Conventional Process Research Articles

Green and sustainable technologies for extraction of carotenoids from natural sources: a comprehensive review.

In recent years, driven by increasing consumer demand for natural and healthy convenient foods, the food industry has been shifting from synthetic to natural products. This shift is also reflected in the growing popularity of non-conventional extraction methods for pigments, which are favored for sustainability and environment-friendliness compared to conventional processes. This review aims to investigate the extraction of carotenoids from a variety of natural sources, including marine sources like fungus, microalgae, and crustaceans, as well as widely studied plants like tomatoes and carrots. Additionally, it delves into the recovery of valuable carotenoids from waste products like pomace and peels, highlighting the nutritional and environmental benefits. The review also emphasizes the role of green solvents such limonene, vegetable oils, ionic liquids, supercritical fluids, and natural deep eutectic solvents in effective and ecologically friendly carotenoid extraction. These technologies support the ideas of a circular and sustainable economy in addition to having a smaller negative impact on the environment. Overall, the present study highlights the crucial importance of green extraction technologies in achieving the dual goals of sustainability and public safety.

Kinetic Study of Oxidation of Ag-Sn-Zn Solid Solution Powders via Hot Mechanochemical Processing.

Ag-based electrical contact materials are essential in low-voltage devices such as relays, switches, circuit breakers, and contactors. Historically, Ag-CdO composites have been preferred due to their superior electrical and thermal conductivities, resistance to arcing, and mechanical strength. However, the toxicity of Cd has led to increased restrictions on its use. With the aim of contributing to the development of a new environment-friendly, Ag-Zn2SnO4-based electrical contact material, the kinetics of the hot mechanochemical oxidation of a Ag-Sn-Zn solid solution obtained by mechanical alloying were investigated. The results indicated that the proposed synthesis route produces Ag-based composites with a homogeneous distribution of nanoscale Zn2SnO4 precipitates, which is unattainable through conventional material processing methods. This kinetic study established that the mechanochemical oxidation of the Ag-Sn-Zn solid solution follows the Johnson-Mehl-Avrami-Kolmogorov model. An analysis of the microstructure and the relationship between the activation energy "Ea" and the Avrami exponent "n" from experimental data fitting suggests that the primary mechanism for the oxidation of the Ag-Sn-Zn solid solution during the hot mechanochemical process is related to the three-dimensional oxide growth being limited by oxygen diffusion after its immediate initial nucleation.

An Evaluation of Biochar Derived from Agro-Industrial Waste as an Alternative Material for the Elimination of Pathogenic Load from Water

The contamination of water bodies is becoming more frequent due to uncontrolled discharges into them, including those of domestic or industrial wastewater (WW) characterized by the presence of heavy metals, a high pathogenic load, pesticides, and pharmaceuticals, among other pollutants, which represent a risk to both humans and the health of the ecosystem. Consequently, conventional water treatment processes have been implemented. However, they are not efficient enough. In this regard, exploring and analyzing new alternatives and sustainable systems that efficiently degrade the different pollutants found in WW are required, and biochar can be considered as an attractive treatment option, since it is an adsorbent carbonaceous material that allows for the removal of several pollutants. The generation and use of biochar contribute to the promotion of the circular bioeconomy and the achievement of sustainable development goals by enhancing the reuse and recycling of agricultural and agro-industrial waste as raw material for its production. The objective of this work is to evaluate the utilization of biochar as an alternative material for the elimination of the pathogenic load in water.

Benzyldimethyldodecyl Ammonium Chloride-Doped Denture-Based Resin: Impact on Strength, Surface Properties, Antifungal Activities, and In Silico Molecular Docking Analysis.

