Extended-spectrum ß-lactamase-producing bacteria and their resistance determinants in different wastewaters and rivers in Nepal.

Wastewaters serve as significant reservoirs of antibiotic resistant bacteria. Despite the evidence of antimicrobial resistance in wastewaters and river water in Kathmandu, direct linkage between them is not discussed yet. This study investigated the prevalence of extended-spectrum ß-lactamase (ESBL)-producing bacteria and associated resistance genes in wastewaters and river water. Out of 246 bacteria from wastewaters, 57.72% were ESBL producers and 77.64% of them were multidrug resistant (MDR). ESBL producing E. coli was dominant in municipal and hospital wastewaters (HWW) as well as in river water while K. pneumoniae was common in pharmaceutical wastewater. The blaSHV and blaTEM genes were prevalent and commonly co-occurred with aac(6')-Ib-cr in K. pneumoniae isolated pharmaceutical wastewater. blaCTX-M carrying E. coli from hospital co-harbored aac(6')-Ib-cr while that from municipal influent and river water co-harbored qnrS. Whole genome sequencing data revealed the presence of diverse ARGs in bacterial isolates against multiple antibiotics. In average, an E. coli and a K. pneumoniae isolate contained 55.75 ± 0.96 and 40.2 ± 5.36 ARGs, respectively. Multi-locus sequence typing showed the presence of globally high-risk clones with wider host range such as E. coli ST10, and K. pneumoniae ST15 and ST307 in HWW and river indicating frequent dissemination of antimicrobial resistance in wastewater of Kathmandu. Whole genome sequence data aligned with phenotypic antibiograms and resistance genes detected by PCR in selected isolates. The presence of significant plasmid replicons (IncF, IncY) and mobile genetic elements (IS903, IS26) indicate high frequency of spreading antibiotic resistance. These findings indicate burden and dissemination of antimicrobial resistance in the environment and highlight the need for effective strategies to mitigate the antibiotic resistance.

IS6 family insertion sequences promote optrA dissemination between plasmids varying in transfer abilities.

Plasmids are the primary vectors for intercellular transfer of the oxazolidinone and phenicol cross-resistance gene optrA, while insertion sequences (ISs) are mobile genetic elements that can mobilize plasmid-borne optrA intracellularly. However, little is known about how the IS-mediated intracellular mobility facilitates the dissemination of the optrA gene between plasmid categories that vary in transfer abilities, including non-mobilizable, mobilizable, and conjugative plasmids. Here, we performed a holistic genomic study of 52 optrA-carrying plasmids obtained from searches guided by the Comprehensive Antibiotic Resistance Database. Among the 132 ISs identified within 10 kbp from the optrA gene in the plasmids, IS6 family genes were the most prevalent (86/132). Homologous gene arrays containing IS6 family genes were shared between different plasmids, especially between mobilizable and conjugative plasmids. All these indicated the central role of IS6 family genes in disseminating plasmid-borne optrA. Thirty-three of the 52 plasmids were harbored by Enterococcus faecalis found mainly in humans and animals. By Nanopore sequencing and inverse PCR, the potential of the enterococcal optrA to be transmitted from a mobilizable plasmid to a conjugative plasmid mediated by IS6 family genes was further confirmed in Enterococcus faecalis strains recovered from the effluents of anaerobic digestion systems for treating chicken manure. Our findings highlight the increased intercellular transfer abilities and dissemination risk of plasmid-borne optrA gene caused by IS-mediated intracellular mobility, and underscore the importance of routinely monitoring the dynamic genetic contexts of clinically important antibiotic resistance genes to effectively control this critical public health threat. KEY POINTS: • IS6 was prevalent in optrA-plasmids varying in intercellular transfer abilities. • Enterococcal optrA-plasmids were widespread among human, animal, and the environment. • IS6 elevated the dissemination risk of enterococcal optrA-plasmids.

Advancements of the CRISPR/Cas9 System in the Treatment of Liver Cancer.

