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It remains unclear whether periphytic biofilms are beneficial to N cycling in paddy fields. Here, based on a national‐scale field investigation covering 220 rice fields in China, the N accumulation potential of periphytic biofilms was found to decrease from 8.8 ± 2.4 to 4.5 ± 0.7 g/kg and 3.1 ± 0.6 g/kg with increasing habitat latitude and longitude, respectively. The difference in abundant and rare subcommunities likely accounts for their geo‐difference in N accumulation potential. The N cycling pathways involved in periphytic biofilms inferred that soil N and N2 were two potential sources for N accumulation in periphytic biofilms. Meanwhile, some of the accumulated N may be lost via N2, N2O, NO, or NH3 outputs. Superficially, periphytic biofilms are double‐edged swords to N cycling by increasing soil N through biological N fixation but accelerating greenhouse gas emissions. Essentially, augmented periphytic biofilms increased change of TN (ΔTN) content in paddy soil from −231.9 to 31.9 mg/kg, indicating that periphytic biofilms overall benefit N content enhancement in paddy fields. This study highlights the contribution of periphytic biofilms to N cycling in rice fields, thus, drawing attention to their effect on rice production and environmental security. [ABSTRACT FROM AUTHOR]

Background and aims: Phosphate-solubilizing bacteria (PSB) possess significant potential for enhancing soil phosphorus bioavailability, but their efficacy may be constrained by carbon and nitrogen availability. Algae exhibit synergistic interactions with bacteria through producing active organic carbon. However, the influence of algae and PSB together on phosphorus bioavailability under varying nitrogen levels remains unclear.We conducted a microcosm experiment to explore the effects of applying Chlorella-Bacillus biofertilizer, along with various nitrate addition amounts, on both soil microbial community composition and phosphorus bioavailability. In addition, we employed a co-culture of Chlorella and Bacillus with different nitrogen concentrations to investigate the possible effects of nitrate addition on the production of organic anions and phosphatases of the Chlorella-Bacillus communities by using metabolomic analysis.Chlorella-Bacillus biofertilizer significantly increased soil Olsen-P concentration via strong interactive effects correlating with the various nitrate addition amounts in the microcosm experiment. These effects were due mainly to reducing the algal diversity, soil pH, and changing dissolved organic matter (DOM) characteristics, especially increasing the humification index (HIX). The metabolomic analyses of co-culture confirm that pathways related to the biosynthesis of fatty acids and phosphatases production are enhanced when nitrogen levels are high.Chlorella-Bacillus biofertilizer has significantly interactive effects with nitrate addition on soil phosphorus bioavailability by influencing soil DOM, pH and production of organic anions and phosphatases. These insights are useful for optimizing bio-fertilizer-nitrate combinations for increasing phosphorus bioavailability thereby reducing chemical fertilizer requirements.Methods: Phosphate-solubilizing bacteria (PSB) possess significant potential for enhancing soil phosphorus bioavailability, but their efficacy may be constrained by carbon and nitrogen availability. Algae exhibit synergistic interactions with bacteria through producing active organic carbon. However, the influence of algae and PSB together on phosphorus bioavailability under varying nitrogen levels remains unclear.We conducted a microcosm experiment to explore the effects of applying Chlorella-Bacillus biofertilizer, along with various nitrate addition amounts, on both soil microbial community composition and phosphorus bioavailability. In addition, we employed a co-culture of Chlorella and Bacillus with different nitrogen concentrations to investigate the possible effects of nitrate addition on the production of organic anions and phosphatases of the Chlorella-Bacillus communities by using metabolomic analysis.Chlorella-Bacillus biofertilizer significantly increased soil Olsen-P concentration via strong interactive effects correlating with the various nitrate addition amounts in the microcosm experiment. These effects were due mainly to reducing the algal diversity, soil pH, and changing dissolved organic matter (DOM) characteristics, especially increasing the humification index (HIX). The metabolomic analyses of co-culture confirm that pathways related to the biosynthesis of fatty acids and phosphatases production are enhanced when nitrogen levels are high.Chlorella-Bacillus biofertilizer has significantly interactive effects with nitrate addition on soil phosphorus bioavailability by influencing soil DOM, pH and production of organic anions and phosphatases. These insights are useful for optimizing bio-fertilizer-nitrate combinations for increasing phosphorus