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637800.9220Metagenomics reveals the divergence of gut microbiome composition and function in two common pika species (Ochotona curzoniae and Ochotona daurica) in China. Gut microbiome plays crucial roles in animal adaptation and evolution. However, research on adaptation and evolution of small wild high-altitude mammals from the perspective of gut microbiome is still limited. In this study, we compared differences in intestinal microbiota composition and function in Plateau pikas (Ochotona curzoniae) and Daurian pikas (O. daurica) using metagenomic sequencing. Our results showed that microbial community structure had distinct differences in different pika species. Prevotella, Methanosarcina, Rhizophagus, and Podoviridae were abundant bacteria, archaea, eukaryotes, and viruses in Plateau pikas, respectively. However, Prevotella, Methanosarcina, Ustilago, and Retroviridae were dominated in Daurian pikas. Functional pathways related to carbohydrate metabolism that refer to the utilization of pectin, hemicellulose, and debranching enzymes were abundant in Plateau pikas, while the function for degradation of chitin, lignin, and cellulose was more concentrated in Daurian pikas. Pika gut had abundant multidrug resistance genes, followed by glycopeptide and beta-lactamase resistance genes, as well as high-risk antibiotic resistance genes, such as mepA, tetM, and bacA. Escherichia coli and Klebsiella pneumoniae may be potential hosts of mepA. This research provided new insights for adaptation and evolution of wild animals from perspective of gut microbiome and broadened our understanding of high-risk antibiotic resistance genes and potential pathogens of wild animals.202439500545
764010.9111Gut microbiome and antibiotic resistance genes in plateau model animal (Ochotona curzoniae) exhibit a relative stability under cold stress. Antibiotic resistance genes (ARGs) carried by gut pathogens may pose a threat to the host and ecological environment. However, few studies focus on the effects of cold stress on intestinal bacteria and ARGs in plateau animals. Here, we used 16S rRNA gene sequencing and gene chip technique to explore the difference of gut microbes and ARGs in plateau pika under 4 °C and 25 °C. The results showed that tetracycline and aminoglycoside resistance genes were the dominant ARGs in pika intestine. Seven kinds of high-risk ARGs (aadA-01, aadA-02, ermB, floR, mphA-01, mphA-02, tetM-02) existed in pika's intestine, and cold had no significant effect on the composition and structure of pika's intestinal ARGs. The dominant phyla in pika intestine were Bacteroidetes and Firmicutes. Cold influenced 0.47 % of pika intestinal bacteria in OTU level, while most other bacteria had no significant change. The diversity and community assembly of intestinal bacteria in pika remained relatively stable under cold conditions, while low temperature decreased gut microbial network complexity. In addition, low temperature led to the enrichment of glycine biosynthesis and metabolism-related pathways. Moreover, the correlation analysis showed that eight opportunistic pathogens (such as Clostridium, Staphylococcus, Streptococcus, etc.) detected in pika intestine might be potential hosts of ARGs.202439137548
638020.9108Seasonal dynamics of anammox bacteria in estuarial sediment of the Mai Po Nature Reserve revealed by analyzing the 16S rRNA and hydrazine oxidoreductase (hzo) genes. The community and population dynamics of anammox bacteria in summer (wet) and winter (dry) seasons in estuarial mudflat sediment of the Mai Po Nature Reserve were investigated by 16S rRNA and hydrazine oxidoreductase (hzo) genes. 16S rRNA phylogenetic diversity showed that sequences related to 'Kuenenia' anammox bacteria were presented in summer but not winter while 'Scalindua' anammox bacteria occurred in both seasons and could be divided into six different clusters. Compared to the 16S rRNA genes, the hzo genes revealed a relatively uniform seasonal diversity, with sequences relating to 'Scalindua', 'Anammoxoglobus', and planctomycete KSU-1 found in both seasons. The seasonal specific bacterial groups and diversity based on the 16S rRNA and hzo genes indicated strong seasonal community structures in estuary sediment of this site. Furthermore, the higher abundance of hzo genes in summer than winter indicates clear seasonal population dynamics. Combining the physicochemical characteristics of estuary sediment in the two seasons and their correlations with anammox bacteria community structure, we proposed the strong seasonal dynamics in estuary sediment of Mai Po to be due to the anthropogenic and terrestrial inputs, especially in summer, which brings in freshwater anammox bacteria, such as 'Kuenenia', interacting with the coastal marine anammox bacteria 'Scalindua'.201121487198
