Non-negligible roles of upstream rivers in determining the antibiotic resistance genes community in an interconnected river-lake system (Dongting lake, China).

Emergence and spread of antibiotic resistance genes (ARGs) in lakes have been considered as a global health threat. However, a thorough understanding of the distribution patterns and ecological processes that shape the ARGs profile in interconnected river-lake systems remains largely unexplored. In this study, we collected paired water and sediment samples from a typical interconnected river-lake system, Dongting Lake in China, during both wet and dry seasons. Using high-throughput quantitative PCR, we investigated the spatial and temporal distribution of ARGs and the factors that influence them. A total of 8 major antibiotic classes and 10 mobile genetic elements were detected across the Dongting Lake basin. The unique hydrological characteristics of this interconnected river-lake system result in a relatively stable abundance of ARGs across different seasons and interfaces. During the wet season, deterministic processes dominated the assembly of ARGs, allowing environmental factors, such as heavy metals, to serve as main driving forces of ARGs distribution. When the dry season arrived, variations in hydrological conditions and changes in ARGs sources caused stochastic processes to dominate the assembly of ARGs. Our findings provide valuable insights for understanding the ecological processes of ARGs in interconnected river-lake systems, emphasizing the necessity of upstream restoration and clarifying river-lake relationships to mitigate ARGs dissemination.

Electron Transfer in the Biogeochemical Sulfur Cycle.

Microorganisms are key players in the global biogeochemical sulfur cycle. Among them, some have garnered particular attention due to their electrical activity and ability to perform extracellular electron transfer. A growing body of research has highlighted their extensive phylogenetic and metabolic diversity, revealing their crucial roles in ecological processes. In this review, we delve into the electron transfer process between sulfate-reducing bacteria and anaerobic alkane-oxidizing archaea, which facilitates growth within syntrophic communities. Furthermore, we review the phenomenon of long-distance electron transfer and potential extracellular electron transfer in multicellular filamentous sulfur-oxidizing bacteria. These bacteria, with their vast application prospects and ecological significance, play a pivotal role in various ecological processes. Subsequently, we discuss the important role of the pili/cytochrome for electron transfer and presented cutting-edge approaches for exploring and studying electroactive microorganisms. This review provides a comprehensive overview of electroactive microorganisms participating in the biogeochemical sulfur cycle. By examining their electron transfer mechanisms, and the potential ecological and applied implications, we offer novel insights into microbial sulfur metabolism, thereby advancing applications in the development of sustainable bioelectronics materials and bioremediation technologies.

Transfer and accumulation of antibiotic resistance genes and bacterial pathogens in the mice gut due to consumption of organic foods.

Over the last few decades, organic food demand has grown largely because of increasing personal health concerns. Organic farming introduces antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) into foods. However, potential effects of organic foods on the gut microbiome and ARGs have been overlooked. Using high-throughput quantitative PCR and 16S rRNA high-throughput sequencing technology, we examined 132 ARGs from major classes, eight transposase genes, universal class I integron-integrase gene (intI), clinical class I integron-integrase gene (cintI), and the bacterial community in mouse gut after 8 weeks with an either organic or inorganic lettuce and wheat diet. A total of 8 types of major ARGs and 10 mobile genetic elements (MGEs) were detected in mice gut, including tetracycline, multidrug, sulfonamide, aminoglycoside, beta-lactamase, chloramphenicol, MLSB and vancomycin resistance genes. We found that abundance and diversity of ARGs, mobile gene elements, and potential ARB in the gut increased with time after consumption of organic foods, whereas no significant changes were observed in inorganic treated groups. Moreover, MGEs, including IS613, Tp614 and tnpA_03 were found to play an important role in regulating ARG profiles in the gut microbiome following consumption of organic foods. Importantly, feeding organic food increased the relative abundance of the potentially antibiotic-resistant pathogens, Bacteroides and Streptococcus. Our results confirm that there is an increasing risk of ARGs and ARB in the gut microbiome, which highlights the importance of organic food industries taking into account the potential accumulation and transmission of ARGs as a risk factor.

Phylogenetic distance affects the artificial microbial consortia's effectiveness and colonization during the bioremediation of polluted soil with Cr(VI) and atrazine.

