Effect of arbuscular mycorrhizal symbiosis on growth and biochemical characteristics of Chinese fir (Cunninghamia lanceolata) seedlings under low phosphorus environment.

Background: The continuous establishment of Chinese fir (Cunninghamia lanceolata) plantations across multiple generations has led to the limited impact of soil phosphorus (P) on tree growth. This challenge poses a significant obstacle in maintaining the sustainable management of Chinese fir. Methods: To investigate the effects of Arbuscular mycorrhizal fungi (AMF) on the growth and physiological characteristics of Chinese fir under different P supply treatments. We conducted an indoor pot simulation experiment in the greenhouse of the Forestry College of Fujian Agriculture and Forestry University with one-and-half-year-old seedlings of Chinese fir from March 2019 to June 2019, with the two P level treatment groups included a normal P supply treatment (1.0 mmol L-1 KH2PO4, P1) and a no P supply treatment (0 mmol L-1 KH2PO4, P0). P0 and P1 were inoculated with Funneliformis mosseae (F.m) or Rhizophagus intraradices (R.i) or not inoculated with AMF treatment. The AMF colonization rate in the root system, seedling height (SH), root collar diameter (RCD) growth, chlorophyll (Chl) photosynthetic characteristics, enzyme activities, and endogenous hormone contents of Chinese fir were estimated. Results: The results showed that the colonization rate of F.m in the roots of Chinese fir seedlings was the highest at P0, up to 85.14%, which was 1.66 times that of P1. Under P0 and P1 treatment, root inoculation with either F.m or R.i promoted SH growth, the SH of R.i treatment was 1.38 times and 1.05 times that of F.m treatment, respectively. In the P1 treatment, root inoculation with either F.m or R.i inhibited RCD growth. R.i inhibited RCD growth more aggressively than F.m. In the P0 treatment, root inoculation with F.m and R.i reduced the inhibitory effect of phosphorus deficiency on RCD. At this time, there was no significant difference in RCD between F.m, R.i and CK treatments (p < 0.05). AMF inoculation increased Fm, Fv, Fv/Fm, and Fv/Fo during the chlorophyll fluorescence response in the tested Chinese fir seedlings. Under the two phosphorus supply levels, the trend of Fv and Fm of Chinese fir seedlings in different treatment groups was F.m > R.i > CK. Under P0 treatment, The values of Fv were 235.86, 221.86 and 147.71, respectively. The values of Fm were 287.57, 275.71 and 201.57, respectively. It increased the antioxidant enzyme activity and reduced the leaf's malondialdehyde (MDA) content to a certain extent. Conclusion: It is concluded that AMF can enhance the photosynthetic capacity of the host, regulate the distribution of endogenous hormones in plants, and promote plant growth by increasing the activity of antioxidant enzymes. When the P supply is insufficient, AMF is more helpful to plants, and R.i is more effective than F.m in alleviating P starvation stress in Chinese fir.

Co-Occurrence, Predictors, and Related Aggressive Behaviors of Cognitive and Emotional Relative Deprivation Based on Latent Class Analysis.

Given the frequent occurrence of relative deprivation among adolescents and its negative effects, this study investigated relative deprivation among adolescents using a person-centered statistical technique (n = 1196; 565 girls). Latent class analysis identified three groups: low cognitive and emotional relative deprivation (Class 1, 33.78% of adolescents), high cognitive and low emotional relative deprivation (Class 2, 37.79% of adolescents), and high cognitive and emotional relative deprivation (Class 3, 28.43% of adolescents). Adolescents with low income and without parental accompaniment were more likely to be assigned to Classes 3 and 2. Compared with Class 1, Classes 3 and 2 had significant positive predictive effects on physical aggression, relational aggression, and overall aggressive behavior. The classes of relative deprivation influenced both physical and relational aggression, but not verbal aggression. Based on these findings, demographic characteristics and latent classes of relative deprivation should be considered together when developing interventions for aggressive behaviors.

Transmission of SARS-CoV-2 Omicron Variant under a Dynamic Clearance Strategy in Shandong, China.

