关键词：
Paddy soil;Type I and II methanotrophs;Methane oxidation rate;Carbon conversion efficiency;PLFA-SIP;Climate zones;Soil pH
摘要：
Conventional aerobic methanotrophs oxidize methane (CH4) and covert CH4-derived carbon (C) into biomass at the oxic-anoxic interface of inundated rice paddy fields, playing indispensable role in mitigating greenhouse gas emissions and loss of organic C from methanogenesis. Two phylogenetically distinct groups of methanotrophs, type I (gamma-proteobacteria) and type II (alpha-proteobacteria) methanotrophs, often co-exist in rice paddy soil and compete for CH4 biotransformation. Since these two methanotrophic groups also possess differential kinetics of CH4 oxidation and pathways of C assimilation, the consequence of their niche differentiation and metabolic differences in soil is expected to affect the CH4 oxidation rate and C conversion efficiency. Here, we examined the microbiology, chemistry, and CH4 metabolism in 24 geographically different paddy soils, covering four climate zones of eastern China. High-throughput sequencing of pmoA gene displayed a clear separation of in situ methanotrophic compositions between temperate (warm and mid-temperate) and warmer (subtropics and tropics) climate zones, likely driven by soil pH. Both methanotrophic groups were detected in soils but proportions of type I methanotrophs increased in temperate soils of higher pH (accounting for 76.1 +/- 12.4% and 44.1 +/- 14.8% in warm temperate and mid-temperate, respectively). Type II methanotrophs prevailed in warmer zones (accounting for 66.2 +/- 21.6% and 70.5 +/- 12.1% in tropics and subtropics, respectively) where soils were more acidic. Higher incorporation of 13C for synthesis in C14+C16 PLFAs (63.1-93.4% of total production of 13C-PLFAs) was found based on microcosm incubation, reflecting type I methanotrophs dominated the CH4 assimilation in paddy soils. Particularly, temperate soils with increased proportions of type I methanotrophs showed higher CH4 oxidation rate and C conversion efficiency. Collectively, this study depicts a continental-scale disparity of methanotrophic dynamics that tightly associates with consequence of niche differentiation of different types of methanotrophs and highlights the importance of microbiological control to maximize the rate and efficiency of methanotrophy.
摘要：
Fe-Mn binary oxides have superior catalytic and oxidation performance, and calcined layered double hydroxides (LDOs) have stably dispersed metals and a large specific surface area. Combining the advantages of both, MgFeMn-LDOs were prepared by co-precipitation and calcination, and applied to monovalent thallium (Tl(I)) removal in aqueous. MgFeMn-LDOs before and after Tl(I) adsorption were characterized by scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS), X-ray Diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The adsorbent has abundant active sites and oxygen-containing groups, and a high specific surface area (76.77m2/g). Its removal efficiency of Tl(I) was more than 96% under a broad pH, and showed high selectivity under the conditions of coexisting Na+, Ca2+, Mg2+, and EDTA. The calculated maximum adsorption capacities by the Langmuir and Freundlich model are 135.3 mg/g at 293 K. The adsorption kinetic fitted the pseudo-second-order model and the adsorption process was spontaneous and endothermic. The excellent Tl(I) adsorption of MgFeMn-LDOs is mainly dominated by surface complexation, oxidation, coprecipitation, and electrostatic adsorption. The high Tl(I) adsorption capacity, selectivity, and wide pH working range of MgFeMn-LDOs is beneficial to practical application.
