Chemical Engineering Journal

This article presents the development of an advanced modeling and simulation platform for carbon capture systems, with a focus on integrated process analysis from upstream CO2 capture through to bioethanol production. The platform supports the evaluation of CO2 mitigation technology by coupling mathematical bioprocess models with an interactive desktop application. The biological system employs Chlorella vulgaris microalgae to fix CO2 through photosynthesis and generate carbohydrate substrates, which are subsequently converted to bioethanol by Saccharomyces cerevisiae yeast via fermentation. The simulation integrates three established kinetic models--the Monod, Logistic, and Luedeking-Piret models--to predict biomass growth, substrate consumption, and ethanol yield under varying operational conditions. A closed-loop CO2 recycling subsystem captures fermentation off-gases and reintroduces them into the bioreactor, enhancing overall carbon utilization efficiency. Three representative simulation scenarios demonstrated process efficiencies ranging from 1.09% to 93.78% of the theoretical maximum CO2-to-ethanol conversion efficiency, confirming the platforms capacity to evaluate a wide operational envelope. The Electron/React-based desktop application provides real-time visualization, interactive 3D bioreactor models, and a simulation history module, making it accessible to researchers, engineers, and students. The platform serves as a digital twin that bridges rigorous bioprocess mathematics with intuitive user interaction, providing a cost-effective tool for designing and optimizing sustainable carbon capture and biofuel production systems.

Granulation is a complex microbial-aggregation process essential for forming aerobic granular sludge (AGS) and other microbial granules used in wastewater treatment. However, the biological mechanisms that drive granule formation remain poorly understood. Cyclic-di-GMP (c-di-GMP) is a well-established second messenger that regulates biofilm formation, suggesting it may be used to enhance microbial granulation. Mycobacterium smegmatis, a nonpathogenic model bacterium for Mycobacterium tuberculosis, naturally forms granules. Because M. smegmatis carries a single c-di-GMP modulating gene, dcpA, that encodes an enzyme with both diguanylate cyclase (DGC) and phosphodiesterase (PDE) activities, it offers a unique opportunity to examine the role of c-di-GMP in granulation. Here, we generated and studied two engineered M. smegmatis strains overexpressing dcpA or dcpA{Delta}EAL, the latter of which is defective in PDE activity. Using these engineered strains, we examined different forms of biofilm growth, cell morphology, plastic surface adhesion, granulation, and settleability. Results of sludge volume index and microscopy indicated that the aggregates of M. smegmatis were granules rather than flocs, and the settleability of the granules was particularly robust when the cells were grown in a carbon rich medium known to promote granulation. Engineered strains sustained stable granulation more effectively than the wildtype under low concentration Tween-80 treatment, which was used to induce dispersion. These results suggest that overproduction of DcpA and thus the modulated level of intracellular c-di-GMP enhances granulation and promotes granule persistence in M. smegmatis. Our study further demonstrates that M. smegmatis is a useful model for elucidating biological mechanisms underlying granulation, which could be leveraged to improve granular technologies for wastewater treatment.

Source-separated organics (SSO) are widely processed via anaerobic digestion to produce biogas, yet alternative conversion pathways could generate higher-value products. Here, we demonstrate long-term continuous production and recovery of medium-chain carboxylic acids (MCCAs) from SSO via microbial chain elongation using a bench-scale anaerobic bioreactor operated for 911 days. The reactor was fed with SSO samples collected from two full-scale municipal organics processing facilities in Toronto, Canada, capturing facility-specific and seasonal variability in SSO composition. MCCA production depended strongly on the availability of lactate as an electron donor, which varied with SSO preprocessing operations and outdoor collection temperatures. To mitigate product inhibition, an in-line extraction system using hollow-fiber polydimethylsiloxane (PDMS, also known as silicone) membranes was integrated with the anaerobic membrane bioreactor, providing a robust and solvent-free alternative to solvent-based extraction methods. Maximum MCCA yields reached 0.31 g MCCA/ g VSfeed, with notable octanoic acid production (up to 20% of total MCCA), and production rates up to 0.84 g L-1 d-1. Acidification of the alkaline extract produced a phase-separated MCCA-rich oil ([~]95% purity) without addition of downstream separation steps. Microbial community analysis of the reactor revealed enrichment of putative chain-elongating bacteria, including Eubacterium and Pseudoramibacter species, while shifts in SSO feedstock microbiomes influenced substrate availability and product spectra. These results demonstrate the feasibility of sustained MCCA production from municipal organic waste streams and highlight opportunities to integrate chain elongation with existing anaerobic digestion infrastructure.

