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At least 19 recordsLinked to original sources

PubMed2025

Unraveling the ecological success of Iodidimonas in a bioreactor treating oil and gas produced water.

UNLABELLED: Iodidimonas sp., a bacterium found in bioreactors treating oil and gas produced water as well as iodide-rich brines, has garnered attention for its unique ability to oxidize iodine. However, little is known about the metabolic capabilities that enable Iodidimonas sp. to thrive in certain unique ecological niches. In this study, we isolated, characterized, and sequenced three strains belonging to the Iodidimonas genus from the sludge of a membrane bioreactor used for produced water treatment. We investigated the genomic features of these isolates and compared them with the four publicly available isolate genomes from this genus, as well as a metagenome-assembled genome from the source bioreactor. Our Iodidimonas isolates had several genes associated with mitigating salinity, heavy metal, and organic compound stress, which likely help these bacteria to survive in produced water. Phenotyping tests revealed that while the isolates could utilize a wide variety of simple carbon substrates, they failed to degrade aliphatic or aromatic hydrocarbons, consistent with the lack of genes associated with common hydrocarbon degradation pathways in their genomes. We hypothesize that these microbes may lead a scavenging lifestyle in the bioreactor and similar iodide-rich brines. IMPORTANCE: Occupying a niche habitat and having few representative isolates, the genus Iodidimonas is a relatively understudied alphaproteobacterial group. Its ability to corrode pipes in iodine production facilities has economic implications, and its ability to generate potentially carcinogenic iodinated organic compounds during treatment of oil and gas produced water may cause environmental and health concerns with the recycling of treated water. Therefore, detailed characterization of the metabolic potential of the Iodidimonas isolates in this study both sheds light on their adaptation to the environmental conditions they inhabit and has environmental and economic significance.

Bioreactors↗

PubMed2026

Small extracellular vesicles reflect senescence progression in human bone marrow-derived mesenchymal stem cells during hollow fiber bioreactor culture.

Prolonged three-dimensional culture exposes stem cells to sustain microenvironmental and mechanical stresses that can promote aging- and senescence-associated phenotypic alterations. This study examined how long-term expansion of human bone marrow-derived mesenchymal stem cells (BMSCs) in a hollow fiber bioreactor (HFB) influences cellular senescence and the molecular composition of secreted small extracellular vesicles (sEVs). During extended HFB culture, BMSCs exhibited progressive morphological flattening and cytoskeletal disorganization, accompanied by increased senescence-associated β-galactosidase activity and immunophenotypic remodeling characterized by reduced fluorescence intensity and spatial redistribution of canonical MSC markers, consistent with a stress-adapted, early senescence-associated cellular state. In parallel, sEVs were collected longitudinally over 40 days and characterized by nanoparticle tracking analysis, immunoblotting, and quantitative proteomics. While vesicle size, marker expression, and yield remained stable throughout culture, proteomic profiling revealed pronounced, phase-dependent remodeling of sEV cargo, including coordinated alterations in oxidative stress-related processes, lysosomal and extracellular matrix-associated pathways, and relative depletion of cytoskeletal and translational components. Notably, these vesicular signatures closely mirrored senescence-associated changes observed at the cellular level. The strong correspondence between cellular phenotypes and sEV proteomic profiles establishes vesicle analysis as a convergent and noninvasive readout of BMSC aging, enabling sensitive monitoring of senescence progression while reducing reliance on parallel, labor-intensive cellular assays. Collectively, these findings indicate that prolonged HFB culture promotes a controlled, stress-associated senescence program in BMSCs and position sEV proteomic profiling as a robust approach for assessing stem cell aging dynamics during long-term three-dimensional bioreactor culture.

Mesenchymal Stem Cells↗

PubMed2026

The making of cells and organs in xenogeneic animal bioreactor.

For patients with end-stage organ dysfunction, organ transplantation is the only viable treatment option. However, the most significant challenge at present is the severe shortage of donor organs, and no technology exists that allows for long-term, sustainable organ generation. The utilization of xenogeneic animals as in vivo bioreactors constitutes a viable method for the generation of functional and transplantable cells, tissues, and organs in vivo. The primary technology, blastocyst complementation, involves the injection of donor pluripotent stem cells into an organogenesis-disabled host embryo. This allows donor stem cells to compensate for organ defects and ultimately generate tissues or organs derived from the donor. Recent advancements in the field have demonstrated the successful generation of xenogeneic tissues and organs in rodents and large animals through the utilization of blastocyst complementation techniques. In addition, the replacement of nephron progenitor cells in the kidneys can be achieved through the application of the organogenic niche method. Furthermore, the expansion of xenogeneic hepatocytes and blood cells in immunodeficient animals is a viable approach. In this review, we introduce the history of blastocyst complementation and the impact of the pluripotent state of stem cells, one of its elements, on chimeric efficiency. Additionally, we provide a synopsis of the research progress concerning the utilization of rodents, pigs, and cattle as in vivo bioreactors to generate xenogeneic cells, tissues, and organs. Finally, the potential opportunities, challenges, and prospects for generating human blood cells in pigs are discussed.