637730.9103Comparative metagenomics and characterization of antimicrobial resistance genes in pasteurized and homemade fermented Arabian laban. The aim of this study was to investigate bacterial diversity and function in a fermented milk drink called laban, which is traditionally served in the Middle East, Africa, and Indian subcontinent. Pasteurized laban (LBP) and unpasteurized, homemade, raw laban (LBR) underwent 16S rRNA gene amplicon and shotgun sequencing to analyze their bacterial community, presence of antimicrobial resistance genes (ARGs), and metabolic pathways. This study highlighted relatively greater diversity in LBR bacterial populations compared to LBP, despite containing similar major taxa that consisted primarily of Firmicutes followed by Proteobacteria, Bacteroidetes, and Actinobacteria. The dominant species, Streptococcus thermophilus, was relatively more abundant in LBP (80.7%) compared to LBR (47.9%). LBR had increased diversity and higher relative abundance of several known probiotic bacteria, such as Streptococcus salivarius and Lactococcus lactis, whereas Lactobacillus acidophilus was detected at a higher abundance in LBP. Pathogens like Acinetobacter baumannii, Streptococcus pneumoniae, Streptococcus pyogenes, and Escherichia coli had lower abundance in LBP compared to LBR. Thirty-three ARGs were detected in LBR compared to nine in LBP and are responsible for resistance to 11 classes of antibiotics. A significant proportion of the metagenomes from both types of laban were assigned to housekeeping functions, such as amino acid metabolism, translation, membrane transport, and carbohydrate metabolism. LBR demonstrated increased diversity in probiotics and metabolic functions compared to LBP. However, the relatively high diversity of pathogenic and opportunistic bacteria and ARGs in LBR raises safety concerns and highlights the need for a more hygienic environment for the processing of homemade fermented dairy foods.202033233218
811040.9075Removal of chlortetracycline and antibiotic resistance genes in soil by earthworms (epigeic Eisenia fetida and endogeic Metaphire guillelmi). The impacts of two ecological earthworms on the removal of chlortetracycline (CTC, 0.5 and 15 mg kg(-1)) and antibiotic resistance genes (ARGs) in soil were explored through the soil column experiments. The findings showed that earthworm could significantly accelerate the degradation of CTC and its metabolites (ECTC) in soil (P < 0.05), with epigeic Eisenia fetida promoting degradation rapidly and endogeic Metaphire guillelmi exhibiting a slightly better elimination effect. Earthworms alleviated the abundances of tetR, tetD, tetPB, tetG, tetA, sul1, TnpA, ttgB and intI1 in soil, with the total relative abundances of ARGs decreasing by 35.0-44.2% in earthworm treatments at the 28th day of cultivation. High throughput sequencing results displayed that the structure of soil bacteria community was modified apparently with earthworm added, and some possible CTC degraders, Aeromonas, Flavobacterium and Luteolibacter, were promoted by two kinds of earthworms. Redundancy analysis demonstrated that the reduction of CTC residues, Actinobacteria, Acidobacteria and Gemmatimonadetes owing to earthworm stimulation was responsible for the removal of ARGs and intI1 in soil. Additionally, intI1 declined obviously in earthworm treatments, which could weaken the risk of horizontal transmission of ARGs. Therefore, earthworm could restore the CTC-contaminated soil via enhancing the removal of CTC, its metabolites and ARGs.202133798888
811350.9072Fate of antibiotic resistance genes in mesophilic and thermophilic anaerobic digestion of chemically enhanced primary treatment (CEPT) sludge. Anaerobic digestion (AD) of chemically enhanced primary treatment (CEPT) sludge and non-CEPT (conventional sedimentation) sludge were comparatively operated under mesophilic and thermophilic conditions. The highest methane yield (692.46±0.46mL CH(4)/g VS(removed) in CEPT sludge) was observed in mesophilic AD of CEPT sludge. Meanwhile, thermophilic conditions were more favorable for the removal of total antibiotic resistance genes (ARGs). In this study, no measurable difference in the fates and removal of ARGs and class 1 integrin-integrase gene (intI1) was observed between treated non-CEPT and CEPT sludge. However, redundancy analysis indicated that shifts in bacterial community were primarily accountable for the variations in ARGs and intI1. Network analysis further revealed potential host bacteria for ARGs and intI1.201728797965