Soils co-contaminated with heavy metals and organic pollutants are common and threaten the natural environment and human health. Although artificial microbial consortia have advantages over single strains, the mechanism affecting their effectiveness and colonization in polluted soils still requires determination. Here, we constructed two kinds of artificial microbial consortia from the same or different phylogenetic groups and inoculated them into soil co-contaminated with Cr(VI) and atrazine to study the effects of phylogenetic distance on consortia effectiveness and colonization. The residual concentrations of pollutants demonstrated that the artificial microbial consortium from different phylogenetic groups achieved the highest removal rates of Cr(VI) and atrazine. The removal rate of 400 mg/kg atrazine was 100%, while that of 40 mg/kg Cr(VI) was 57.7%. High-throughput sequence analysis showed that the soil bacterial negative correlations, core genera, and potential metabolic interactions differed among treatments. Furthermore, artificial microbial consortia from different phylogenetic groups had better colonization and a more significant effect on the abundance of native core bacteria than consortia from the same phylogenetic group. Our study highlights the importance of phylogenetic distance on consortium effectiveness and colonization and offers insight into the bioremediation of combined pollutants.

Geographic characteristics and environmental variables determine the diversities and assembly of the algal communities in interconnected river-lake system.

Algal blooms in lakes are a major hazard worldwide. Although various geographical and environmental patterns affect algal communities during river-lake transit, a thorough understanding of what patterns shape the algal communities is still rarely researched, particularly in complex interconnected river-lake systems. In this study, focusing on the most typical interconnected river-lake system in China, the Dongting Lake, we collected paired water and sediment samples in summer, when algal biomass and growth rate are at high levels. Based on 23S rRNA gene sequencing, we investigated the heterogeneity and the differences in assembly mechanisms of planktonic and benthic algae in Dongting Lake. Planktonic algae contained more Cyanobacteria and Cryptophyta, while sediment harbored higher proportions of Bacillariophyta and Chlorophyta. For planktonic algae, stochastic dispersal dominated the assembly of the communities. Upstream rivers and confluences were important sources of planktonic algae in lakes. Meanwhile, for benthic algae, deterministic environmental filtering shaped the communities, and the proportion of benthic algae exploded with increasing N:P ratio and Cu concentration until reaching thresholds of 1.5 and 0.013 g/kg respectively, and then started falling, showing non-linear responses. This study revealed the variability of different aspects of algal communities in different habitats, traced the main sources of planktonic algae, and identified the thresholds for benthic algal shifts in response to environmental filters. Hence, upstream and downstream monitoring as well as thresholds of environmental factors should be considered in further aquatic ecological monitoring or regulatory programs of harmful algal blooms in these complex systems.

Engineering artificial microbial consortia based on division of labor promoted simultaneous removal of Cr(VI)-atrazine combined pollution.

Combined pollution caused by organic pollutants and heavy metals is common in polluted sites and wastewater. Engineering artificial microbial consortia offers a promising approach to address this complex issue. However, the mutualistic interactions and the critical function of specific microbe within microbial consortia remain unclear. In this study, based on division of labor, we respectively co-cultured two Cr(VI)-reducing strains, Paenarthrobacter nitroguajacolicus C1 and Pseudomonas putida C2, with an atrazine-degrading strain, Paenarthrobacter ureafaciens AT. After 5 days, up to 95 % Cr(VI) and 100 % atrazine were removed from the cocultures. Strain AT degraded nearly all atrazine and contributed only to a fraction of Cr(VI) reduction, whereas C1 promoted 41 % Cr(VI) transformation to Cr(III) fixed in cells, and C2 promoted 91 % Cr(VI) transformation to soluble Cr(III). Metabolic analyses of the cocultures and monocultures demonstrated that AT provided C1 with isopropylamine by passive diffusion and C2 with other effective nitrogen resources by cell-cell surface contact to promote their growth. Soil experiments also showed that treatments with AT and C2 achieved the highest Cr(VI) reduction and no atrazine residue. Our results indicate that engineering artificial microbial consortia based on division of labor and metabolic interactions is effective in promoting highly efficient bioremediation of combined pollution.

Comparison of the efficiency and microbial mechanisms of chemical- and bio-surfactants in remediation of petroleum hydrocarbon.