SARS-CoV-2 Omicron caused a large wave of COVID-19 cases in China in spring 2022. Shandong was one of the most affected regions during this epidemic yet was also among those areas that were able to quickly contain the transmission. We aimed to investigate the origin, genetic diversity, and transmission patterns of the Omicron epidemic in Shandong under a dynamic clearance strategy. We generated 1,149 Omicron sequences, performed phylogenetic analysis, and interpreted results in the context of available epidemiological information. We observed that there were multiple introductions of distinct Omicron sublineages into Shandong from foreign countries and other regions in China, while a small number of introductions led to majority of local cases. We found evidence suggesting that some local clusters were potentially associated with foreign imported cases. Superspreading events and cryptic transmissions contributed to the rapid spread of this epidemic. We identified a BA.1.1 genome with the R493Q reversion mutation in the spike receptor binding domain, potentially associated with an escape from vaccine and Omicron infection elicited neutralizing immunity. Our findings illustrated how the dynamic clearance strategy constrained this epidemic's size, duration, and geographical distribution. IMPORTANCE Starting in March 2022, the Omicron epidemic caused a large wave of COVID-19 cases in China. Shandong was one of the most affected regions during this epidemic but was also among those areas that were able to quickly contain the transmission. We investigated the origin, genetic diversity, and transmission patterns of Omicron epidemic in Shandong under a dynamic clearance strategy. We found that there were multiple introductions of distinct Omicron sublineages into Shandong from foreign countries and other regions in China, while a small number of introductions led to most local cases. We found evidence suggesting that some local clusters were associated with foreign imported cases. Superspreading events and cryptic transmissions contributed to the rapid spread of this epidemic. Our study illustrated the transmission patterns of Omicron epidemic in Shandong and provided a looking glass onto this epidemic in China.

Ternary Ca-Mg-Al layered double-hydroxides for synergistic remediation of As, Cd, and Pb from both contaminated soil and groundwater: Characteristics, effectiveness, and immobilization mechanisms.

Layered double hydroxides (LDH) are the cost-effective and high-efficiency materials for remediation of potentially toxic elements (PTEs) in contaminated soil and groundwater. Herein, the effectiveness and mechanisms of a ternary Ca-Mg-Al LDH (CMAL) for the synergistic remediation of As, Cd, and Pb were investigated in contaminated soils and simulative groundwaters for the first time. The immobilization efficiencies of As, Cd, and Pb in both black soil (BS) and red soil (RS) amended by CMAL at 5 wt% were all > 75%. CMAL amendment transferred more mobile As, Cd, and Pb fractions in soils to immobile species than did Ca-Al LDH and Mg-Al LDH treatments. Furthermore, using a pump-and-treat technology, 82-98% of these 3 PTEs from contaminated groundwater were successfully immobilized in both CMAL treated BS and RS top-soils. Meanwhile, leaching of Ca, Mg, and Al from CMAL was minimal indicating the material was stable. The excellent immobilization performance of CMAL for these PTEs was attributed to the coating of soil microparticles by CMAL nanosheets that allowed complexation of Ca-O-As/Cd or Mg-O-As/Cd/Pb formation, co-precipitation of Ca/Fe-As and Cd(OH)2, and formation of Ca-bridged ternary complex (FeO-Ca-As/Cd). The adverse effect of oppositive pH/Eh-dependence between As and Cd/Pb was overshadowed by these mechanisms and thus allowed As immobilization. Immobilization of As, Cd, and Pb by CMAL amendment was more favorable for RS soil due to its lower reduction potential and more participation of metal-(hydr)oxides for complexation. Overall, the ternary-LDH is a promising synergistic remediation strategy for multi-PTEs contaminated soil and groundwater.

Propagation Methods Decide Root Architecture of Chinese Fir: Evidence from Tissue Culturing, Rooted Cutting and Seed Germination.