bioavailability thereby reducing chemical fertilizer requirements.Results: Phosphate-solubilizing bacteria (PSB) possess significant potential for enhancing soil phosphorus bioavailability, but their efficacy may be constrained by carbon and nitrogen availability. Algae exhibit synergistic interactions with bacteria through producing active organic carbon. However, the influence of algae and PSB together on phosphorus bioavailability under varying nitrogen levels remains unclear.We conducted a microcosm experiment to explore the effects of applying Chlorella-Bacillus biofertilizer, along with various nitrate addition amounts, on both soil microbial community composition and phosphorus bioavailability. In addition, we employed a co-culture of Chlorella and Bacillus with different nitrogen concentrations to investigate the possible effects of nitrate addition on the production of organic anions and phosphatases of the Chlorella-Bacillus communities by using metabolomic analysis.Chlorella-Bacillus biofertilizer significantly increased soil Olsen-P concentration via strong interactive effects correlating with the various nitrate addition amounts in the microcosm experiment. These effects were due mainly to reducing the algal diversity, soil pH, and changing dissolved organic matter (DOM) characteristics, especially increasing the humification index (HIX). The metabolomic analyses of co-culture confirm that pathways related to the biosynthesis of fatty acids and phosphatases production are enhanced when nitrogen levels are high.Chlorella-Bacillus biofertilizer has significantly interactive effects with nitrate addition on soil phosphorus bioavailability by influencing soil DOM, pH and production of organic anions and phosphatases. These insights are useful for optimizing bio-fertilizer-nitrate combinations for increasing phosphorus bioavailability thereby reducing chemical fertilizer requirements.Conclusion: Phosphate-solubilizing bacteria (PSB) possess significant potential for enhancing soil phosphorus bioavailability, but their efficacy may be constrained by carbon and nitrogen availability. Algae exhibit synergistic interactions with bacteria through producing active organic carbon. However, the influence of algae and PSB together on phosphorus bioavailability under varying nitrogen levels remains unclear.We conducted a microcosm experiment to explore the effects of applying Chlorella-Bacillus biofertilizer, along with various nitrate addition amounts, on both soil microbial community composition and phosphorus bioavailability. In addition, we employed a co-culture of Chlorella and Bacillus with different nitrogen concentrations to investigate the possible effects of nitrate addition on the production of organic anions and phosphatases of the Chlorella-Bacillus communities by using metabolomic analysis.Chlorella-Bacillus biofertilizer significantly increased soil Olsen-P concentration via strong interactive effects correlating with the various nitrate addition amounts in the microcosm experiment. These effects were due mainly to reducing the algal diversity, soil pH, and changing dissolved organic matter (DOM) characteristics, especially increasing the humification index (HIX). The metabolomic analyses of co-culture confirm that pathways related to the biosynthesis of fatty acids and phosphatases production are enhanced when nitrogen levels are high.Chlorella-Bacillus biofertilizer has significantly interactive effects with nitrate addition on soil phosphorus bioavailability by influencing soil DOM, pH and production of organic anions and phosphatases. These insights are useful for optimizing bio-fertilizer-nitrate combinations for increasing phosphorus bioavailability thereby reducing chemical fertilizer requirements. [ABSTRACT FROM AUTHOR]

Temperature can fluctuate widely between different seasons, and this may greatly impact many biological processes. However, little is known about its influence on the functioning of benthic microbial communities. Here we investigated the nutrient accumulation capability of periphytic biofilm under temperature fluctuations (17–35°C). Periphytic biofilm maintained the same nutrient accumulation capacity after experiencing the 'warming-hot-cooling' temperature fluctuation under both lab and outdoor conditions as those without temperature disturbance. In response to temperature increase, both community composition and species richness changed greatly and the increase in biodiversity was identified as being the underlying mechanism boosting the sustainable function in nutrient accumulation, indicating zero net effects of community changes. These findings provide insights into the underlying mechanisms of how benthic microbial communities adapt to temperature fluctuations to maintain nutrient accumulation capacity and elucidate that periphytic biofilm plays important roles in influencing nutrient cycling in aquatic ecosystems under temperature changes such as seasonal fluctuations. [ABSTRACT FROM AUTHOR]