通讯机构：
[Vladimir Matichenkov] H;Hunan University of Finance and Economics, Changsha, China<&wdkj&>Institute Basic Biological Problems Russian Academy of Sciences, Pushchino, Russia
摘要：
This review aims to provide a holistic synopsis of the current state of the art knowledge on caproic acid pro-duction via anaerobic fermentation from the perspectives of microbes and metabolic pathway. The pure bacterial isolations with ability of caproic acid synthesis were summarized for metabolic identification and syntrophic potentials. Compared with single bacterium, mixed microflora with caproic acid production capacity is more conducive to caproic acid recovery and stability of the fermentation system. The anaerobic fermentation influ-encing factors, such as pH, temperature, electron donor and acceptor, hydrogen partial pressure, and competition between microbes were discussed. It is found that these factors essentially affect the performance of microbes causing system fluctuation thus decreased caproic acid production. Facing with the immature caproic acid separation technology, were compared from the prospect of application and electrodialysis was proposed as the mainstream technology in future. Simultaneously, it is believed that in-situ separation strategy can improve the yield and purity of caproic acid. Targeting on a large scale caproic acid production through anaerobic fermen-tation, it is also necessary to strengthen the research on the synergy and competition between microbes in the process of anaerobic fermentation, and to establish a readiness caproic acid separation technology. This work is expected to contribute to the goal of carbon summit and carbon neutrality.
关键词：
Crop rotation;Rice production;Rhizosphere metabolites;Microbial diversity;Functional microbial population
摘要：
Plants are increasingly revealed to have the ability to shape microbiome composition and function by triggering rhizosphere metabolites. Rotation, a model of crop diversification, promotes crop production by influencing rhizosphere microbiome. However, the rhizosphere metabolites of different rice rotations are rarely reported and, in particular, the regulation of key metabolites on rhizosphere microbiome is unclear. To address this gap, we collected the bulk and rhizosphere soils of four crop rotations (rice-rice, tobacco-rice, rice-oilseed rape, and rice-rice-oilseed rape) to assess rhizosphere metabolites, soil bacterial and fungal diversity, as well as functional microbial populations from a long-term (more than 20 years) field experiment. Compared with the rice-rice system, rhizosphere metabolites, such as deazaflavin, 10-Deacetylbaccatin III, and paclobutrazol, significantly increased in the rice rotation systems with tobacco and oilseed rape. Metabolite components (e.g., azelaic acid, soyasapogenol B, and canrenone) and microbial taxa (Xanthobacteraceae, Bradyrhizobium, and Mortierella) were the keystones regulating the co-occurring correlations of rhizosphere metabolites and soil microorganisms. Compared with the rice-rice, the bulk and rhizosphere soil of rice rotations with oilseed rape or tobacco showed higher abundance of the microbial populations related to C degradation and fixation, N fixation, nitrification, nitrate reduction, inorganic P (Pi) solubilization, and organic P (Po) mineralization. Metabolites, such as 7-chloro-norlichexanthone, daidzein, and soyasapogenol B, were the keystones regulating the co-occurrence relationships of rhizosphere metabolites and functional microbial populations. Rhizosphere metabolite composition was positively related to the populations associated with C fixation and degradation, nitrification, and P solubilization, and negatively related to those associated with methane metabolism, nitrate reduction, denitrification, and anammox (P ≤ 0.05). Soyasapogenol B, daidzei, and [1,1'-biphenyl]− 2,2'-dicarboxylic acid enriched in rotation systems were negatively correlated with dominant microbial taxa such as phylum Bacteroidetes and Chytridiomycota, and positively correlated with phylum Zoopagomycota and the populations associated with key soil functions such as C degradation, nitrate reduction, and P solubilization (P ≤ 0.05). These results demonstrated the importance of rhizosphere metabolites in regulating soil microbiome composition and functional capacity, which deepens understanding of rotations improving rice production via rhizosphere effect.