Animals↗

PubMed2026

Genomic and bioreactor evaluation of newly isolated cellulase-producing bacteria.

Cellulose is a renewable resource with broad biotechnological potential, and its hydrolysis by cellulases underpins applications such as biofuel production and biowaste valorization. This study combined isolation, screening, molecular identification, enzyme assays, genome sequencing, and bioreactor evaluation to characterize novel cellulase-producing bacteria. Preliminary screening identified and selected bacterial isolates by hydrolysis halo formation, with strains showing halos ≥ 20 mm selected for further quantitative assays. Streptomyces olivaceus C1_7A, Bacillus thuringiensis FBB7BB, and Bacillus licheniformis strains AT081C and AT082C showed the highest endoglucanase activities (from 0.11 to 0.26 U mL-1). Further testing on Arundo donax and Avicel led to the selection of B. thuringiensis FBB7BB and S. olivaceus C1_7A as the most promising strains for biotechnological application. Whole genome sequencing confirmed the presence of genes involved in polysaccharide degradation. Finally, lab-scale fermentation trials using 1-2% CMC showed that B. thuringiensis FBB7BB reached a maximum endo-1,4-β-glucanase activity of 0.30 ± 0.04 U mL-1 after 8 h at 37 °C, whereas S. olivaceus C1_7A achieved 0.36 ± 0.03 U mL-1 after 216 h at 30 °C.

Cellulase↗

PubMed1976

Use of a tapered fluidized bed as a continuous bioreactor.

Reactor systems based on tapered fluidized beds are being developed for aqueous bioprocesses in which adhering microorganisms or immobilized active biological fractions are used. The use of a fluidized bed prevents biomass buildup, accommodates particulates in the feed stream, is compatible with gas sparging, and allows easy removal or addition of the active materials. The tapered reactor tends to stabilize the fluidized bed, thus allowing a much wider range of operating conditions. Preliminary experimental results and an empirical mathematical model of the tapered bed indicate that bed stability is associated with a decreasing velocity and void-fraction profile up the bed and the pressure drop across the bed decreases with increasing flow rates. The tapered fluidized bed bioreactor is being evaluated for use in the enzymatic production of hydrogen, microbiological denitrification, and microbiological degradation of coal conversion aqueous waste streams. The enzyme catalyzed conversion of lactose to glucose and galactose was used in the evaluation of the reactor concept.

Biochemistry↗

PubMed2026

Simultaneous removal of nitrogen, Cu2+, and bisphenol A in a hydrogel-biochar-AQDS immobilized bioreactor with added bicarbonate: Performance and metagenomic insights.

As the complexity of industrial wastewater pollution continues to increase, the simultaneous removal of nitrogen, metal contaminants, and persistent organic pollutants under low carbon conditions has become a key challenge for biological treatment systems. To address the operational instability and dependence on carbon sources observed in immobilized systems when exposed to copper (Cu2+) and bisphenol A (BPA), the Pseudoalteromonas japonicus strain LY0623 was integrated into a hydrogel-biochar-AQDS composite carrier to construct a multifunctional immobilized biofilm system. Notably, under conditions containing only NaHCO3, the R4 system achieved an NH4+-N removal rate of 89%. Under conditions where Cu2+ and BPA coexist, the R4 system achieved removal of NH4+-N (89%), NO3--N (100%), Cu2+ (85%), and BPA (88%). Sediment characterization confirmed that Cu2+ was immobilized through adsorption, complexation, and microbiologically induced carbonate precipitation (MICP). Metagenomic analysis further indicated that the Pseudomonadota phylum remained the dominant phylum, while functional pathways associated with inorganic carbon assimilation, HNAD nitrogen metabolism, endogenous carbon transformation, biomineralization, electron transfer, and aromatic compound degradation were preserved. By combining ammonia oxidation driven energy production, inorganic carbon utilization, redox mediated processes, and biomineralization, this study provides a highly promising low carbon strategy for treating industrial wastewater containing mixed pollutants.