The root is the main organ of a plant for absorbing resources and whose spatial distribution characteristics play an important role in the survival of seedlings after afforestation. Chinese fir (Cunninghamia lanceolata) is one of China's most important plantation species. To clarify the effects of propagation methods on root growth and spatial distribution characteristics of Chinese fir trees, sampled trees cultivated by seed germination, tissue culture, and asexual cutting of Chinese fir were taken as the research objects. The root morphology, geometric configuration, and spatial distribution characteristics of different trees were analyzed. The influence of geometric root morphology on its spatial distribution pattern was explored by correlation analysis, and the resource acquisition characteristics reflected by the roots of Chinese fir trees with different propagation methods are discussed. The main results showed that the root mean diameter (1.56 mm, 0.95 mm, and 0.97 mm), root volume (2.98 m3, 10.25 m3, and 4.07 m3), root tip count (397, 522, and 440), main root branch angle (61°, 50° and 32°) and other geometric configurations of Chinese fir under seed germination, tissue culture and rooted cutting respectively, were significantly different, which resulted in different distribution characteristics of roots in space. Chinese fir seed germination had noticeable axial roots, and the growth advantage was obvious in the vertical direction. A fishtail branch structure (TI = 0.87) was constructed. The shallow root distribution of tissue culture and rooted cutting was obvious, and belonged to the fork branch structure (TI = 0.71 and 0.74, respectively). There was a tradeoff in the spatial growth of the root system of Chinese fir trees with different propagation methods to absorb nutrients from heterogeneous soil patches. A negative correlation was present between the root system and root amplitude. There was an opposite spatial growth trend of Chinese fir trees with different propagation methods in the vertical or horizontal direction. In conclusion, selecting suitable propagation methods to cultivate Chinese fir trees is beneficial to root development and the "ideal" configuration formation of resource acquisition to improve the survival rate of Chinese fir afforestation.

Effect of Single Loading Time to the Cyclic Ablation of C/C-SiC-ZrC Composite.

To understand the influence of single loading time on the cyclic ablation of carbide modified C/C composites, a C/C-SiC-ZrC composite was impacted by plasma at 2600 K for 50 s under reciprocating 0.5 (C0.5) and 5 s (C5), respectively. The composites displayed similar negative mass and rising positive linear ablation rates from C0.5 to C5. Phases, micro-morphologies, and surface temperature analysis suggested that the partially oxidized SiC-ZrC covering on the ablated sample cracked and was persistently peeled off. The mass gain resulted from the ceramic's protection of the nearby carbon from complete oxidation. The longer single loading of 5 s caused strengthened thermal chemical reaction and mechanical erosion, which resulted in the bigger linear loss.

Analysis of the Transmission of SARS-CoV-2 Delta VOC in Yantai, China, August 2021.

Objective: Starting 31 July 2021, a SARS-CoV-2 outbreak occurred in Yantai, Shandong Province. The investigation showed that this outbreak was closely related to the epidemic at Nanjing Lukou Airport. In view of the fact that there were many people involved in this outbreak and these people had a complex activity area, the transmission route cannot be analyzed by simple epidemiological investigation. Here we combined the SARS-COV-2 whole-genome sequencing with epidemiology to determine the epidemic transmission route of Yantai. Methods: Thirteen samples of SARS-CoV-2 outbreak cases from 31 July to 4 August 2021 were collected and identified by fluorescence quantitative PCR, then whole-genome deep sequencing based on NGS was performed, and the data were analyzed and processed by biological software. Results: All sequences were over 29,000 bases in length and all belonged to B.1.617.2, which was the Delta strain. All sequences shared two amino acid deletions and 9 amino acid mutations in Spike protein compared with reference sequence NC_045512.2 (Wuhan virus strain). Compared with the sequence of Lukou Airport Delta strain, the homology was 99.99%. In order to confirm the transmission relationship between patients, we performed a phylogenetic tree analysis. The results showed that patient 1, patient 2, and patient 9 belong to an independent branch, and other patients have a close relationship. Combined with the epidemiological investigation, we speculated that the epidemic of Yantai was transmitted by two routes at the same time. Based on this information, our prevention and control work was carried out in two ways and effectively prevented the further spread of this epidemic.

[Effects of Earthworms/Biochar on Bacterial Diversity and Community in As-contaminated Red Soil].