Polyethylene (PE) plastics are extensively utilized across agricultural, industrial, and medical sectors owing to their favorable physicochemical properties. However, their chemical stability and escalating production have resulted in severe waste accumulation and environmental pollution. Conventional disposal methods are plagued by resource inefficiency and secondary pollution. While emerging strategies offer promise, physicochemical methods demand harsh operating conditions, and biological routes remain inefficient. This research presents an integrated "chemical pretreatment-biodegradation-upcycling" system that combines the efficiency of chemical catalysis with the sustainability of biological conversion. Ester bonds were introduced into PE via Baeyer-Villiger oxidation, followed by enzymatic hydrolysis using the cutinase from Thermobifida fusca WSH03-11 (TfCut). Specifically, machine learning-aided optimization of reaction conditions and computational redesign of TfCut enhanced degradation efficiency, yielding a maximum weight loss of approximately 71.19%. The degradation intermediates were bio-converted into poly(3-hydroxybutyrate) (PHB) by the wild-type strain LETBE-HOU, isolated in this study, achieving a concentration of 16.75 mg/L. Multi-omics analysis of LETBE-HOU further revealed the PHB biosynthesis pathway and fatty acid degradation regulation. This work breaks the long-standing reliance on physiochemically-derived degradation intermediates for microbial conversion of PE, establishing a fully circular system that opens new avenues for future research.

Maintaining gut-microbiome homeostasis is the biggest issue worldwide as per public health concerns. Gut probiotics not only inhibit pathogen invasion in the systemic circulation but also help us metabolize complex food. Therefore, for decades, gut dysbiosis has been proven to be the gateway to several diseases, leading to comorbidity and even mortality. Prebiotics are natural products, mainly nondigestible food ingredients, that help the selective growth of probiotic bacteria in the gut. This study focuses on the novel Gum-Odina (GO) prebiotic and its efficacy on gut microbial metabolite modulation and maintaining gut barrier integrity. Gut wall enterocytes are integrated by a series of tight junctional (TJ) proteins. This study explains the effect of GO prebiotic-modulated gut metabolites on tight-junctional (TJ) protein expression in a murine colon Organoid model. Fecal microbiota from a colitis patient were used to inoculate the SHIME gut simulator, comprising a colitis control run and a Gum-Odina-supplemented run to enrich commensal bacteria selectively. Metabolites from both groups were then applied to healthy colon organoids. According to the mRNA expression analysis, tight junctional sealing proteins such as Zonula occludens, or ZO-1, Occludin, Claudin-1, 4, and 5 were significantly upregulated in the colon organoids upon Gum-Odina administration, whereas no change in the Junctional Adhesion Molecule-A or JAM-A was observed. Downregulation of sealing TJ proteins is the Hallmark of Leaky gut, which was successfully reversed using the Gum-Odina supplement. Hence, Gum-Odina prebiotics have a promising capability to reduce colitis-induced gut permeability and can be considered to be a therapeutic agent in the future.

Our increasing global population combined with the UN Sustainable Development Goals of zero hunger and good health require greater protein intake per capita and higher protein production. Consequently, sustainable food alternatives such as cultivated meat (CM) are urgently required. However, large-scale CM cell-systems face key challenges, particularly high media costs driven by amino acids and the need for ethically-sourced growth factors. Microalgae offer promising solutions, producing high protein yields with all essential amino acids simply from light, CO2, water and nutrients or spent CM media. Here we present Chlorella BDH-1 grown in spent CM media waste as a substitute-source for reduced amino acids and fetal bovine serum in cell culture media, enabling a circular strategy through beneficial mammalian cell-algae co-cultivation. We identified optimal algal growth conditions for maximum protein yield and demonstrated that two recycling rounds using industry-derived spent CM media maximize microalgal biomass yield per unit volume of waste media. We obtained algal lysate, determined thermal processing as the most cost-effective and mammalian cell-beneficial approach, and identified consumed lysate components. Compared to standard media, our lysate increased mammalian cell proliferation over 2-fold in reduced serum and amino acid conditions, replacing costly cell media components. We finally closed the loop by demonstrating a synergistic effect of the algal lysate with our co-cultivation - which co-produces algal biomass. The combination boosted mammalian cell proliferation 1.45-fold, conservatively estimating a media cost reduction by [~]66%. These findings establish parameters to advance the field towards cost-effective sustainable circular cell culture systems with applications in CM production and other biotechnology fields requiring large-scale tissue culture. Technology Readiness:

Thermoplastic polyesters are widely used in commodity and high-performance applications due to their tunable and exceptional properties, versatile performance, and increasing relevance in sustainable materials. Integrating biological functionality into these polymers offers a promising route to enhance performance and end-of-life behavior beyond what conventional additives can achieve. Here, we report the generalization of an embedded spore-based engineered living material concept to three representative thermoplastic polyesters; polycaprolactone (PCL), polylactic acid (PLA), and poly(butylene adipate-co-terephthalate) (PBAT). Heat-shock-tolerized Bacillus subtilis spores were compounded with each polyester as a living biofiller via hot melt extrusion. The resulting biocomposite polyesters retained high spore viability (>90%) after extrusion and exhibited improved mechanical performance (up to 41% toughness improvement compared to neat polymers). End-of-life behavior was evaluated in a microbially-limited composting environment, where spore-containing PCL exhibited nearly complete disintegration within five months, corresponding to a [~]7-fold increase in degradation kinetics relative to neat PCL. Finally, 3D printing of biocomposite PCL was demonstrated through fused deposition modeling and direct ink writing methodologies. Together, this work demonstrated the successful extension of spore-based engineered living materials from thermoplastic polyurethane to multiple thermoplastic polyesters. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=86 SRC="FIGDIR/small/707801v2_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@4eaafaorg.highwire.dtl.DTLVardef@bb17c2org.highwire.dtl.DTLVardef@114e4ceorg.highwire.dtl.DTLVardef@b9bd0c_HPS_FORMAT_FIGEXP M_FIG C_FIG

Clover grass blends are promising sources of nutritional and techno-functional proteins, but currently mainly utilized for animal feeding. The application as a physical and oxidative stabilizer in food emulsions remains underexplored. In this study, the stabilizing effects of clover grass proteins (CGPs), produced through a pilot-scale, two-stage membrane filtration process yielding a native GPC concentrate (DC), as well as enzymatic hydrolysate hereof (DCH), were compared with commercial plant proteins (soy and pea) and animal sources (sodium caseinate). Both DC and DCH produced emulsions (0.4% (w/w) protein and 5% fish oil) with smaller size droplets and larger electrostatic repulsion between droplets compared to the other proteins tested. Moreover, DC and DCH exhibited higher protection against the generation of both primary and secondary oxidation products. Furthermore, emulsions stabilized with CGPs were well-protected from off-flavor compounds. Mass spectrometry-based proteomics analysis revealed that DC included a high RuBisCO content (38%) and the membrane process successfully depleted pigment-binding proteins affiliated with grassy color and sensory attributes. Moreover, DC was enriched (compared to the initial green juice) in known antioxidant proteins, constituting 10% of the total protein. In the hydrolysate (DCH), 30% of the total MS1 peptide signal originated from peptides predicted as probable free radical scavengers. These findings demonstrate that refined, native CGP, as well as its hydrolysate, improved both physical and oxidative stability of emulsions compared to plant and animal-based reference proteins due to a high endogenous antioxidant properties of the protein.

Bioenergetics models serve as mechanistic tools to predict growth by linking energy intake, metabolic expenditure, and nutrient partitioning. However, traditional models rely primarily on gross energy (GE) intake, thereby oversimplifying the effects of feed composition and nutrient availability on fish growth. This work therefore proposed a refined bioenergetics model incorporating nutrient-specific digestibility coefficients (ADCs) and feed composition and tested using a compiled dataset (n=235; 165 for calibration and 70 for independent validation) and a field experimental dataset of largemouth bass (Micropterus salmoides). We first optimized parameters of a gross energy intake-based bioenergetics model, increasing R2 from 0.62 to 0.96 and thereby providing a calibrated foundation for subsequent refined model. The refined model demonstrated superior predictive performance on the compiled dataset (R2 = 0.97) with RMSE = 19.86 g and MAE = 10.31 g), representing reductions of 4.13% in RMSE and 19.98% in MAE and a 1.03% increase in R2 compared with the optimized GE-based model. In the field experiment, the refined model achieved high predictive accuracy (R2 = 0.98 and 0.97), whereas the optimized GE-based model showed poor performance (R2 = 0.33 and 0.06 respectively). This study is, to our knowledge, the first bioenergetics framework for largemouth bass that decomposes feed composition and nutrient-specific ADCs to compute macronutrient-resolved digestible energy, enabling formulation-aware growth prediction and nutrient-oriented optimization.