Candida albicans (C. albicans) adhering to denture-based resins (DBRs) is a known cause of denture stomatitis. A new approach to prevent denture stomatitis is to include antimicrobial substances within DBRs. Here, we examined the mechanical performance and antifungal properties of DBRs containing benzyldimethyldodecyl ammonium chloride (C12BDMA-Cl) as an antimicrobial compound. C12BDMA-Cl is a quaternary ammonium compound, and its antifungal properties have never been investigated when combined with dental acrylic resin. Therefore, we modified a commercially available heat-polymerized acrylic DBR to contain 3 and 5 wt.% of C12BDMA-Cl. Unmodified DBR was used as a control group. Specimens were prepared using the conventional heat processing method. The specimen's flexural strength, elastic modulus, microhardness, and surface roughness were evaluated. C. albicans biofilm was grown on the specimens and assessed via colony-forming units (CFUs) and scanning electron microscopy (SEM). In silico molecular docking was applied to predict the potential C12BDMA-Cl inhibition activity as an antifungal drug. The 3% C12BDMA-Cl DBR demonstrated antifungal activities without a deterioration effect on the mechanical performance. SEM images indicated fewer colonies in DBR containing C12BDMA-Cl, which can be a potential approach to managing denture stomatitis. In conclusion, C12BDMA-Cl is a promising antifungal agent for preventing and treating denture stomatitis.

Bis(2-butoxyethyl) Ether-Promoted O2-Mediated Oxidation of Alkyl Aromatics to Ketones under Clean Conditions.

Conventional oxidation processes for alkyl aromatics to ketones employ oxidants that tend to generate harmful byproducts and cause severe equipment corrosion, ultimately creating critical environmental problems. Thus, in this study, a practical, efficient, and green method was developed for the synthesis of aromatic ketones by applying a bis(2-butoxyethyl) ether/O2 system under external catalyst-, additive-, and base-free conditions. This O2-mediated oxidation system can tolerate various functional groups and is suitable for large-scale synthesis. Diverse target ketones were prepared under clean conditions in moderate-to-high yields. The late-stage functionalization of drug derivatives with the corresponding ketones and one-pot sequential chemical conversions to ketone downstream products further broaden the application prospects of this approach.

High-Precision Numerical Investigation of a VAWT Starting Process

For both conventional and renewable energy conversion processes, computational fluid dynamics (CFD) has been used to address more energy-related challenges in recent decades. Using CFD to investigate vertical-axis wind turbines has become more common in recent years. The main goals of this application have been to more accurately predict the turbine’s performance and to comprehend the complicated nature of the complex turbulent flow. The vertical-axis wind turbine (VAWT) simulation for energy-generating applications has several intricate components. One of them is the study of the chaotic flow that occurs during the first stages of the starting process, and which greatly influences overall effectiveness. In this article, the performance of the wind turbine was increased using a passive flow control approach. The numerical research was carried out using Large Eddy Simulation for four alternative tip speed ratios in both cases, the classic and the optimized case, equipped with a vortex trap on the extrados of the blades. The power and torque coefficient variations, as well as the velocity magnitude contours, show that the starting process may begin with a significant improvement in efficiency when flow control is used.

Image processing tools for petabyte-scale light sheet microscopy data.

Light sheet microscopy is a powerful technique for high-speed three-dimensional imaging of subcellular dynamics and large biological specimens. However, it often generates datasets ranging from hundreds of gigabytes to petabytes in size for a single experiment. Conventional computational tools process such images far slower than the time to acquire them and often fail outright due to memory limitations. To address these challenges, we present PetaKit5D, a scalable software solution for efficient petabyte-scale light sheet image processing. This software incorporates a suite of commonly used processing tools that are optimized for memory and performance. Notable advancements include rapid image readers and writers, fast and memory-efficient geometric transformations, high-performance Richardson-Lucy deconvolution and scalable Zarr-based stitching. These features outperform state-of-the-art methods by over one order of magnitude, enabling the processing of petabyte-scale image data at the full teravoxel rates of modern imaging cameras. The software opens new avenues for biological discoveries through large-scale imaging experiments.