Surfactant-enhanced remediation (SER) is one of the most effective methods for petroleum hydrocarbon-contaminated sites compared to single physical and chemical methods. However, biosurfactants are not as commonly used as chemical surfactants, and the actual remediation effects and related mechanisms remain undefined. Therefore, to comprehensively compare the remediation effects and biological mechanisms of biosurfactants and chemical surfactants, soil column leaching experiments including two biosurfactants (rhamnolipids and lipopeptide) and three commercially used chemical surfactants (Tween 80, Triton X-100, and Berol 226SA) were conducted. After seven days of leaching, rhamnolipids exhibited the highest petroleum hydrocarbon removal rate of 61.01%, which was superior to that of chemical surfactants (11.73-18.75%) in n-alkanes C10-C30. Meanwhile, rhamnolipids exhibited a great degradation advantage of n-alkanes C13-C28, which was 1.22-30.55 times that of chemical surfactants. Compared to chemical surfactants, biosurfactants significantly upregulated the soil's biological functions, including soil conductivity (80.90-155.56%), and soil enzyme activities of lipase (90.31-497.10%), dehydrogenase (325.00-655.56%), core enzyme activities of petroleum hydrocarbon degradation, and quorum sensing between species. Biosurfactants significantly changed the composition of Pseudomonas, Citrobacter, Acidobacteriota, and Enterobacter at the genus level. Meanwhile, chemical surfactants had less influence on the bacterial community and interactions between species. Moreover, the biosurfactants enhanced the microbial interactions and centrality of petroleum hydrocarbon degraders in the community based on the network. Overall, this work provides a systematic comparison and understanding of the chemical- and bio-surfactants used in bioremediation. In the future, we intend to apply biosurfactants to practical petroleum hydrocarbon-contaminated fields to observe realistic remediation effects and compare their functional mechanisms.

Optimization of conditions for a surfactant-producing strain and application to petroleum hydrocarbon-contaminated soil bioremediation.

Petroleum hydrocarbon-contaminated sites have been mainly remediated through the surfactant-enhanced soil leaching method. However, the commonly used chemical surfactants have poor biocompatibility and are prone to form residues in fields. Therefore, the purpose of this research is to establish an effective system of biosurfactant remediation in the field and provide instructions for common bioremediation challenges. First, wild-type Bacillus amyloliquefaciens A3, which produced lipopeptide biosurfactant, was used to improve the production of biosurfactant by atmosphere and room temperature plasma (ARTP) mutagenesis. Second, the mutant 1-24 was selected from a total of 174 mutants due to the outstanding yield. Subsequently, 1-24 was applied in the soil column leaching experiments and removed 45.44% of petroleum hydrocarbons by changing the relevant enzyme activities. Biosurfactant addition and 1-24 inoculation effectively activated a portion of the petroleum hydrocarbons in the soil columns, and 1-24 presented potential as a desired candidate for bioremediation. This is the first report of using ARTP mutagenesis to improve the production of biosurfactants. Simultaneously, we first propose a theoretical system in which the yield of biosurfactant was increased using ARTP mutagenesis for strains and applied the mutants in situ soil bioremediation. This research indicated that the theoretical system was useful in soil columns to simulate field remediation conditions, providing practical references for the bioremediation of contaminated soil.

Markedly Increasing Antibiotic Resistance and Dual Treatment of Neisseria gonorrhoeae Isolates in Guangdong, China, from 2013 to 2020.