Microbial fuel cell offers a promising approach to improve wastewater quality and generate bioenergy from dark fermented effluents. In this study, the use of dark-fermented palm oil mill effluent as an electron donor for bioelectricity generation was investigated using a double-chambered microbial fuel cell (MFC). The MFCs were operated at room temperature (29 {+/-} 2{degrees}C), anode electrolytes adjusted to pH 7, and a chemical catholyte as the oxidizing agent. The maximum power {+/-} 8.07 mW/m2 and 155.16 {+/-} 12.88 mA/m2, respectively, were generated from the MFCs inoculated with sludge, which was 5.9 times higher than control without inoculum. Microbial community analysis revealed the enrichment of fermentative and electrogenic representative taxa from the phyla Bacillota, Bacteroidota and Pseudomonadota on the anode electrodes. Optimizations of the running conditions were carried out, suggesting the optimum parameters of 0.5 k{Omega} external resistance, anolyte initial pH 9, and 75% DFPOME substrate concentration. Operation under the optimized conditions increased current production, wastewater treatment, and Coulombic efficiency compared to the non-optimized conditions. Multiple configurations were also evaluated, showing higher cumulative voltage, power, and current densities with the stacked MFC connections, compared to single MFC units. Parallel circuit connection produced higher power and current density than serial connection. This study demonstrated the feasibility of MFC as a promising downstream treatment for biohydrogen production processes, towards higher treatment efficiency and resource recovery.

This study investigated the effects of different downstream processes for protein isolation on the bulk properties and composition of clover grass protein prototypes (CGPs). A clarified clover grass juice, obtained using membrane filtration (MF), underwent precipitation by acid (AP), heat (HP), or acid+heat (AHP), or underwent ultra- and diafiltration to produce a concentrate (DC) as well as subsequent tryptic hydrolysis of DC (DCH). HP had the highest protein content (p<0.05) and was whiter than other CGPs, although it showed lower aqueous solubility. In contrast, DC showed excellent solubility across a broad pH range. CGPs efficiently decreased oil-water interfacial tension (16-13 mN/m) and displayed viscoelastic and solid-like interfacial behavior. CGPs-stabilized emulsions displayed low physical stability with larger droplets despite high absolute {zeta}-potentials. CGPs were rich in RuBisCO (37-47%) but had varying levels of other proteins. Despite significant protein-level differences, overall protein composition of CGPs was comparable, highlighting that protein state governs bulk functionality more than subtle compositional changes. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/701969v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@f37756org.highwire.dtl.DTLVardef@1fb5beorg.highwire.dtl.DTLVardef@1d4efe2org.highwire.dtl.DTLVardef@d11ef8_HPS_FORMAT_FIGEXP M_FIG C_FIG Created with BioRender.com HighlightsO_LIThe effect of different processes on functional properties of CGPs was explored. C_LIO_LIHeat treatment increased protein purity and whiteness at the expense of solubility. C_LIO_LICGPs efficiently reduced O/W interfacial tension but produced unstable emulsions. C_LIO_LICGPs were found rich in RuBisCO (34-47%) using quantitative proteomics. C_LIO_LIProtein state had larger influence on functionality than protein-level composition. C_LI

