Search Results (660)

Bioreactors used for the maturation of cell-seeded tissue-engineered scaffolds should essentially mimic the dynamic in vivo environments experienced by the native tissues they intend to substitute. In addition to perfusion of growth medium to facilitate continuous mass transfer, application of appropriate mechanical stimulation is important to enhance cellular responses in scaffolds for tissues such as tendons, skin, and cardiac muscle that experience dynamic loading. This study focuses on the development of a multi-modal custom bioreactor capable of applying cyclic tensile stimulation and perfusion within physiologically relevant ranges while minimizing shear stress detrimental to cells seeded on scaffolds. To validate the bioreactor design and operation, we assessed the effects of tensile stimulation (0.1 Hz, 2000 cycles/day) and perfusion (media flow rate = 0.15 mL/min) over 21 days on the biofunctional performance of 3D-bioplotted polycaprolactone (PCL) auxetic scaffolds with a representative design (missing-rib pattern) characterized by negative Poisson’s ratio similar to the aforementioned soft tissues. The scaffold had a tensile yield strain of 9.14%, yield strength of 0.25 MPa, elastic modulus of 2.85 MPa, and ultimate tensile strength (UTS) of 1.32 MPa. The application of perfusion and tensile stimulation (0–5% cyclic strain) for 21 days did not adversely affect the yield strength and elastic modulus of the scaffold but affected its UTS (22.5% decrease) compared to the control cultured without perfusion or stimulation. Notably, it resulted in significantly improved fibroblast cellular responses (DNA = 29 µg/g sample and collagen = 371.78 µg/g sample) compared to the control (7.52 µg/g sample and 163.51 µg/g sample, respectively). These results validate the bioreactor system operation and the ability of multi-modal stimulation to control biofunctional responses of auxetic scaffolds, which will serve as the basis for future studies that will optimize auxetic scaffold design and dynamic culture parameters for NPR tissue-specific applications. Full article

Phosphorus is a key nutrient regulating algal growth and eutrophication in aquatic systems, yet its isolated effect on microalgae-based wastewater treatment remains underexplored. This study evaluated how varying phosphorus loads drive microalgal community structure and purification performance in controlled photobioreactors fed synthetic wastewater. The synthetic wastewater was formulated with constant carbon and nitrogen but graded phosphorus at C/N/P ratios of 100/5/1, 100/5/10, and 100/5/20 under 6000 lux, a 14 h photoperiod, and 24 ± 2 °C with a 15-day hydraulic retention time. Monitoring of chlorophyll a, pH, total and volatile suspended solids, and algal composition showed that phosphorus enrichment significantly increased chlorophyll a (up to 43.9 µg/L at 20 mg P/L) and particulate biomass (TSS and VSS), while pH remained near neutral to slightly alkaline, with no significant differences among the three bioreactors. Although the same core taxa—Chlorella spp., Scenedesmus spp., Navicula spp., and filamentous algae were present across all bioreactors, their relative abundances shifted significantly with phosphorus concentration. A two-way ANOVA confirmed a highly significant interaction between bioreactor (P level) and genus (p < 0.001), demonstrating phosphorus-driven changes in the microalgal community. Notably, filamentous cyanobacteria (Anabaena spp.) were undetectable in the low- and medium-phosphorus treatments but emerged prominently only at the highest phosphorus level (20 mg/L). Nutrient removal efficiencies peaked in this high-phosphorus bioreactor (C), achieving 85% for bCOD, 78% for nitrogen, and >70% for phosphorus. These results show that phosphorus loading drives predictable shifts in microalgal community composition toward fast-growing algae and cyanobacteria and that these shifts likely contribute to enhanced nutrient removal. The findings support optimization of phosphorus supply and hydraulic residence time in low-cost, sunlight-driven systems to improve polishing performance for small settlements in arid regions. Full article