作者机构：
[Yan, Binghua; Jin, Hongyu; Niu, Hongyu] College of Resources and Environment, Hunan Agricultural University, 410128, Changsha, China;[Jin, Hongyu] Yueyang Agricultural and Rural Development Group Co., Ltd., 414022, Yueyang, China;[Nie, Zimeng] School of Environment and Energy, South China University of Technology, Guangzhou 510006, China;[Tan, Ju] Changsha Environmental Monitoring Center Station, 410001, Changsha, China;[Huang, Shuie] Changsha Xinkaipu Water Purification Factory, 410002, Changsha, China
通讯机构：
[Haijun Yang] C;College of Resources and Environment, Hunan Agricultural University, 410128, Changsha, China
摘要：
Microbial consortia HY3 and JY3 with high degradation efficiency of 2-Diethylamino-4-hydroxy-6-methylpyrimidine (DHMP) were isolated from aerobic and parthenogenic ponds of DHMP-containing pharmaceutical wastewater, respectively. Both consortia were enriched and reached stable degradation performance with a DHMP concentration of 1500mgL(-1). The DHMP degradation efficiencies of HY3 and JY3 were 95.66%±0.24% and 92.16%±2.34% under the condition of shaking at 180 r·min(-1) and the temperature of 30°C for 72h. And the removal efficiencies of chemical oxygen demand were 89.14%±4.78% and 80.30%±11.74%, respectively. High-throughput sequencing results indicated that three bacterial phyla of Proteobacteria, Bacteroidetes, and Actinobacteria were dominant in both HY3 and JY3, but their dominances varied. At the genus level, the richness of Unclassified Comamonadaceae (34.23%), Paracoccus (14.75%), and Brevundimonas (13.94%) ranked top three in HY3 whereas Unclassified Comamonadaceae (40.80%), Unclassified Burkholderiales (13.81%) and Delftia (13.11%) were dominant in JY3. The metabolites of DHMP degradation by HY3 and JY3 were analyzed in detail. Two pathways for cleavage of the nitrogenous heterocyclic ring were speculated, one of which was identified for the first time in this study.
通讯机构：
[Gongwen Luo] C;College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China<&wdkj&>National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Changsha 410128, China
关键词：
C mineralization;Compost maturity;Composting;Functional gene;Nutrient transformation
摘要：
With the extensive development of industrial livestock and poultry production, a considerable part of agricultural wastewater containing tremendous ammonium and antibiotics have been indiscriminately released into the aquatic systems, causing serious harms to ecosystem and human health. In this review, ammonium detection technologies, including spectroscopy and fluorescence methods, and sensors were systematically summarized. Antibiotics analysis methodologies were critically reviewed, including chromatographic methods coupled with mass spectrometry, electrochemical sensors, fluorescence sensors, and biosensors. Current progress in remediation methods for ammonium removal were discussed and analyzed, including chemical precipitation, breakpoint chlorination, air stripping, reverse osmosis, adsorption, advanced oxidation processes (AOPs), and biological methods. Antibiotics removal approaches were comprehensively reviewed, including physical, AOPs, and biological processes. Furthermore, the simultaneous removal strategies for ammonium and antibiotics were reviewed and discussed, including physical adsorption processes, AOPs, biological processes. Finally, research gaps and the future perspectives were discussed. Through conducting comprehensive review, future research priorities include: (1) to improve the stabilities and adaptabilities of detection and analysis techniques for ammonium and antibiotics, (2) to develop innovative, efficient, and low cost approaches for simultaneous removal of ammonium and antibiotics, and (3) to explore the underlying mechanisms that governs the simultaneous removal of ammonium and antibiotics. This review could facilitate the evolution of innovative and efficient technologies for ammonium and antibiotics treatment in agricultural wastewater.
摘要：
Water pollution caused by heavy metals poses a serious threat to the ecological environment and human health, which requires the exploration of efficient, economical and convenient methods to solve such urgent problems. In this work, agricultural waste straw was prepared and modified by spinel bimetal through sol-gel method to obtain novel MnFe2O4 loaded biochar with the purpose of efficiently cadmium (Cd) removal from water. Results showed that the as-prepared composites showed much higher Cd adsorption capacity as compared to the original biochar (127.37 vs 25.73 mg/g). Further investigation showed that the integrity of crystal plane structure contributes to the appearance of net-like pore and the 18-fold enlarged specific surface area. Strong anti -interference ability of the spinel loaded biochar was observed in binary and quaternary systems through adsorption affinity investigation using separation factor (alpha CdMetal, Metal=Pb, Zn, Cu). Due to its magnetic prop-erties, the adsorbent was easily separated and recovered from aquatic solutions, and the adsorption capacity showed little decrease after five cycles. This work provided the references for resource utilization of agricultural wastes and its application in wastewater treatment.