Intensification of n-butyl ethanoate synthesis using ultrasound over ammonium sulphate supported on silica extracted from rice husk ash as an efficient heterogeneous catalyst

ABSTRACT The silica extracted from rice husk ash was used as support to load ammonium sulphate ((NH4)2SO4) (10–40 wt.%) and ammonium sulphate supported on rice husk silica ((NH4)2SO4/RHS) catalysts were characterised by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and scanning electron microscope (SEM) with EDS techniques. The catalyst was further used to convert butan-1-ol to n-butyl ethanoate in an ultrasonic batch reactor. The study demonstrated the influence of ultrasound and operating parameters on the conversion. The maximum conversion of 88.77% was attained at the optimal operating conditions of temperature 353 K, molar ratio 1:2 (ethanoic acid to butan-1-ol), catalyst loading 4% (w/w), duty cycle 75% and ultrasound power 80 W. When compared with the conventional process, the reaction time was reduced by 54% in ultrasound-assisted synthesis over conventional synthesis. It has been observed that intensification benefits as it lowers reaction time for the ultrasound-assisted approach.

An in vitro and in vivo study of biodegradable Zn–Cu–Li alloy with high strength and ductility fabricated by hot extrusion combined with room-temperature ECAP

Deformation processing is a commonly used strategy to improve the microstructure and hence mechanical properties of biodegradable Zn alloys. However, a single conventional processing method is usually limited in achieving this goal. In this work, hot extrusion combined with room-temperature equal channel angular pressing (ECAP) was used to fabricate biodegradable Zn–Cu–Li alloy. Compared to the hot-extruded alloy, the further ECAPed alloys have significantly finer Zn grains and precipitate more submicron- and nano-sized ε-CuZn4 particles. Moreover, the 4-pass as-ECAPed alloy exhibits the best comprehensive mechanical properties with yield strength of 315 ± 3 MPa, ultimate tensile strength of 444 ± 13 MPa and elongation of 81 ± 5%, which are 13.3%, 38.8% and 72.3% higher than those of the hot-extruded alloy, respectively. In addition, in vitro and in vivo tests were performed on the 4-pass as-ECAPed alloy to evaluate its corrosion behavior, antibacterial property, cytotoxicity and biocompatibility. In vitro results showed that the 4-pass as-ECAPed alloy exhibits better corrosion resistance than the 8-pass alloy. Also, it shows good antibacterial property, hemocompatibility and cytocompatibility. In vivo results demonstrated that the 4-pass as-ECAPed alloy exhibits faster and more uniform degradation than the pure Zn (as a control group). Both the pure Zn and 4-pass as-ECAPed alloy promote formation of new bone, the mass of which increases over time. The 4-pass as-ECAPed alloy shows slightly weaker osteogenic capacity but better overall osteointegration than the pure Zn. Furthermore, both the pure Zn and 4-pass as-ECAPed alloy exhibit good in vivo biosafety.

Web-Based Congregation Data Management Information System at Sumba Christian Church Kanjonga Bakul

The rapid development of technology in the current era of globalization has provided many benefits in progress in various social aspects. Every action we take today is closely related to the use of technology, especially in the field of computerization and the internet. Data Management of the Sumba Christian Church (SCC) / Gereja Kristen Sumba (GKS) Kanjonga Bakul Congregation is one of the activities that must be carried out by the church every year, this activity is carried out by BPMJ officers or administrators and monitored by pastors. However, in GKS Kanjonga basket, the system for GKS Jamaat Data Management is still carried out by each congregation assembly to collect data conventionally by collecting photocopies of Family Cards and collecting data directly at each congregation house to recap back to the physical ledger. This process experienced various obstacles, including the difficulty in recapitulating the entire data managed, as well as the lack of efficiency in managing the data of the GKS Congregation. This conventional process leads to a waste of time and effort that should not be happening today, as well as a high risk of errors and inaccuracies in the recorded data. From the problem of data management of the GKS congregation in Kanjonga Bakul, this research will develop an Information System for the Management of Data of the Sumba Christian Church using the Rapid Application Development (RAD) method. The web development in this study will use the Hypertext Preprocessor (PHP) programming language with the CodeIgniter framework that implements the Model-View-Control (MVC) concept. This technology can optimize and improve the quality of data management of GKS congregations in Kanjonga Bakul.