Rapid urbanization in China has driven annual food waste production to 130 million tons, posing severe environmental challenges for anaerobic digestate management. To resolve trade-offs among drying efficiency, resource recovery (fertilizer/fuel), and carbon neutrality by optimizing the biodried product (BDP) recycling ratio (0–15%), six BDP treatments were tested in 60 L bioreactors. Metrics included drying kinetics, product properties, and environmental–economic trade-offs. The results showed that 12% BDP achieved a peak temperature integral (514.13 °C·d), an optimal biodrying index (3.67), and shortened the cycle to 12 days. Furthermore, 12% BDP yielded total nutrients (N + P₂O₅ + K₂O) of 4.19%, meeting the NY 525-2021 standard in China, while ≤3% BDP maximized fuel suitability with LHV > 5000 kJ·kg⁻¹, compliant with CEN/TC 343 RDF standards. BDP recycling reduced global warming potential by 27.3% and eliminated leachate generation, mitigating groundwater contamination risks. The RDF pathway (12% BDP) achieved the highest NPV (USD 716,725), whereas organic fertilizer required farmland subsidies (28.57/ton) to offset its low market value. A 12% BDP recycling ratio optimally balances technical feasibility, environmental safety, and economic returns, offering a closed-loop solution for global food waste valorization. Full article

Reverse osmosis (RO) is the key process for textile dyeing wastewater reuse applications. Membrane fouling reduces both permeability and rejection capability, negatively affecting the technological economy of RO process. Membrane cleaning is critical to recovery of the permeability of fouled RO membranes. Based on multi-batch filtration and cleaning experiments, this study systematically evaluated the RO membrane fouling potential of pre-treated textile dyeing wastewater by a membrane bioreactor and the recovery performance of fouled RO membranes after different cleaning methods. A significant decline (more than 15%) in RO membrane permeability occurred after RO membrane permeate production of 625 L/m² at a water recovery ratio of 60%. Protein-like substances and soluble microbial products were identified as the primary organic foulants via three-dimensional fluorescence excitation-emission matrix spectrometry (3D-FEEM). The single forward flushing with either pure water, acid, alkaline, or sodium hypochlorite solutions with a low active chlorine concentration showed very limited recovery of fouled RO membrane permeability. The combined forward flushing with acid followed by alkaline solutions restored fouled membrane permeability by up to 87% of a new RO membrane. The addition of pure water backwashing at a transmembrane pressure (TMP) of 0.5 MPa after both acid and alkaline solutions combined forward flushing restored fouled membrane permeability by up to 97% of a new RO membrane but deteriorated the rejection capability of the RO membrane. The backwashing parameters were further optimized at a TMP of 0.125 MPa and crossflow velocity (CFV) of 0.5 m/s, achieving fouled RO membrane permeability by up to 96% of a new RO membrane, and there were no negative effects on the rejection capability of the RO membrane. Alkaline forward flushing followed by pure water backwashing was the dominant contributor for fouled RO membrane permeability recovery. A preliminary economic analysis showed that the total chemical cost per RO production was 0.763 CNY/m³ and could be further reduced via removing acid cleaning and replacing combined alkaline flushing and pure water backwashing with alkaline backwashing. Full article

