Occurrence, transmission and risks assessment of pathogens in aquatic environments accessible to humans.

Pathogens are ubiquitously detected in various natural and engineered water systems, posing potential threats to public health. However, it remains unclear which human-accessible waters are hotspots for pathogens, how pathogens transmit to these waters, and what level of health risk associated with pathogens in these environments. This review collaboratively focuses and summarizes the contamination levels of pathogens on the 5 water systems accessible to humans (natural water, drinking water, recreational water, wastewater, and reclaimed water). Then, we showcase the pathways, influencing factors and simulation models of pathogens transmission and survival. Further, we compare the health risk levels of various pathogens through Quantitative Microbial Risk Assessment (QMRA), and assess the limitations of water-associated QMRA application. Pathogen levels in wastewater are consistently higher than in other water systems, with no significant variation for Cryptosporidium spp. among five water systems. Hydraulic conditions primarily govern the transmission of pathogens into human-accessible waters, while environmental factors such as temperature impact pathogens survival. The median and mean values of computed public health risk levels posed by pathogens consistently surpass safety thresholds, particularly in the context of recreational waters. Despite the highest pathogens levels found in wastewater, the calculated health risk is significantly lower than in other water systems. Except pathogens concentration, variables like the exposure mode, extent, and frequency are also crucial factors influencing the public health risk in water systems. This review shares valuable insights to the more accurate assessment and comprehensive management of public health risk in human-accessible water environments.

Molecular Mechanism of Chloramphenicol and Thiamphenicol Resistance Mediated by a Novel Oxidase, CmO, in Sphingomonadaceae.

Antibiotic resistance mediated by bacterial enzyme inactivation plays a crucial role in the degradation of antibiotics in the environment. Chloramphenicol (CAP) resistance by enzymatic inactivation comprises nitro reduction, amide bond hydrolysis, and acetylation modification. However, the molecular mechanism of enzymatic oxidation of CAP remains unknown. Here, a novel oxidase gene, cmO, was identified and confirmed biochemically. The encoded CmO oxidase could catalyze the oxidation at the C-1' and C-3' positions of CAP and thiamphenicol (TAP) in Sphingobium sp. strain CAP-1. CmO is highly conserved in members of the family Sphingomonadaceae and shares the highest amino acid similarity of 41.05% with the biochemically identified glucose methanol choline (GMC) oxidoreductases. Molecular docking and site-directed mutagenesis analyses demonstrated that CAP was anchored inside the protein pocket of CmO with the hydrogen bonding of key residues glycine (G) 99, asparagine (N) 518, methionine (M) 474, and tyrosine (Y) 380. CAP sensitivity tests demonstrated that the acetyltransferase and CmO could enable a higher level of resistance to CAP than the amide bond-hydrolyzing esterase and nitroreductase. This study provides a better theoretical basis and a novel diagnostic gene for understanding and assessing the fate and resistance risk of CAP and TAP in the environment. IMPORTANCE Rising levels of antibiotic resistance are undermining ecological and human health as a result of the indiscriminate usage of antibiotics. Various resistance mechanisms have been characterized-for example, genes encoding proteins that degrade antibiotics-and yet, this requires further exploration. In this study, we report a novel gene encoding an oxidase involved in the inactivation of typical amphenicol antibiotics (chloramphenicol and thiamphenicol), and the molecular mechanism is elucidated. The findings provide novel data with which to understand the capabilities of bacteria to tackle antibiotic stress, as well as the complex function of enzymes in the contexts of antibiotic resistance development and antibiotic removal. The reported gene can be further employed as an indicator to monitor amphenicol's fate in the environment, thus benefiting risk assessment in this era of antibiotic resistance.

Complementary Biotransformation of Antimicrobial Triclocarban Obviously Mitigates Nitrous Oxide Emission toward Sustainable Microbial Denitrification.