Deciphering the piezoelectric and conductive mechanisms of Nb-doped Bi3Ti1.5W0.5O9 high-temperature piezoelectric ceramics

The study utilizes Bi3Ti(1.5-x)NbxW0.5O9 (BTW-xNb, x=0.00, 0.01, 0.02, 0.04, 0.06) bismuth layered piezoelectric ceramics synthesized via a conventional solid-phase reaction process. This is the study to investigate the impact of B-site Nb ion doping on the structural and electrical properties of BTW-xNb ceramic. The results show that all ceramics have a single bismuth layer structure, with reduced lattice distortion according to Rietveld refinement findings. The presence of oxygen vacancies in the ceramic is the main factor that affects the high temperature conductivity of the samples. The XPS results, the increase in the activation energy of AC and DC conductivity confirm that doping with Nb5+ ions reduces oxygen vacancy concentration. The ceramics with the highest overall electrical performance are the BTW-0.02 Nb ceramics. Notably, the DC resistivity at 500 °C was enhanced from 9.16 × 105 Ω·cm (x = 0.00) to 8.24 × 106 Ω·cm. The TC was enhanced from 730 °C(undoped) to 743 °C. At 500 °C, tanδ decreases from 21.1 % to 8.2 %. The ceramic's increased resistivity increases the polarization voltage, resulting in more complete polarization. The d33 is increased from 7.5 pC/N (undoped) to 13 pC/N. Furthermore, the piezoelectric properties remain stable up to 700°C, suggesting that the material has considerable potential for use at elevated temperatures.

Improvement of electro-Fenton process by using heterogeneous Fe-MIL-88B nanocatalyst and simultaneous rotation of cathode and anode for dye removal

In this study, improvement of the electro-Fenton process using Fe-MIL-88B along with the innovation in the reactor with the simultaneous rotation of the cathodes and anodes was carried out to remove Acid Blue 25. For this purpose, the Fe-MIL-88B nanocatalyst was synthesised by the thermal solvent method and was characterised by FT-IR, EDAX, XRD, and FESEM. For the experiments, an electrochemical cell with a useful volume of 1 L and rotating cathodes and anodes were used and nanoparticles were added to the system as a slurry. To determine the appropriate values of the effective parameters, the OFAT method was used. According to the results, 0.3 g/L Fe-MIL-88B, pH equal to 3, dye concentration of 75 mg/L, a current intensity of 0.228 A, and a rotation velocity of 100 rpm were chosen as suitable values for the process. In optimal conditions, the dye removal efficiency reached to 92.3% after 90 min, which resulted in a 14.5% improvement in the dye removal efficiency compared to the conventional process under the same conditions. Also, after 90 min, the removal efficiencies of 77.08 and 63.63% were obtained for COD and TOC, respectively. The results indicated acceptable decomposition of the effluent into less hazardous compounds.

Simulation and optimization of DMC synthesis process based on conventional and advanced exergy analyses

Dimethyl carbonate has received more and more attentions as an organic solvent in electrolytes. Aiming at the problem of high energy consumption in the process of dimethyl carbonate (DMC) production, the root of the problem was analyzed by using exergy analysis, which provides a theoretical basis for the construction of energy-saving process. Firstly, the overall process of DMC production was constructed, including propylene carbonate (PC) synthesis, DMC synthesis, azeotrope separation and propylene glycol (PG) purification processes. Secondly, the conventional and advanced exergy analyses of the four proposed processes were carried out. The distributions of exergy and exergy destruction were obtained through conventional exergy analysis. The exergy destructions were further divided through advanced exergy analysis, and the avoidable parts were focused on. Based on the above analyses, the corresponding heat integration processes were proposed. Finally, the conventional processes and the heat integration processes were evaluated with the performance indicators of the exergy destruction, total annual cost (TAC), total energy consumption (TEC) and CO2 emissions.