The oleaginous yeast Rhodotorula glutinis is a promising industrial host for the simultaneous production of lipids and carotenoids, yet the transcriptional regulation governing carbon flux toward these metabolites is poorly understood. As a foundational step, we performed a comparative transcriptomic analysis on bioreactor cultures under optimized fed-batch conditions with varying carbon-to-nitrogen (C/N) ratios and metal supplementation, comparing a nutrient-replete control (C) with conditions favoring high lipid (HLP) or high carotenoid (HCP) production. This study was designed as a preliminary, in-depth case study using single, well-controlled bioreactor runs per condition, with the goal of generating a comprehensive transcriptional map to identify key candidate genes for future validation. The data delineates two distinct presumptive metabolic strategies. The HLP regime was associated with broad transcriptional downregulation, channeling carbon toward lipogenesis via specific upregulation of the fatty acid synthase complex (FAS1/2, Log₂FC(HLP/HCP) > 2.99) and concerted suppression of β-oxidation genes (Log₂FC < −9.70). Conversely, the HCP condition was characterized by significant upregulation of NADPH-supplying pathways, including the pentose phosphate pathway (e.g., rpiA, Log₂FC(HCP/C) = 11.39) and an NADP⁺-dependent glyceraldehyde-3-phosphate dehydrogenase (gapN, Log₂FC(HCP/C) = 12.24). Notably, a putative beta-carotene hydroxylase (CrtZ) was uniquely sustained in the HCP condition (Log₂FC(HLP/HCP) = −10.65), strongly correlating with torularhodin accumulation and suggesting its novel role in torulene hydroxylation. This exploratory study reveals prospective transcriptional determinants of carbon partitioning in R. glutinis and provides a prioritized genetic blueprint for future hypothesis-driven research with full biological replication. Full article

Trametes polyzona is a white-rot basidiomycete with increasing relevance in environmental biotechnology due to its ligninolytic enzymes, biodegradation capacity, and versatile metabolic responses to diverse substrates. To provide an integrated and updated understanding of its biotechnological potential, we conducted a systematic review following PRISMA guidelines. A total of 46 studies published between 1991 and 2024 were analyzed, covering enzymatic production profiles, degradation of xenobiotics, extraction of bioactive metabolites, and experimental conditions influencing performance. Across the literature, T. polyzona consistently exhibits high ligninolytic activity, including laccase specific activities reported up to 1637 U/mg, together with efficient transformation of dyes, pesticides, and phenolic pollutants, and promising antioxidant and antimicrobial properties. However, substantial methodological heterogeneity was identified, particularly in strain characterization, fermentation parameters, and analytical approaches used to quantify enzymatic and biodegradation outcomes. These inconsistencies limit cross-study comparability and hinder process standardization. This review integrates current evidence; highlights critical gaps, such as limited ecotoxicological assessment of degradation products and scarce multi-omics characterization; and identifies key opportunities for process optimization in submerged/solid-state fermentation, bioreactor scaling, and the valorization of fungal metabolites. Overall, T. polyzona remains an underutilized resource with distinct advantages for applied mycology, environmental remediation, and industrial biotechnology. Full article

Itaconic acid (IA) is an important bio-based platform chemical produced via submerged fermentation by the filamentous Ascomycete Aspergillus terreus. In this study, we examined the impact of initial phosphate concentration on IA production from D-glucose and D-xylose in optimized, manganese-limited fermentations. Nine phosphate concentrations ranging from 0.04 to 4 g L⁻¹ were tested, and representative low (0.04 g L⁻¹), optimal (0.1 g L⁻¹), and high (0.8 g L⁻¹) conditions were analyzed in detail in controlled, 6 L scale bioreactors. Phosphate availability primarily influenced biomass formation and the biomass-to-product ratio rather than directly affecting IA accumulation. Both lower- and higher-than-optimal phosphate concentrations decreased the volumetric and specific IA yields, while the highest productivity was observed at 0.1 g L⁻¹. Expression of the aoxA gene, encoding the cyanide-resistant alternative oxidase (AOX), and AOX enzymatic activity were inversely correlated with extracellular phosphate concentration, consistent with a role in redox homeostasis under phosphate-limited conditions. In contrast, total respiration rates and pellet-type morphology remained unaffected. These findings indicate that phosphate acts mainly as a secondary modulator of IA fermentation performance through its influence on biomass formation, whereas other metabolic constraints play a more dominant role in controlling IA overflow in A. terreus. Full article