Nonpoint source (NPS) pollution produced by human activities in rural areas has induced excessive nutrient input into surface waters and the decline of water quality. The essence of NPS pollution is the transport of nutrients between soil and water. Traditional NPS pollution control strategies, however, are mainly based on the solid and liquid phases, with little focus on the bio-phase between water and soil. The pollutants produced from NPS can be regarded as a resource if recycled or reused in an appropriate way in the agricultural ecosystem. This mini review proposes novel strategies for NPS pollution control based on three phases (liquid, solid and bio-phase) and highlights the regulating services of an agricultural ecosystem by optimizing land use/cover types. [ABSTRACT FROM AUTHOR]

Interactions among microbes determine the prevalence of harmful algal blooms that threaten water quality. These interactions can be indirectly mediated by shared resources or consumers, or through interference by the production of allelochemicals. Allelopathic interactions and resource competition have been shown to occur among algae and associated microbes. However, little work has considered seasonal influences on ecosystem structure and function. Here, we report results of our investigations on seasonal changes in the interactions between benthic microbial assemblies and the bloom forming cyanobacterium Microcystis aeruginosa. We show that phosphorus (P) competition and allelopathy by the microbial assembly vary seasonally and inhibit growth of M. aeruginosa. The interactions per unit biomass of the microbial assembly are stronger under winter than summer conditions and inhibit the recruitment of the cyanobacteria, thereby preventing the reoccurrence of cyanobacterial blooms in the following summer. The seasonality of these interactions correlates with changes in composition, metabolic activity and functional diversity of the microbial assembly. Our findings highlight the importance of competitive and allelopathic interactions in regulating the occurrence of harmful algal blooms. Our results also imply that seasonal variation of competition and allelopathy of the microbial assembly might be beneficial to adjust aquatic ecosystem structure and function. [ABSTRACT FROM AUTHOR]

Periphyton is widely distributed in paddy fields and its interactions with paddy soil and rice growth have been reported rarely. In this study, model paddy ecosystems with different additional soil substrates were simulated under controlled conditions to investigate the effects of periphyton on rice seed germination and seedling growth. Results show that the selected soil substrates had significant effects on the metabolic activities and growth of periphyton in paddy fields. The addition of straw to soil enhances but the addition of biochar leads to attenuation of periphyton growth. The presence of periphyton in the paddy system, especially with straw in soil greatly increased the germination index of rice seed (by maximally 21%). However, the biochar treatment in the presence of periphyton was detrimental for the seed vitality with a decrease of 30%. As a result, the periphyton cover on paddy soil surface significantly inhibited the growth of rice seedling, including rice height, leaf width and biomass. To summarize, this study indicates that the presence of periphyton during seed germination period was detrimental for rice growth, but could be used to control the weed growth. Thus, this study provided insight into understanding the periphyton-plant relationships with different soil-substrates and also new approaches to controlling weeds in paddy fields by regulating the growth of periphyton. [ABSTRACT FROM AUTHOR]

Periphyton is ubiquitous in paddy field, but its importance in influencing the bioavailability of phosphorus (P) in paddy soil has been rarely recognized. A paddy field was simulated in a greenhouse to investigate how periphyton influences P bioavailability in paddy soil. Results showed that periphyton colonizing on paddy soil greatly reduced P content in paddy floodwater but increased P bioavailability of paddy soil. Specifically, all the contents of water-soluble P (WSP), readily desorbable P (RDP), algal-available P (AAP), and NaHCO-extractable P (Olsen-P) in paddy soil increased to an extent compared to the control (without periphyton) after fertilization. In particular, Olsen-P was the most increased P species, up to 216 mg kg after fertilization, accounting for nearly 60 % of total phosphorus (TP) in soil. The paddy periphyton captured P up to 1.4 mg g with Ca-P as the dominant P fraction and can be a potential crop fertilizer. These findings indicated that the presence of periphyton in paddy field benefited in improving P bioavailability for crops. This study provides valuable insights into the roles of periphyton in P bioavailability and migration in a paddy ecosystem and technical support for P regulation. [ABSTRACT FROM AUTHOR]