The Degradation of Rhodamine B by an Electro-Fenton Reactor Constructed with Gas Diffusion Electrode and Heterogeneous CuFeO@C Particles

Compared with conventional Fenton processes, the electro-Fenton process consumes fewer chemicals and produces less sludge, as it can generate the required Fenton’s reagents in situ. In this work, an electro-Fenton reactor was constructed to treat synthetic rhodamine B (Rh B) wastewater, in which a gas diffusion electrode (GDE) was used as a cathode to produce H2O2, and heterogeneous CuFeO@C particles were used to generate Fe2+ in situ. The results indicated that the gas diffusion electrode made of elements N-S-B and r-graphene oxide (NSB-r-GO) composites produced more H2O2 than the one made from r-graphene oxide (r-GO), under the conditions of 0.1 mol ·L−1 Na2SO4 electrolyte, 10 mA·cm−2 current density, and 1.0 L·min−1 O2 flow rate, with the accumulated H2O2 production reaching 105.43 mg·L−1. Additionally, different iron morphologies, including octahedral Fe (II), octahedral Fe (III), and tetrahedral Fe (III), were found in the calcined CuFeO@C particles, approximately 1.0 mg·L−1 of iron ions dissolved in the electrolyte was detected, which worked simultaneously as conductive electrodes in a conceptual three-dimensional electrochemical reactor consisting of a gas diffusion electrode cathode, Ti/RuSn anode, and CuFeO@C particle electrodes. No external Fenton reagents were necessary.

A single-atom manganese nanozyme mediated membrane reactor for water decontamination

Single-atom nanozymes possess high catalytic activity and selectivity, and are emerging as advanced heterogeneous catalysts for environmental applications. Herein, we present the innovative synthesis and characterization of a single-atom manganese-doped carbon nitride (SA-Mn-CN) nanozyme, integrated into a polyvinylidene fluoride (PVDF) membrane for advanced water treatment applications. The SA-Mn-CN nanozyme demonstrates high peroxidase-like activity, efficiently catalyzing the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and generating reactive oxygen species (ROS) for effective antibacterial action. Notably, the SA-Mn-CN/PVDF membrane showcases enhanced water permeability, superior antifouling properties, and ultra-fast degradation kinetics of organic pollutants. Mechanistic studies reveal that the nanozyme selectively generates Mn(IV)-oxo species via peroxymonosulfate (PMS) activation, crucial for the efficient oxidation processes. Our integrated membrane system effectively removes (within 1 min, > 92 % removal) a variety of organic micropollutants in continuous-flow operations, demonstrating excellent stability and minimal manganese leaching. Compared to conventional advanced oxidation process (AOPs)/membrane system, the SA-Mn-CN/PVDF/PMS system holds the advantages of high catalytic activity and selectivity for generation of reactive species, wide working pH range (pH3–11) and excellent stability and reusability under the backwashing conditions. The developed device-scale AOPs/membrane system was proven to be effective in bacterial inactivation and pollutants degradation, verifying the vast application potential of the SA-Mn-CN/PVDF membrane for practical water decontamination. This work pioneers the development of enzyme-mimicking nanozyme membranes, offering a sustainable and high-performance solution for wastewater treatment, and sets a new benchmark for the design of nanozyme-based catalytic membranes in environmental applications.

A convolutional neural network to optimize multi-mission satellite altimeter fusion for improving the marine gravity field

Satellite altimetry is the main tool for constructing global or regional marine gravity fields. To improve the accuracy and spatial resolution, it is necessary to fuse multi-mission altimeters. How to determine the weights of multi-mission altimeters is a crucial issue, making the conventional calculation process very complex. In addition, traditional satellite inversion methods are often independent of shipborne gravity, which is used only as validation data, thus not take full advantages of high accuracy and resolution of shipborne gravity. In this study, we introduce a convolutional neural network (CNN) to merge the vertical deflections (DOVs) obtained from multi-altimeter missions to construct a marine gravity model in the South China Sea. High-accuracy shipborne gravity and a dataset comprising DOVs and geo-locations are employed as input data for neural network training. For the validation of CNN method, the gravity model is also computed by conventional Inverse Vening Meinesz (IVM) method. Independent shipborne gravity measurements and SIO V32.1, DTU17 models are used as validation data. The evaluation results show that the CNN-derived model achieves a higher level of accuracy, yielding a standard deviation (STD) of 3.21 mGal, with an improvement of 36.56% compared to IVM-derived model. More than 92% of the differences between the CNN-derived model and shipborne gravity are less than 5 mGal. In addition, spectral analysis results further show that the CNN-derived model has stronger energy at short wavelengths (less than 25 km) compared to other models. These findings reveal that CNN method is feasible for marine gravity recovery and the CNN-derived model can achieve higher accuracy. The CNN method can improve the accuracy and spectral characteristics of the constructed gravity model by taking advantage of the high accuracy and high resolution of shipborne gravity.Graphical

