Spatial and temporal patterns of phytoplankton community succession and characteristics of realized niches in Lake Taihu, China.

Understanding the dynamics and succession of phytoplankton in large lakes can help inform future lake management. The study analyzed phytoplankton community variations in Lake Taihu over a 21-year period, focusing on realized niches and their impact on succession. The study developed a niche periodic table with 32 niches, revealing responses to environmental factors and the optimal number of niches. Results showed that the phytoplankton in Lake Taihu showed significant spatial and temporal heterogeneity, with biomass decreasing as one moved from the northwest to the southeast and expanding towards central lake area, and towards autumn and winter. Different phytoplankton groups in Lake Taihu occupied realized niches shaped by temperature, nitrate, and phosphate. To predict the response of eutrophic freshwater lake ecosystems to human activities and climate change, it is critical to interpret the law of phytoplankton bloom and niche succession.

Grain size distribution drives microbial communities vertically assemble in nascent lake sediments.

Sediment microbes are crucial for maintaining biogeochemical cycles in aquatic ecosystems, yet the influence of sediment geophysical structure on microbial communities remains unclear. In this study, we collected sediment cores from a nascent reservoir in its initial stage of deposition and utilized the multifractal model to comprehensively characterize the heterogeneity of sediment grain size and pore space. Our results demonstrate that both environmental physiochemistry and microbial community structures varied significantly with depth, with the grain size distribution (GSD) being the key driver of sediment microbial diversity, as revealed by the partial least squares path model (PLS-PM) method. GSD can potentially impact microbial communities and biomass by controlling pore space and organic matter. Overall, this study represents the first attempt to apply soil multifractal models into the integrated description of physical structure in sediment. Our findings provide valuable insights into the vertical distribution of microbial communities.

The response mechanism of microorganisms to the organic carbon-driven formation of black and odorous water.

The formation of black and odorous water is a complex process influenced by various factors such as organic matter and environmental conditions. However, there are limited studies on the role of microorganisms in water and sediment during the blackening and odorization process. In this study, we investigated the characteristics of black and odorous water formation by simulating organic carbon-driven black and odorous water through indoor experiments. The study revealed that the water turned black and odorous when DOC reached 50 mg/L and the microbial community structure in the water changed significantly during this process, with the relative abundance of Desulfobacterota increasing significantly and Desulfovibrio being the main dominant genus in Desulfobacterota. Additionally, we observed a notable decrease in the α-diversity of the microbial community in water and a considerable increase in microbial function of sulfur compounds respiration in water. In contrast, the sediment microbial community changed slightly, and the main functions of the sediment microbial community remained unchanged. The partial least squares path model (PLS-PM) suggested that organic carbon will drive the blackening and odorization process by affecting DO levels and microbial community structure and that the contribution of Desulfobacterota in water to the formation of black and odorous water was higher than that in sediment. Overall, our study provides insights into the characteristics of black and odorous water formation and suggests potential ways to prevent its formation by controlling DOC and inhibiting the growth of Desulfobacterota in water bodies.

Microbial community structure and its driving mechanisms in the Hangbu estuary of Chaohu Lake under different sedimentary areas.

Estuaries are known for their high ecological diversity and biological productivity. Sediment microorganisms, as crucial components of estuarine ecosystems, play a pivotal role in reflecting the intricate and dynamic ecological niches. However, our research on microbial community characteristics in estuarine ecosystems under different sedimentary types remains limited. In this study, we collected a total of 27 samples from three sampling sites at Hangbu estuary in Chaohu Lake, and three sedimentary areas were classified based on the overlying water flow conditions and sediment particle properties to elucidate their microbial community structure, environmental drivers, assembly processes, and co-occurrence network characteristics. Our results showed significant differences in microbial community composition and diversity among three sedimentary areas. Redundancy analysis indicated that the differences in microbial community composition at the OTU level among the three sedimentary areas were mainly determined by nitrate-nitrogen, temperature, and water content. Phylogenetic bin-based null model analysis revealed that temperature was a key factor influencing deterministic processes among the three sedimentary areas, while stochastic processes predominantly governed the assembly of microbial communities. In addition, co-occurrence network analysis demonstrated that the network in the hydraulically driven sedimentary area of the lake, consisting mainly of medium and fine silt, had the highest complexity, stability, and cohesion, but was missing potential keystone taxa. The remaining two sedimentary areas had 5 and 8 potential keystone taxa, respectively. Overall, our study proposes the delineation of sedimentary types and comprehensively elucidates the microbial community characteristics under different sedimentary areas, providing a new perspective for studying sediment microbial community structure and helping future scholars systematically study ecological dynamics in estuaries.