Micronutrient deficiencies in soils are a critical challenge in agriculture, particularly in acidic soil environments where nutrient availability is strongly limited by fixation, leaching, and altered metal speciation. These constraints contribute to inefficient nutrient uptake and reduced crop yields. Conventional micronutrient supplementation methods are often inefficient, environmentally harmful, and unsustainable, underscoring the need for smarter delivery systems tailored to soil pH conditions. In this study, we developed biodegradable, pH-responsive microbeads from {kappa}-carrageenan ({kappa}-CG) and trans-ferulic acid (TFA) for targeted micronutrient release. The {kappa}-CG-TFA microbeads were synthesized via an eco-friendly process and optimized for size, morphology, stability, and nutrient retention. Characterization confirmed the successful incorporation of functional groups, while swelling, degradation, and release studies demonstrated efficient delivery of essential micronutrients (Mn2+, Zn2+, Cu2+, and Fe3+) under acidic conditions (pH 4.0), mimicking acidic soil environments. The inherent antioxidant activity of TFA conferred strong radical-scavenging capacity, further enhancing its functionality. Soil water and plant growth assays revealed that the microbeads improved micronutrient availability, significantly increased chlorophyll content and leaf area, promoted vigorous seedling growth, and caused no phytotoxic effects. Collectively, these findings establish {kappa}-CG-TFA microbeads as a promising, eco-friendly platform for sustainable micronutrient delivery and stress reduction, thereby improving crop productivity in agriculture.

Current mechanical and chemical recycling strategies address less than 10% of global plastic waste, necessitating alternative valorization routes. Biological upcycling via enzymatic depolymerization combined with microbial conversion of the resulting monomers offers a promising pathway to transform mixed plastic waste into valuable alternatives. Here, we employed a single engineered Pseudomonas putida KT2440 for simultaneous co-utilization of five plastic monomers including ethylene glycol, terephthalic acid, adipic acid, 1,4-butanediol, and L-lactic acid, which can be derived from enzymatic hydrolysis of polyethylene terephthalate (PET), polybutylene adipate-co-terephthalate (PBAT), polyester-polyurethanes (PUs), and polylactic acid (PLA). Continuous fermentation over 21 days with alternating mixed-monomer feeds achieved steady state growth and complete substrate depletion, yielding adaptive mutations that informed iterative strain improvement. Further engineering enabled the biosynthesis of (R)-3-hydroxybutyrate (R-3HB), and 0.70 g L-1 R-3HB was produced directly from enzymatic hydrolysates of blended PET, PBAT, and TPU. These results establish a viable bio-based approach for upcycling realistic mixed plastics into value-added bioproducts.

Microbial fuel cells (MFCs) represent a promising technology for the simultaneous treatment of wastewater and bioelectricity generation. In this study, the MFCs are conceived as functional modules to be integrated into hydroponic cultivation systems, acting as a prosthetic rhizosphere capable of coupling wastewater treatment and bioelectrochemical activity with plant nutrition improvement. We compared the electrochemical performance of different microbial consortia comprising the electroactive bacterium Shewanella oneidensis, the plant growth promoting rhizobacterium (PGPR) Pseudomonas putida, and the plant biomass-degrading fungus Ophiostoma piceae, along with the supplementation with the quorum sensing (QS) analogue molecule 1{square} dodecanol. These microbial consortia are tested in MFCs fed with wastewater and root exudates to analyze enhanced feedstock assimilation, electricity production, and the generation of plant growth-promoting substances (PGPS). From an electrochemical perspective, we evaluated planktonic growth, anode adhesion, substrate consumption, and the production of redox-active molecules and PGPS such as flavins and siderophores respectively alongside key electrical production parameters, including current output and power. Among the different microbial configurations tested, the consortium combining S. oneidensis, P. putida, and O. piceae exhibited the highest electrical production potential. Moreover, within this framework, we detected the extracellular production of siderophores in MFCs containing P. putida, suggesting a potential role supporting hydroponic crop growth. Furthermore, the addition of 1-dodecanol led to an improvement of the bioelectrochemical parameters. These results highlight the potential of synthetic microbial consortia in MFC-based systems not only to enhance electricity generation from wastewater but also to provide added value in integrated hydroponic applications through rhizosphere-like functions.