Sustainable nitrogen cycle is an essential biogeochemical process that ensures ecosystem safety and byproduct greenhouse gas nitrous oxide reduction. Antimicrobials are always co-occurring with anthropogenic reactive nitrogen sources. However, their impacts on the ecological safety of microbial nitrogen cycle remain poorly understood. Here, a denitrifying bacterial strain Paracoccus denitrificans PD1222 was exposed to a widespread broad-spectrum antimicrobial triclocarban (TCC) at environmental concentrations. The denitrification was hindered by TCC at 25 µg L-1 and was completely inhibited once the TCC concentration exceeded 50 µg L-1. Importantly, the accumulation of N2O at 25 µg L-1 of TCC was 813 times as much as the control group without TCC, which attributed to the significantly downregulated expression of nitrous oxide reductase and the genes related to electron transfer, iron, and sulfur metabolism under TCC stress. Interestingly, combining TCC-degrading denitrifying Ochrobactrum sp. TCC-2 with strain PD1222 promoted the denitrification process and mitigated N2O emission by 2 orders of magnitude. We further consolidated the importance of complementary detoxification by introducing a TCC-hydrolyzing amidase gene tccA from strain TCC-2 into strain PD1222, which successfully protected strain PD1222 against the TCC stress. This study highlights an important link between TCC detoxification and sustainable denitrification and suggests a necessity to assess the ecological risks of antimicrobials in the context of climate change and ecosystem safety.

Determining the Contribution of Micro/Nanoplastics to Antimicrobial Resistance: Challenges and Perspectives.

Microorganisms colonizing the surfaces of microplastics form a plastisphere in the environment, which captures miscellaneous substances. The plastisphere, owning to its inherently complex nature, may serve as a "Petri dish" for the development and dissemination of antibiotic resistance genes (ARGs), adding a layer of complexity in tackling the global challenge of both microplastics and ARGs. Increasing studies have drawn insights into the extent to which the proliferation of ARGs occurred in the presence of micro/nanoplastics, thereby increasing antimicrobial resistance (AMR). However, a comprehensive review is still lacking in consideration of the current increasingly scattered research focus and results. This review focuses on the spread of ARGs mediated by microplastics, especially on the challenges and perspectives on determining the contribution of microplastics to AMR. The plastisphere accumulates biotic and abiotic materials on the persistent surfaces, which, in turn, offers a preferred environment for gene exchange within and across the boundary of the plastisphere. Microplastics breaking down to smaller sizes, such as nanoscale, can possibly promote the horizontal gene transfer of ARGs as environmental stressors by inducing the overgeneration of reactive oxygen species. Additionally, we also discussed methods, especially quantitatively comparing ARG profiles among different environmental samples in this emerging field and the challenges that multidimensional parameters are in great necessity to systematically determine the antimicrobial dissemination risk in the plastisphere. Finally, based on the biological sequencing data, we offered a framework to assess the AMR risks of micro/nanoplastics and biocolonizable microparticles that leverage multidimensional AMR-associated messages, including the ARGs' abundance, mobility, and potential acquisition by pathogens.

Enhancing harvest of biodiesel-promising microalgae using Daphnia domesticated by amino acids.

Mass production of microalgal biodiesel is hindered by microalgae harvesting efficiency and costs. In this study, Daphnia domesticated by amino acids were used to harvest microalgae via ingesting. The main factors (density of Daphnia, salinity, pH, light-environment, temperature and algal concentration) that were conducive to Daphnia feeding were optimized. Under the optimal condition, Microalgae-feeding Daphnia were domesticated by adding D-glutamic acid and L-cysteine as stimulating factors. After that, the ingestion rate of domesticated Daphnia increased by 24.93%. The presence of Daphnia as a predator can induce microalgae to mass into clusters. Combining Daphnia feeding and the inductive defense flocculation of microalgae, the harvesting rate of mixed algae (Chlorella pyrenoidosa and Scenedesmus obliquus) reached over 95% after 9 h. Overall, this work suggested that Daphnia feeding process is a green and economical approach for microalgae harvesting.