Cerium-manganese modified biochar (MBC) combined with earthworms (Eisenia foetida) can immobilize arsenic (As) in red soils. In this study, high-throughput sequencing technology was used to explore the combined effects of MBC and E. foetida on bacterial diversity and community structure in As-contaminated red soils. The results showed that the single earthworm treatment had the highest diversity index, whereas the diversity index decreased in the single biochar or MBC treatment, indicating that earthworms can boost the growth of bacteria in the soil, and the addition of biochar/MBC all decreased the bacterial diversity of soils. When biochar/MBC was combined with earthworms, the diversity index increased to some degree. In terms of bacterial community structure, the relative abundance of Proteobacteria and Bacteroidetes increased significantly in each treatment, especially for MBC-earthworm treated soil, in which the relative abundance was increased by 17.08% and 329.47% for Proteobacteria and Bacteroidetes, respectively, compared to that in the control (CK). Otherwise, those abundances were decreased by 19.18% and 48.76%, respectively, for Acidobacteria and Chloroflexi. Correlation analysis results showed that the soil water-soluble As (WSAs) was negatively correlated with the relative abundances of Proteobacteria and Bacteroides (P<0.05) but was positively correlated with Acidobacteria and Chloroflexi (P<0.05), which indicated that with the decrease in WSAs in soils, the bacteria of Proteobacteria and Bacteroides reproduced rapidly, whereas the Acidobacteria and Chloroflexi were inhibited. Moreover, different treatments induced selective changes in the bacterial community, in which earthworms significantly promoted the proliferation of γ-Proteobacteria, Flavobacteriales, Aeromonadales, and Variovorax and earthworms improved the immobilization effect of As by promoting the growth of these bacteria.

Effect of Glomus intraradices on root morphology, biomass production and phosphorous use efficiency of Chinese fir seedlings under low phosphorus stress.

Introduction: Available phosphorus (P) scarcity in the highly weathered soils of the subtropical forests in southern China is a serious concern. To ensure whether inoculation of arbuscular mycorrhizal fungi (AMF) with Chinese fir (Cunninghamia lanceolata) under low P stress conditions could promote its growth and P utilization capacity, an indoor pot simulation experiment was carried out with the different P supply treatments and Chinese fir seedlings as the tested material. Methods: The experiment had two P supply treatments, no P supply (P0, 0 mmol·L-1 KH2PO4) and normal P supply (P1, 1.0 mmol·L-1 KH2PO4). The seedling in each P supply treatment was inoculated with Glomus intraradices (Gi), a widespread species of AMF in the natural environment, and with no AMF inoculation as a control treatment (CK). The Gi infection rate in the root system, root cortex tissue dissolution rate, root morphological indexes and biomass, whole plant P use efficiency, and root P use efficiency of Chinese fir were determined under different treatment conditions. Results and Discussion: The results showed that P0 treatment significantly increased the Gi infection rate (p< 0.05). After inoculating AMF with different P supply treatments, the root cortex tissue dissolution rate was considerably enhanced. In contrast, the Chinese fir's root length and surface area were reduced; however, the root volume did not change significantly. The average root diameter in the P0 treatment and inoculated with AMF was significantly more prominent than in the uninoculated treatment (p< 0.05). The root biomass and root-to-shoot ratio at different P supply treatments were significantly higher in the Gi infection treatment than in the CK group. Under different P supply treatments, root inoculation with Gi promoted root P use efficiency and whole plant P use efficiency. In conclusion, low P stress condition promoted the colonization of AMF in the root system, increased the dissolution of root cortex tissue, root volume, and the average diameter, and promoted root biomass accumulation and P use efficiency.

Case Report: Near-Fatal Intestinal Hemorrhage and Acute Acalculous Cholecystitis due to Vi-Negative and Fluoroquinolone-Insensitive Salmonella enterica Serovar Typhi Infection: A Rare Entity.

Typhoid fever is usually a mild clinical disease. Typhoid fever with massive intestinal hemorrhage is rare in the antibiotic era. Acute acalculous cholecystitis (AAC) is also rare in adults. Here, we describe the first adult case of typhoid fever with both complications due to Vi-negative and fluoroquinolone-insensitive Salmonella enterica serovar Typhi (S. Typhi) infection. We aim to alert physicians to this rare condition.

Hydrothermal liquefaction of Chlorella pyrenoidosa and effect of emulsification on upgrading the bio-oil.