The emergence of multidrug resistance in Neisseria gonorrhoeae is concerning, especially the cooccurrence of azithromycin resistance and decreased susceptibility to extended-spectrum cephalosporin. This study aimed to confirm the antibiotic resistance trends and provide a solution for N. gonorrhoeae treatment in Guangdong, China. A total of 5,808 strains were collected for assessment of antibiotic MICs. High resistance to penicillin (53.80 to 82%), tetracycline (88.30 to 100%), ciprofloxacin (96 to 99.8%), cefixime (6.81 to 46%), and azithromycin (8.60 to 20.03%) was observed. Remarkably, spectinomycin and ceftriaxone seemed to be the effective choices, with resistance rates of 0 to 7.63% and 2.00 to 16.18%, respectively. Moreover, the rates of azithromycin resistance combined with decreased susceptibility to ceftriaxone and cefixime reached 9.28% and 8.64%, respectively. Furthermore, genotyping identified NG-STAR-ST501, NG-MAST-ST2268, and MLST-ST7363 as the sequence types among representative multidrug-resistant isolates. Evolutionary analysis showed that FC428-related clones have spread to Guangdong, China, which might be a cause of the rapid increase in extended-spectrum cephalosporin resistance currently. Among these strains, the prevalence of N. gonorrhoeae was extremely high, and single-dose ceftriaxone treatment might be a challenge in the future. To partially relieve the treatment pressure, a susceptibility test for susceptibility to azithromycin plus extended-spectrum cephalosporin dual therapy was performed. The results showed that all the representative isolates could be effectively killed with the coadministration of less than 1 mg/liter azithromycin and 0.125 mg/liter extended-spectrum cephalosporin, with a synergistic effect according to a fractional inhibitory concentration (FIC) of <0.5. In conclusion, dual therapy might be a powerful measure to treat refractory N. gonorrhoeae in the context of increasing antibiotic resistance in Guangdong, China.

Nitrogen Removal Characteristics and Constraints of an Alphaproteobacteria with Potential for High Nitrogen Content Heterotrophic Nitrification-Aerobic Denitrification.

The discovery of heterotrophic nitrification-aerobic denitrification (HN-AD) microorganisms has opened a new window for wastewater treatment. The underlying mechanism of HN-AD, however, is not fully understood because of the phylogenetic diversity of HN-AD microbes. The isolation and characterization of new HN-AD microorganisms are encouraging for furthering the understanding of this process. In this study, we found an Alphaproteobacteria isolate W30 from a historically polluted river in China through an HN-AD microbes screening process, which we identified as Pannonibacter sp. A potential HN-AD pathway for W30 was proposed based on N conversion analyses and the successful amplification of the entire denitrification gene series. The isolate exhibited high efficiency of aerobic inorganic nitrogen transformation, which accounted for 97.11% of NH4+-N, 100% of NO3--N, and 99.98% of NO2--N removal with a maximum linear rate of 10.21 mg/L/h, 10.46 mg/L/h, and 10.77 mg/L/h, respectively. Assimilation rather than denitrification was the main mechanism for the environmental nitrogen depletion mediated by W30. The effect of environmental constraints on aerobic NO3--N removal were characterized, following a membrane bioreactor effluent test under an oxic condition. Compared to known Alphaproteobacterial HN-AD microbes, we showed that Pannonibacter sp. W30 could deplete nitrogen with no NO2--N or NO3--N accumulation in the HN-AD process. Therefore, the application of Pannonibacter sp. W30 has the potential for developing a felicitous HN-AD technology to treat N-laden wastewater at the full-scale level.

The Immediate Hotspot of Microbial Nitrogen Cycling in an Oil-Seed Rape (Brassica campestris L.) Soil System Is the Bulk Soil Rather Than the Rhizosphere after Biofertilization.

Biofertilizers are substances that promote plant growth through the efficacy of living microorganisms. The functional microbes comprising biofertilizers are effective mediators in plant-soil systems in the regulation of nitrogen cycling, especially in nitrification repression. However, the deterministic or stochastic distribution of the functional hotspot where microbes are active immediately after biofertilization is rarely investigated. Here, pot experiments with oil-seed rape (Brassica campestris L.) were conducted with various chemical and biological fertilizers in order to reveal the distribution of the hotspot after each fertilization. A stimulated dynamic of the nitrogen cycling-related genes in the bulk soil inferred that the bulk soil was likely to be the hotspot where the inoculated bacterial fertilizers dominated the nitrogen cycle. Furthermore, a network analysis showed that bulk soil microbial communities were more cooperative than those in the rhizosphere after biofertilization, suggesting that the microbiome of the bulk soils were more efficient for nutrient cycling. In addition, the relatively abundant ammonia-oxidizing bacteria and archaea present in the networks of bulk soil microbial communities further indicated that the bulk soil was the plausible hotspot after the application of the biofertilizers. Therefore, our research provides a new insight into the explicit practice of plant fertilization and agricultural management, which may improve the implementational efficiency of biofertilization.

Protistan consumers and phototrophs are more sensitive than bacteria and fungi to pyrene exposure in soil.