Bioelectrochemical catabolism of triclocarban through the cascade acclimation of triclocarban-hydrolyzing and chloroanilines-oxidizing microbial communities.

Chlorinated antimicrobial triclocarban (3,4,4'-trichlorocarbanilide, TCC) is an emerging refractory contaminant omnipresent in various environments. Preferential microbial hydrolysis of TCC to chloroanilines is essential for its efficient mineralization. However, the microbial mineralization of TCC in domestic wastewater is poorly understood. Here, the bioelectrochemical catabolism of TCC to chloroanilines (3,4-dichloroaniline and 4-chloroaniline) and then to CO2 was realized through the cascade acclimation of TCC-hydrolyzing and chloroanilines-oxidizing microbial communities. The biodegradation of chloroanilines was obviously enhanced in the bioelectrochemical reactors. Pseudomonas, Diaphorobacter, and Sphingomonas were the enriched TCC or chloroanilines degraders in the bioelectrochemical reactors. The addition of TCC enhanced the synergistic effect within functional microbial communities based on the feature of the phylogenetic ecological networks. This study provides a new idea for the targeted domestication and construction of functionally differentiated microbial communities to efficiently remove TCC from domestic wastewater through a green and low-carbon bioelectrochemical method.

Cuproof: Range Proof with Constant Size.

Zero-Knowledge Proof is widely used in blockchains. For example, zk-SNARK is used in Zcash as its core technology to identifying transactions without the exposure of the actual transaction values. Up to now, various range proofs have been proposed, and their efficiency and range-flexibility have also been improved. Bootle et al. used the inner product method and recursion to construct an efficient Zero-Knowledge Proof in 2016. Later, Benediky Bünz et al. proposed an efficient range proof scheme called Bulletproofs, which can convince the verifier that a secret number lies in [0,2κ-1] with κ being a positive integer. By combining the inner-product and Lagrange's four-square theorem, we propose a range proof scheme called Cuproof. Our Cuproof can make a range proof to show that a secret number v lies in an interval [a,b] with no exposure of the real value v or other extra information leakage about v. It is a good and practical method to protect privacy and information security. In Bulletproofs, the communication cost is 6+2logκ, while in our Cuproof, all the communication cost, the proving time and the verification time are of constant sizes.

Microbial Interactions Drive the Complete Catabolism of the Antibiotic Sulfamethoxazole in Activated Sludge Microbiomes.

Microbial communities are believed to outperform monocultures in the complete catabolism of organic pollutants via reduced metabolic burden and increased robustness to environmental challenges; however, the interaction mechanism in functional microbiomes remains poorly understood. Here, three functionally differentiated activated sludge microbiomes (S1: complete catabolism of sulfamethoxazole (SMX); S2: complete catabolism of the phenyl part of SMX ([phenyl]-SMX) with stable accumulation of its heterocyclic product 3-amino-5-methylisoxazole (3A5MI); A: complete catabolism of 3A5MI rather than [phenyl]-SMX) were enriched. Combining time-series cultivation-independent microbial community analysis, DNA-stable isotope probing, molecular ecological network analysis, and cultivation-dependent function verification, we identified key players involved in the SMX degradation process. Paenarthrobacter and Nocardioides were primary degraders for the initial cleavage of the sulfonamide functional group (-C-S-N- bond) and 3A5MI degradation, respectively. Complete catabolism of SMX was achieved by their cross-feeding. The co-culture of Nocardioides, Acidovorax, and Sphingobium demonstrated that the nondegraders Acidovorax and Sphingobium were involved in the enhancement of 3A5MI degradation. Moreover, we unraveled the internal labor division patterns and connections among the active members centered on the two primary degraders. Overall, the proposed methodology is promisingly applicable and would help generate mechanistic, predictive, and operational understanding of the collaborative biodegradation of various contaminants. This study provides useful information for synthetic activated sludge microbiomes with optimized environmental functions.