In recent years, the CRISPR/Cas9 system has become a rapidly advancing gene editing technology with significant advantages in various fields, particularly biomedicine. Liver cancer is a severe malignancy that threatens human health and is primarily treated with surgery, radiotherapy, and chemotherapy. However, surgery may not be suitable for advanced cases of liver cancer with distant metastases. Moreover, radiotherapy and chemotherapy have low specificity and numerous side effects that limit their effectiveness; therefore, more effective and safer treatments are required. With the advancement of the biomolecular mechanism of cancer, CRISPR/Cas9 gene editing technology has been widely used in the study of liver cancer to gain insights into gene functions, establish tumor models, screen tumor phenotype-related genes, and perform gene therapy. This review outlines the research progress of CRISPR/Cas9 gene editing technology in the treatment of liver cancer and provides a relevant theoretical basis for its research and application in the treatment of liver cancer.

Assessing impacts of municipal wastewater treatment plant upgrades on bacterial hazard contributions to the receiving urban river using SourceTracker.

Upgrading municipal wastewater treatment plants (MWTPs) has been implemented in many megacities of China to reduce the discharges of nutrients and other pollutants and improve water quality of highly urbanized rivers. However, the contribution of MWTP discharge to bacterial hazards in the receiving rivers after upgrades has been largely unknown. In this study, high-throughput sequencing and shotgun metagenomics were applied to investigate the changes in the abundance, composition, potential risks, and contributions of bacteria and antibiotic resistance genes (ARGs) from effluent to receiving river after upgrading the third-largest MWTP in China with denitrification biofilters, ultrafiltration, ozonation, and disinfection processes. The annual loadings of total nitrogen and 27 types of pharmaceuticals were reduced by 42.4% ± 13.2% and 46.2% ± 15.4%, respectively. Bacterial biomass decreased from (3.58 ± 0.49) to (1.23 ± 0.27) × 107 16S rRNA gene copies/mL, and identified biomarkers in effluent and downstream shifted due to the adopted processes. Opportunistic pathogen bacteria downstream were also reduced. Although the relative abundance of total ARGs in MWTP effluent increased from 1.10 ± 0.02 to 2.19 ± 0.03 copies/16S rRNA gene after upgrades, that of total and high-risk ARGs downstream showed no significant difference. More importantly, the Bayesian-based SourceTracker method provided valuable insight by revealing that the contributions of MWTP discharge to downstream bacteria (from 44.2% ± 1.5%-31.4% ± 0.9%) and ARGs (from 61.2% ± 5.3%-47.6% ± 4.1%) were significantly reduced following the upgrades, indicating upgrading MWTP showed integrated benefits to the bacterial hazards in the receiving river. This study provides useful information for better control of bacterial hazard risks and operational strategy for the improvement of the urban aquatic ecosystem.

Occurrence, distribution, and behaviors of erythromycin A, production byproducts, transformation products, and resistance genes in a full-scale erythromycin A production wastewater treatment system.

