Abundance Of Microbial Communities Research Articles

The contrasting responses of abundant and rare microbial community structures and co-occurrence networks to secondary forest succession in the subalpine region.

Knowledge of variations in abundant and rare soil microbial communities and interactions during secondary forest succession is lacking. Soil samples were gathered from different secondary successional stages (grassland, shrubland, and secondary forest) to study the responses of abundant and rare bacterial and fungal communities, interactions and driving factors to secondary forest succession by Illumina sequencing of the 16S and ITS rRNA genes. The results showed that the α-diversities (Shannon index) of abundant bacteria and fungi revealed no significant changes during secondary forest succession, but increased significantly for rare bacteria. The abundant and rare bacterial and fungal β-diversities changed significantly during secondary forest succession. Network analysis showed no obvious changes in the topological properties (nodes, links, and average degree) of abundant microbial networks during secondary forest succession. In contrast, these properties of the rare microbial networks in the secondary forest were higher than those in the grassland and shrubland, indicating that rare microbial networks are more responsive to secondary forest succession than abundant microorganisms. Additionally, rare microbial networks revealed more microbial interactions and greater network complexity than abundant microbial networks due to their higher numbers of nodes and links. The keystone species differed between the abundant and rare microbial networks and consisted of 1 and 48 keystone taxa in the abundant and rare microbial networks, respectively. Soil TP was the most important influencing factor of abundant and rare bacterial communities. Successional stages and plant richness had the most important influences on abundant and rare fungal communities, respectively. C:P, SM and N:P were mainly related to abundant and rare microbial network topological properties. Our study indicates that abundant and rare microbial communities, interactions and driving factors respond differently to secondary forest succession.

107 Abundance and Diversity of Microbial Community in Bioaerosol Samples Taken from a French Cheese Dairy

Abstract Bioaerosol samples were taken at a cheese company producing about ten different products. The aims were (i) to investigate airborne microbial community (quantity/diversity) using molecular analytical methods and (ii) to appreciate how molecular methods improve the characterization of bioaerosols. Ambient bioaerosol samples were performed using 37-mm 3-pieces closed-face polypropylene cassettes equipped with 0.8 µm pore size polycarbonate membrane at 2 or 10 L.min-1, in several work areas during winter and summer seasons. Airborne bacteria and fungi were quantified by counting colonies on culture media and by quantitative PCR (qPCR). The microbial community was identified using 16SrRNA and ITS1 genes high-throughput sequencing with sequence analysis performed on the Galaxy Migale platform using the FROGS data processing pipeline. The results showed that ambient concentration levels were working area dependent. A massive emission of microorganisms into the air was found in areas in which a brushing task of cheeses was performed, leading to high concentrations of cultivable (up to 107 CFU/m3) and total (up to 1010 18SrRNA copies/m3) fungi. The correlation between cultivable and total mold is discussed and individual exposures are evoked. The microbial community was characterized by the predominance of the fungal genus Penicillium and their species composition depended on the type of cheese or season. This work has shed new light on these still poorly documented work situations and is essential to refine the diagnosis of the immunoallergic risks of the workers concerned. The presentation discusses the complementarity between culture-based and molecular-based methods for the assessment of bioaerosols.

Repeated manure inputs to a forage production soil increase microbial biomass and diversity and select for lower abundance genera

Adding manure to croplands restores carbon and nutrients in depleted soils, while addressing a waste disposal need. This practice depends on the abundance and activity of microbial communities to break down manure inputs, which provide carbon for microbial growth and release nutrients for plant and microbial uptake. In a 2-year field study, we measured changes to soil physicochemical properties and microbial community composition in a conventional rotation of summer sileage corn and winter wheat. Three ratios of manure to mineral N fertilizer were used: all manure (100% of plant N from manure), mixed (50% plant N from by manure and 50% from mineral fertilizer), and all mineral (100% plant N from mineral fertilizer). Yields of corn and wheat were similar across treatments. Soil microbial community dissimilarity increased with higher ratios of application, suggesting a dose-dependent relationship between manure application and microbial community composition. Both microbial biomass and dissolved organic carbon showed the greatest response immediately following manure application, then decreased until the next application. The Shannon index increased shortly after manure application, with the largest increase observed in soils receiving manure input. Many of the taxa that increased in relative abundance following manure application were specifically taxa known to be present in manure and not common or present in soil before manure application. Microbial community changes following manure application were transitory, indicating that without continual inputs of resources, these alterations are not maintained. This was in contrast to microbial biomass which slowly increased in size over the 2-year study period. Better understanding of how manure interacts with microbial communities will help in developing better nutrient management practices and help reduce our reliance on mineral fertilizers.

