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Graphical abstract Highlights • Hydrothermal treatment (HT) is effective to remove lincomycin resistance genes. • Mobile genetic elements (MGEs) were also reduced efficiently during HT. • The fate of target genes was described using biphasic first-order kinetic model. • Heavy metals transformed from weakly bounded to stable state after HT. • Environmental risk of heavy metals was declined after HT. Abstract In this study, fate of antibiotic resistance genes (ARGs – lmr A, lmr B, erm B, lnu A, lnu B and vga C) and species distribution of heavy metals during lincomycin mycelial residues hydrothermal treatment (HT) process were investigated. The results showed that HT could reduce both ARGs and mobile genetic elements effectively by 1.02 to 4.14 logs. Total bacterial biomass reflecting by 16S rRNA decreased from 1.27 × 109 to 4.47 × 105 copies g−1 dry weight. Moreover, half-lives of these targets varied from 2.4 min (erm B) to 8.9 min (lmr B) in the first 30 min of treatment based on a biphasic first-order kinetic model. After the first 30 min, however, half-lives ranged between 15.4 min (lmr A) and 247.6 min (ISCR 1). Complexation and precipitation resulted in the transformation of heavy metals from weakly bounded to relatively stable fraction in HT process. Simultaneously, their environmental risk level decreased by at least one grade. [ABSTRACT FROM AUTHOR]

• TAP effectively promoted the disintegration and solubilization of SFR. • The high level of residual SPM could be completely eliminated by TAP. • The antibacterial activity of SPM was greatly reduced after TAP treatment. • The Antibiotic resistance genes could be almost inactivated. Spiramycin fermentation residue (SFR) can be managed to recycle organic substances through bioprocesses. However, its rigid matrix structure and high residual antibiotic of spiramycin (SPM) are not conducive to the high efficiency of bioprocesses. The pretreatment of SFR by thermally activated peroxydisulfate (TAP) was first employed for improving its biodegradability by matrix structure disintegration and residual SPM degradation. The results demonstrated that the SFR were efficiently disintegrated to smaller particles. The effective destruction of SFR matrix structure was predicted by the release of carbohydrates and proteins, and was intuitively confirmed by scanning electron microscopy (SEM). The production of dissolved organic matters was clearly enhanced by TAP treatment, but the increment decreased with the increase of PDS dosage due to the mineralization of radicals. The degradation of SPM fitted to first-order kinetics model, and its degradation rate was promoted by increasing PDS dosage, increasing activation temperature and decreasing pH. The degradation pathway of SPM was mainly the separation of sugar groups (mycarose, mycaminose and forosamine) from the lactone ring, and the final oxidation product of SPM that have been identified was predicted to be harmless. The efficient and powerful TAP might be a suitable pretreatment approach for improving the biodegradability of SFR. [ABSTRACT FROM AUTHOR]

• An effective dehalogenation electrocatalyst of Fe‒CoP NTs/NiF is developed. • The electrocatalyst exhibits a superior dehalogenation performance towards FLO. • Dehalogenation pretreatment of FLO guarantees microbial richness and diversity. • Dehalogenation pretreatment of FLO reduces resistance genes expression. Resistance gene expression and microbial inhibition by halogenated antibiotics is a major environmental concern. Although electrocatalytic dehalogenation can detoxify halogenated antibiotics, the effect of dehalogenation treatment on resistance gene expression and microbial inhibition is poorly understood. Herein, a novel electrocatalyst of Fe-doped CoP nanotubes array on nickel foam (Fe-CoP NTs/NiF) is prepared through a simple ultrasonication of Fe-doped CoP nanowires hydrothermally grown on NiF. The transformation from nanowires to nanotubes improves the crystallinity of CoP and fully exposes active sites, producing energetic atomic hydrogen for dehalogenation. Fe-CoP NTs/NiF exhibits a superior dehalogenation performance towards refractory florfenicol (FLO), achieving 100% removal within 20 min (‒1.2 V vs Ag/AgCl, C 0 = 20 mg L‒1). The dechlorination ratio reaches nearly 100%, and the defluorination ratio achieves 36.8% within 50 min, showing the best electrocatalytic dehalogenation performance reported so far. Microbial community and correlation analysis show that Proteobacteria is the main potential host of FLO resistance gene. Electrocatalytic reductive dehalogenation pretreatment of FLO can reduce microbial inhibition, maintaining microbial richness and diversity in the subsequent biochemical treatment unit. The electrocatalytic reductive dehalogenation treatment can significantly reduce the relative abundance of FLO resistance gene, showing a reliable process for safe treatment of halogenated antibiotic containing wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hydrothermal treatment (HT) is effective to remove residual erythromycin and ARGs. • The hydrolysate exists certain antimicrobial activity against S. aureus. • HT enhanced the release of the protein-like polymers for bioenergy recycling. • The obtained solid products have the higher heating value of approx. 20 MJ/kg. • Hydrothermal technology was proved effective to recycle and harmlessly dispose EFR. Erythromycin fermentation residue (EFR) is a byproduct of bio-fermentation process for producing erythromycin, representing both an economic and environmental burden for the pharmaceutical industry. While hydrothermal treatment (HT) can solve the pollution and toxic problems, the impacts of HT on harmless performance and the bioresource properties of the complex EFR matrix remain unclear. In this study, the abatement of residual erythromycin, its associated antibiotic resistance genes and antimicrobial activity were investigated to evaluate the harmless performance of HT for EFR, and the feasibility of recycling hydrolysates as bioenergy was also assessed. The results showed that raising HT temperature significantly improved the harmless performance. The removal rate of residual erythromycin in EFR reached over 88% and the total absolute abundance of erythromycin resistance genes decreased by more than 3 logs with HT at 160°C for 60 min, but the hydrolysates still existed specific antimicrobial activity against S. aureus.. Additionally, the HT temperature remarkably influenced the bioresource properties of EFR-hydrolyzed products. The release of the protein-like polymers into the liquid phase was enhanced, while high HT temperature worsened the nutrient substances. The elevated drying property of solid products from EFR was observed along with the higher heating value of around 20 MJ/kg, indicating a potential of recycling solid products as biofuel. Total energy production from biogas conversion and biofuel incineration treating 1.0 kg raw EFR was 1875 kJ. Hydrothermal technology was proved to realize the harmless treatment of EFR and meanwhile to be promising for recycling EFR as bioenergy. [ABSTRACT FROM AUTHOR]