Antibiotic production wastewater from pharmaceutical manufacturing is a significant source of antibiotic and resistance gene pollution in the environment. Given that Erythromycin A (Ery-A) is a widely used antibiotic in both human clinical and livestock breeding, it is imperative to ascertain its presence, along with related compounds, in the biological treatment processes of production wastewater. In this study, the occurrence and behavior of Ery-A, its production byproducts, transformation products, and resistance genes were first systematically investigated in a full-scale anaerobic-aerobic system for treating Ery-A production wastewater. Simultaneously, residual antibacterial activity in wastewater and sludge was evaluated throughout the wastewater treatment process. Ery-A contributes only 24.2 - 36.0% to the antibacterial activities. Ery-A-derived compounds including production byproducts (erythromycin B and erythromycin C) and transformation products (anhydro erythromycin A, N-demethyl-erythromycin A, and erythromycin A enol ether), are determined to contribute to the antibacterial activities of the wastewater treatment system. High concentrations of antibiotics with antibacterial activity (up to 1,258.9 mg/kg·TS for erythromycin A enol ether) adsorbed in the sludge result in near collapse of the first-stage anaerobic sludge system. Sludge biodegradation in second-stage anaerobic and anoxic-aerobic tanks is essential in removing Ery-A-related compounds from wastewater. The Ery-A-related compounds in the secondary effluent and excess sludge are determined to be 44.5 g/h and 1.5 g/h through the mass balance analysis, respectively. The discharge of MLS resistance genes from the secondary effluent and excess sludge is 1.0 × 1016 copies/h and 7.1 × 1015 copies/h, respectively. These findings highlight the significant concern over the release of Ery-A-related compounds and MLS resistance genes from the Ery-A production wastewater treatment system. As a result, it is crucial to implement strategies for the removal of Ery-A-related compounds from production wastewater before biological processes. This study is the first to report the occurrence and behavior of Ery-A-related compounds and resistance genes along the full-scale wastewater treatment processes. Additionally, it sheds light on the importance of byproducts and transformation products with antibacterial activity from Ery-A in the Ery-A production wastewater treatment system.

Incidence of acute kidney injury after hematopoietic stem cell transplantation in children: a systematic review and meta-analysis.

While acute kidney injury (AKI) has been reported after hematopoietic stem cell transplantation (HCT) in children, the incidence of this condition in the pediatric population has not been fully addressed. To assess the incidence of pediatric AKI after HCT treatment,we conducted a systematic literature review. Databases PubMed, Embase, Cochrane Library, and WOS were searched as of June 2022 to identify studies on the incidence and the risk of death in AKI children undergoing HCT. Random effects and generic inverse variance methods were used, and effect estimates were subsequently derived from individual studies. Twelve cohort studies with 2 159 HCT cases were included in this analysis. The combined estimated incidence of AKI and severe AKI (stage AKI III) was 51% (95% confidence interval (CI) 39-64%) and 12% (95%CI 4-24%), respectively. The estimated incidence of AKI based on RIFLE (pRIFLE), AKIN, and KDIGO criteria was 61% (95%CI 40-82% score I 95.1%), 64% (95%CI 49-79% score I 90.4%), and 51% (95%CI 2-100% score 99.0%), respectively. However, we found no significant correlation between the years of publication of the included studies and the incidence of AKI.  Conclusions: AKI affects approximately half of the children after HCT. With the advancements in medical techniques, it is expected that AKI in this population will decrease gradually. What is Known: • Hematopoietic stem cell transplantation is recognized as a treatment for malignant and non-malignant diseases in children. • Hematopoietic stem cell transplantation causes acute kidney injury in children. What is New: • This metanalysis showed that the overall frequency of post-HCT AKI in children is 51%. • The frequency of severe AKI after HCT was found to be 12%.

Hyper-thermophilic anaerobic pretreatment enhances the removal of transferable oxazolidinone and phenicol cross-resistance gene optrA in enterococci.

The extensive use of florfenicol in poultry industry results in the emergence of optrA gene, which also confers resistance to clinically important antibiotic linezolid. This study investigated the occurrence, genetic environments, and removal of optrA in enterococci in mesophilic (37 °C) and thermophilic (55 °C) anaerobic digestion systems, and a hyper-thermophilic (70 °C) anaerobic pretreatment system for chicken waste. A total of 331 enterococci were isolated and analyzed for antibiotic resistance against linezolid and florfenicol. The optrA gene was frequently detected in enterococci from chicken waste (42.7%) and effluents from mesophilic (72%) and thermophilic (56.8%) reactors, but rarely detected in the hyper-thermophilic (5.8%) effluent. Whole-genome sequencing revealed that optrA-carrying Enterococcus faecalis sequence type (ST) 368 and ST631 were the dominant clones in chicken waste, and they remained dominant in mesophilic and thermophilic effluents, respectively. The plasmid-borne IS1216E-fexA-optrA-erm(A)-IS1216E was the core genetic element for optrA in ST368, whereas chromosomal Tn554-fexA-optrA was the key one in ST631. IS1216E might play a key role in horizontal transfer of optrA due to its presence in different clones. Hyper-thermophilic pretreatment removed enterococci with plasmid-borne IS1216E-fexA-optrA-erm(A)-IS1216E. A hyper-thermophilic pretreatment is recommended for chicken waste to mitigate dissemination of optrA from animal waste to the environment.