Microalgae harvesting by magnetic flocculation for biodiesel production: current status and potential.

With the increasing demand for energy, microalgae, as one of the promising feedstocks of biodiesel, has raised great awareness. Because of its small size, similar density to water and electrical stability, harvesting methods of microalgae that have low energy consumption and that are highly efficient, easy to large-scale and environmentally friendly have become a bottleneck restricting development of the whole process. Among the numerous possible harvesting methods, magnetic flocculation has the advantages of simple operation, fast separation and energy saving and thus is considered as a promising novel harvesting method. In this review, we have summarized the updated status and application potential of magnetic flocculation, including the principle of magnetic flocculation, magnetic flocculating materials, flocculating efficiency and its effect on downstream process. The major challenges such as magnetic materials recovery, large-scale magnetic flocculation device design, and magnetic flocculation costs are also discussed.

Effect of monoacylglycerol lipase on the tumor growth in endometrial cancer.

AIM: Abnormal lipid metabolism plays a dual role in tumorigenesis, specifically in the occurrence and development of cancers. Monoacylglycerol lipase (MAGL), a hydrolase that is important for lipid metabolism, plays a vital role in different aspects of tumorigenesis. Many studies have shown that MAGL is highly elevated in a variety of cancers and plays an active role. However, its potential role in supporting endometrial cancer (EC) growth and progression has not yet been explored in depth. METHODS: Immunohistochemistry and quantitative real-time reverse transcription polymerase chain reaction were performed to estimate the protein and messenger RNA (mRNA) levels of MAGL in tumor tissues. Then, JZL184 and small interfering RNA (siRNA) were used to decrease the expression of MAGL in EC cells. The gene and protein expression levels of MAGL were measured using quantitative real-time PCR and western blotting, respectively. Additionally, the effect of MAGL on tumor growth in EC was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide , cell cycle and western blotting assay in vitro. RESULTS: We found that MAGL was overexpressed in EC and was significantly correlated with surgical-pathological stage, myometrial invasion, number of pregnancies and body mass index. The growth and cell cycle progression of tumor cells were significantly impaired in vitro by the pharmacological and siRNA-mediated MAGL inhibition. In addition, MAGL inhibition seemed to repress two target genes, Cyclin D1 and Bcl-2. CONCLUSION: In summary, we have demonstrated that MAGL is involved in EC growth and progression. Our results suggest that targeting MAGL may be a novel and valid treatment for EC.

Biodegradation of Polyethylene and Plastic Mixtures in Mealworms (Larvae of Tenebrio molitor) and Effects on the Gut Microbiome.

Recent studies have demonstrated the ability for polystyrene (PS) degradation within the gut of mealworms ( Tenebrio molitor). To determine whether plastics may be broadly susceptible to biodegradation within mealworms, we evaluated the fate of polyethylene (PE) and mixtures (PE + PS). We find that PE biodegrades at comparable rates to PS. Mass balances indicate conversion of up 49.0 ± 1.4% of the ingested PE into a putative gas fraction (CO2). The molecular weights ( Mn) of egested polymer residues decreased by 40.1 ± 8.5% in PE-fed mealworms and by 12.8 ± 3.1% in PS-fed mealworms. NMR and FTIR analyses revealed chemical modifications consistent with degradation and partial oxidation of the polymer. Mixtures likewise degraded. Our results are consistent with a nonspecific degradation mechanism. Analysis of the gut microbiome by next-generation sequencing revealed two OTUs ( Citrobacter sp. and Kosakonia sp.) strongly associated with both PE and PS as well as OTUs unique to each plastic. Our results suggest that adaptability of the mealworm gut microbiome enables degradation of chemically dissimilar plastics.