Effects of electrochemical intervention on the remediation of black-odorous water: insights into microbial community dynamics and functional shifts in sediments.

Black-odorous water is a severe environmental issue that has received continuous attention. The major purpose of the present study was to propose an economical, practical, and pollution-free treatment technology. In this study, the in situ remediation of black-odorous water was conducted by applying different voltages (2.5, 5, and 10 V) to improve oxidation conditions of the surface sediments. The study investigated the effects of voltage intervention on water quality, gas emissions, and microbial community dynamics in surface sediments during the remediation process. The results indicated that the voltage intervention can effectively increase the oxidation-reduction potential (ORP) of the surface sediments and inhibit the emissions of H2S, NH3, and CH4. Moreover, the relative abundances of typical methanogens (Methanosarcina and Methanolobus) and sulfate-reducing bacteria (Desulfovirga) decreased because of the increase in ORP after the voltage treatment. The microbial functions predicted by FAPROTAX also demonstrated the inhibition of methanogenesis and sulfate reduction functions. On the contrary, the total relative abundances of chemoheterotrophic microorganisms (e.g., Dechloromonas, Azospira, Azospirillum, and Pannonibacter) in the surface sediments increased significantly, which led to enhanced biochemical degradability of the black-odorous sediments as well as CO2 emissions.

Isolation and characterization of a novel nicotinophilic bacterium, Arthrobacter sp. aRF-1 and its metabolic pathway.

Nicotine is a potent parasympathomimetic stimulant and an important natural alkaloid mainly found in the Nicotiana genus of plants. It can directly threaten ecological security and human health in tobacco waste, wastewater, and other forms of tobacco production. Therefore, it is the basis of nicotine pollution prevention and of great application value to explore efficient and a wide range of nicotinophilic bacteria for tobacco industry and environmental protection. In this study, one nicotinophilic bacterium was isolated from the soil, which accumulated tobacco waste over 50 years at a Hefei cigarette factory. The strain was named aRF-1, which was identified as Arthrobacter sp. by analysis. The nicotine degradation tests showed that the optimum temperature for cell growth and metabolism of nicotine of Arthrobacter sp. aRF-1 was 30 °C, and the optimum initial pH value was about 7.0. Under the optimum experimented conditions, it can tolerance nicotine concentration as high as 8 g·L-1 . The highest removal rate of nicotine was 93.8% in 72 H in nonsterilization contaminated soil by Arthrobacter sp. aRF-1. LC-MS/MS was used to analyze the nicotine metabolic intermediates of strain Arthrobacter sp. aRF-1. A total of nine major metabolites that were detected were able to metabolize nicotine along a variant pathway of pyridine and pyrrolidine, and there may be more than two nicotine metabolic pathways for Arthrobacter sp. aRF-1 through the analysis of the main intermediate products.

Effects of 17ß-estradiol on typical greenhouse gas emissions in aquatic anaerobic ecosystem.