Phosphorus stored in lake sediments is an inner nutrient source and can be released into overlying water to exacerbate algal blooms. A simulated microcosm of Dianchi Lake was built to investigate phosphorus release from sediments to overlying water and its effect on the growth of Microcystis aeruginosa. The sediments of Dianchi Lake had a total phosphorus (TP) content of 1.7-1.8 mg g with Ca bound phosphorus (Ca-P, 50-54 %) and organic phosphorus (Org-P, 28-32 %) as the main fractions. The sediments released 8 % of TP into the overlying water with Fe/Al bound phosphorus (Fe/Al-P, 26 %) and Org-P (65 %) being the main fractions released. The phosphorus concentration of the overlying water increased from 0.14-0.16 to 0.28-0.33 mg L. The biomass density of M. aeruginosa was positively correlated ( R = 0.825) with the concentration of orthophosphate, which was the predominant bioavailable phosphorus fraction for algal growth. Org-P can be partly utilized by M. aeruginosa but will not cause a bloom. A good understanding of the geochemical cycles of phosphorus is needed for regulating phosphorus release from sediments and thereby reducing the risk of cyanobacterial blooms. [ABSTRACT FROM AUTHOR]

• Ag+ released from AgNPs has heavier impact on photosynthesis than intact AgNPs. • Ag+ blocks electron transport and damages phycobilisome of algae in periphyton. • Energy absorption is increased to maintain electron transfer in photosynthesis. • PSII and PSI work in complement to cope with stress by intact AgNPs and Ag+. Silver nanoparticles (AgNPs) including a mix of intact nanoparticle-Ag and 'free' Ag+ pose high risks to benthic photoautotrophs, but the photosynthetic responses of benthic microbial aggregates to AgNPs still remain largely unknown. Here, periphyton and Nostoc were used to elucidate the photosynthetic responses of benthic algae community to intact nanoparticle-Ag and Ag+. During exposure, both intact nanoparticle-Ag and Ag+ imposed negative effects on photosynthesis of benthic algae, but via different pathways. Specifically, Ag+ had stronger effects on damaging the oxygen-evolving complex (OEC) and thylakoid membrane than intact nanoparticle-Ag. Ag+ also suppressed electron transfer from Q A to Q B , and impaired phycobilisome. Intact nanoparticle-Ag inhibited the expression of PsbD and PsbL in PSII, but prompted the ROS scavenging capacity. In response to the stress of AgNPs, the benthic algae increased light energy absorption to maintain the electron transport efficiency, and up-regulated PSI reaction center protein (PsaA) to compensate the degraded PSII. These results reveal how intact nanoparticle-Ag and Ag+ influence electron transport, energy conversion and protein expression in the photosynthesis of periphyton, and provide deep insights into the responses of benthic photoautotrophs to different components of AgNPs. [ABSTRACT FROM AUTHOR]

