Anthropogenic pressure induced discontinuities of microbial communities along the river.

Microorganisms play a fundamental role in driving biogeochemical functions within rivers. Theoretically, the directional flowing nature of river contributes to the continuous downstream change pattern of microbial communities. This continuity is anticipated to be influenced by human activities as anthropogenic materials lead to the mixing of environmental substances and their resident microorganisms with local communities.

Comparative analysis of niche adaptation strategies of AOA, AOB, and comammox along a gate-controlled river-estuary continuum.

Ammonia oxidizers are key players in the biogeochemical nitrogen cycle. However, in critical ecological zones such as estuaries, especially those affected by widespread anthropogenic dam control, our understanding of their occurrence, ecological performance, and survival strategies remains elusive. Here, we sampled sediments along the Haihe River-Estuary continuum in China, controlled by the Haihe Tidal Gate, and employed a combination of biochemical and metagenomic approaches to investigate the abundance, activity, and composition of ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and complete ammonia oxidizers (comammox).

Brownification increases the abundance of microorganisms related to carbon and nitrogen cycling in shallow lakes.

Brownification in aquatic ecosystems under global change has attracted attention. The composition and quantity of dissolved organic matter transported from various land use types to lakes differ significantly, causing varying ecological effects of lake brownification by region. Bacterial communities make a significant contribution to the material cycle of ecosystems and are sensitive to environmental changes.

Urban and agricultural land use led to niche differentiation of AOA, AOB and comammox along the Beiyun River continuum.

River ecological health has been severely threatened by anthropogenic land-use pressures. Here, by combining remote sensing and molecular biology methods, we evaluated the impact of land-use activities on nitrification, a fundamental ecological process in rivers, which is conducted by ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB), or the newly discovered complete ammonia oxidisers (comammox). We explored the relationships of the abundance, activity, and diversity of AOA, AOB, and comammox in river sediments with land-use pressure by proposing a quantitative land use pattern index (LPI) over a 184 km continuum along the Beiyun River in North China.

Optimization of operating parameters and microbiological mechanism of a low C/N wastewater treatment system dominated by iron-dependent autotrophic denitrification.

Ferrous iron (Fe) reduces the amount of external carbon source used for the denitrification of low-C/N wastewater. The effects of key operating parameters on the efficiency of ferrous-dependent autotrophic denitrification (FDAD) and the functioning mechanism of the microbiome can provide a regulatory strategy for improving the denitrification efficiency of low C/N wastewater. In this study, the response surface method (RSM) was used to explore the influence of four important parameters-the molar ratio of Fe to NO-N (Fe/N), total organic carbon (TOC), the molar ratio of inorganic carbon to NO-N (IC/N) and sludge volume (SV, %)-on the FDAD efficiency.

Distinctive species interaction patterns under high nitrite stress shape inefficient denitrifying phosphorus removal performance.

Denitrifying phosphorus removal using nitrite as an electron acceptor is an innovative, resource-efficient approach for nitrogen and phosphorus removal. However, the inhibitory effects of nitrite on anoxic phosphorus uptake and process stability are unclear. This study investigated the total phosphorus removal performance under nitrite stress and analyzed microbiome responses in 186 sludge samples.

Abundance, community and driving factor of nitrifiers in western China plateau.

Complete ammonia oxidation (comammox) is one of the most important biogeochemical processes, with recent studies showing that comammox process dominates nitrification in many ecosystems. However, the abundance, community and driving factor of comammox bacteria and other nitrifying microorganisms in plateau wetland is still unclear. Here, the abundances and community features of comammox bacteria, ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in the wetland sediments of western China plateaus were examined using qPCR and high-throughput sequencing.

Nitrite-resistance mechanisms on wastewater treatment in denitrifying phosphorus removal process revealed by machine learning, co-occurrence, and metagenomics analysis.