787460.9068Phenacetin promoted the rapid start-up and stable maintenance of partial nitrification: Responses of nitrifiers and antibiotic resistance genes. Phenacetin (PNCT) belongs to one of the earliest synthetic antipyretics. However, impact of PNCT on nitrifying microorganisms in wastewater treatment plants and its potential microbial mechanism was still unclear. In this study, PN could be initiated within six days by PNCT anaerobic soaking treatment (8 mg/L). In order to improve the stable performance of PN, 21 times of PNCT aerobic soaking treatment every three days was conducted and PN was stabilized for 191 days. After PN was damaged, ten times of PNCT aerobic soaking treatment every three days was conducted and PN was recovered after once soaking, maintained over 88 days. Ammonia oxidizing bacteria might change the dominant oligotype to gradually adjust to PNCT, and the increase of abundance and activity of Nitrosomonas promoted the initiation of PN. For nitrite-oxidizing bacteria (NOB), the increase of Candidatus Nitrotoga and Nitrospira destroyed PN, but PN could be recovered after once aerobic soaking illustrating NOB was not resistant to PNCT. KEGG and COG analysis suggested PNCT might disrupt rTCA cycle of Nitrospira, resulting in the decrease of relative abundance of Nitrospira. Moreover, PNCT did not lead to the sharp increase of absolute abundances of antibiotic resistance genes (ARGs), and the risk of ARGs transmission was negligible.202438744392
787570.9065Phenacetin enhanced the inorganic nitrogen removal performance of anammox bacteria naturally in-situ enriched system. Among the earliest synthetic antipyretic drugs, phenacetin (PNCT) could be used as the novel partial nitrification (PN) inhibitor to effectively inhibit nitrite-oxidizing bacteria (NOB). In practical application, the rapidly starting of PN could provide stable source of nitrite for anaerobic ammonium oxidation (anammox) process. However, impact of PNCT on anaerobic ammonia oxidizing bacteria (AnAOB) and its underlying mechanisms were not clear. In this research, totally 14 times of PNCT aerobic soaking treatment were performed in the AnAOB naturally enrichment system to improve total inorganic nitrogen removal efficiency (TINRE). After once of PNCT treatment, TINRE rose from 61.89 % to 79.93 %. After 14 times of PNCT treatment, NOB Nitrospira relative abundance decreased from 9.82 % to 0.71 %, though Candidatus Brocadia relative abundance also declined, it might gradually adjust to PNCT by converting the leading oligotype species. The activity and relative abundances of NOB were reduced by PNCT via decreasing the abundances of genes amoA and nxrB, enzymes NxrA and NxrB. Moreover, Candidatus Jettenia and Ca. Brocadia might be the potential host of qacH-01 and they played the crucial role in the shaping profile of antibiotic resistance genes (ARGs). The explosive propagation or transmission of ARGs might not take place after PNCT treatment.202439566627
794380.9065Effects of microplastics on dissipation of oxytetracycline and its relevant resistance genes in soil without and with Serratia marcescens: Comparison between biodegradable and conventional microplastics. The biodegradable (polybutylene adipate terephthalate: PBAT) and conventional (polyethylene: PE) microplastics (MPs) at 0.5 %, 1 %, and 2 % dosages (w/w) were added into soils with and without Serratia marcescens ZY01 (ZY01, a tet-host strain) to understand their different effects on the dissipation of oxytetracycline (OTC) and tet. The results showed that the dosages of PBAT MP exhibited different inhibition degrees of OTC biodegradation in soils regardless of ZY01, while the dosages of PE MP did not change the enhancement degree of OTC biodegradation in soils without ZY01. These differences were due to the higher adsorption capacity of OTC on PBAT MP and the stronger toxicity of PBAT MP to microorganisms. Besides soil organic matter, pH and total phosphorus were important factors regulating specific tet-host bacteria in soils with