Subcritical n-hexane/isopropanol extraction of lipid from wet microalgal pastes of Scenedesmus obliquus.

Subcritical co-solvents of n-hexane/isopropanol were primarily utilized to extract lipid from wet microalgal pastes of Scenedesmus obliquus. The effects of key operational parameters were investigated, and the optimal parameters were obtained: solvent ratio of n-hexane to isopropanol was 3:2 (V:V), phase ratio of co-solvents to microalgal biomass was 35:1 (mL:g), reactor stirring speed was 900 rpm, extraction time was 60 min. Additional pretreatment with acid, ultrasonic and microwave as well as enhanced subcritical pressure/heating treatments were also applied to further study their effects on lipid extraction. The results showed that the lipid recovery rate with acid pretreatment was 8.6 and 6.2% higher than ultrasonic and microwave pretreatment; the optimum enhanced subcritical condition was 55 °C with atmospheric pressure. Under optimal operating conditions, the lipid and FAME yield were 13.5 and 7.2%, which was 82.6 and 135.1% higher than the traditional method. The results indicated that the subcritical n-hexane/isopropanol extraction process had promising application potential.

Enhancing dewaterability of waste activated sludge by combined oxidative conditioning process with zero-valent iron and peroxymonosulfate.

The enhancement of sludge dewaterability is of great importance for facilitating the sludge disposal during the operation of wastewater treatment plants. In this study, a novel oxidative conditioning approach was applied to enhance the dewaterability of waste activated sludge by the combination of zero-valent iron (ZVI) and peroxymonosulfate (PMS). It was found that the dewaterability of sludge was significantly improved after the addition of ZVI (0-4 g/g TSS) (TSS: total suspended solids) and PMS (0-1 g/g TSS). The optimal addition amount of ZVI and PMS was 0.25 g/g TSS and 0.1 g/g TSS, respectively, under which the capillary suction time of the sludge was reduced by approximately 50%. The decomposition of sludge flocs could contribute to the improved sludge dewaterability. Economic analysis demonstrated that the proposed conditioning process with ZVI and PMS was more economical than the ZVI + peroxydisulfate and the traditional Fenton conditioning processes.

Antimicrobial Effects of Free Nitrous Acid on Desulfovibrio vulgaris: Implications for Sulfide-Induced Corrosion of Concrete.

Hydrogen sulfide produced by sulfate-reducing bacteria (SRB) in sewers causes odor problems and asset deterioration due to the sulfide-induced concrete corrosion. Free nitrous acid (FNA) was recently demonstrated as a promising antimicrobial agent to alleviate hydrogen sulfide production in sewers. However, details of the antimicrobial mechanisms of FNA are largely unknown. Here, we report the multiple-targeted antimicrobial effects of FNA on the SRB Desulfovibrio vulgaris Hildenborough by determining the growth, physiological, and gene expression responses to FNA exposure. The activities of growth, respiration, and ATP generation were inhibited when exposed to FNA. These changes were reflected in the transcript levels detected during exposure. The removal of FNA was evident by nitrite reduction that likely involved nitrite reductase and the poorly characterized hybrid cluster protein, and the genes coding for these proteins were highly expressed. During FNA exposure, lowered ribosome activity and protein production were detected. Additionally, conditions within the cells were more oxidizing, and there was evidence of oxidative stress. Based on an interpretation of the measured responses, we present a model depicting the antimicrobial effects of FNA on D. vulgaris These findings provide new insight for understanding the responses of D. vulgaris to FNA and will provide a foundation for optimal application of this antimicrobial agent for improved control of sewer corrosion and odor management.IMPORTANCE Hydrogen sulfide produced by SRB in sewers causes odor problems and results in serious deterioration of sewer assets that requires very costly and demanding rehabilitation. Currently, there is successful application of the antimicrobial agent free nitrous acid (FNA), the protonated form of nitrite, for the control of sulfide levels in sewers (G. Jiang et al., Water Res 47:4331-4339, 2013, http://dx.doi.org/10.1016/j.watres.2013.05.024). However, the details of the antimicrobial mechanisms of FNA are largely unknown. In this study, we identified the key responses (decreased anaerobic respiration, reducing FNA, combating oxidative stress, and shutting down protein synthesis) of Desulfovibrio vulgaris Hildenborough, a model sewer corrosion bacterium, to FNA exposure by examining the growth, physiological, and gene expression changes. These findings provide new insight and underpinning knowledge for understanding the responses of D. vulgaris to FNA exposure, thereby benefiting the practical application of FNA for improved control of sewer corrosion and odor.