Combined exposure to microplastics and amitriptyline caused intestinal damage, oxidative stress and gut microbiota dysbiosis in zebrafish (Danio rerio).

The potential toxicity of microplastics (MPs) and hydrophilic pharmaceuticals to aquatic organisms has recently raised great public concern, yet their combined effects on aquatic organisms remain largely unknown. Herein, the combined effects of MPs and the commonly prescribed amitriptyline hydrochloride (AMI) on the intestinal tissue and gut microbiota of zebrafish (Danio rerio) were investigated. Adult zebrafish were exposed to microplastics (polystyrene, PS, 440 µg/L), AMI (2.5 µg/L), PS+AMI (440 µg/L PS + 2.5 µg/L AMI), and dechlorinated tap water (control) for 21 days, respectively. Our results showed that zebrafish rapidly ingested PS beads and accumulated them in the gut. Exposure to PS+AMI significantly enhanced the SOD and CAT activities compared to the control group, suggesting that combined exposure might increase ROS production in the zebrafish gut. Exposure to PS+AMI led to severe gut injuries, including cilia defects, partial absence and cracking of intestinal villi. Exposure to PS+AMI caused shifts in the gut bacterial communities, increasing the abundance of Proteobacteria and Actinobacteriota, and decreasing the abundance of Firmicutes, Bacteroidota and beneficial bacteria Cetobacterium, which caused dysbiosis in the gut microbiota, and subsequently may induce intestinal inflammation. Furthermore, exposure to PS+AMI disordered the predicted metabolic functions of gut microbiota, but functional changes in the PS+AMI group at KEGG level 1 and level 2 were not significantly different from those in the PS group. The results of this study extend our knowledge of the combined effects of MPs and AMI on the health of aquatic organisms, and will be helpful in assessing the combined effects of MPs and tricyclic antidepressants on aquatic organisms.

Uncovering the diverse hosts of tigecycline resistance gene tet(X4) in anaerobic digestion systems treating swine manure by epicPCR.

The tet(X4) gene is a clinically important tigecycline resistance gene and has shown high persistence in livestock-related environments. However, the bacterial hosts of tet(X4) remain unknown due to the lack of appropriate approaches. Herein, a culture-independent and high-throughput epicPCR (emulsion, paired isolation, and concatenation polymerase chain reaction) method was developed, optimized, and demonstrated for the identification of bacterial hosts carrying tet(X4) from environmental samples. Considering the high sequence similarity between tet(X4) and other tet(X)-variant genes, specific primers and amplification conditions were screened and optimized to identify tet(X4) accurately and link tet(X4) with the 16S rRNA gene, which were further validated using artificially constructed bacterial communities. The epicPCR targeting tet(X4) was applied for the identification of bacterial hosts carrying this resistance gene in anaerobic digestion systems treating swine manure. A total of 19 genera were identified as tet(X4) hosts, which were distributed in the phyla Proteobacteria, Bacteroidota, Firmicutes, and Caldatribacteriota. Sixteen genera and two phyla that were identified have not been previously reported as tet(X4) bacterial hosts. The results indicated that a far more diverse range of bacteria was involved in harboring tet(X4) than previously realized. Compared with the tet(X4) hosts determined by correlation-based network analysis and metagenomic binning, epicPCR revealed a high diversity of tet(X4) hosts even at the phylum level. The epicPCR method developed in this study could be effectively employed to reveal the presence of tet(X4) bacterial hosts from a holistic viewpoint.