The levels of organic pollutants, in particular polycyclic aromatic hydrocarbons (PAHs), are increasing worldwide, yet we lack clarity on how these pollutants affect microbial communities of different trophic levels, including protists, fungi, and bacteria. Herein, we conducted soil microcosm incubation experiments to investigate the effects of pyrene, a typical PAH, on microbial communities along concentration gradients from 0 to 500 mg kg-1 soil. Protistan communities were more sensitive to pollutants than fungal and bacterial communities, and protistan consumers and phototrophs were the dominant trophic functional groups. In addition, by assessing changes in the diversity and structure of the soil microbiome and ecological networks, we found that the microbial communities, including the protistan community and the two trophic communities composed of protists and their prey, were destabilized with increasing stress and pyrene concentrations. We identified links and complicated relationships between phototrophs, bacteria, and consumers in food webs, which explain the importance of protists in stabilizing the microbial community. Collectively, our work provides novel evidence that protists are considerably sensitive to pollution stress, and caution should be exercised in future evaluations of the protistan and multitrophic communities in polluted soil ecosystems.

Impact of influent strengths on nitrous oxide emission and its molecular mechanism in constructed wetlands treating swine wastewater.

Constructed wetlands (CWs) can remove nitrogen (N) through plant assimilation and microbial nitrification and denitrification, while it also releases large greenhouse gas nitrous oxide (N2O) into the atmosphere. However, N2O emissions and the underlying microbial mechanisms of CWs when treating high-strength wastewater have not been systematically surveyed. Here, the effect of three influent strengths on N2O emissions in a pilot-scale CW treatment of swine wastewater was determined and the underlying microbial mechanisms were explored. The results showed that the removal rates of ammonium (NH4+) and total nitrogen (TN) increased significantly with the increasing influent strengths, however, the ratio of N2O emission/TN removal rose by 1.5 times at the same time. Quantitation of microorganisms responsible for N-cycle in the sediment indicated that the abundance of ammonia-oxidizing bacteria (AOB) in high influent strengths (COD, 962.38 ± 3.05 mg/L; NH4+, 317.89 ± 4.24 mg/L) was 51.6-fold compared with that in low influent strengths (COD, 516.94 ± 4.18 mg/L; NH4+, 100.65 ± 2.65), and AOB gradually replaced ammonia-oxidizing archaea (AOA) to dominate ammonia oxidizers. Structural equation models demonstrated that NO2- accumulations promoted the ratio of AOB/AOA, which further led to an increase in the ratio of N2O emission/TN removal. It is worth noting both the N removal rates and N2O emissions increased with the increasing influent strength. To obtain reduced N2O emissions, pretreatment technology for strength reduction should be supplemented before high-strength wastewater enters the CWs. This study may shed new light on the sustainable operation and application of CWs.

Ecological selection of bacterial taxa with larger genome sizes in response to polycyclic aromatic hydrocarbons stress.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous priority pollutants that cause great damage to the natural environment and health. Average genome size in a community is critical for shedding light on microbiome's functional response to pollution stress within an environment. Here, microcosms under different concentrations were performed to evaluate the selection of PAHs stress on the average genome size in a community. We found the distinct communities of significantly larger genome size with the increase of PAHs concentration gradients in soils, and consistent trends were discovered in soils at different latitudes. The abundance of Proteobacteria and Deinococcus-Thermus with relatively larger genomes increased along with PAHs stress and well adapted to polluted environments. In contrast, the abundance of Patescibacteria with a highly streamlined and smaller genome decreased, implying complex interactions between environmental selection and functional fitness resulted in bacteria with larger genomes becoming more abundant. Moreover, we confirmed the increased capacity for horizontal transfer of degrading genes between communities by showing an increased connection number per node positively related to the nidA gene along the concentration gradients in the co-occurrence network. Our findings suggest PAHs tend to select bacterial taxa with larger genome sizes, with significant consequences for community stability and potential biodegradation strategies.

Distinct Functions and Assembly Mechanisms of Soil Abundant and Rare Bacterial Taxa Under Increasing Pyrene Stresses.