Determining Multiple Responses of Pseudomonas aeruginosa PAO1 to an Antimicrobial Agent, Free Nitrous Acid.

Free nitrous acid (FNA) has recently been demonstrated as an antimicrobial agent on a range of micro-organisms, especially in wastewater-treatment systems. However, the antimicrobial mechanism of FNA is largely unknown. Here, we report that the antimicrobial effects of FNA are multitargeted. The response of a model denitrifier, Pseudomnas aeruginosa PAO1 (PAO1), common in wastewater treatment, was investigated in the absence and presence of inhibitory level of FNA (0.1 mg N/L) under anaerobic denitrifying conditions. This was achieved through coupling gene expression analysis, by RNA sequencing, and with a suite of physiological analyses. Various transcripts exhibited significant changes in abundance in the presence of FNA. Respiration was likely inhibited because denitrification activity was severely depleted, and decreased transcript levels of most denitrification genes occurred. As a consequence, the tricarboxylic acid (TCA) cycle was inhibited due to the lowered cellular redox state in the FNA-exposed cultures. Meanwhile, during FNA exposure, PAO1 rerouted its carbon metabolic pathway from the TCA cycle to pyruvate fermentation with acetate as the end product as a possible survival mechanism. Additionally, protein synthesis was significantly decreased, and ribosome preservation was evident. These findings improve our understanding of PAO1 in response to FNA and contribute toward the potential application for use of FNA as an antimicrobial agent.

The effect of surfactant on fermentation of kitasamycin in Streptomyces kitasatoensis.

Soybean oil is an important carbon source in kitasamycin fermentation by Streptomyces kitasatoensis. In this study, three different surfactants, Tween 80, Tween 85, and sodium dodecyl sulfate (SDS), were added in the fermentation medium to improve soybean oil utilization. Results indicated that all of these surfactants promote kitasamycin biosynthesis. When 0.5 g/L SDS was added at the beginning of fermentation, kitasamycin production increased by 55% and A5 content improved by 12%, compared with the control treatment (i.e., no surfactant added). Oil consumption rate and lipase activity were also improved in the presence of SDS, producing more organic acids benefiting kitasamycin biosynthesis. High butyric acid concentration in the fermentation medium containing SDS repressed C-3 acetylation and promoted A5 component accumulation. Additionally, utilization of oil components by S. kitasatoensis was altered. Specifically, linoleic acid was primarily used in the fermentation process with SDS, whereas oleic acid was primarily used in the fermentation process where no surfactant had been added.

The concentration-determined and population-specific antimicrobial effects of free nitrous acid on Pseudomonas aeruginosa PAO1.

There is great potential to use free nitrous acid (FNA/HNO2), the protonated form of nitrite, as an antimicrobial agent due to its bacteriostatic and bactericidal effects on a range of microorganisms. Here, we determine the effects of FNA on the opportunistic pathogen Pseudomonas aeruginosa PAO1, a well-studied denitrifier capable of nitrate/nitrite reduction in its anaerobic respiration. It was seen that lower FNA concentrations in the range of 0.1 to 0.2 mg N/L exerted a temporary inhibitory effect on the growth of P. aeruginosa, while respiratory inhibition was not detected until an FNA concentration of 1.0 mg N/L was applied. The FNA concentration of 5.0 mg N/L caused complete cell killing and likely cell lysis. The results suggest concentration-related and multiple antimicrobial effects of FNA. Differential killing of FNA in the P. aeruginosa subpopulations was detected, suggesting intrastrain heterogeneity, and does not support the idea of specific concentrations of FNA bringing about bacteriostatic and bactericidal effects on this species. A delayed recovery from FNA treatment suggested that FNA caused cell damage which required repair prior to the organism showing cell growth. The results of the study provide insight of the inhibitory and biocidal mechanisms of FNA on this important microorganism.