Simultaneous determination of erythromycin and its transformation products in treated erythromycin fermentation residue and amended soil.

Erythromycin fermentation residue (EFR) is a solid waste generated from the fermentation process of erythromycin A production. Some byproducts are produced during the fermentation process of erythromycin A production, and erythromycin A can also undergo hydrolysis and biodegradation reactions in the environment with the formation of transformation products. Herein, an accurate analytical method was established and validated to quantify erythromycin A, two byproducts and five hydrolysis or biodegradation products, in solid or semi-solid media of waste EFR and the amended soil. The method mainly included ultrasonic solvent extraction, solid phase extraction, and ultra-performance liquid chromatography-tandem mass spectrometry quantification. All analytes could be effectively extracted in a single process, and the recoveries ranged from 76% to 122% for different matrices. Low matrix effects and excellent precision were achieved by optimizing the mass spectrometry parameters, extraction solution, number of extractions and eluent. This method was applied to evaluate the residual analytes in EFR, treated EFR after industrial-scale hydrothermal treatment, and the subsequent soil application. Seven analytes were detected in the EFR, while six were found in the treated EFR and amended soils. The concentration of erythromycin A in EFR was 1,629 ± 100 mg/kg·TS, and the removal efficiency of hydrothermal treatment (180 °C, 60 min) was about 99.6%. Three hydrolysis products were the main residuals in treated EFR, with anhydroerythromycin A showing the highest concentration. The concentrations of the analytes in soil ranged from 2.17 ± 1.04 to 92.33 ± 20.70 µg/kg·TS, and anhydroerythromycin A contributed 65%-77% of the total concentration. Erythromycin B, a byproduct, was still detected in soil. This work provides an accurate analytical method which would be useful to evaluate the potential risk of byproducts and transformation products of erythromycin A in environment.

Mobile tigecycline resistance gene tet(X4) persists with different animal manure composting treatments and fertilizer receiving soils.

The emergence of plasmid-mediated tigecycline-resistant genes [tet(X3)to tet(X6)] in animals and humans has raised serious concerns over their possible cross-environmental dissemination. However, behavior of these emerging mobile tet(X)-variant genes in manure treatment processes, particularly for different composting treatments, has not yet been studied. Here, we explored the environmental behavior of mobile tet(X)-variant genes in two typical manure composting treatments and amended soils based on a large-scale molecular investigation across eight provinces in China. Results showed that tet(X4) was the predominant mobile tet(X)-variant gene in fresh manure, natural and thermophilic composting products with both the highest detection frequency (82.5% ± 14.7%), and absolute abundance of tet(X4)[4.26 ± 0.09) × 1010] copies/g dry weight, followed by tet(X3), tet(X6), and tet(X5). The occurrence of all mobile tet(X)-variant genes, particularly tet(X4), in receiving soil following composting fertilizer application indicated their transmission from manure to soil. Paired-sampling strategy revealed no significant reduction in mobile tet(X)-variant genes by natural composting, while thermophilic composting exhibited clear efficacy in removing tet(X)-variant genes. After thermophilic composting, tet(X4) exhibited the lowest reduction (94.1%) compared with other mobile tet(X)-variant genes (96.9%-99.9%), which may be attributable to its significant correlation with ISCR2 (P < 0.05) facilitating its transfer to various hosts including persisted thermotolerant bacteria. Thus, tet(X4) showed better persistence in livestock-related environments. Collectively, this study highlights the importance of controlling the environmental dissemination of clinically relevant mobile tet(X)-variant genes by establishing a sound process and operational strategy.

Exposure to amitriptyline induces persistent gut damages and dysbiosis of the gut microbiota in zebrafish (Danio rerio).