MPs (e.g., the nitrogen-cycling bacteria Steroidobacter and Nitrospira) and MPs + ZY01 (e.g., the phosphorus-cycling bacteria Saccharimonadales and Haliangium), respectively. Regardless of ZY01, a stronger selective harboring of tet-host bacteria in PE MP treatments than PBAT MP treatments was observed at the MP dosage of 1 % (w/w), while the opposite trend was true at the MP dosages of 0.5 % and 2 % (w/w). Some specific genera belonging to Actinobacteriota strongly associated with the class 1 integron-integrase gene (intI1), playing a critical role in the horizontal gene transfer of tet in soils especially for the co-existence of MPs and ZY01. This study will be helpful for understanding on how biodegradable and conventional MPs as hotspots affect the environmental behavior of antibiotics and ARGs in soil.202439500253
705490.9063Effective removal of antibiotic resistance genes and potential links with archaeal communities during vacuum-type composting and positive-pressure composting. As a major reservoir of antibiotics, animal manure contributes a lot to the augmented environmental pressure of antibiotic resistance genes (ARGs). This might be the first study to explore the effects of different ventilation types on the control of ARGs and to identify the relationships between archaeal communities and ARGs during the composting of dairy manure. Several ARGs were quantified via Real-time qPCR and microbial communities including bacteria and archaea were analyzed by High-throughput sequencing during vacuum-type composting (VTC) and positive-pressure composting (PPC). The total detected ARGs and class I integrase gene (intI1) under VTC were significantly lower than that under PPC during each stage of the composting (p<0.001). The relative abundance of potential human pathogenic bacteria (HPB) which were identified based on sequencing information and correlation analysis decreased by 74.6% and 91.4% at the end of PPC and VTC, respectively. The composition of archaeal communities indicated that methane-producing archaea including Methanobrevibacter, Methanocorpusculum and Methanosphaera were dominant throughout the composting. Redundancy analysis suggested that Methanobrevibacter and Methanocorpusculum were positively correlated with all of the detected ARGs. Network analysis determined that the possible hosts of ARGs were different under VTC and PPC, and provided new sights about potential links between archaea and ARGs. Our results showed better performance of VTC in reducing ARGs and potential HPB and demonstrated that some archaea could also be influential hosts of ARGs, and caution the risks of archaea carrying ARGs.202031892399
6918100.9062Variations in antibiotic resistance genes and removal mechanisms induced by C/N ratio of substrate during composting. For a comprehensive insight into the potential mechanism of the removal of antibiotic resistance genes (ARGs) removal induced by initial substrates during composting, we tracked the dynamics of physicochemical properties, bacterial community composition, fungal community composition, the relative abundance of ARGs and mobile genetic genes (MGEs) during reed straw and cow manure composting with different carbon to nitrogen ratio. The results showed that the successive bacterial communities were mainly characterized by the dynamic balance between Firmicutes and Actinobacteria, while the fungal communities were composed of Ascomycota. During composting, the interactions between bacteria and fungi were mainly negative. After composting, the removal efficiency of ARGs in compost treatment with C/N ≈ 26 (LL) was higher than that in compost treatment with C/N ≈ 35 (HL), while MGEs were completely degraded in HL and enriched by 2.3% in LL. The large reduction in the relative abundance of ARGs was possibly due to a decrease in the potential host bacterial genera, such as Advenella, Tepidimicrobium, Proteiniphilum, Acinetobacter, Pseudomonas, Flavobacteria and Arcbacter. Partial least-squares path modeling (PLS-PM) revealed that the succession of bacterial communities played a more important role than MGEs in ARGs removal, while indirect factors of the fungal communities altered the profile of ARGs by affecting the bacterial communities. Both direct and indirect factors were affected by composting treatments. This study provides insights into the role of fungal communities in affecting ARGs and highlights the role of different composting treatments with different carbon to nitrogen ration on the underlying mechanism of ARGs removal.202134375241