Anaerobic microecosystems designed with different concentrations of 17ß-estradiol (17ß-E2) (0.0-10,000.0 ng/L) were simulated in this study. The influence of different concentrations of 17ß-E2 on the emissions of typical greenhouse gases (CH4 and CO2) in simulated anaerobic microecosystems is analyzed to primarily explore the relationship between 17ß-E2 and such emissions in aquatic anaerobic ecosystems. The results showed that 17ß-E2 could promote or significantly stimulate aquatic anaerobic micro-organisms' production of CH4. The degree and the promotion time of CH4 production were both enhanced with the increase of 17ß-E2 concentration. Furthermore, under higher concentration of 17ß-E2 (≥500.0 ng/L), the increasing tendency of aquatic anaerobic microbial populations' activity and the function of methanogenic activity under corresponding experimental conditions had a synchronous relationship.

Community Structure, Drivers, and Potential Functions of Different Lifestyle Viruses in Chaohu Lake.

Viruses, as the most prolific entities on Earth, constitute significant ecological groups within freshwater lakes, exerting pivotal ecological roles. In this study, we selected Chaohu Lake, a representative eutrophic freshwater lake in China, as our research site to explore the community distribution, driving mechanisms, and potential ecological functions of diverse viral communities, the intricate virus-host interaction systems, and the overarching influence of viruses on global biogeochemical cycling.

Effects of 17ß-Estradiol Pollution on Microbial Communities and Methane Emissions in Aerobic Water Bodies.

17ß-Estradiol (E2) is a widely present trace pollutant in aquatic environments. However, its impact on microbial communities in aerobic lake waters, which are crucial for methane (CH4) production, remains unclear. This study conducted an E2 contamination experiment by constructing laboratory-simulated aerobic microecosystems. Using 16S rRNA high-throughput sequencing, the effects of E2 on bacterial and archaeal communities were systematically examined. Combined with gas chromatography, the patterns and mechanisms of E2's impact on CH4 emissions in aerobic aquatic systems were uncovered for the first time. Generally, E2 contamination increased the randomness of bacterial and archaeal community assemblies and weakened microbial interactions. Furthermore, changes occurred in the composition and ecological functions of bacterial and archaeal communities under E2 pollution. Specifically, two days after exposure to E2, the relative abundance of Proteobacteria in the low-concentration (L) and high-concentration (H) groups decreased by 6.99% and 4.01%, respectively, compared to the control group (C). Conversely, the relative abundance of Planctomycetota was 1.81% and 1.60% higher in the L and H groups, respectively. E2 contamination led to an increase in the relative abundance of the methanogenesis functional group and a decrease in that of the methanotrophy functional group. These changes led to an increase in CH4 emissions. This study comprehensively investigated the ecotoxicological effects of E2 pollution on microbial communities in aerobic water bodies and filled the knowledge gap regarding aerobic methane production under E2 contamination.

Evolution mechanism of microbial community structure and metabolic activity in aquatic nutrient-poor sedimentary environments driven by 17ß-estradiol pollution.

17ß-Estradiol (E2) is a novel micro-pollutant that is widely distributed in aquatic sediments and has a universal toxicological effect on aquatic organisms. However, its ecological impact on aquatic microorganisms is not yet clear. In this study, we designed a simulation system for oligotrophic water deposition in the laboratory, analyzed the impact of different concentrations of E2 pollution on the carbon metabolism activity (carbon gas emission rate) of water microorganisms. Based on high-throughput sequencing results, we revealed the impact of E2 pollution on the community structure succession and metabolic function of bacteria, archaea, and methanogens in the simulated system, explored the impact mechanism of E2 pollution on microbial carbon metabolism in water bodies. Our results suggested that E2 significantly impacts the bacterial and archaeal community rather than the methanogen community, thereby indirectly inhibiting methane production. The achievements will bridge the theoretical gap between estrogen metabolism and carbon metabolism in sedimentary environments and contribute to enriching the ecological toxicology theory of steroid estrogen.

Anthropogenic activities mediate stratification and stability of microbial communities in freshwater sediments.

