOD5). The color increased during the treatment, indicating anoxic zones being formed in the inner part of this type of carrier. Periodic micrographs showed the evolution of extracellular polymeric substances and materials like fungi and bacteria adhered to the carriers. Genetic sequencing confirmed the presence of Bacillus sp. and Paenibacillus glucanolyticus, species with the potential to degrade and discolor pulp industrial effluents. Results offer a potential basis to enhance treatment facilities of pulp and paper mills based on microbial activities.

THE ECOLOGICAL SIGNIFICANCE OF VIRUSES IN AQUATIC ECOSYSTEMS: A COMPREHENSIVE ANALYSIS


 It is widely acknowledged that viruses are essential elements of the aquatic Environment, contributing significantly to various ecological processes and altering the dynamics of aquatic ecosystems. The variety of viruses in aquatic habitats, including freshwater and marine ecosystems, is enormous. Numerous different types of organisms, such as bacteria, algae, protozoa, and even multicellular organisms, are susceptible to these viral interactions, and these organisms have a significant impact on the design and operation of aquatic ecosystems. In aquatic ecosystems, viral-mediated mortality facilitates the recycling of nutrients and energy by influencing the composition of microbial populations. Additionally, viruses participate in genetic transfer procedures and are essential for horizontal gene transfer. They also serve as genetic material carriers, allowing the transfer of genes between various organisms. This phenomenon affects the ecological balance in the aquatic Environment and the evolution and adaption of microbial communities. Viruses can be used as instruments to investigate microbial ecology, comprehend host-virus interactions, and create fresh antiviral tactics. Viruses are essential to the health and stability of aquatic environments. Aquatic viruses have attracted attention because of their potential utility in various sectors, including biotechnology and medical research; they are essential elements of the aquatic environment due to their capacity to control microbial populations, reduce toxic algal blooms, and offer insights into microbial ecology. Our comprehension of these complex interactions and their larger implications for environmental health and management will be improved by additional study and investigation of viral dynamics and interactions within aquatic ecosystems. This review attempts to present an overview of the significance of viruses in aquatic ecosystems by highlighting their variety of roles and interactions.