7880110.9061The synergistic mechanism of β-lactam antibiotic removal between ammonia-oxidizing microorganisms and heterotrophs. Nitrifying system is an effective strategy to remove numerous antibiotics, however, the contribution of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) and heterotrophs for antibiotic removal are still unclear. In this study, the mechanism of β-lactam antibiotic (cefalexin, CFX) removal was studied in a nitrifying sludge system. Results showed that CFX was synergistically removed by AOB (Nitrosomonas, played a major role) and AOA (Candidatus_Nitrososphaera) through ammonia monooxygenase-mediated co-metabolism, and by heterotrophs (Pseudofulvimonas, Hydrogenophaga, RB41, Thauera, UTCFX1, Plasticicumulans, Phaeodactylibacter) through antibiotic resistance genes (ARGs)-encoded β-lactamases-mediated hydrolysis. Regardless of increased archaeal and heterotrophic CFX removal with the upregulation of amoA in AOA and ARGs, the system exhibited poorer CFX removal performance at 10 mg/L, mainly due to the inhibition of AOB. This study provides new reference for the important roles of heterotrophs and ARGs, opening the possibilities for the application of ARGs in antibiotic biodegradation.202336174754
8070120.9061Impacts of combined pollution under gradient increasing and gradient decreasing exposure modes on activated sludge: Microbial communities and antibiotic resistance genes. The responses of microbial communities and antibiotic resistance genes (ARGs) to azithromycin and copper combined pollution under gradient increasing (from 0.5 to 10 mg/L) and decreasing exposure (from 10 to 0.5 mg/L) modes were investigated. Nitrification was inhibited more obviously under gradient increasing exposure mode. Responses of archaeal community and function structure were more obvious than bacteria under both exposure modes. The dominant bacterial and archaeal compositions (Hyphomicrobium, Euryarchaeota, etc.) were affected by two exposure modes, except some rare archaea (Methanoregula and Methanosarcina). There were more positive correlations between bacteria and archaea, and Nitrospira was keystone genus. Ammonia-oxidizing archaea (0.37-3.06%) and complete ammonia oxidizers (Nitrospira_ENR4) were enriched, and Nitrososphaera_viennensis was closely related to denitrifying genes (napA/B, nosZ, etc.). 50 ARG subtypes were detected and specific ARG subtypes (aac, ImrA, etc.) proliferated in two exposure modes. Bacteria and archaea were common hosts for 24 ARGs and contributed to their shifts.202234921920
8117130.9061Composting of oxytetracycline fermentation residue in combination with hydrothermal pretreatment for reducing antibiotic resistance genes enrichment. Hydrothermal pretreatment can efficiently remove the residual antibiotics in oxytetracycline fermentation residue (OFR), but its effect on antibiotic resistance genes (ARGs) during composting remains unclear. This study compared the shifts in bacterial community and evolutions in ARGs and integrons during different composting processes of OFRs with and without hydrothermal pretreatment. The results demonstrated that hydrothermal pretreatment increased the bacterial alpha diversity at the initial phase, and increased the relative abundances of Proteobacteria and Actinobacteria but decreased that of Bacteroidetes at the final phase by inactivating mycelia and removing residual oxytetracycline. Composting process inevitably elevated the abundance and relative abundance of ARGs. However, the increase in ARGs was significantly reduced by hydrothermal pretreatment, because the removal of oxytetracycline decreased their potential host bacteria and inhibited their horizontal gene transfer. The results demonstrated that hydrothermal pretreatment is an efficient strategy to reduce the enrichment of ARGs during the OFR composting.202033099099