Microalgae from Cold Environments and Their Possible Biotechnological Applications.

Cold environments include deep ocean, alpine, and polar areas. Even if the cold conditions are harsh and extreme for certain habitats, various species have been adapted to survive in them. Microalgae are among the most abundant microbial communities which have adapted to live in low light, low temperature, and ice coverage conditions typical of cold environments by activating different stress-responsive strategies. These species have been shown to have bioactivities with possible exploitation capabilities for human applications. Even if they are less explored compared to species living in more accessible sites, various activities have been highlighted, such as antioxidant and anticancer activities. This review is focused on summarizing these bioactivities and discussing the possible exploitation of cold-adapted microalgae. Thanks to the possibility of mass cultivating algae in controlled photobioreactors, eco-sustainable exploitation is in fact possible by sampling a few microalgal cells without impacting the environment.

Unraveling the response of water quality and microbial community to lake water backflowing in one typical estuary of Lake Taihu, China.

To investigate the effect of lake water backflowing on the aquatic ecosystem in the estuary, surface water samples in the backflowing and unbackflowing areas were collected from one typical estuary of Lake Taihu, Xitiaoxi River. 16S rRNA sequencing and redundancy analysis were conducted to quantitatively elucidate the correlation between microbial community and water quality parameters. Results indicated lake water backflowing would affect the relative distribution of nitrogen species and increase the concentration of total nitrogen (TN) and nitrate, especially in the outlets of municipal sewage and agricultural drainage. For backflowing areas, more frequent water exchange could lower the seasonal fluctuation of the abundance and diversity of microbial community. RDA results showed crucial water quality parameters that greatly influence bacterial community were total organic carbon (TOC), total dissolved solids (TDS), salinity (SAL), ammonia, nitrate, TN for backflowing areas, and TOC, TDS, SAL, ammonia, TN without nitrate for unbackflowing areas. Verrucomicrobia, Proteobacteria, Microcystis, and Arcobacter were dominant with 27.7%, 15.7%, 30.5%, and 25.7% contribution to the overall water quality in backflowing areas. Chloroflexi, Verrucomicrobia, Flavobacterium, and Nostocaceae were dominant with 25.0%, 18.4%, 22.3%, and 11.4% contribution to the overall water quality in unbackflowing areas. And lake water backflowing might mainly affect the amino acid and carbohydrate metabolism based on the metabolism function prediction. A better understanding of the spatiotemporal changes in water quality parameters and microbial community was obtained from this research to comprehensively assess the effect of lake water backflowing on the estuarine ecosystem.

Dynamics of vanadium and response of inherent bacterial communities in vanadium–titanium magnetite tailings to beneficiation agents, temperature, and illumination