Biomass separation represents a critical bottleneck in Komagataella phaffii-based biopharmaceutical processes, as typically high cell densities of 40 - 50 % create significant operational, technical and economic challenges for harvest operations. Yeast cell aggregation (flocculation) provides a solution to accelerate cell sedimentation by increasing particle size, thus allowing to improve biomass-supernatant separation efficiency during both natural gravity settling and (continuous) centrifugation operations. This study demonstrates successful engineering of K. phaffii strains with an inducible flocculation phenotype using CRISPR/Cas9-based genome editing to integrate the Saccharomyces cerevisiae FLO1 (ScFLO1) gene under control of various regulatory elements, including methanol-inducible and derepressible promoters. Flocculation strength could be enhanced by implementing transcriptional positive feedback circuits based on the methanol-inducible AOX1 promoter. To address methanol-free production requirements, we developed alternative systems to retrofit PAOX1-based ScFLO1 expression and exploited the derepressible PDF promoter, offering broader compatibility with biopharmaceutical manufacturing facilities. Flocculating cells cultivated in a bioreactor demonstrated significantly improved sedimentation behavior, with considerably lower supernatant turbidity after short low-speed centrifugation compared to non-flocculating controls. Crucially, cell flocculation had no negative impact on product amount and quality when expressing a multivalent NANOBODY(R) VHH molecule with pharmaceutical relevance. Thus, this work establishes the first genetically engineered flocculation system in K. phaffii compatible with recombinant protein production, providing the basis for an innovative approach to streamline harvest operations in biopharmaceutical processes.

Nanoplastics generated from plastic waste in our ecosystems are becoming increasingly prevalent as bulk plastics exposed to natural factors like water and sunlight fragment to the nanoscale over time. These incidental nanoplastics span a wide range of physicochemical properties, which makes studying nanoplastic interactions in biological systems difficult. Here, we characterized the behavior of incidental nanoplastics generated through mechanical abrasion within coacervate droplets to probe the surface properties of the nanoplastics. We used elastin-like polypeptides (ELPs) to create hydrophobic or charged coacervate microenvironments. Using optical microscopy and fluorescence quantification, we observed that nanoplastics made from polyethylene terephthalate (nPET), nylon 6 (nPA), and polystyrene (nPS) exhibited distinct partitioning behavior with more favorable interactions with hydrophobic droplets. This indicated that the hydrophobic polymer backbone was the predominate surface feature despite exposed functional groups of the incidental nanoplastics, in contrast to findings with model carboxylated latex nanospheres (nPS-COOH). Furthermore, the selective partitioning of incidental nanoplastics into the hydrophobic droplets was able to capture over 80% of nPET in solution, and after recovery of the protein droplet, was able to cumulatively capture over 75% of the nPET feedstock across multiple cycles. This work explores the nuanced surface characteristics of incidental nanoplastics, expands the application of coacervates as chemical probes, and demonstrates a biopolymer approach for effective nanoplastic removal.

The growing prevalence of obesity necessitates innovative treatments. This study investigates a spray-dried konjac glucomannan-montmorillonite (KGM-MMT) hybrid designed to combine the fermentable, satiety-promoting effects of KGM with the lipid-binding and anti-inflammatory properties of MMT. In HFD-fed mice treated for 42 days with 2% w/w KGM-MMT, body weight gain was reduced by 7.6%, with an AUC of 5094[{+/-}[52.95, compared to 5513[{+/-}[81.35 in HFD controls (p < 0.0001). Serum IL-6 concentrations were reduced by 97% (p = 0.0002), while blood glucose decreased by 46% (p < 0.0001), outperforming reductions seen with MMT (24%, p = 0.0271) and KGM (16%, ns). Gut microbiota profiling demonstrated a significant 6.2-log[ fold increase in Lactobacillaceae (p = 0.023) and a 2.4-log[ fold increase in Enterococcaceae (p = 0.015) with KGM-MMT treatment. Predicted functional shifts revealed a 1.9-fold increase in short-chain fatty acid synthesis pathways and a 5.4-fold increase in bile acid deconjugation. Although the KGM-MMT hybrid did not consistently outperform its individual components in all measurements within the current study, it generally consolidated their metabolic benefits within a single dosage form. These findings support the utility of spray-dried KGM-MMT as a gut-targeted dietary strategy with additive effects on metabolic health. Future studies should explore underlying mechanisms and dosage effects of the hybrid formulation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/701163v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@738445org.highwire.dtl.DTLVardef@1f0d465org.highwire.dtl.DTLVardef@86e5aorg.highwire.dtl.DTLVardef@184fba8_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LISpray-dried KGM-MMT reduced HFD-induced weight gain by 7.6% in obese mice C_LIO_LISerum IL-6 and glucose levels decreased by 97% and 46%, respectively C_LIO_LI6.2-log[J and 2.4-log[J increases in Lactobacillaceae & Enterococcaceae relative abundance C_LIO_LIBile acid deconjugation and SCFA pathways increased 5.4- and 1.9-fold C_LIO_LIKGM-MMT microparticles offer additive gut-targeted benefits in metabolic disease C_LI