7643140.9059Heterofermentative Lentilactobacillus buchneri and low dry matter reduce high-risk antibiotic resistance genes in corn silage by regulating pathogens and mobile genetic element. The study of antibiotic resistance in the silage microbiome has attracted initial attention. However, the influences of lactic acid bacteria inoculants and dry matter (DM) content on antibiotic resistance genes (ARGs) reduction in whole-plant corn silage remain poorly studied. This study accessed the ARGs' risk and transmission mechanism in whole-plant corn silage with different DM levels and treated with Lactiplantibacillus plantarum or Lentilactobacillus buchneri. The macrolide and tetracycline were the main ARGs in corn silage. The dominant species (Lent. buchneri and Lactobacillus acetotolerans) were the main ARGs carriers in whole-plant corn silage. The application of Lent. buchneri increased total ARGs abundance regardless of corn DM. Whole-plant corn silage with 30 % DM reduced the abundances of integrase and plasmid compared with 40 % DM. The correlation and structural equation model analysis demonstrated that bacterial community succession, resulting from changes in DM content, was the primary driving factor influencing the ARGs distribution in whole-plant corn silage. Interestingly, whole-plant corn silage inoculated with Lent. buchneri reduced abundances of high-risk ARGs (mdtG, mepA, tetM, mecA, vatE and tetW) by regulating pathogens (Escherichia coli), mobile genetic elements (MGEs) genes (IS3 and IS1182), and this effect was more pronounced at 30 % DM level. In summary, although whole-plant corn silage inoculated with Lent. buchneri increased the total ARGs abundance at both DM levels, it decreased the abundance of high-risk ARGs by reducing the abundances of the pathogens and MGEs, and this effect was more noticeable at 30 % DM level.202439241365
6921150.9059Impacts of Chemical and Organic Fertilizers on the Bacterial Communities, Sulfonamides and Sulfonamide Resistance Genes in Paddy Soil Under Rice-Wheat Rotation. The responses of sulfonamides, sulfonamide-resistance genes (sul) and soil bacterial communities to different fertilization regimes were investigated by performing a field experiment using paddy soil with no fertilizer applied, chemical fertilizer applied, organic fertilizer applied, and combination of chemical and organic fertilizer applied. Applying organic fertilizer increased the bacterial community diversity and affected the bacterial community composition. Eutrophic bacteria (Bacteroidetes, Gemmatimonadetes, and Proteobacteria) were significantly enriched by applying organic fertilizer. It was also found organic fertilizer application increased sulfamethazine content and the relative abundances of sul1 and sul2 in the soil. In contrast, applying chemical fertilizer significantly increased the abundance of Nitrospirae, Parcubacteria, and Verrucomicrobia and caused no obvious changes on sul. Correlation analysis indicated that sul enrichment was associated with the increases in sulfamethazine content and potential hosts (e.g., Novosphingobium and Rhodoplanes) population. The potential ecological risks of antibiotics in paddy soil with organic fertilizer applied cannot be ignored.202236547725
7973160.9055Microplastic and antibiotic proliferated the colonization of specific bacteria and antibiotic resistance genes in the phycosphere of Chlorella pyrenoidosa. Despite that the phycosphere was an important niche for the proliferation of various bacteria and antibiotic resistance genes (ARGs), the factors that affect the colonization of bacteria and ARGs in the phycosphere are still poorly understood. In this study, sterile C. pyrenoidosa co-cultured with bacteria from different sources and provided with polylactic acid microplastic (PLA MPs) and florfenicol (FF) was examined. Results showed that bacteria promoted the growth of C. pyrenoidosa and increased its chlorophyll contents. PLA MPs and FF also showed positive effects on C. pyrenoidosa due to the "Hormesis effect". The occurrence of bacteria in the phycosphere was significantly affected by their sources and the addition of PLA MPs and FF. However, the core microbiota of the phycosphere in each group was similar. Additionally, PLA MPs and FF proliferated the abundance of phenicol-related ARGs (especially floR) and mobile genetic elements in the phycosphere. Notably, PLA MPs and FF enhanced the abundance of Flavobacterium, a potential host of ARGs. Our results highlighted the important roles of bacteria in microalgae and demonstrated exogenous pollutants could promote the spread of ARGs between surrounding environments and the phycosphere, which provide new insights into the occurrence and spread of ARGs in the phycosphere.202337201280