Vanadium-titanium (V–Ti) magnetite tailings contain toxic metals that could potentially pollute the surrounding environment. However, the impact of beneficiation agents, an integral part of mining activities, on the dynamics of V and the microbial community composition in tailings remains unclear. To fill this knowledge gap, we compared the physicochemical properties and microbial community structure of V–Ti magnetite tailings under different environmental conditions, including illumination, temperature, and residual beneficiation agents (salicylhydroxamic acid, sodium isobutyl xanthate, and benzyl arsonic acid) during a 28-day reaction. The results revealed that beneficiation agents exacerbated the acidification of the tailings and the release of V, among which benzyl arsonic acid had the greatest impact. The concentration of soluble V in the leachate of tailings with benzyl arsonic acid was 6.4 times higher than that with deionized water. Moreover, illumination, high temperatures, and beneficiation agents contributed to the reduction of V in V-containing tailings. High-throughput sequencing revealed that Thiobacillus and Limnohabitans adapted to the tailings environment. Proteobacteria was the most diverse phylum, and the relative abundance was 85.0%–99.1%. Desulfovibrio, Thiobacillus, and Limnohabitans survived in the V–Ti magnetite tailings with residual beneficiation agents. These microorganisms could contribute to the development of bioremediation technologies. The main factors affecting the diversity and composition of bacteria in the tailings were Fe, Mn, V, SO42−, total nitrogen, and pH of the tailings. Illumination inhibited microbial community abundance, while the high temperature (39.5 °C) stimulated microbial community abundance. Overall, this study strengthens the understanding of the geochemical cycling of V in tailings influenced by residual beneficiation agents and the application of inherent microbial techniques in the remediation of tailing-affected environments.

Functional analysis of the apple fruit microbiome based on shotgun metagenomic sequencing of conventional and organic orchard samples.

Fruits harbour abundant and diverse microbial communities that protect them from post-harvest pathogens. Identification of functional traits associated with a given microbiota can provide a better understanding of their potential influence. Here, we focused on the epiphytic microbiome of apple fruit. We suggest that shotgun metagenomic data can indicate specific functions carried out by different groups and provide information on their potential impact. Samples were collected from the surface of 'Golden Delicious' apples from four orchards that differ in their geographic location and management practice. Approximately 1 million metagenes were predicted based on a high-quality assembly. Functional profiling of the microbiome of fruits from orchards differing in their management practice revealed a functional shift in the microbiota. The organic orchard microbiome was enriched in pathways involved in plant defence activities; the conventional orchard microbiome was enriched in pathways related to the synthesis of antibiotics. The functional significance of the variations was explored using microbial network modelling algorithms to reveal the metabolic role of specific phylogenetic groups. The analysis identified several associations supported by other published studies. For example, the analysis revealed the nutritional dependencies of the Capnodiales group, including the Alternaria pathogen, on aromatic compounds.

Characterization of gut microbiota associated with metabolic syndrome and type-2 diabetes mellitus in Mexican pediatric subjects

BackgroundChildhood obesity is a serious public health concern that confers a greater risk of developing important comorbidities such as MetS and T2DM. Recent studies evidence that gut microbiota may be a contributing factor; however, only few studies exist in school-age children. Understanding the potential role of gut microbiota in MetS and T2DM pathophysiology from early stages of life might contribute to innovative gut microbiome-based interventions that may improve public health. The main objective of the present study was to characterize and compare gut bacteria of T2DM and MetS children against control subjects and determine which microorganisms might be potentially related with cardiometabolic risk factors to propose gut microbial biomarkers that characterize these conditions for future development of pre-diagnostic tools.ResultsStool samples from 21 children with T2DM, 25 with MetS, and 20 controls (n = 66) were collected and processed to conduct 16S rDNA gene sequencing. α- and β-diversity were studied to detect microbial differences among studied groups. Spearman correlation was used to analyze possible associations between gut microbiota and cardiometabolic risk factors, and linear discriminant analyses (LDA) were conducted to determine potential gut bacterial biomarkers. T2DM and MetS showed significant changes in their gut microbiota at genus and family level. Read relative abundance of Faecalibacterium and Oscillospora was significantly higher in MetS and an increasing trend of Prevotella and Dorea was observed from the control group towards T2DM. Positive correlations were found between Prevotella, Dorea, Faecalibacterium, and Lactobacillus with hypertension, abdominal obesity, high glucose levels, and high triglyceride levels. LDA demonstrated the relevance of studying least abundant microbial communities to find specific microbial communities that were characteristic of each studied health condition.ConclusionsGut microbiota was different at family and genus taxonomic levels among controls, MetS, and T2DM study groups within children from 7 to 17 years old, and some communities seemed to be correlated with relevant subjects’ metadata. LDA helped to find potential microbial biomarkers, providing new insights regarding pediatric gut microbiota and its possible use in the future development of gut microbiome-based predictive algorithms.