Amitriptyline (AMI), the most commonly prescribed tricyclic antidepressant, is widely detected in water environments. Exposure to AMI may lead to diverse adverse effects on aquatic organisms, but little is known about the effect of short-term exposure to AMI on the gut microbiota of aquatic organisms and their recovery characteristics. In the present study, adult zebrafish (Danio rerio) were exposed to AMI (0, 2.5, 10, and 40 µg/L) for seven days, and then allowed to recover in AMI-free culture water for 21 days. The exposure caused gut damages in all the AMI treated groups of zebrafish, which became more severe after recovery compared to the control group. AMI exposure also disturbed the microbiota of zebrafish guts and rearing water even after the 21-day recovery period. Furthermore, AMI exposure affected microbes involved in the substance and energy metabolic functions in zebrafish guts and tended to increase the abundance of microbial genera associated with opportunistic pathogens. In addition, the microbial predicted metabolic functions in AMI-exposed guts of zebrafish were significantly altered after the 21-day recovery period, explaining the persistent effects of short-term exposure to AMI. The results of this study suggest that acute exposure to AMI may have persistent impacts on the gut histomorphology and the gut microbiota in aquatic organisms.

Case Report: Novel CA12 Homozygous Variant Causing Isolated Hyperchloridrosis in a Chinese Child With Hyponatremia.

Isolated hyperchloridrosis (HYCHL; OMIM 143860) is a rare autosomal recessive disorder caused by biallelic mutations in the carbonic anhydrase 12 (CA12; OMIM 603263) gene, which is characterized by abnormally high levels of salt in sweat that can lead to dehydration associated with low levels of sodium in the blood. To date, only four variants of the CA12 gene have been identified to be associated with HYCHL. Here, we presented a rare Chinese case of HYCHL in an infant with decreased food intake, mild diarrhea, severe dehydration, and hypovolemic shock who was hospitalized in our department three times. Laboratory tests showed hyponatremia and hypochloremia. Because of recurrent attacks, whole-exome sequencing (WES) was performed and revealed a novel homozygous missense variant c.763A>C (p.Thr255Pro) in the CA12 gene (NM_001218.5). In total 0.9% sodium chloride (NaCl) solution was orally administered until 1 year and 6 months of age. Followed up to 3 years of age, the patient showed good growth and development without similar manifestations. This study reported a novel CA12 gene mutation leading to HYCHL for the first time in China, which enriched the genotype of HYCHL and emphasized the early suspicion and identification of the rare condition to adequate treatment.

Dissolved nitrogen in salt-affected soils reclaimed by planting rice: How is it influenced by soil physicochemical properties?

Planting rice is an effective way to reclaim salt-affected soils, but overapplying nitrogen fertilizer has resulted in a large loss in the amounts of soil dissolved nitrogen (SDN) from paddy fields. While the dynamic of SDN and its response to changes in soil physicochemical properties by planting rice are well-studied in non-salt-affected soils, little is known about the relationship between the SDN and soil physicochemical properties in reclaimed salt-affected soils. To fill this knowledge gap, soil samples were collected from bare salt-affected soils and three paddy fields with different reclaimed years (4, 9, 20) in six soil layers. Compared with bare salt-affected soils, soil salinity and sodicity exhibited trends of firstly increasing and then decreasing, whereas organic matter and total nitrogen tended to increase with the extension of the reclamation year. Soil dissolved organic carbon and total dissolved phosphorous showed decreasing trends. The sand content showed an increasing tendency, whereas the silt and clay contents tended to decrease. Ammonium nitrogen concentrations in reclaimed paddy fields were higher than those of bare salt-affected soils, and nitrate nitrogen concentrations in reclaimed paddy fields were smaller than those of bare salt-affected soils. However, the changing trends of dissolved organic nitrogen concentrations were not consistent among paddy fields with different reclamation years. Meanwhile, statistical analysis results revealed significant correlations between SDN and soil physicochemical properties. Moreover, dominant drivers influencing SDN were grouped using principal component analysis, identifying the following factors including soil sodicity, active nutrients, soil texture and water retention. Redundancy analysis also revealed that the soil physicochemical properties explained 69.65% of the variation in SDN and the influenced relationship between soil physicochemical properties and SDN nutrients. This study enhances our understanding of the mechanisms influencing SDN during planting rice and has implications for the management of the nutrient application of reclaimed salt-affected soils.