Elucidating the relative importance of species interactions and assembly mechanisms in regulating bacterial community structure and functions, especially the abundant and rare subcommunities, is crucial for understanding the influence of environmental disturbance in shaping ecological functions. However, little is known about how polycyclic aromatic hydrocarbon (PAH) stress alters the stability and functions of the abundant and rare taxa. Here, we performed soil microcosms with gradient pyrene stresses as a model ecosystem to explore the roles of community assembly in determining structures and functions of the abundant and rare subcommunities. The dose-effect of pyrene significantly altered compositions of abundant and rare subcommunities. With increasing pyrene stresses, diversity increased in abundant subcommunities, while it decreased in the rare. Importantly, the abundant taxa exhibited a much broader niche width and environmental adaptivity than the rare, contributing more to pyrene biodegradation, whereas rare taxa played a key role in improving subcommunity resistance to stress, potentially promoting community persistence and stability. Furthermore, subcommunity co-occurrence network analysis revealed that abundant taxa inclined to occupy the core and central position in adaptation to the pyrene stresses. Stochastic processes played key roles in the abundant subcommunity rather than the rare subcommunity. Overall, these findings extend our understanding of the ecological mechanisms and interactions of abundant and rare taxa in response to pollution stress, laying a leading theoretical basis that abundant taxa are core targets for biostimulation in soil remediation.

Characterization of tetracycline-resistant microbiome in soil-plant systems by combination of H218O-based DNA-Stable isotope probing and metagenomics.

The emergence and spread of antibiotic resistance have been considered as a global health threat. However, effective methods to identify antibiotic-resistant bacteria (ARB) in complex microbial community are lacking, and the potential transmission pathways of ARB and antibiotic resistance genes (ARGs) in the soil-plant system remain scarce. Here in this study, tetracycline was chosen as the target antibiotic due to its globally wide usage and clinical significance. DNA-based stable isotope probing with H218O was applied to identify the tetracycline-resistant bacteria from soil-plant systems. Eighteen-year organic fertilization significantly changed the composition of the tetracycline-resistant microbiome in the soil-wheat system and resulted in a higher relative abundance of ARGs in the wheat endophyte. Rhizosphere harboring the most diverse ARGs and mobile genetic elements was identified as a hot spot for horizontal gene transfer and an important bridge between bulk soil and wheat endophyte. Micrococcaceae and Sphingomonadaceae carrying ARGs associated with abundant mobile genetic elements, were identified as the core bacterial taxa in long-term manure-amended and untreated soil-wheat systems, respectively. This method contributes to a more precise track of ARB in the environment, and our work depicts the high potential of ARG transfer in the rhizosphere mediated by the core species.

Enhancing nitrogen removal from anaerobically-digested swine wastewater through integration of Myriophyllum aquaticum and free nitrous acid-based technology in a constructed wetland.

Despite of low operation costs and convenient maintenance, the application of natural systems for swine wastewater treatment has been limited by large construction area and unsatisfactory effluent quality. Introducing ammonium high uptake aquatic plants and shifting nitrogen removal pathway from nitrate to nitrite in constructed wetlands (CWs) has been regarded as promising approach to promote their performances. This study aimed to establish nitrite pathway and enhance N removal via free nitrous acid (FNA)-sediment treatment and Myriophyllum aquaticum vegetation in the CWs treating anaerobically digested swine wastewater. Nitrite pathway was successfully and stably achieved in the M. aquaticum CW with FNA-treated sediment. The overall removal efficiencies of ammonium nitrogen and total nitrogen were 42.3 ± 10.2% and 37.7 ± 9.3% in the planted CWs with FNA-treated sediment, which were 76.3% and 65.4% higher than those in the conventional oxidation pond system, respectively. Microbial community analysis (qPCR and metagenomics) suggested that the nitrite pathway established through FNA-sediment treatment was based on the inactivation of nitrite oxidizing bacteria (lower nxrA gene abundance) and the reduction of relative abundances of NOB (especially Nitrobacter and Nitrospira). During the denitrification processes, the integration of M. aquaticum vegetation with FNA-sediment treatment can lower the nitrate reduction by decreasing narG gene abundances and decreasing the relative abundances of napA affiliated bacteria (especially Bradyrhizobium), while strengthening reduction of nitrite and nitrous oxide by increasing nirK and nosZ gene abundances and enriching the corresponding affiliated microbial taxa, Mycobacterium and Bacillus, respectively. Our findings suggest that applying FNA-based technology in CW systems is technically and economically feasible, which holds promise for upgrading current CW systems treating swine wastewater to meet future water quality requirements.