Leaf Species-Dependent Fungicide Effects on the Function and Abundance of Associated Microbial Communities

Microbially-mediated leaf litter decomposition is a critical ecosystem function in running waters within forested areas, which can be affected by fungicides. However, fungicide effects on leaf litter decomposition have been investigated almost exclusively with black alder leaves, a leaf species with traits favourable to consumers (i.e., low recalcitrance and high nutrient content). At the same time, little is known about fungicide effects on microbial colonisation and decomposition of other leaf species with less favourable traits. In this 21 day lasting study, we explore the effects of increasing fungicide sum concentrations (0–3000 µg/L) on microbial colonisation and decomposition of three leaf species (black alder, Norway maple and European beech) differing in terms of recalcitrance and nutrient content. Leaf litter decomposition rate, leaf-associated fungal biomass and bacterial density were quantified to observe potential effects at the functional level. Beech, as the species with the least favourable leaf traits, showed a substantially lower decomposition rate (50%) in absence of fungicides than alder and maple. In the presence of high fungicide concentrations (300–3000 µg/L), beech showed a concentration-related decrease not only in microbial leaf litter decomposition but also fungal biomass. This suggests that favourable traits of leaf litter (as for alder and maple) enable leaf-associated microorganisms to acquire leaf-bound energy more easily to withstand potential effects induced by fungicide exposure. Our results indicate the need to deepen our understanding on how leaf species’ traits interact with the impact of chemical stressors on the leaf decomposition activity of microbial communities.

Treatment of high-phosphorus load wastewater by column packed with non-burning compound filler/gravel/ceramsite: evaluation of performance and microorganism community.

Cost-effective and environmental-friendly substrates are essential for the constructed wetlands (CWs). In this study, the column test was used to explore the differences in pollutant purification performance, microbial community structure and abundance between non-burning compound filler and conventional CWs substrates (i.e. gravel and ceramsite) at low temperature (0-15℃). It was found that the maximum phosphorus removal efficiency of compound filler (99%) was better than gravel (18%) and ceramsite (21%). Besides, the proportion of aerobic heterotrophic bacteria capable of ammonium oxidation, nitrification and denitrification (i.e. Pseudomonas, Acinetobacter, and Acetoanaerobium) was enhanced by compound filler, which has an excellent potential for nitrogen removal in the subsequent purification process. These results demonstrated that the self-made non-burning compound filler was a potential substrate for CWs, which was of great significance for the resource utilization of solid wastes such as polyaluminum chloride residue.

Bioaugmentation Strategies for Enhancing Methane Production from Shrimp Processing Waste through Anaerobic Digestion

Bioaugmentation strategies were tested to improve energetic valorization of shrimp processing waste (SPW) by anaerobic digestion (AD). A fermenting bacteria pool (F210) obtained from coastal lake sediments and two strains of anaerobic fungi (AF), Orpynomyces sp. and Neocallimastix sp., commonly found as components of microbial community of AD plants, were used with the aim of improving the fermentative and hydrolytic phases of AD, respectively. The experiment was carried out by testing single bioaugmentation at an SPW concentration of 6.5 gVS L−1 and combined bioaugmentation at three SPW concentrations (6.5, 9.7 and 13.0 gVS L−1, respectively), in batch mode and mesophilic conditions. Cumulative CH4 productions were higher in the combined bioaugmentation tests and increased in line with SPW concentration. The F210 played a key role in enhancing CH4 production while no effect was attributable to the addition of AFs. The CH4 content (%) in the biogas increased with substrate concentrations, with average values of 67, 70, and 73%, respectively. Microbial community abundance increased in line with the SPW concentration and the acetoclastic Methanosarcina predominated within the methanogen Archaea guild in the combined bioaugmentation test (in all cases > 65%).

Effects of cadmium and diethylhexyl phthalate on skin microbiota of Rana chinensis tadpoles.