BACKGROUND: Freshwater sediment microbes are crucial decomposers that play a key role in regulating biogeochemical cycles and greenhouse gas emissions. They often exhibit a highly ordered structure along depth profiles. This stratification not only reflects redox effects but also provides valuable insights into historical transitions, as sediments serve as important archives for tracing environmental history. The Anthropocene, a candidate geological epoch, has recently garnered significant attention. However, the human impact on sediment zonation under the cover of natural redox niches remains poorly understood. Dam construction stands as one of the most far-reaching anthropogenic modifications of aquatic ecosystems. Here we attempted to identify the ecological imprint of damming on freshwater sediment microbiome. RESULTS: We conducted a year-round survey on the sediment profiles of Lake Chaohu, a large shallow lake in China. Through depth-discrete shotgun metagenomics, metataxonomics, and geophysiochemical analyses, we unveiled a unique prokaryotic hierarchy shaped by the interplay of redox regime and historical damming (labeled by the 137Cs peak in AD 1963). Dam-induced initial differentiation was further amplified by nitrogen and methane metabolism, forming an abrupt transition governing nitrate-methane metabolic interaction and gaseous methane sequestration depth. Using a random forest algorithm, we identified damming-sensitive taxa that possess distinctive metabolic strategies, including energy-saving mechanisms, unique motility behavior, and deep-environment preferences. Moreover, null model analysis showed that damming altered microbial community assembly, from a selection-oriented deterministic process above to a more stochastic, dispersal-limited one below. Temporal investigation unveiled the rapid transition zone as an ecotone, characterized by high species richness, low community stability, and emergent stochasticity. Path analysis revealed the observed emergent stochasticity primarily came from the high metabolic flexibility, which potentially contributed to both ecological and statistical neutralities. CONCLUSIONS: We delineate a picture in which dam-induced modifications in nutrient availability and sedimentation rates impact microbial metabolic activities and generate great changes in the community structure, assembly, and stability of the freshwater sediment microbiome. These findings reflect profound ecological and biogeochemical ramifications of human-Earth system interactions and help re-examine the mainstream views on the formation of sediment microbial stratification. Video Abstract.

Degradation characteristics of polyethylene film by microorganisms from lake sediments.

Polyethylene (PE) exists widely in many habitats as a persistent organic pollution and poses a major threat to the ecological environment. In this study, bacterial communities in freshwater lake sediments were exposed to culture media using PE films as the sole carbon source in aerobic and anaerobic microculture environments, and they were able to adhere and adapt to the PE films for a longer period of time. The results demonstrated that the pH value of the medium in the two cultural conditions was distinct, as were the rates of films weight loss and surface functional group alterations. We also concluded the certain bacterial genera from freshwater lake sediments who may be able to degrade PE films under either aerobic or anaerobic conditions. Simultaneously, the dominating bacterial communities between the medium and the film differed significantly under two cultural settings, as did the community composition, while metabolism was the primary function.

Whether interstitial space features were the main factors affecting sediment microbial community structures in Chaohu Lake.

Sediments cover a majority of Earth's surface and are essential for global biogeochemical cycles. The effects of sediment physiochemical features on microbial community structures have attracted attention in recent years. However, the question of whether the interstitial space has significant effects on microbial community structures in submerged sediments remains unclear. In this study, based on identified OTUs (operational taxonomic units), correlation analysis, RDA analysis, and Permanova analysis were applied into investigating the effects of interstitial space volume, interstitial gas space, volumetric water content, sediment particle features (average size and evenness), and sediment depth on microbial community structures in different sedimentation areas of Chaohu Lake (Anhui Province, China). Our results indicated that sediment depth was the closest one to the main environmental gradient. The destruction effects of gas space on sediment structures can physically affect the similarity of the whole microbial community in all layers in river dominated sedimentation area (where methane emits actively). However, including gas space, none of the five interstitial space parameters were significant with accounting for the microbial community structures in a sediment layer. Thus, except for the happening of active physical destruction on sediment structures (for example, methane ebullition), sediment interstitial space parameters were ineffective for affecting microbial community structures in all sedimentation areas.

Responses of oxidation rate and microbial communities to methane in simulated landfill cover soil microcosms.