Zearalenone (ZEN) is a thermostable, lipophilic, non-steroidal estrogenic mycotoxin produced by Fusarium spp. that persistently contaminates food and feed. Its strong estrogenic activity and resistance to conventional detoxification strategies pose significant threats to food safety and human and animal health. Conventional physical and chemical degradation methods often compromise nutritional quality and leave toxic residues. Here we report the engineering of a novel Clonostachys rosea lactone hydrolase, Cr2zen, for efficient ZEN degradation in Pichia pastoris under mild conditions. Native Cr2zen exhibited a protein concentration of 0.076 mg/mL, achieving a degradation rate of approximately 17.9% within 30 min, with kinetic parameters of K_m 75.9 µM and V_max 0.482 µmol/L/s at 30 °C and pH 8.0. By integrating signal peptide screening and codon optimization, we identified Ser-Cr2 as the most effective variant, achieving a rapid 81.53% degradation of 10 ppm ZEN under mild conditions. Fed-batch cultivation in a 7.5 L bioreactor resulted in high cell densities of OD₆₀₀ 332.8 for Ser-Cr2 and 310.8 for Oser-Cr2, with extracellular protein concentrations of 0.62 and 0.79 g/L, respectively. The results demonstrate that signal peptide engineering and codon optimization substantially improved the production of lactone hydrolase in P. pastoris. This study establishes a scalable ZEN degradation under mild conditions in P. pastoris and outlines a strategy to integrate protein and process engineering for enhanced enzymatic mycotoxin degradation. Full article

Second cheese whey (SCW), a major by-product of ricotta cheese production, poses significant environmental challenges due to its high organic load. Biohydrogen (bio-H₂) and poly-β-hydroxybutyrate (PHB) production offer a sustainable reuse of SCW, that provides ideal nutrients for microbial growth. This study aimed to convert SCW into Bio-H₂ and PHB using a 5-liter tubular bioreactor in a sequential lactic fermentation and photofermentation system. Two lighting conditions were tested: white LED (WL) and selected LED (SL). Optimal results were achieved with a co-inoculum of Lactococcus lactis MK L84 and Lacticaseibacillus paracasei MK L49 at pH 4.5–5.5, followed by photofermentation with Rhodopseudomonas palustris 42OL under SL condition. The process yielded an average of 0.47 L of H₂ per liter of substrate and 1.66% wPHB/wCDW. This approach successfully transformed dairy waste into high-value products, promoting circular economy principles. Full article

Current food systems are highly complex, with interdependencies across regions, resources, and actors, and conventional food production is a major contributor to climate change. Transitioning to sustainable protein sources is therefore critical to meet the nutritional needs of a growing global population while reducing environmental pressures. Filamentous fungi present a promising solution by converting agro-industrial side streams into mycoproteins—nutrient-dense, sustainable proteins with a carbon footprint more than ten times lower than beef. This review evaluates the potential of mycoproteins derived from fungi cultivated on low-cost substrates, focusing on their role in advancing sustainable food systems. Evidence indicates that mycoproteins are rich in protein (13.6–71% dw), complete amino acids, fiber (4.8–25% dw), essential minerals, polyphenols, and vitamins while maintaining low fat and moderate carbohydrate content. Fermentation efficiency and product quality depend on substrate type, nutrient availability, and fungal strain, with advances in bioreactor design and AI-driven optimization enhancing scalability and traceability. Supported by emerging regulatory frameworks, mycoproteins can reduce reliance on animal-derived proteins, valorize agricultural by-products, and contribute to climate-resilient, nutritionally rich diets. Integration into innovative food products offers opportunities to meet consumer preferences while promoting environmentally sustainable, socially equitable, and economically viable food systems within planetary boundaries. Full article