Skin microbiotas play a crucial role in the health, homeostasis, and immune function of amphibians. The contaminants in water could affect the structure and composition of microbial communities. The effects of coexisting pollutants on frogs cannot be adequately explained by a single exposure due to the coexistence of Cd and DEHP in the environment. Following exposure to Cd and/or DEHP, we examined the histological characteristics of Rana chensinensis tadpoles. We also used the 16S rRNA gene sequencing technique to assess the relative abundance of skin microbial communities among tadpoles from each treatment group. Our findings indicate that R. chensinensis' skin experienced some degree of injury due to exposure to Cd and DEHP, which led to the imbalance of their skin microbial community homeostasis and thus interfered with the normal trial status of the host. That may eventually lead to the decline of the amphibian population.

The microbiomes of two Singaporean corals show site-specific differentiation and variability that correlates with the seasonal monsoons

Corals host abundant microbial communities, or microbiomes, that play essential roles in the function of the coral holobiont. We examined the mucus microbiome in corals within the port of Singapore, where corals persist despite intense anthropogenic impacts. The coral mucus microbiomes of Pectinia paeonia and Platygyra sinensis at three reef sites were tracked by 16S rRNA gene amplicon sequencing from January 2019 to January 2020. Both coral species displayed spatial and temporal differences in microbiome composition, suggesting site specificity and seasonality in microbiome composition consistent with the monsoons. The temporal shifts in relative abundance of dominant taxa were different between the two coral species. Nonetheless, Proteobacteria was the most abundant phylum in both coral species and was reduced during the southwest (SW) monsoon, while Cyanobacteria and Crenarchaeota increased. The presumptive beneficial endosymbiont Endozoicomonas was only associated with corals at the reef site located the farthest from the Singapore mainland. The coral microbiomes reflected seasonal changes, while the seawater displayed distinct temporal microbial compositions and site-specific differentiation within all sampling dates. The persistence of coral reefs within the port of Singapore highlights the adaptive ability of corals to respond to stressful environments, and this study provides further evidence that a flexible microbiome could be an important part of the strategy employed by corals to remain resilient.

Soil Microbial Community Involved in Nitrogen Cycling in Rice Fields Treated with Antiozonant under Ambient Ozone.

Ethylenediurea (EDU) can effectively mitigate the crop yield loss caused by ozone (O3), a major, phytotoxic air pollutant. However, the relevant mechanisms are poorly understood, and the effect of EDU on soil ecosystems has not been comprehensively examined. In this study, a hybrid rice variety (Shenyou 63) was cultivated under ambient O3 and sprayed with 450 ppm EDU or water every 10 days. Real time quantitative polymerase chain reaction (RT-qPCR) showed that EDU had no significant effect on the microbial abundance in either rhizospheric or bulk soils. By applying both metagenomic sequencing and the direct assembly of nitrogen (N)-cycling genes, EDU was found to decrease the abundance of functional genes related to nitrification and denitrification processes. Moreover, EDU increased the abundance of genes involved in N-fixing. Although the abundance of some functional genes did not change significantly, nonmetric multidimensional scaling (NMDS) and a principal coordinates analysis (PCoA) suggested that the microbial community structure involved in N cycling was altered by EDU. The relative abundances of nifH-and norB-harboring microbial genera in the rhizosphere responded differently to EDU, suggesting the existence of functional redundancy, which may play a key role in sustaining microbially mediated N-cycling under ambient O3. IMPORTANCE Ethylenediurea (EDU) is hitherto the most efficient phytoprotectant agent against O3 stress. However, the underlying biological mechanisms of its mode of action are not clear, and the effects of EDU on the environment are still unknown, limiting its large-scale application in agriculture. Due to its sensitivity to environmental changes, the microbial community can be used as an indicator to assess the environmental impacts of agricultural practices on soil quality. This study aimed to unravel the effects of EDU spray on the abundance, community structure, and ecological functions of microbial communities in the rhizosphere of rice plants. Our study provides a deep insight into the impact of EDU spray on microbial-mediated N cycling and the structure of N-cycling microbial communities. Our findings help to elucidate the mode of action of EDU in alleviating O3 stress in crops from the perspective of regulating the structure and function of the rhizospheric soil microbial community.

Biochar-Assisted Catalytic Pyrolysis of Oily Sludge to Attain Harmless Disposal and Residue Utilization for Soil Reclamation.