Nitrite is a key intermediate in nitrogen metabolism that determines microbial transformations of N and P, greenhouse gas (NO) emissions, and system nutrient removal efficiency. However, nitrite also exerts toxic effects on microorganisms. A lack of understanding of high nitrite-resistance mechanisms at community- and genome-scale resolutions hinders the optimization for robustness of wastewater treatment systems.

Anthropogenic land-use activities within watersheds reduce comammox activity and diversity in rivers.

Nitrogen cycling plays a key role in maintaining river ecological functions which are threatened by anthropogenic activities. The newly discovered complete ammonia oxidation, comammox, provides novel insights into the ecological effects of nitrogen on that it oxidizes ammonia directly to nitrate without releasing nitrite as canonical ammonia oxidization conducted by AOA or AOB which is believed to play an important role in greenhouse gas generation. Theoretically, contribution of commamox, AOA and AOB to ammonia oxidization in rivers might be impacted by anthropogenic land-use activities through alterations in flow regime and nutrient input.

Nitrifiers Cooperate to Produce Nitrous Oxide in Plateau Wetland Sediments.

The thawing of dormant plateau permafrost emits nitrous oxide (NO) through wetlands; however, the NO production mechanism in plateau wetlands is still unclear. Here, we used the N-O double tracer technique and metagenomic sequencing to analyze the NO production mechanism in the Yunnan-Kweichow and Qinghai-Tibet plateau wetlands during the summer of 2020. NO production activity was detected in all 16 sediment samples (elevation 1020-4601 m: 2.

Comparing with oxygen, nitrate simplifies microbial community assembly and improves function as an electron acceptor in wastewater treatment.

Biochemical oxidation and reduction are key processes in treating biological wastewater and they require the presence of electron acceptors. The functional impact of electron acceptors on microbiomes provides strategies for improving the treatment efficiency. This research focused on two of the most important electron acceptors, nitrate and oxygen.

Brownification of freshwater promotes nitrogen-cycling microorganism growth following terrestrial material increase and ultraviolet radiation reduction.

Brownification is an increasingly concerning phenomenon faced by aquatic ecosystems in the changing environments, and the microbiome plays an irreplaceable role in material circulation and food web construction. Insight into the influence of brownification on microbial communities is crucial from an ecological standpoint. In this study, we simulated brownification using a the mesocosm system and explored the relationship between the characteristics of microbial communities and brownification using excitation-emission matrix (EEM) fluorescence spectroscopy and ultraviolet (UV) spectroscopy combined with high-throughput amplicon sequencing techniques.

Ecological Insights Into Community Interactions, Assembly Processes and Function in the Denitrifying Phosphorus Removal Activated Sludge Driven by Phosphorus Sources.

The microbial characteristics in the wastewater treatment plants (WWTPs) strongly affect their optimal performance and functional stability. However, a cognitive gap remains regarding the characteristics of the microbial community driven by phosphorus sources, especially co-occurrence patterns and community assembly based on phylogenetic group. In this study, 59 denitrifying phosphorus removal (DPR) activated sludge samples were cultivated with phosphorus sources.

Comammox activity dominates nitrification process in the sediments of plateau wetland.

The recent discovery of complete ammonia oxidation (comammox) has increased our understanding of nitrification. Although comammox has been shown to play an important role in plain wetland ecosystems, studies of comammox contribution are still limited in plateau wetland ecosystems. Here, we analyzed the abundance, activity, community and biogeochemical mechanisms of the comammox bacteria in Yunnan-kweichow and Qinghai-Tibet plateau wetlands from elevations of 1000-5000 m.

Balance Between Soil Remediation and Economic Benefits of Eucalyptus globulus.

A long term experiment was conducted to verify the phytoremediation effect of large biomass plants and to seek the balance between remediation effect and economy. Eucalyptus globulus were planted with rotation periods of respectively 3, 6 and 9 years to examine the effect on soil remediation. Biomass and concentrations of Cd, Pb and Cu in E.