Unraveling Mechanisms and Impact of Microbial Recruitment on Oilseed Rape (Brassica napus L.) and the Rhizosphere Mediated by Plant Growth-Promoting Rhizobacteria.

Plant growth-promoting rhizobacteria (PGPR) are noticeably applied to enhance plant nutrient acquisition and improve plant growth and health. However, limited information is available on the compositional dynamics of rhizobacteria communities with PGPR inoculation. In this study, we investigated the effects of three PGPR strains, Stenotrophomonas rhizophila, Rhodobacter sphaeroides, and Bacillus amyloliquefaciens on the ecophysiological properties of Oilseed rape (Brassica napus L.), rhizosphere, and bulk soil; moreover, we assessed rhizobacterial community composition using high-throughput Illumina sequencing of 16S rRNA genes. Inoculation with S. rhizophila, R. sphaeroides, and B. amyloliquefaciens, significantly increased the plant total N (TN) (p < 0.01) content. R. sphaeroides and B. amyloliquefaciens selectively enhanced the growth of Pseudomonadacea and Flavobacteriaceae, whereas S. rhizophila could recruit diazotrophic rhizobacteria, members of Cyanobacteria and Actinobacteria, whose abundance was positively correlated with inoculation, and improved the transformation of organic nitrogen into inorganic nitrogen through the promotion of ammonification. Initial colonization by PGPR in the rhizosphere affected the rhizobacterial community composition throughout the plant life cycle. Network analysis indicated that PGPR had species-dependent effects on niche competition in the rhizosphere. These results provide a better understanding of PGPR-plant-rhizobacteria interactions, which is necessary to develop the application of PGPR.

Anaerobic degradation of xenobiotic organic contaminants (XOCs): The role of electron flow and potential enhancing strategies.

In groundwater, deep soil layer, sediment, the widespread of xenobiotic organic contaminants (XOCs) have been leading to the concern of human health and eco-environment safety, which calls for a better understanding on the fate and remediation of XOCs in anoxic matrices. In the absence of oxygen, bacteria utilize various oxidized substances, e.g. nitrate, sulphate, metallic (hydr)oxides, humic substance, as terminal electron acceptors (TEAs) to fuel anaerobic XOCs degradation. Although there have been increasing anaerobic biodegradation studies focusing on species identification, degrading pathways, community dynamics, systematic reviews on the underlying mechanism of anaerobic contaminants removal from the perspective of electron flow are limited. In this review, we provide the insight on anaerobic biodegradation from electrons aspect - electron production, transport, and consumption. The mechanism of the coupling between TEAs reduction and pollutants degradation is deconstructed in the level of community, pure culture, and cellular biochemistry. Hereby, relevant strategies to promote anaerobic biodegradation are proposed for guiding to an efficient XOCs bioremediation.

Conceptualization, Development and Psychometric Evaluations of a New Medication-Related Health Literacy Instrument: The Chinese Medication Literacy Measurement.

There is a need for valid and reliable instruments to focus on medication aspects of health literacy and help healthcare professionals address patients' barriers to medication use. This cross-sectional study describes the conceptualization, development, and psychometric properties of the first Chinese Medication Literacy Measurement (ChMLM) to assess the level of health literacy on medication use. The 17-item ChMLM (ChMLM-17) and its short form, 13-item ChMLM (ChMLM-13), consist of four sections (vocabulary, over-the-counter labels, prescription labels, and advertisements) to cover six domains of medication-related health literacy. Multistage stratified quota sampling was attempted to recruit a representative sample in Taiwan. Receiver operating characteristic curves were used to identify the cut-off point for differentiating high and low medication literacy. Psychometric analyses were performed (n = 1410) to assess the reliability and validity separately on all samples and sociodemographic subgroups. The 17- and 13-item versions both had high construct validity among all patients and patients with low medication literacy. The developed ChMLM-17 and ChMLM-13 is expected to help healthcare providers and researchers to accurately measure medication-related health literacy and improve medication use in the real-world practice.