Impact of self-induced anaerobiosis fermentation (SIAF) on chemical and sensorial characteristics of Coffea canephora

Coffea canephora is responsible for over 40% of global production and holds industrial relevance, especially in the production of soluble coffee. However, issues related to beverage quality still need improvement to meet the demand for high-quality coffees. This study investigated chemical and sensory changes in Coffea canephora var. conilon during Self-induced Anaerobiosis Fermentation (SIAF) versus Conventional processing, with or without starter yeasts. Hanseniaspora opuntiae and Meyerozyma caribbica populations were monitored using qPCR, while sugar and acid concentrations were measured by HPLC. Pulped coffees showed higher sugar consumption (71%–79%) than natural ones (12%–24%) during 72 h of SIAF, with lactic acid uniquely present in SIAF treatments. GC-MS identified 35 volatile compounds in roasted coffees, with esters and ketones differing between SIAF and Conventional treatments. Ethyl isovalerate and ethyl palmitate were found only in Natural SIAF inoculated with H. opuntiae, which received the highest cupping score (82 points). Consumers perceived all Natural SIAF coffees as distinct from Natural Conventional. In Natural SIAF coffee, H. opuntiae contributed to an exotic and fruity profile, while in Pulped SIAF, M. caribbica yielded a balanced and mild coffee. The SIAF method, with or without yeast addition, holds the potential for producing specialty Canephora coffee.

Localized heating coupling with radical oxidation eliminating antibiotic resistance genes (ARGs) in interfacial photothermal Fenton-like disinfection process

Conventional oxidative disinfection processes are inefficient in eliminating intracellular antibiotic resistance genes (iARGs) due to the barrier of the cell membrane and the competitive reaction of cellular constituents within antibiotic-resistant bacteria (ARB), resulting in the widespread prevalence of ARGs in recycled water. This study presented the first application of localized heating coupling with advanced oxidation to destroy the resistant Escherichia coli cells and improved subsequent iARGs (blaTEM-1) degradation in a novel photothermal Fenton-like disinfection process. The Fe-Mn@CNT microfiltration membrane, comprising carbon nanotubes wrapped with Fe and Mn nanoparticles (Fe-Mn@CNT), was employed as a nanomaterial for photothermal conversion and H2O2 activation. The highly efficient absorption of full-spectrum photons by CNTs enabled the Fe-Mn@CNT membrane to concentrate light to generate localized intense heat, resulting in the destruction of ARB nearby, and the subsequent release of iARGs. Interfacial heat favored Fe-Mn-induced H2O2 activation, leading to the production of more ·OH, which in turn promoted the oxidation for ARG degradation and ARB cell damage. The results of the acetylcysteine quenching experiments indicated that interfacial heating and radical oxidation-induced accumulation of intracellular reactive oxygen species contributed to the elimination of about 1-log iARGs through direct attack. The integrity of the cell membrane, the morphology of ARB and the variation of i/e ARG copy numbers were observed to reveal that the introduction of interfacial heating aggravated the cell lysis and accelerated the iARGs release, resulting in the inactivation of 7.27-log ARB and the elimination of 4.64-log iARGs and 2.23-log eARGs. Localized heating coupling with ·OH oxidation achieved a 143 % increase in iARGs removal compared to the conventional Fenton-like oxidation. The interfacial photothermal Fenton-like disinfection process exhibited remarkable material stability, robust disinfection performance, and effective suppression of horizontal gene transfer, underscoring its immense potential to mitigate the risk of ARG dissemination in reclaimed water systems.