Pyrolysis of oily sludge (OS) is a feasible technology to match the principle of reduction and recycling; however, it is difficult to confirm the feasible environmental destination and meet the corresponding requirements. Therefore, an integrated strategy of biochar-assisted catalytic pyrolysis (BCP) of OS and residue utilization for soil reclamation is investigated in this study. During the catalytic pyrolysis process, biochar as a catalyst intensifies the removal of recalcitrant petroleum hydrocarbons at the expense of liquid product yield. Concurrently, biochar as an adsorbent can inhibit the release of micromolecular gaseous pollutants (e.g. HCN, H2S, and HCl) and stabilize heavy metals. Due to the assistance of biochar, pyrolysis reactions of OS are more likely to occur and require a lower temperature to achieve the same situation. During the soil reclamation process, the obtained residue as a soil amendment can not only provide a carbon source and mineral nutrients but can also improve the abundance and diversity of microbial communities. Thus, it facilitates the plant germination and the secondary removal of petroleum hydrocarbons. The integrated strategy of BCP of OS and residue utilization for soil reclamation is a promising management strategy, which is expected to realize the coordinated and benign disposal of more than one waste.

Intestinal microbiome in crayfish: Its role upon growth and disease presentation

The intestine-associated microbiota in crustaceans are considered a key element for maintaining homeostasis and health within the organisms. Recently, efforts have been made to characterize bacterial communities of freshwater crustaceans, including crayfish, and their interplay with the host's physiology and the aquatic environments. As a result, it has become evident that crayfish intestinal microbial communities display high plasticity, which is strongly influenced by both the diet, especially in aquaculture, and the environment. Moreover, studies regarding the characterization and distribution of the microbiota along the gut portions led to the discovery of bacteria with probiotic potential. The addition of these microorganisms to their food has shown a limited positive correlation with the growth and development of crayfish freshwater species. Finally, there is evidence that infections, particularly those from viral etiology, lead to low diversity and abundance of the intestinal microbial communities. In the present article, we have reviewed data on the crayfish’ intestinal microbiota, highlighting the most frequently observed taxa and emphasizing the dominance of phylum within this community. In addition, we have also searched for evidence of microbiome manipulation and its potential impact on productive parameters, and discussed the role of the microbiome in the regulation of diseases presentation, and environmental perturbations.

Metabolomic profiles reveals the dose-dependent effects of rice grain yield and nutritional quality upon exposure zero-valent iron nanoparticles

Zero-valent iron nanoparticles (nZVI) were widely used material in environmental remediation, which has attracted increasing concern for their safety. Previous studies have shown that the addition of nZVI could inhibit rice seedling growth. However, the effect of nZVI on the soil-rice system during the entire life cycle was not reported. Furthermore, the effect of nZVI on the quality of rice grain has also not been studied. Therefore, we investigated the effects of rice grain yield and nutritional quality upon exposure nZVI. The results showed that the soil pH value, redox potential and Fe (II) content in the nZVI-treated group were decreased in a dose-dependent manner. Interestingly, 2500 mg/kg nZVI significantly decreased the relative abundance of several functional microbial communities (10.52–73.53 %) associated with carbon and nitrogen cycles in response to plants compared to the control. Meanwhile, the nZVI treatment clearly reduced grain yield (8.71–18.21 %). Furthermore, the content of protein (51.72–57.79 %) and several essential nutrients (Zn, Cu, Mn and Mo) in the nZVI-treated grains was also decreased in a dose-dependent manner. The results of grain metabolomics indicated that nZVI could interfere with the relative expression of lysine and glutathione by regulating the metabolic pathways of antioxidant and protein synthesis in rice.

Relationship of environmental factors in pond water and dynamic changes of gut microbes of sea bass Lateolabrax japonicus.