CH4 oxidation capacities and microbial community structures developed in response to the presence of CH4 were investigated in two types of landfill cover soil microcosms, waste soil (fine material in stabilized waste) and clay soil. CH4 emission fluxes were lower in the waste soil cover over the course of the experiment. After exposure to CH4 flow for 120 days, the waste soil developed CH4 oxidation capacity from 0.53 to 11.25-13.48micromol CH4gd.w.(-1)h(-1), which was ten times higher than the clay soil. The topsoils of the two soil covers were observed dried and inhibited CH4 oxidation. The maximum CH4 oxidation rate occurred at the depth of 10-20cm in the waste soil cover (the middle layer), whereas it took place mainly at the depth of 20-30cm in the clay soil cover (the bottom layer). The amounts of the phospholipid fatty acid (PLFA) biomarks 16:1omega8c and 18:1omega8c for type I and II methanotrophs, respectively, showed that type I methanotrophic bacteria predominated in the clay soil, while the type II methanotrophic bacteria were abundant in the waste soil, and the highest population in the middle layer. The results also indicated that a greater active methanotrophic community was developed in the waste soil relative to the clay soil.

Isolation and characterization of Pseudomonas sp. strain HF-1, capable of degrading nicotine.

A nicotine-degrading bacterium, strain HF-1, was isolated from tobacco waste-contaminated soil and identified as a member of Pseudomonas sp. based on morphology, physiological tests, Vitek system (GN+), Biolog GN, 16S rDNA sequence and phylogenetic characteristics. The thermal denaturation test indicated that the G+C content of the DNA of HF-1 was 62.7 mol%. The relationship between growth and nicotine degradation of the isolate suggested that strain HF-1 could utilize nicotine as sole source of carbon, nitrogen and energy. Viridescent pigment was observed during nicotine degradation by strain HF-1. The isolate grew optimally at 30 degrees C, initial pH 6.5-7.5 and 1.3 g l(-1) of nicotine concentration in the nicotine inorganic salt medium, which is basically consistent with degradation of nicotine by the isolate. Strain HF-1 could degrade 99.6% of nicotine under the optimized incubation conditions for 25 h monitored by high-performance liquid chromatography. This study demonstrates that Pseudomonas sp. strain HF-1 had strong ability to degrade nicotine, and may be useful for bioremediation of environments contaminated by tobacco waste.

Effects of 17ß-estradiol on emissions of greenhouse gases in simulative natural water body.

Environmental estrogens are widely spread across the world and are increasingly thought of as serious contaminators. The present study looks at the influence of different concentrations of 17ß-estradiol on greenhouse gas emissions (CO2 , CH4 , and N2 O) in simulated systems to explore the relationship between environmental estrogen-pollution and greenhouse gas emissions in natural water bodies. The present study finds that 17ß-estradiol pollution in simulated systems has significant promoting effects on the emissions of CH4 and CO2 , although no significant effects on N2 O emissions. The present study indicates that 17ß-estradiol has different effects on the different elements cycles; the mechanism of microbial ecology is under review.

Photochemical degradation of PAHs in estuarine surface water: effects of DOM, salinity, and suspended particulate matter.

The photodegradation of several polycyclic aromatic hydrocarbons (PAHs) including phenanthrene, benzo(a)pyrene, and benzo(e)pyrene was studied under different estuarine conditions to elucidate the effects of dissolved organic matter (DOM), salinity, and suspended particles on PAH photodegradation in the estuarine surface water. Besides the competitive light absorption effect, DOM can accelerate the photodegradation of small PAHs such as phenanthrene by enhancing the formation of reactive intermediates and inhibit the photodegradation of large PAHs such as benzo[a]pyrene (BaP) and benzo[e]pyrene (BeP) by binding the PAH molecules. High salinity would accelerate the photodegradation of PAHs; however, the magnitude and direction of the salt effect are complicated in the presence of DOM due to the "salting-out" effect on the binding of PAHs with DOM. Suspended particulate matter in the estuary provides an alternative solid-phase photodegradation pathway for PAHs, which proceeds faster than the aqueous phase. Particulates apparently exert different effects on the photodegradation of phenanthrene (Phe) and BaP as a result of the combined effects of light absorption, particulate organic matter, PAH surface sorption, and concentration dilution in the presence of suspended particulate matter.