Erythromycin fermentation residue (EFR) is the precipitation of fermentative biowaste used for extracting erythromycin (ERY) and may be disposed via land application after heat-activated persulfate (PS) oxidation treatment. However, the effects of the treated EFR as a soil amendment on soil chemical properties and the potential resistance risks caused by introduced ERY remain unclear. Here, a laboratory soil incubation experiment was performed to investigate the soil pH, salinity, introduced antibiotics, antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs), as well as bacterial community structure in the treated EFR-amended soil. The results indicated that pH in treated EFR-amended soil decreased firstly and then increased. The salinity of soil increased but soil was still non-saline soil. In addition, the introduced ERY in the treated EFR-amended soil decreased with the half-life of 12.3 d. Moreover, the relative abundances of ERY resistance genes and MGEs in the treated EFR-amended soil were much lower than those in the control at the end of incubation. Bacterial community structure in the treated EFR-amended soil converged to similar structure in control soil after 49 d incubation. Our results showed that heat-activated PS oxidation treatment of EFR prior to application to soil might be in favor of limiting the spread of ERY resistance genes and MGEs. Unlabelled Image • The introduced erythromycin showed a decline trend with the half-life of 12.3 d. • The heat-activated persulfate treated EFR did not enrich resistance genes in soil. • The effect of heat-activated PS treated EFR on soil bacteria was alleviated. • Genes relative abundances were influenced by bacterial community structure. [ABSTRACT FROM AUTHOR]

Land utilization of the biogas residue (BR) produced by anaerobic co-digestion of gentamicin mycelial residues (GMRs) and wheat straw is a promising method to achieve the deep recycling of GMRs. This study evaluated the feasibility and efficacy of application of using BR as a soil amendment by using a pot experiment. Results indicated that BR could improve the soil fertility better than commercial chicken manure fertilizer (CMF) in terms of the soil enzyme activities and nutrients supply. Random Forest (RF) model was applied to predict soil enzyme activities and identify key influencing factors. Combining the Random Forest (RF) model with the Three-dimensional Excitation–emission Matrix and Parallel Factor (3D-EEM-PARAFAC) analysis, revealing that humic-like substances provided by BR protected soil enzymes, thus improving soil fertility. Furthermore, gentamicin and antibiotic resistance genes (ARGs)/mobile genetic elements (MEGs) introduced by BR decreased greatly after cultivation, implying a low risk of antimicrobial resistance. This study suggested that reasonable application of BR could improve soil nutrients supply, soil enzyme activity and control antimicrobial resistance risk. [Display omitted] • BR increased the supply of soil nutrients and humic-acid substances. • BR performed better than CMF in the enhancement of soil enzyme activities. • RF model combined with EEM-PARAFAC was first applied in the cultivation process. • Microbial analysis indicated BR had more readily biodegradable matters than CMF. • Long cultivation cycle favored gentamicin degradation and ARGs attenuation. [ABSTRACT FROM AUTHOR]