This work develops and analyzes a novel fractional-order chemostat system (FOCS) with a Caputo fractional derivative (CFD) featuring a sliding memory window and periodic boundary conditions (PBCs), designed to model microbial pollutant degradation in sustainable water treatment. By incorporating the Caputo fractional derivative with sliding memory (CFDS), the model captures time-dependent behaviors and memory effects in biological systems more realistically than classical integer-order formulations. We reduce the two-dimensional fractional differential equations (FDEs) governing substrate and biomass concentrations to a one-dimensional FDE by utilizing the PBCs. The existence and uniqueness of non-trivial, periodic solutions are established using the Carathéodory framework and fixed-point theorems, ensuring the system’s well-posedness. We prove the positivity and boundedness of solutions, demonstrating that substrate concentrations remain within physically meaningful bounds and biomass concentrations stay strictly positive, with solution trajectories confined to a biologically feasible invariant set. Additionally, we analyze non-trivial equilibria under constant dilution rates and derive their stability properties. The rigorous mathematical results confirm the viability of FOCS models for representing memory-driven, periodic bioprocesses, offering a foundation for advanced water treatment strategies that align with Sustainable Development Goal 6 (Clean Water and Sanitation). This work establishes a comprehensive mathematical framework that bridges fractional calculus with sustainable water treatment applications, providing both theoretical foundations and practical implications for optimizing bioreactor performance in environmental biotechnology. Full article

In this study, nine different Propionibacterium freudenreichii strains were isolated from Kars Gravyer produced by traditional methods in Turkey and identified by sequencing the 16S–23S intergenic region using species-specific primers. The isolated strains were examined in vitro for the presence of the β-galactosidase enzyme, autoaggregation ability, sensitivity against eight selected antibiotics and survivability under harsh conditions in order to determine their potential probiotic properties. After probiotic potentials were evaluated, an experimental design was made to optimize the production of vitamin B12 in a 3 L glass bioreactor P. freudenreichii NUV774. While all strains showed similar resistance (92–98%) to gastric juice (0.3% pepsin, pH 3.0), they showed resistance to intestinal fluid (0.1% pancreatin, 0.3% bile salt, pH 8.0) between 60% and 92%. It was determined that the viability after 3 and 6 h of incubation in 0.5% and 1% bile salt differed between strains. All isolates exhibited resistance to ciprofloxacin, ampicillin, and trimethoprim–sulphamethoxazole; however, most were sensitive to ofloxacin. Overall, P. freudenreichii strains showed resistance to the gastrointestinal tract, tolerance to pH 3.0, and high tolerance to bile salts. As a result of optimization, maximum vitamin B12 production was found to be 156.8 mg/L. The optimum operating conditions were calculated as temperature = 36.9 °C, aeration = 2.430 vvm, and agitation = 159.120 rpm. Hence, P. freudenreichii, as future probiotic strain candidates, will offer an alternative source to Lactobacillus, Bifidobacterium and some Bacillus spp. In addition, this study denoted that the alteration of the production of active vitamin B12 by P. freudenreichii occurs in a strain-dependent manner. Full article

Spearmint phytochemicals exhibit remarkable antidiabetic, antioxidant, and broad pharmacological activities. In vitro organ cultures offer an efficient and sustainable platform for enhancing the production of these bioactive metabolites, although optimized media and cultivation strategies are essential to maximize yields. Here, four Murashige and Skoog (MS) medium variants and three cultivation systems—agar-solidified, static-liquid (L), and agitated-liquid (LA)—were evaluated to assess phenolics, antioxidant capacity, antidiabetic potential, and metabolic biochemical markers in in vitro-grown spearmint shoots. Half-strength MS (MS/2) consistently produced the highest antioxidant activity and accumulation of phenolics and sugars across all systems. The MS/2–L combination markedly boosted antioxidant responses, increasing 2,2-diphenyl-1-picrylhydrazyl (DPPH) values up to 27-fold and ferric reducing antioxidant power (FRAP) values tenfold relative to full-strength MS. Antioxidant capacity strongly correlated with total phenolics, flavonoids, rosmarinic acid, antidiabetic activity, and carbohydrate levels. Lipid peroxidation analysis further revealed that shoots cultured under LA conditions showed the highest level of malondialdehyde (MDA) accumulation, whereas MSN/2 (half-strength nitrogen) consistently yielded the lowest MDA levels across all cultivation systems. Collectively, these results highlight the strong influence of nutrient availability and culture system on the metabolic performance of in vitro-grown spearmint. In conclusion, nutrient limitation combined with liquid cultivation effectively enhances antioxidant metabolite accumulation, providing valuable criteria for the future design and optimization of scalable bioreactor systems. Full article