The effect of structure of gut microbes on the health of host has attracted increasing attention. Sea bass Lateolabrax japonicus is an important farmed fish in China. The relationship of the dynamic changes of intestinal bacterial communities in L. japonicus and the cultural water environment is very important for healthy culture. Here, the diversity and abundance of the gut microbial communities of L. japonicus were evaluated during the culture using 16S rRNA Illumina sequencing. Both the opportunistic pathogens Aeromonas (1.68%), Vibrio (1.59%), and Acinetobacter (1.22%); and the potential probiotics Lactobacillus (2.27%), Bacillus (1.16%), and Lactococcus (0.37%) were distributed in the gut of L. japonicus. The increasing concentration of nitrogen of water environments with the increase of culture time significantly correlated with shifts in the microbial community structure: 40.04% of gut microbial changes due to nitrogen concentration. Higher concentrations of nitrogen showed a significantly negative correlation with intestinal probiotics in L. japonicus. The results indicate that the abundance of intestinal bacteria of L. japonicus is mainly driven by the changes of environmental factors (e.g., nitrogen), and it's very important that the linking environmental parameters with bacterial data of guts could be used as an early warning indicator in L. japonicus heath culture.

In abandoned aquaculture ponds, the anammox process contributes relatively more to nitrogen removal

Impact of the development of coastal aquaculture on nitrogen (N) cycle has been a central issue in wetland ecological and environmental protection project. However, the process of N removal in offshore aquaculture remains unclear. Here this study reported the rates, abundance and community structure of anaerobic ammonium oxidation (anammox) and denitrification using 15N isotope tracing technology, quantitative polymerase chain reaction (qPCR), and high-throughput sequencing methods in different types of aquaculture ponds including the Sinonovacula constricta ponds, the Shrimp-crab polyculture ponds and the abandoned aquaculture ponds along the coast of Fujian Province. Results showed that anammox rates in the abandoned aquaculture ponds were 1.44 ± 0.11 nmol·g−1·h−1, contributing to 15.15% ± 1.18% of the N removal, which were significantly higher than those in the S.constricta ponds and the Shrimp-crab polyculture ponds (P < 0.01). Denitrification remained the main pathway for the N removal. The abundance of AMX, nirS, and nirK genes in the Shrimp-crab polyculture ponds was higher than the other two types of aquaculture ponds, but the anammox and denitrifying microbial community structure was the simplest. In contrast, the abandoned aquaculture ponds showed the most abundant and complex microbial community structure. Aquaculture ponds abandoned significantly increased the anammox rates and community structure. The microbial diversity, species composition, and stable substrate condition such as DO, pH, NH4+, NO3−, TN, and C:N ratio were the main factors affecting the anammox process in the abandoned aquaculture ponds. The abundance of nirS and nirK gene, the human management, and aquaculture substrate environment including DO, pH, NH4+, and NO2− enhanced the denitrification process in the S.constricta ponds and the Shrimp-crab polyculture ponds. These findings indicated that aquaculture ponds abandoned improved environmentally friendly the anammox N removal process and restored biodiversity.

Identification of microbial consortia for sustainable disposal of constructed wetland reed litter wastes.

Reed is a typical emerged plant in constructed wetlands (CWs). Its litters were used as raw materials for preparing Fe-C ceramic-filler (Fe-C-CF). The physical and chemical properties of Fe-C-CF were studied under different conditions, including the mass ration of Fe to carbon (Fe/C ratio), sintering temperature, and time, to determine the optimum preparing conditions. Meanwhile, the denitrification performance and CO2 emission flux of the surface flow constructed wetland (SFCW) systems were investigated when using Fe-C-CF as the matrix. The optimum preparing conditions for Fe-C-CF were Fe/C ratio of 1:1, sintering temperature and time of 500°C and 20min, respectively. The SFCW system with Fe-C-CF obtained a higher total nitrogen (TN), nitrate nitrogen (NO3--N), and ammonia nitrogen (NH3-N) removal efficiencies than the control SFCW system without Fe-C-CF. Compared with the heterotrophic denitrification process, the SFCW system with Fe-C-CF decreased CO2 emission by 67.9gm-2 per year. The results of microbial community analysis indicated that addition of Fe-C-CF increased the diversity and abundance of microbial communities in the SFCW systems. The dominant genus of the SFCW system with Fe-C-CF was Bacillus, while Uliginosibacterium was the dominant genus in the system without the filler.