This work studied the hydrothermal liquefaction of Chlorella pyrenoidosa and effect of emulsification on upgrading the bio-oil. The fuel properties and storage stability characteristics of emulsion fuels were explored. The combustion characteristic analysis showed that the ignition temperatures of emulsion fuels (139.6-151.3 °C) were lower than that of bio-oil (176.9 °C). Besides, emulsion fuels had higher comprehensive combustion indexes (7.24-14.08 × 10-6 × min-2 × C-3) than bio-oil (1.51 × 10-6 × min-2 × C-3), indicating that emulsion fuels had better combustion performance. The kinetic analysis showed that emulsification could effectively reduce the activation energy, resulting in less energy input for combustion. Based on chemical composition evolution during the storage process, a possible stability mechanism was proposed. The storage stability analysis indicated that the diesel-solvable fractions in bio-oil had better stability. Overall, this work provides a feasible way for bio-oil upgrading through emulsification. In addition, a better understanding of the stability property of emulsion fuel was provided.

Co-hydrothermal carbonization of water hyacinth and polyvinyl chloride: Optimization of process parameters and characterization of hydrochar.

The co-hydrothermal carbonization (co-HTC) of water hyacinth (WH) and polyvinyl chloride (PVC) was investigated and the response surface methodology, which could deduce the interactions among process parameters and establish reliable mathematical models forecasting the behavior of output variables, was implemented to optimize process parameters, including reaction temperature (200-260 °C), residence time (30-90 min) and WH/PVC mixing ratios (0.5-2). Statistical analysis revealed that reaction temperature was the predominant parameter affecting hydrochar dechlorination efficiency, yield, calorific value, energetic recovery efficiency and electricity consumption. The predicted condition of 200-30-0.5 could simultaneously acquire the optimal energetic recovery efficiency and electricity consumption for producing unit HHV, corresponding to 94.96% and 13.81. The characterization results identified that hydrochar could harvest lower H/C and O/C ratios as well as superior inorganics removal ability. Overall, the co-HTC of WH and PVC could definitely be a promising alternative to bridge the gap from solid wastes to renewable fuels.

Identification of high-risk patients for ADR induced by traditional Chinese medicine injection: a nested case-control study.

The adverse drug reaction (ADR) of traditional Chinese medicine injection (TCMI) has become one of the major concerns of public health in China. There are significant advantages for developing methods to improve the use of TCMI in routine clinical practice. The method of predicting TCMI-induced ADR was illustrated using a nested case-control study in 123 cases and 123 controls. The partial least squares regression (PLSR) models, which mapped the influence of basic characteristics and routine examinations to ADR, were established to predict the risk of ADR. The software was devised to provide an easy-to-use tool for clinic application. The effectiveness of the method was evaluated through its application to new patients with 95.7% accuracy of cases and 91.3% accuracy of controls. By using the method, the patients at high-risk could be conveniently, efficiently and economically recognized without any extra financial burden for additional examination. This study provides a novel insight into individualized management of the patients who will use TCMI.

Parental Psychological Control and Adolescent Aggressive Behavior: Deviant Peer Affiliation as a Mediator and School Connectedness as a Moderator.

Abundant evidence has demonstrated an association between parental psychological control and adolescent aggressive behavior. However, the mediating and moderating mechanisms underlying this relation are still under-investigated. Grounded in the social development model and stress-buffering model, this study investigated whether deviant peer affiliation mediates the relation between parental psychological control and adolescent aggressive behavior, and whether this indirect link is moderated by school connectedness. A total of 4265 adolescents (Mean age = 13.66 years, SD = 2.74, 48.63% male) from southern China completed questionnaires regarding parental psychological control, deviant peer affiliation, school connectedness, and aggressive behavior. Structural equation models revealed that the relation between parental psychological control and aggressive behavior is partially mediated by deviant peer affiliation. Moreover, this indirect link was stronger for adolescents with low levels of school connectedness than for those with high levels of school connectedness. This study thus identifies the potential underlying mechanism by which parental psychological control is associated with adolescent aggressive behaviors, which has important implications for theory and prevention.