Removal of sulfamethoxazole in an algal-bacterial membrane aerated biofilm reactor: Microbial responses and antibiotic resistance genes

Antibiotics are frequently detected in wastewater, but often are poorly removed in conventional wastewater treatment processes. Combining microalgal and nitrifying bacterial processes may provide synergistic removal of antibiotics and ammonium. In this research, we studied the removal of the antibiotic sulfamethoxazole (SMX) in two different reactors: a conventional nitrifying bacterial membrane aerated biofilm reactor (bMABR) and algal-bacterial membrane aerated biofilm reactor (abMABR) systems. We investigated the synergistic removal of antibiotics and ammonium, antioxidant activity, microbial communities, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and their potential hosts. Our findings show that the abMABR maintained a high sulfamethoxazole (SMX) removal efficiency, with a minimum of 44.6 % and a maximum of 75.8 %, despite SMX inhibition, it maintained a consistent 25.0 % ammonium removal efficiency compared to the bMABR. Through a production of extracellular polymeric substances (EPS) with increased proteins/polysaccharides (PN/PS), the abMABR possibly allowed the microalgae-bacteria consortium to protect the bacteria from SMX inactivation. The activity of antioxidant enzymes caused by SMX was reduced by 62.1–98.5 % in the abMABR compared to the bMABR. Metagenomic analysis revealed that the relative abundance of Methylophilus, Pseudoxanthomonas, and Acidovorax in the abMABR exhibited a significant positive correlation with SMX exposure and reduced nitrate concentrations and SMX removal. Sulfonamide ARGs (sul1 and sul2) appeared to be primarily responsible for defense against SMX stress, and Hyphomicrobium and Nitrosomonas were the key carriers of ARGs. This study demonstrated that the abMABR system has great potential for removing SMX and reducing the environmental risks of ARGs.

Comparative evaluation of the extracellular production of a polyethylene terephthalate degrading cutinase by Corynebacterium glutamicum and leaky Escherichia coli in batch and fed-batch processes

BackgroundWith a growing global population, the generation of plastic waste and the depletion of fossil resources are major concerns that need to be addressed by developing sustainable and efficient plastic recycling methods. Biocatalytic recycling is emerging as a promising ecological alternative to conventional processes, particularly in the recycling of polyethylene terephthalate (PET). However, cost-effective production of the involved biocatalyst is essential for the transition of enzymatic PET recycling to a widely used industrial technology. Extracellular enzyme production using established organisms such as Escherichia coli or Corynebacterium glutamicum offers a promising way to reduce downstream processing costs.ResultsIn this study, we compared extracellular recombinant protein production by classical secretion in C. glutamicum and by membrane leakage in E. coli. A superior extracellular release of the cutinase ICCGDAQI was observed with E. coli in batch and fed-batch processes on a litre-scale. This phenomenon in E. coli, in the absence of a signal peptide, might be associated with membrane-destabilizing catalytic properties of the expressed cutinase. Optimisations regarding induction, expression temperature and duration as well as carbon source significantly enhanced extracellular cutinase activity. In particular, in fed-batch cultivation of E. coli at 30 °C with lactose as carbon source and inducer, a remarkable extracellular activity (137 U mL−1) and cutinase titre (660 mg L−1) were achieved after 48 h. Literature values obtained with other secretory organisms, such as Bacillus subtilis or Komagataella phaffii were clearly outperformed. The extracellular ICCGDAQI produced showed high efficacy in the hydrolysis of PET textile fibres, either chromatographically purified or unpurified as culture supernatant. In less than 18 h, 10 g L−1 substrate was hydrolysed using supernatant containing 3 mg cutinase ICCGDAQI at 70 °C, pH 9 with terephthalic acid yields of up to 97.8%.ConclusionExtracellular production can reduce the cost of recombinant proteins by simplifying downstream processing. In the case of the PET-hydrolysing cutinase ICCGDAQI, it was even possible to avoid chromatographic purification and still achieve efficient PET hydrolysis. With such production approaches and their further optimisation, enzymatic recycling of PET can contribute to a more efficient and environmentally friendly solution to the industrial recycling of plastics in the future.