Removal efficacy of opportunistic pathogen gene markers in drinking water supply systems: an in situ and large-scale molecular investigation.

The prevalence and interactions with biofilm and disinfectant of opportunistic pathogens in drinking water supply systems (DWSSs) have been extensively interpreted. In contrast, the large geographical distribution and in situ removal of opportunistic pathogens are overlooked aspects. Here, paired source and tap water samples of 36 parallel DWSSs across China were collected, with five common waterborne pathogens characterized by qPCR. From source to tap, the removal of bacterial biomass (16S rRNA gene copy number) was 1.10 log, and gene marker removal of five opportunistic pathogens ranged from 0.66 log to 2.27 log, with the order of Escherichia coli > Mycobacterium spp. > Clostridium perfringens > Bacillus cereus > Aeromonas hydrophila. Different with bacterial community, geographical location and source water types (river or reservoir) were not key contributor to variation of opportunistic pathogens. Gene marker removal efficacies of E. coli, Mycobacterium spp., and C. perfringens from source to tap were restricted to removal efficacy of overall bacterial biomass, while abundance of B. cereus in tap water linked to the input of B. cereus from source water. Although culture-dependent approach is important for pathogen enumeration in drinking water, qPCR-based molecular survey shows advantages of quantifiable high-throughput and easy operation, providing abundant and timely information on pathogen occurrence in water. This study provides the in situ, molecular-level evidence toward differential propagation features of multiple opportunistic pathogens in DWSSs and suggests the source protection and early warning of treatment-resistant pathogens.

The effect of anthropogenic activities on the environmental fate of chlorinated paraffins in surface soil in an urbanized zone of northern China.

Chlorinated paraffins (CPs) have been widely used as halogenated flame retardants and plasticizers since the mid-20th century. The prevalence of CPs in soil has been widely reported, but the distribution pattern of CPs in urbanized zones and their association with multiple socioeconomic variables have not been adequately explored. Herein, short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) were investigated in surface soil samples from Tianjin, China, a typical urbanized area. The concentration distributions of SCCPs and MCCPs showed similar trends in different administrative divisions and land use types: urban areas > suburbs > outer suburbs (p < 0.001) and residential areas > greenbelts > agricultural areas (p < 0.001). The CP congeners in residential surface soils mainly included those with longer carbon chains and high degree of chlorination, while the CP congeners in agricultural surface soils mainly consisted of those with shorter carbon chains and fewer chlorine substituents. Multiple statistical approaches were used to explore the association between socioeconomic factors and CP distribution. CP concentration was significantly correlated to population density and gross domestic product (GDP) (p < 0.001), and structural equation models incorporating administrative regional planning showed an indirect impact on the distribution of MCCP concentration due to the influence of regional planning on population density. These results highlight the association between CP contamination and the degree of urbanization, and this paper provides useful information toward mitigating the exposure risk of CPs for urban inhabitants.

Effect of temperature on the persistence of fecal bacteria in ambient anaerobic digestion systems treating swine manure.