Improvement of ribonucleic acid production in Cyberlindnera jadinii and optimization of fermentation medium.

To enhance the ribonucleic acid (RNA) productivity for industrial applications, this study employed strain screening and medium optimization to improve the content of RNA in Cyberlindnera jadinii. A rapid screening method, combining atmospheric and room temperature plasma mutagenesis, 48-deep-well plates fermentation, and microplate reader detection, was developed. A mutant strain named WB15 with high RNA content was successfully obtained, exhibiting the RNA content of 156 ± 4.5 mg/g DCW, 1.4 times of the starting strain CCTCC AY 92020. Furthermore, Plackett-Burman design and response surface methodology were employed to identify three significant factors (yeast extract, soybean peptone, and KH2PO4) affecting the RNA content. By utilizing the optimal medium composed of 13.43 g/L yeast extract, 12.12 g/L soybean peptone and 2.78 g/L KH2PO4, the RNA content of WB15 further increased to 184 ± 4.9 mg/g DCW. Additionally, the mutant strain WB15 exhibited a greater cellular width compared to AY 92020, along with increased growth rate and single-cell RNA content by 22% and 48.9%, respectively. Perturbations in ribosome assembly, specifically a reduction in the ratio of ribosomal proteins to ribosomal RNA of the large subunit, might indirectly contribute to the higher RNA content in the WB15 strain. Overall, the combination of rapid screening with fermentation medium optimization proved to be an effective approach for improving the RNA content of C. jadinii, thus facilitating the industrial production of RNA.

Towards carbon neutrality: Sustainable recycling and upcycling strategies and mechanisms for polyethylene terephthalate via biotic/abiotic pathways.

Polyethylene terephthalate (PET), one of the most ubiquitous engineering plastics, presents both environmental challenges and opportunities for carbon neutrality and a circular economy. This review comprehensively addressed the latest developments in biotic and abiotic approaches for PET recycling/upcycling. Biotically, microbial depolymerization of PET, along with the biosynthesis of reclaimed monomers [terephthalic acid (TPA), ethylene glycol (EG)] to value-added products, presents an alternative for managing PET waste and enables CO2 reduction. Abiotically, thermal treatments (i.e., hydrolysis, glycolysis, methanolysis, etc.) and photo/electrocatalysis, enabled by catalysis advances, can depolymerize or convert PET/PET monomers in a more flexible, simple, fast, and controllable manner. Tandem abiotic/biotic catalysis offers great potential for PET upcycling to generate commodity chemicals and alternative materials, ideally at lower energy inputs, greenhouse gas emissions, and costs, compared to virgin polymer fabrication. Remarkably, over 25 types of upgraded PET products (e.g., adipic acid, muconic acid, catechol, vanillin, and glycolic acid, etc.) have been identified, underscoring the potential of PET upcycling in diverse applications. Efforts can be made to develop chemo-catalytic depolymerization of PET, improve microbial depolymerization of PET (e.g., hydrolysis efficiency, enzymatic activity, thermal and pH level stability, etc.), as well as identify new microorganisms or hydrolases capable of degrading PET through computational and machine learning algorithms. Consequently, this review provides a roadmap for advancing PET recycling and upcycling technologies, which hold the potential to shape the future of PET waste management and contribute to the preservation of our ecosystems.