Effects of 17ß-estradiol pollution on water microbial methane oxidation activity.

17ß-estradiol (17ß-E2), a widespread and natural estrogen in the environment, has imposed a serious threat to the safety and function of aquatic ecosystems because of worsening pollution and high potential toxicity. In the present study, the authors focus on the impact of 17ß-E2 pollution on water microbial methane oxidation function. The authors investigated the mechanism of its influence on water microbial activity and discuss the growth rate of methane-oxidizing bacteria. The results showed that 17ß-E2 could significantly inhibit the function of water microbial methane oxidation. When 17ß-E2 concentration was ≥ 5 ng L(-1) , the methane oxidation rate increased with increasing 17ß-E2 and finally settled to a constant value. Furthermore, the authors found no significant linear correlation between 17ß-E2 concentrations and its methane oxidation rate. However, increasing 17ß-E2 dramatically improved water microbial community activity, because a significant or highly significant promotion in the generation rate of CO2 was measured. Moreover, within a certain period of time and at certain concentrations, positive linear correlation existed between water CO2 generation rate and 17ß-E2 concentrations. In addition, the growth rate of culturable methane-oxidizing bacteria was promoted when 17ß-E2 pollution concentration from 2 ng L(-1) to 20 ng L(-1) . Therefore, 17ß-E2 pollution can inhibit microbial methane oxidation function in water, which indirectly promotes the release of water methane and directly contributes to the rate of water-generated and released CO2 . Specifically, 17ß-E2 pollution can promote water emissions of greenhouse gases. Environ

Effect of low concentration 17ß-estradiol on the emissions of CH4 and CO2 in anaerobic sediments.

The estrogen17ß-estradiol (E2) is one of the most widely distributed natural estrogens and is the most potent estrogen in the environment. For the present study, methanogenic bacteria communities were chosen as study objects to analyze the effects of E2 on the production of methane and carbon dioxide. Microecological systems in anaerobic pore water were constructed in the laboratory. The results show that E2 played an enhancing role in methanogenic activity when the concentrations were ≤0.5 ng/L. The enhancement was the strongest at 0.3 ng/L. However, when the E2 concentration exceeded 1.0 ng/L, it inhibited the methanogenic activities of bacteria. The inhibition effect persisted for up to 264 h, beyond which the trend became unclear. On the other hand, E2 has an inhibition effect on CO2 production in anaerobic sediments, which indicates that E2 had a significant inhibition effect on microbial activities under anaerobic conditions. Based on these experiments, the authors believe that E2 in anaerobic sediments can affect sediment microbial activities and therefore influence the self-purification of water bodies and methane ebullition.

Effects of varying estuarine conditions on the sorption of phenanthrene to sediment particles of Yangtze Estuary.

The sorption of phenanthrene on the Yangtze Estuary sediment was studied under varying conditions of particle size, sediment organic contents, salinity, and dissolved organic matter (DOM) concentrations. Small sediment particles showed higher trapping capacity for phenanthrene due to the higher organic contents associated. The organic carbon-based partition coefficient of phenanthrene to the Yangtze Estuary sediment was obtained as 7120 L/kg, lower than the values for other soils or sediments reported in previous studies. The magnitude and direction of the salt effect were complicated by the specific DOM studied. The sediment sorption capacity was greatly increased in saline water in the absence of DOM but decreased in the presence of DOM. Given the conditions in the Yangtze Estuary, the equilibrium sorption of phenanthrene would be decreased with increasing salinity. Overall, the nature and content of both sediment-bound and dissolved organic matter dominate the sorption of hydrophobic organic contaminants in the estuary.