6937170.9055Differential responses of bacterial and archaeal communities to biodegradable and non-biodegradable microplastics in river. Microplastics are widespread environmental pollutants that pose risks to ecosystems, yet their effects on bacterial and archaeal communities in aquatic ecosystems remain understudied. In this study, we performed a 14-day microcosm experiment combined with metagenomic sequencing to compare bacterial and archaeal responses to a biodegradable microplastic (polylactic acid, PLA) and a non-biodegradable microplastic (polyvinyl chloride, PVC). Microplastics selectively enriched distinct microbial assemblages, with Pseudomonadota and Euryarchaeota identified as the dominant bacterial and archaeal phyla, accounting for 67.83 % and 15.95 %, respectively. Archaeal community in surrounding water were more sensitive to colonization time than bacterial community. Compared to the surrounding water, the plastisphere displayed simpler and more loosely connected microbial networks. Notably, co-occurrence networks of both bacteria and archaea in the PVC plastisphere were predominantly shaped by symbiotic interactions. Both bacteria and archaea carried diverse antibiotic resistance genes (ARGs), but PLS-PM indicated that bacteria were the primary drivers of ARG dissemination (path coefficient = 0.952). While the PVC plastisphere showed higher ARG abundance than the PLA plastisphere, elevated intI1 expression in the PLA plastisphere suggests a potentially greater risk of ARG dissemination associated with PLA microplastics. These findings reveal the distinct effects of PLA and PVC microplastics on microbial communities and highlight the role of microplastics in ARG dissemination, emphasizing their ecological risks in aquatic ecosystems.202540712359
8118180.9055Effects of biocontrol Bacillus and fermentation bacteria additions on the microbial community, functions and antibiotic resistance genes of prickly ash seed oil meal-biochar compost. This study evaluated the effects of biocontrol Bacillus and fermenting bacteria addition on the microbial community, metabolic functions and antibiotic resistance genes (ARGs) of new prickly ash seed oil meal (PSOM)-biochar composting. The results showed that the addition of Bacillus subtilis and fermentation bacteria significantly increased the NH(4)(+)-N, bacterial abundance and fungal diversity of compost while decreasing the relative abundances (RAs) of carbon metabolism genes in mature compost. NH(4)(+)-N was significantly correlated with microbial abundance and diversity, and its increase was closely related to microbial amino acid metabolism. The addition of biocontrol and fermenting bacteria changed the RAs of ARGs, which was caused by changes in the potential hosts Proteobacteria, Bacteroidota and Firmicutes in the compost. Consequently, adding Bacillus and fermenting bacteria into PSOM to make composting was suggested as an effective method to promote nutrient transformation, regulate microbial activity and decrease RAs of tetracycline and vancomycin ARGs.202134339999
7972190.9054Sulfadiazine proliferated antibiotic resistance genes in the phycosphere of Chlorella pyrenoidosa: Insights from bacterial communities and microalgal metabolites. The phycosphere is an essential ecological niche for the proliferation of antibiotic resistance genes (ARGs). However, how ARGs' potential hosts change and the driving mechanism of metabolites under antibiotic stress in the phycosphere have seldom been researched. We investigated the response of Chlorella pyrenoidosa and the structure and abundance of free-living (FL) and particle-attached (PA) bacteria, ARGs, and metabolites under sulfadiazine by using real-time quantitative PCR, 16 S rRNA high-throughput. The linkage of key bacterial communities, ARGs, and metabolites through correlations was established. Through analysis of physiological indicators, Chlorella pyrenoidosa displayed a pattern of "low-dose promotion and high-dose inhibition" under antibiotic stress. ARGs were enriched in the PA treatment groups by 117 %. At the phylum level, Proteobacteria, Bacteroidetes, and Actinobacteria as potential hosts for ARGs. At the genus level, potential hosts included Sphingopyxis, SM1A02, Aquimonas, Vitellibacter, and Proteiniphilum. Middle and high antibiotic concentrations induced the secretion of metabolites closely related to potential hosts by algae, such as phytosphingosine, Lysophosphatidylcholine, and α-Linolenic acid. Therefore, changes in bacterial communities indirectly influenced the distribution of ARGs through alterations in metabolic products. These findings offer essential details about the mechanisms behind the spread and proliferation of ARGs in the phycosphere.202438795485