Pseudomonas putida KT2440, renowned for its diverse metabolic capabilities, is a promising platform for downstream processing and revalorization of recalcitrant molecules. In this study, we examined and optimized P. putida KT2440s ability to utilize long-chain alcohols. These molecules are byproducts of the degradation of polyethylene (PE), the most widely used plastic. Using them as feedstock for microbial growth would close the plastic-derived carbon cycle, reducing environmental pollution. First, we discovered that P. putida KT2440 can use long-chain alcohols as the sole carbon and energy source. Using adaptive laboratory evolution (ALE), we generated variants with improved growth rates on long-chain alcohols, specifically 1-hexadecanol and 1-eicosanol. Mutations that became fixed during ALE provided insights into the mechanism, highlighting the importance of cell-substrate interaction. By heterologously expressing a hydrocarbon transporter-encoding gene, we successfully reproduced the ALE-derived phenotype, demonstrating that the bottleneck in long-chain alcohol utilization is not substrate transformation but uptake. These findings lay the groundwork for the potential application of P. putida KT2440 for the degradation of PE.

Promyelocytic leukemia (PML) proteins are known to form phase-separated nuclear punctate structures called PML-nuclear bodies (PML-NBs). The integrity disruption of PML-NBs is linked with the pathogenesis of acute promyelocytic leukemia (APL), and trivalent arsenic (As3+) has been used for the clinical treatment of APL to restore normal PML-NBs. As3+ is considered to bind to cysteine residues and enhances modification of PML with small-ubiquitin-like protein (SUMO). We exposed U-2OS and CHO-K1 cells stably overexpressing PML-VI to As3+ and found that the solubility of PML decreased and SUMOylation of PML increased after 2 h-exposure to 3 M As3+. Contrary to As3+-induced remarkable biochemical changes including the solubility change and SUMOylation of PML, microscopic observation of PML-NBs was not changed clearly after a short-term exposure to As3+. The number of PML-NBs decreased and extranuclear PML bodies (EnPBs), which are remniscences of PML-NBs after nuclear membrane breakdown at mitosis, increased after exposure to As3+ for 24 - 72 h. The amount of SUMOylated PML decreased after prolonged exposure to As3+ while the solubility of PML was kept low, suggesting that As3+ stabilized EnPB without SUMOylation. The effects of As3+ on EnPBs were clearly observed at as low as 0.3 M As3+ which corresponds to inorganic arsenic level in drinking water worldwide.

Propionic acid (HPr) accumulation is a major indicator of anaerobic digestion (AD) dysfunction, yet the relative contributions of acidity, undissociated HPr, and propionate ions (Pr-) to process inhibition remain poorly understood. We investigated these effects in mesophilic batch AD microcosms fed with municipal sewage sludge, using a comparative design involving HPr, sodium propionate (NaPr), NaCl, and HCl treatments across two series of experiments. While 20 mM HPr caused a 22% reduction in the maximal methane production rate, 81 mM HPr led to complete inhibition, with the initial pH dropping to 5.1. By contrast, 81 mM NaPr reduced methane production rate by only 40%, and 81 mM NaCl caused no inhibition, demonstrating that acidity is the dominant inhibitory factor, with Pr- exerting a secondary concentration-dependent effect. 16S rRNA gene amplicon sequencing revealed strong, compound-specific shifts in microbial community composition, affecting key functional groups including syntrophs and methanogenic archaea. The proportion of methanogens dropped from 2-3% in control reactors to less than 0.2% under 81 mM HPr, consistent with the observed methane production inhibition. Under HPr81, over 100 ASVs were differentially abundant compared to controls, a pattern largely shared with HCl-treated reactors, further confirming the predominant role of acidity. The number of differentially abundant ASVs was negatively correlated with methane production rates (R{superscript 2} = 0.97), underscoring the link between community reshaping and process impairment. These results provide a unifying framework for propionate inhibition in AD and suggest that microbial community profiling could serve as an early warning tool for process imbalance detection.