General distributed activation energy model (G-DAEM) on co-pyrolysis kinetics of bagasse and sewage sludge.

In this work, pyrolysis kinetic evolution of mixture of bagasse and sewage sludge with 10%, 30% and 50% (respect to dry initial weight). In terms of kinetic mechanism, the uncertainty of the activation energy obtained by mode-free method was barely known. We found that increasing number of heating rates made result more reliable, but the modeling process more dependent on redundant experiments with extra data. We adapted a novel general distributed activation energy model (G-DAEM) with 5 pseudocomponents for the analysis of kinetic evolution with proposing a more applicable approximation to the general temperature integral. The G-DAEM was trained by data for 20 K/min, and the predictions were performed on data for 15 K/min and 25 K/min. The predictions were well matched to the experimental data. The G-DAEM enhances modeling efficiency of kinetics and provides a effective pathway for high precise model of complicated co-pyrolysis process.

Peer Victimization and Aggressive Behavior Among Chinese Adolescents: Delinquent Peer Affiliation as a Mediator and Parental Knowledge as a Moderator.

Grounded in social network theory and a risk-buffering model, this study examined whether delinquent peer affiliation mediated the association between peer victimization and adolescent aggressive behavior and whether this mediating process was moderated by parental knowledge. A total of 4,209 Chinese adolescents (48.47% male, Mage = 13.68) completed questionnaires on peer victimization, parental knowledge, delinquent peer affiliation, and adolescent aggressive behavior. Path analyses showed that delinquent peer affiliation partially mediated the relationship between peer victimization and aggressive behavior. Moreover, parental knowledge had a protective effect of buffering the adverse influence of peer victimization on aggressive behavior. This indirect link was stronger for adolescents with low parental knowledge than for those with high parental knowledge. This finding highlights delinquent peer affiliation as a potential link between peer victimization and aggressive behavior and provides an effective intervention for addressing the adverse effects of peer victimization.

Factors influencing the removal of antibiotic-resistant bacteria and antibiotic resistance genes by the electrokinetic treatment.

The performance of the electrokinetic remediation process on the removal of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) was evaluated with different influencing factors. With chlortetracycline (CTC), oxytetracycline (OTC), and tetracycline (TC) as template chemicals, the removal of both ARB and ARGs was enhanced with the increase of voltage gradient (0.4-1.2 V cm-1) and prolonged reaction time (3-14 d). The greatest removal (26.01-31.48% for ARB, 37.93-83.10% for ARGs) was obtained applying a voltage of 1.2 V cm-1, leading to the highest electrical consumption. The effect of polarity reversal intervals on the inactivation ratio of ARB followed the order of 0 h (66.06-80.00%) > 12 h (17.07-24.75%) > 24 h (10.44-13.93%). Lower pH, higher current density, and more evenly-distributed voltage drop was observed with a polarity reversal interval of 12 h compared with that of 24 h, leading to more efficient electrochemical reactions in soil. Compared with sul genes, tet genes were more vulnerable to be attacked in an electric field. It was mainly attributed to the lower abundance of tet genes (except tetM) and the varied effects of electrokinetic remediation process on different ARGs. Moreover, a relatively less removal ratio of tetC and tetG was obtained mainly due to the mechanism of the efflux pump upregulation. Both tet and sul genes were positively correlated with TC-resistant bacteria. The efflux pump genes like tetG and the cellular protection genes like tetM showed different correlations with ARB. This study enhances the current understanding on the removal strategies of ARB and ARGs, and it provides important parameters for their destruction by the electrokinetic treatment.

Sensation Seeking, Deviant Peer Affiliation, and Internet Gaming Addiction Among Chinese Adolescents: The Moderating Effect of Parental Knowledge.