Periphyton plays a significant role in heavy metal transfer in wetlands, but its contribution to cadmium (Cd) bioavailability in paddy fields remains largely unexplored. The main aim of this study was to investigate the effect of periphyton on Cd behavior in paddy fields. Periphyton significantly decreased Cd concentrations in paddy waters. Non-invasive micro-test technology analyses indicated that periphyton can absorb Cd from water with a maximum Cd2+ influx rate of 394 pmol cm−2 s−1 and periphyton intrusion significantly increased soil Cd concentrations. However, soil Cd bioavailability declined significantly due to soil pH increase and soil redox potential (Eh) decrease induced by periphyton. With periphyton, more Cd was adsorbed and immobilized on organic matter, carbonates, and iron and manganese oxides in soil. Consequently, Cd content in rice decreased significantly. These findings give insights into Cd biogeochemistry in paddy fields with periphyton, and may provide a novel strategy for reducing Cd accumulation in rice. Image 1 • Periphyton significantly decreased Cd accumulation in the rice. • Periphyton growth significantly reduced Cd content in paddy water. • The maximal Cd2+ influx of periphyton was 390 pmol cm−2 s−1. • Periphyton immobilized Cd in paddy soil by regulating the soil Eh and pH. Capsule: Paddy periphyton stored Cd and inactivated Cd in soil. [ABSTRACT FROM AUTHOR]

Objective. To evaluate the effect of hemp cotton sanitary pads on the vaginal microecology. Methods. A randomized controlled field trial was used to recruit 1002 community-based women of childbearing age. The women were randomly divided into experimental and control groups. The experimental group used hemp cotton sanitary pads, while the control group used two types of cotton sanitary randomly chosen from the top five sanitary pads in terms of market share in China. The vaginal microecology was compared between the two groups after three months. Results. According to the vaginal microecologic examination results at baseline, 1002 women were included in 3 groups: normal vaginal microecologic, vaginal microecological disorders, and suspected vaginal infections. The number of patients in three groups were 39 (3.9%), 652 (65.1%), and 311 (31%), respectively. Three months later, the vaginal microecologic status and vaginal pH value of the suspected vaginal infection group were not significantly different between the experimental group and control group. The experimental group outperformed the control group with respect to vaginal cleanliness and vaginal microecology status in the women without a vaginal infection (normal vaginal microecology or microecological disorders group). The rate of abnormal cleanliness in the experimental group was lower than the control group (31.95% [108/338] vs. 43.62% [154/353]). The incidence of suspected vaginitis in the experimental group was lower than the control group (15.29% [51/338] vs. 23.51% [83/353]). Conclusion. For women without vaginal inflammation, the use of hemp cotton sanitary pads during menstruation can help maintain the balance of the vaginal microecology to prevent reproductive tract infections. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • UCPs were first used to stimulate nitrogen removal of periphytic biofilms. • UCPs optimized the microbial community structure of periphytic biofilms. • Periphytic biofilms simulated by UCPs could adapt to nitrogen fluctuation. Abstract The application of periphytic biofilm in removing nitrogen from water is limited by the fluctuating nitrogen concentration. Here, we delineate a novel approach to enhance periphytic biofilm performance in nitrogen removal via upconversion luminescence of upconversion phosphors (UCPs). Nitrogen removal rates (14 d) in high nitrogen wastewater (26 mg/L) were significantly improved to 58.6% and 61.4% by UCPs doped with Pr3+ and Li+ and UCPs doped with Pr3+, respectively, and to 95.1% and 95.9% in low nitrogen surface water (2 mg/L), respectively. The stimulation of UCPs optimized the microbial community structure in the periphytic biofilms, and also resulted in good acclimation to use different carbon sources. The enhanced synergic action of cyanobacterial biomass, ratio of Gram +ve to Gram −ve bacteria and carbon source metabolic capacity contributed to the improved nitrogen removal. This novel approach is promising in nitrogen removal from wastewater and surface water with fluctuating initial nitrogen concentration. [ABSTRACT FROM AUTHOR]