This study aimed to explore the effect of temperature on the persistence of fecal bacteria by multiple approaches in ambient anaerobic digestion systems treating swine manure. Both lab-scale (15 °C, 20 °C, and 25 °C) and field (26 °C on average) studies were conducted by high-throughput sequencing and culture-based methods. A community-wide Bayesian SourceTracker method was used to identify and estimate the fecal bacterial proportion in anaerobic effluent. High proportional contributions of fecal bacteria were observed in effluent at 15 °C (73%) and 20 °C (75%), while less was found at 25 °C (19%). This was further verified by a field study (23%) and an anaerobic reactor study at 37 °C (0.01%). To explore the potential reasons for differences in fecal bacterial proportions, bacterial taxa were divided into "lost" and "survivor" taxa in manure waste by LEfSe. The "survivor" taxa abundance was positively correlated with SourceTracker proportion (r = 0.913, P = 0.001), but negatively correlated with temperature (r = -0.826, P = 0.006). In addition, biomarkers in effluent were divided into "enriched" and "de novo" taxa. "Enriched" taxa, including acidogenic and acetogenic bacteria, were found at all temperatures, whereas taxa related to organic degradation were multiplied "de novo" at 25 °C. Variation partition analysis showed that temperature could explain 30% of variations in effluent bacterial community. Moreover, coliforms isolated from the manure and effluents at 15 °C and 20 °C were also phylogenetically related. This study provided comprehensive insight into the impact of temperature on the persistence of fecal bacteria in anaerobic effluent, with temperatures over 25 °C recommended to reduce fecal pollution.

Assessing the effect of treated erythromycin fermentation residue on antibiotic resistome in soybean planting soil: In situ field study.

As a by-product in the pharmaceutical industry, antibiotic fermentation residue is expected to be able to be utilized after effectively removing the antibiotics. However, evaluation of the effect of fermentation residue application on soil, especially the in situ environmental consequences considering not only the antibiotic resistance gene (ARG) abundance but also the resistome risk, has still not been sufficiently evaluated. Herein, the impact of treated erythromycin fermentation residue (EFR) on the resistome and risk score in soybean planting soil was investigated. Treated EFR application with dosages of 3750 kg (EFR250) and 7500 kg (EFR500) per hm2 soil did not increase the diversity (Shannon index, 2.84-3.38) or relative abundance (0.086-0.142 copies/16S rRNA gene) of the soil resistome compared with the Control (CK: 2.92-3.2, 0.088-0.096 copies/16S rRNA gene). Soil resistome risk scores calculated by metagenomic assembly, showing the dissemination potential of ARGs, ranged from 22.9 to 25.0, and were also not significantly different between treated EFR amended soil and the Control. Notably, the diversity of the resistome increased at the sprout stage (Mann-Whitney U test, P < 0.05) and the abundance of some ARG types (macrolide-lincosamide-streptogramin, aminoglycoside and tetracycline, etc.) shifted along the course of soybean growth (Kruskal-Wallis test, P < 0.05). Structural equation model analysis showed that the soybean growth period affected the composition of ARGs by affecting the microbial community, which was further supported by Procrustes analysis (P < 0.05) and metagenomic binning. Our findings emphasized that soil ARG abundance and resistome risk did not increase during one-time field application of treated EFR at the studied dosage. Comprehensive consideration including resistome risk and multiple influencing factors also should be given for further assessment of fermentation residue application.

Persistence of Salmonella Typhimurium in apple-pear (Pyrus bretschneideri Rehd.) orchard soils influenced by bacterial communities and soil properties.

2In this study, we investigated the persistence of Salmonella Typhimurium in 26 soil samples from apple-pear orchards in Yanji, Longjing and Helong in northeastern China. The time to reach detection limit (ttds) of Salmonella Typhimurium in soils varied from 20 to 120 days. Redundancy analysis and variation partition analysis elucidated that bacterial communities, clay content, pH, electrical conductivity (EC) salinity, and NO3--N could explain more than 85% of overall variation of the persistence behaviors. Results of structural equation models and Mantel tests revealed that clay content and EC displayed both direct and indirect effect on ttds, while NO3--N and pH exhibited direct and indirect effect on the survival patterns, respectively. Furthermore, Actinobacteria, Acidobacteria and Deltaproteobacteria at class level showed highly close correlations with ttds. Our results revealed that certain biotic and abiotic factors could greatly contribute to the overall persistence of Salmonella in apple-pear orchard soils.