Although there is abundant evidence that an association between sensation seeking and adolescent Internet gaming addiction (IGA) exists, research has provided little insight into why adolescents with high sensation seeking are more likely to be focused on Internet and video games. Grounded in the social development model and ecological systems theory, this study investigated whether deviant peer affiliation mediated the relationship between sensation seeking and adolescent IGA, and whether this indirect link was moderated by parental knowledge. Participants were 1293 Chinese adolescents (49.65% male, M age = 12.89 ± 0.52 years) who completed questionnaires assessing sensation seeking, deviant peer affiliation, parental knowledge, and IGA. Structural equation models revealed that the positive association between sensation seeking and adolescent IGA was partially mediated by deviant peer affiliation. In addition, this indirect link was significantly moderated by parental knowledge. Specifically, the indirect path from sensation seeking to adolescent IGA was stronger for adolescents with low parental knowledge than for those with high parental knowledge. Identifying the role of peers and parents in the onset of adolescent IGA has key implications for prevention and intervention.

Evolution of microbial communities during electrokinetic treatment of antibiotic-polluted soil.

The evolution of microbial communities during the electrokinetic treatment of antibiotic-polluted soil (EKA) was investigated with chlortetracycline (CTC), oxytetracycline (OTC) and tetracycline (TC) as template antibiotics. The total population of soil microorganisms was less affected during the electrokinetic process, while living anti-CTC, anti-OTC, anti-TC and anti-MIX bacteria were inactivated by 10.48%, 31.37%, 34.76%, and 22.08%, respectively, during the 7-day treatment compared with antibiotic-polluted soil without an electric field (NOE). Accordingly, samples with NOE treatment showed a higher Shannon index than those with EKA treatment, indicating a reduction of the microbial community diversity after electrokinetic processes. The major taxonomic phyla found in the samples of EKA and NOE treatment were Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria. And the distribution of Actinobacteria, Cyanobacteria, and Chloroflexi was greatly decreased compared with blank soil. In the phylum Proteobacteria, the abundance of Alphaproteobacteria was greatly reduced in the soils supplemented with antibiotics (from 13.40% in blank soil to 6.43-10.16% after treatment); while Betaproteobacteria and Deltaproteobacteria showed a different trend with their abundance increased compared to blank soil, and Gammaproteobacteria remained unchanged for all treatments (2.36-2.78%). The varied trends for different classes indicated that the major bacterial groups changed with the treatments due to their different adaptability to the antibiotics as well as to the electric field. SulI being an exception, the reduction ratio of the observed antibiotic resistance genes (ARGs) including tetC, tetG, tetW, tetM, intI1, and sulII in the 0-2cm soil sampled with EKA versus NOE treatment reached 55.17%, 3.59%, 99.26%, 89.51%, 30.40%, and 27.92%, respectively. Finally, correlation analysis was conducted between antibiotic-resistant bacteria, ARGs and taxonomic bacterial classes. It was found that sulII was the most representative of many different bacteria among the seven ARGs studied. This is the first report on the changes in microbial communities before and after EKA, and the present results demonstrated that the application of EKA is a useful and effective approach to suppressing both antibiotic resistant microorganisms and ARGs.

Isolation of a fluoroglycofen-degrading KS-1 strain and cloning of a novel esterase gene fluE.

The bacterium KS-1, capable of degrading fluoroglycofen, was isolated from sludge collected at a herbicide factory. The isolate was identified as Lysinibacillus sp. according to its phenotypic features and 16S rDNA phylogeny. KS-1 degraded 85.25% of the fluoroglycofen (50 mg L-1) within 3 days of incubation. The optimum temperature and pH for fluoroglycofen degradation were 30°C and 7.0, respectively. Furthermore, Zn2+ and Cu2+ could significantly decrease the degradation rate. Three degradation products, which appeared during KS-1-mediated fluoroglycofen metabolism, were identified as deethyl-fluoroglycofen, acifluorfen and decarboxylate-acifluorfen. The fluE gene, which encodes a novel esterase that catalyzes the cleavage of carboxyl ester bonds of fluoroglycofen, was cloned from the KS-1 strain. Sequence alignment reveals that FluE shares 30%-40% amino acid sequence identity with members of the hormone sensitive lipase family. FluE was expressed in Escherichia coli BL21 and purified by Ni-NTA affinity chromatography. Purified FluE could efficiently hydrolyze fluoroglycofen and short-chain p-nitrophenol esters. However, no lipolytic activity was observed with esters containing acyl chains longer than 10 carbon atoms, thereby indicating that this enzyme is an esterase.