Production of sulfide and methane due to anaerobic biological transformations in sewer pipes causes serious problems to sewer maintenance. For gravity sewers, enhancing ventilation is a practical method that reduces the production of both sulfide and methane. This study aimed to determine the effectiveness of a new method, Upstream Natural Pulsed Ventilation (UNPV), to control sulfide and methane production in gravity sewers. Two lab-scale reactors simulating the gravity sewer pipe with and without ventilation were set up to assess the effectiveness. The results show that compared with the gravity sewer pipe without ventilation, under the UNPV condition, the total sulfide concentration reduced by 39.08% and 58.74%, and the methane concentration reduced by 42.29% and 35.70% in the upstream and downstream sewer pipe, respectively. High-throughput sequencing analysis showed that the UNPV method could inhibit the proliferation of sulfate-reducing bacteria and stimulate the proliferation of sulfur-oxidizing bacteria within the whole sewer pipe. The composition of methanogenic archaea that are responsible for methane production was changed by ventilation. The increased oxidation-reduction potential and organic carbon transportation in wastewater under ventilation may be responsible for the microbial community changes. The findings of this study may provide new insight to reduce sulfide and methane production in gravity sewers. Unlabelled Image • A simple method to control harmful gas in sewer by ventilation was proposed. • Sulfide emissions were reduced by ≈60% during upstream ventilation. • Methane emissions were reduced by ≈40% during upstream ventilation. • The biofilm community under ventilation was elucidated. [ABSTRACT FROM AUTHOR]

Periphytic biofilms (PB) at the soil-water interface contributes 7-38% of the methane emission from rice paddies, yet the biogeographical mechanism underlying and affecting the process remain elusive. In this study, rice fields along an edapho-vclimatic gradient were sampled, and the environmental drivers affecting distribution of methanogenic and methanotrophic communities were evaluated. The methanogenic and methanotrophic communities at soil-water interface showed less complex inter/intra-generic interactions than those in soil, and their relative abundances were weakly driven by spatial distance, soil organic carbon, soil total nitrogen and pH. The nutrient supply and buffering capacity of extracellular polymeric substance released by PB reduced their interaction and enhanced the resilience on edaphic environment changes. Climate affected soil metal content, extracellular polymeric substance content, and thus the methane-related communities, and caused geographical variation in the impacts of PB on methane emissions from rice paddies. This study facilitates our understanding of geographical differences in the contribution of PB to methane emission., Competing Interests: The authors declare no competing interests., (© 2022.)

Phototrophic biofilms are easy to grow at sediment/soil-water interfaces (SWIs) in shallow aquatic ecosystems and greatly impact nutrient biogeochemical cycles. However, the pathways by which they contribute to nitrogen interception and interact with sediment/soil remains largely unknown. Here, we conducted a field investigation in paddy fields in various regions of China and found that nitrogen immobilized in biofilm biomass significantly positively correlated with soil organic carbon (SOC) content. A microcosm experiment showed that this was due to increased bacterial and algal diversity, biomass accumulation, and inorganic nitrogen assimilation at high SOC, especially high dissolved organic carbon (DOC) levels. The metatranscriptomics results further verified that many KO groups of PSII, PSI, AP, and PC in antenna proteins and glutamate synthesis were distinctly expressed at elevated SOC and DOC levels. Our results elucidated the effects and possible pathways of how SOC enrichment triggers photosynthesis and nitrogen immobilization by phototrophic biofilms. The results will provide meaningful information for in situ nitrogen interception by using phototrophic biofilms at the SWI in human-made wetlands to change internal nitrogen cycling.

The toxic effects of nanoparticles on individual organisms have been widely investigated, while few studies have investigated the effects of nanoparticles on ubiquitous multicommunity microbial aggregates. Here, periphyton as a model of microbial aggregates, was employed to investigate the responses of microbial aggregates exposed continuously to Fe 2 O 3 nanoparticles (5.0 mg L -1 ) for 30 days. The exposure to Fe 2 O 3 nanoparticles results in the chlorophyll (a, b, and c) contents of periphyton increasing and the total antioxidant capacity decreasing. The composition of the periphyton markedly changes in the presence of Fe 2 O 3 nanoparticles and the species diversity significantly increases. The changes in the periphyton composition and diversity were due to allelochemicals, such as 3-methylpentane, released by members of the periphyton which inhibit their competitors. The functions of the periphyton represented by metabolic capability and contaminant (organic matter, nitrogen, phosphorus and copper) removal were able to acclimate to the Fe 2 O 3 nanoparticles exposure via self-regulation of morphology, species composition and diversity. These findings highlight the importance of both physiological and ecological factors in evaluating the long-term responses of microbial aggregates exposed to nanoparticles.