Tetracycline mycelial residue (TMR), a byproduct derived from the tetracycline fermentation process, is rich in organic matter, making it a promising resource. However, the presence of residual tetracycline and antibiotic resistance genes (ARGs) limits its potential for resource utilization. In this study, torrefaction was employed for the harmless treatment of low-moisture TMR, and the optimized condition was 200.0 °C for 30.0 min. Under this condition, 97.2% of tetracycline (TC) in TMR could be efficiently removed, with more organic matter reserved for resource utilization. The plausible degradation pathway was proposed, involving the formation of lactone structure and anhydro-tetracycline (ATC) during TC degradation, followed by a series of reactions among main functional groups, including concerted reactions, retro-Diels-Alder (RDA), cleavage reactions, and rearrangement. Furthermore, the antibacterial efficacy of degradation products from TC has significantly diminished, and the structure of ARGs and bacteria was disrupted during the torrefaction of TMR. After the treated TMR was amended into the soil as fertilizer, the dissemination of ARGs could also be effectively controlled. Therefore, torrefaction could be recommended as a promising harmless treatment for the resource utilization of low-moisture TMR. [Display omitted] • 97.2% of tetracycline in TMR was removed through torrefaction (200.0 °C, 30.0 min). • The products (200.0 °C, 30.0 min) showed no significant inhibition on the target bacteria. • The antibiotic resistance genes (ARGs) in TMR could be greatly removed. • No significant spread of ARGs was observed in the soil amended with treated TMR. [ABSTRACT FROM AUTHOR]

In this study, aerobic co-composting of tylosin fermentation dregs (TFDs) and sewage sludge with different adding concentrations of copper (Cu) was investigated to inspect the fate of antibiotic resistance genes (ARGs), metal resistance genes (MRGs) and mobile genetic elements (MGEs). Results showed that two concentrations of Cu did affect not only the abiotic factors but the relative abundances of resistance genes. High concentration of Cu inhibited the metabolic capacity of microbial community and the nitrogen-fixing process while had little effect on the degradation of TYL and TOC. The abundance of ermT , mefA , mphA increased partly attributed to the toxic effects and co-selective pressure from heavy metal reflected by MRGs. There was significant correlation among some environmental factors like pH, bio-Cu, organic matters and ARGs. [ABSTRACT FROM AUTHOR]

The antibiotic mycelial residue (AMR), a bio-waste, always generated with the antibiotics production by fermentation. It could lead to serious environmental risks after discharge due to the antibiotic residues. To date various harmless treatment processes for AMR have been investigated, while there is still lack of a systematic summary. In this review, typical treatments were comprehensively summarized and critically appraised according to the treatment cost, secondary pollution, operation difficulty and security. It was concluded that the aerobic composting was regarded as the most promising and feasible treatment process for AMR, because the huge dehydration cost and tedious post-treatment of digestate could be avoided while effectively reducing the antibiotic residues in AMR. However, the safety assessment of the AMR fertilizer is necessary, and a comprehensive assessment should include fertilizer quality, the fertilized soil quality, antibiotic residues and the antibiotic resistance risk. For the further research, the safety limit of antibiotic content in fertilizer was discussed as well as the source control for the spread of antibiotic resistance in fertilizer, which is of great significance to control the antibiotic resistance of AMR fertilizer. [Display omitted] • Harmless treatment processes of antibiotic mycelial residue (AMR) are appraised. • Aerobic composting of AMR is more feasible and promising. • The safety assessment for the AMR fertilizer are summarized. • Methods for the antibiotic limit in fertilizer is discussed. • The source control for antibiotic resistance of fertilizers is explored. [ABSTRACT FROM AUTHOR]

To reduce the adverse effects of antibiotics and antibiotic resistance genes (ARGs) in the environment, nitrogen-doped biochar (NLBH), derived from lincomycin fermentation dregs (LFD), was employed as an activator in a persulfate (PDS) oxidation system. The system was evaluated for its ability to degrade tetracycline (TC), inactivate antibiotic resistant bacteria (ARB) and remove ARGs. The degradation efficiency of TC in the NLBH/PDS system (70.1%) was higher than that in the pristine biochar/PDS system (10.3%). It was confirmed that the defects and edge pyridinic nitrogen generated in the nitrogen doping process were the reactive sites for PDS activation. According to electron paramagnetic resonance (EPR) and radical quenching experiments, the major mechanism for PDS activation was a non-radical pathway dominated by singlet oxygen (1O 2). Radical pathways involving sulfate (SO 4 ·-) and hydroxyl radicals (·OH) were also at play in the NLBH/PDS system, but their role was minor. TC was principally degraded by hydroxylation, demethylation, and decarboxylation, and within 90 min, the NLBH/PDS system effectively inactivated 71.5% of ARB (Pseudomonas sp. HLS-6). Intracellular ARGs (iARGs; sul 1, sul 2) and intI 1 had log reduction efficiencies of 2.73–4.04 and 2.70, respectively, whereas, extracellular ARGs (sul 1 and sul 2) and intI 1 accumulated noticeably by 1.52–4.18-and 4.92-log, respectively. This work highlights a promising alternative technique for the removal of antibiotics, ARB and iARGs in future advanced wastewater treatment systems. [Display omitted] • N-doped biochar exhibited excellent performance for PDS activation. • Pyridinic N and defects in N-doped biochar might be the essential catalytic sites. • Nonradical pathway involved 1O 2 makes major contribution on pollutants removal. • More than 70% of TC and ARBs were degraded and inactivated in reaction system. • A 4.04-log reduction of iARGs was achieved in N-doped biochar/PDS system. [ABSTRACT FROM AUTHOR]