This study aimed to select Metschnikowia pulcherrima strains with antimicrobial potential and high biomass content, optimize their cultivation conditions, evaluate growth characteristics at different scales, and assess antimicrobial activity on apple plants (Malus domestica cv. Golden Delicious) infected with phytopathogens. Of the nine tested strains, M. pulcherrima D2 was selected for its strong inhibitory activity against all tested phytopathogenic molds: Venturia inaequalis, Botrytis cinerea, Phoma exigua, Colletotrichum coccodes, Monilia laxa, Alternaria alternata, Alternaria tenuissima, Fusarium sambucinum, and Fusarium oxysporum, both in vitro on laboratory media (inhibition zones from 13.5 to 35.0 mm) and in vivo on stems, leaves, flowers, and fruits of apple. Morphological observations of treated plants showed the complete absence or significant delays of disease symptoms for up to 10 days. Disease symptoms for several pathogens (V. inaequalis, A. alternata, A. tenuissima, B. cinerea, F. sambucinum) remained reduced by ≥50% for up to 31 days post-treatment compared to the untreated control. Optimal cultivation conditions for M. pulcherrima D2 were established: a complex medium containing yeast extract (5.0 g/L), soy peptone (5.0 g/L), and glucose (2.6 g/L), at pH 5 and 25 °C, with shaking at 180 rpm, resulted in high biomass contents (10⁷–10⁸ CFU/mL). Scale-up in 5 L bioreactors confirmed efficient biomass production (10⁸ CFU/mL and from 3.1 to 3.9 g/L of dry biomass). These findings highlight the strong biotechnological potential of M. pulcherrima D2 for the development of a biocontrol agent to protect apple fruits and trees against fungal phytopathogens. Full article

Microbial electrolysis cells (MECs) are bioreactors that utilize electroactive microorganisms to catalyze the oxidation of organic substrates in wastewater, generating electron flow for hydrogen production. Despite the concept, a persistent performance gap exists where metabolically active anodic biofilms frequently fail to achieve expected current densities by the flow of electrons to produce hydrogen. This review examines the multiple causes that lead to the disconnect between robust biofilm development, electron transfer, and hydrogen production. Factors affecting biofilm generation (formation, substrate selection, thickness, conductivity, and heterogeneity) are discussed. Moreover, factors affecting electron transfer (electrode configuration, mass transfer constraints, key electroactive species, and metabolic pathways) are discussed. Also, substrate diffusion limitations, proton accumulation causing inhibitory pH gradients in stratified biofilms, elevated internal resistance, electron diversion to competing processes like hydrogenotrophic methanogenesis consuming H₂, and detrimental biofilm aging, impacting hydrogen production, are studied. The critical roles of electrode materials, reactor configuration, and biofilm electroactivity are analyzed, emphasizing advanced electrochemical (CV, EIS, LSV), imaging (CLSM, SEM, AFM), and omics (metagenomics, transcriptomics, proteomics) techniques essential for diagnosing bottlenecks. Strategies to enhance extracellular electron transfer (EET) (advanced nanomaterials, redox mediators, conductive polymers, bioaugmentation, and pulsed electrical operation) are evaluated for bridging this performance gap and improving energy recovery. The review presents an integrated framework connecting biofilm electroactivity, EET kinetics, and hydrogen evolution efficiency. It highlights that conventional biofilm metrics may not reflect actual electron flow. Combining electrochemical, microelectrode, and omics insights allows precise evaluation of EET efficiency and supports sustainable MEC optimization for enhanced hydrogen generation. Full article