• A flexible filter-membrane-like peroxydisulfate-coupled photocatalytic system is developed. • The system can produce energetic active species (·OH, SO 4 ·−, h +, O 2 ·− and 1O 2). • The system exhibits a superior performance towards tetracycline degradation. • The pretreatment guarantees microbial diversity and richness. • The pretreatment reduces the emergence and dissemination risk of antibiotic resistance genes. The direct biological treatment of antibiotics containing wastewater brings about a potential risk of antibiotic resistance genes (ARGs) spread. Although advanced oxidation technologies based on photocatalysis generally appear effective at degrading antibiotics in wastewater, the fate of ARGs in succeeding biological treatment system is still unknown. Herein, a filter-membrane-like carbon cloth-immobilized Fe 2 O 3 /g-C 3 N 4 photocatalyst is fabricated through immersion-calcination method. Peroxydisulfate-coupled photocatalysis system is developed to degrade tetracycline (TC, an emerging refractory antibiotic pollutant). The system can produce energetic active species (·OH, SO 4 ·−, h +, O 2 ·− and 1O 2), exhibiting a superior performance towards TC degradation in static and continuous flow processes under visible-light irradiation. The pretreatment can eliminate the antibacterial activity of antibiotics wastewater, and the chemical oxygen demand removal is greatly enhanced in subsequent anaerobic or aerobic process. The microbial diversity and richness in activated sludge for pretreated water sample are significantly higher than those for the water sample without pretreatment. Meanwhile, the pretreatment can decrease the relative abundance of potential hosts of ARGs and reduce the emergence as well as dissemination risk of ARGs. This study uncovers the effect of pretreatment of antibiotics containing wastewater using advanced oxidation technologies on the treatment efficacy and antibiotic resistome fate in biological treatment system. [Display omitted] [ABSTRACT FROM AUTHOR]

Alkaline-thermal (AT) pretreatment is an economical and efficient pretreatment method to improve anaerobic biodegradability of biowaste. This study investigated the effect of AT pretreatment of spectinomycin mycelial residues (SMRs) for promoting anaerobic biodegradability along with the reduction of antibiotic resistance genes (ARGs), and thus obtained the optimal conditions of AT pretreatment. Biomethane potential (BMP) test was conducted to evaluate the anaerobic biodegradability of untreated and pretreated SMRs, and the fate of ARGs was tracked by quantitative polymerase chain reaction. Results showed that the modified Gompertz model fitted the results of BMP tests satisfactorily. Furthermore, AT pretreatment promoted BMP (B 0) and reduced lag phase (λ) effectively. These were attributed to the solubilization of SMRs. The analyses of the changes in dissolved organic matter indicated that AT pretreatment could facilitate the solubilization of both biodegradable (e.g. protein) and recalcitrant matter (e.g. humic-like, analyzing by EEMs-PARAFAC), which had a significant corresponding positive (Person correlation, p < 0.01) and negative (Partial correlation, p < 0.01) influences on anaerobic biodegradability. However, the positive effects surpassed the negative effects, promoting the overall anaerobic biodegradability of SMRs. In addition, a considerable reduction of ARGs (by 0.62–1.36 log units) was observed at pH ≥ 12, attributed to the hydrolysis of phosphodiester bond of DNA in strong alkaline solution. Considering both anaerobic biodegradability and ARGs, the optimal AT condition was concluded as pH 12, temperature 90 °C and time 120 min. Image 1 • Based on PARAFAC analysis, AT pretreatment accumulated humic-like substances. • The modified Gompertz model fitted the results of BMP tests satisfactorily. • Partial correlation analysis discerned potential bad effects of humic-like on AD. • pH ≥ 12 was proposed to reduce the abundance of ARGs of SMRs in AT pretreatment. [ABSTRACT FROM AUTHOR]