Bisphenol A Compounds↗

PubMed2025

Versatile sugar and valerate metabolic pathways in Paraburkholderia xenovorans LB400 enable tailored poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production.

Poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) polymers are accumulated by diverse prokaryotes. Their distinct monomer compositions enable their use as tailored bioplastics. The aims were to characterize the poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis by Paraburkholderia xenovorans LB400 using different sugars and valerate, and to gain genome-oriented insights into polyhydroxyalkanoate production. d-Glucose, d-mannitol, d-gluconate, and d-xylose were evaluated as sole carbon sources or supplemented with valerate. Polyhydroxyalkanoates synthesized by strain LB400 were characterized through GC-MS, GC-FID, FTIR, and 1H and 13C-NMR. P. xenovorans LB400 reached 1.00-1.39 g L-1 of dry cell weight (DCW) with a P(3HB) content of 21-43% w w-1 when grown on different sugars. The addition of valerate to the sugar-grown LB400 cultures yielded a DCW of 1.79 to 2.29 g L-1 and a P(3HB-co-3HV) content of 50.0‒51.2% w w-1, with varying 3HV compositions (28‒43 mol%). The highest 3HV incorporation was observed with d-xylose and valerate. Genomic analyses of strain LB400 revealed key elements of sugar metabolism influencing growth, polymer accumulation, and monomer composition. LB400 genome encodes the PhaJ-like R-specific hydratase and FadJ epimerase, which are potentially useful for modulating copolymer composition. PHA production under bioreactor conditions was evaluated. In a bioreactor fed with d-glucose, LB400 achieved a P(3HB) concentration of 2.2 g L-1. These findings highlight the metabolic versatility of P. xenovorans LB400 in utilizing diverse sugars to produce either P(3HB) or tailor-made P(3HB-co-3HV), supporting the development of bioplastics for specific applications. KEY POINTS: • Strain LB400 produced P(3HB-co-3HV) from various sugars and valerate. • Sugar type drives LB400 PHA copolymer synthesis and composition. • Strain LB400 PHA production was scaled up to a bioreactor.

Polyesters↗

PubMed2025

Optimized GMP-grade production of non-viral Sleeping Beauty-generated CARCIK cells for enhanced fitness and clinical scalability.

BACKGROUND: Strict adherence to GMP guidelines and regulatory compliance is crucial when transitioning from research to clinical-grade production of ATMPs like CAR T cells. The success of CAR T cell therapy in treating hematological malignancies highlights the need for closed or automated systems to ensure quality and efficacy. Recent evidence also suggests that ex vivo culture conditions can significantly impact CAR T cell functionality. METHODS: We present our optimized methodology for expanding Sleeping Beauty transposon-engineered Chimeric Antigen Receptor-Cytokine-Induced Killer (CARCIK) cells using G-Rex devices and evaluate its impact on CARCIK cell phenotype and T cell fitness. RESULTS: Building on our previously validated protocol, we introduced key simplifications to optimize the CARCIK differentiation process. Delaying the nucleofection step eliminated the need for feeder cells while maintaining efficient CAR expression and high cell viability. Transitioning from T-flasks to G-Rex bioreactors reduced operator hands-on time from 21 to 28 days to 14-17 days and resulted in a less differentiated CARCIK cell product. Metabolic and transcriptional analyses showed that the novel protocol improves CARCIK cell fitness and in vivo efficacy against B-cell lymphoma. The novel method was validated in Good Manufacturing Practices (GMP) conditions at our two Cell Factories and yielded enough numbers of CARCIK-CD19 cells for clinical use. CONCLUSIONS: Optimizing non-viral CARCIK cell production using G-Rex bioreactors and refined timing adjustments has streamlined the workflow, enhanced cell fitness, and resulted in a highly effective therapeutic product with demonstrated in vivo efficacy in mice. These improvements reduced manipulation and contamination risks, while optimizing logistics and space efficiency, facilitating allogeneic CARCIK generation for a current phase I/II clinical trial (NCT05869279) in patients with R/R CD19 + non-Hodgkin Lymphoma (B-cell NHL) and Chronic Lymphocytic Leukemia (CLL), confirming the approach's scalability and clinical potential.

Humans↗

PubMed2026

Genome-scale overexpression screening identifies product tolerance and efflux transport as key determinants of high-level L-tryptophan production in Escherichia coli.

L-tryptophan is a high-value aromatic amino acid widely used in the food, feed, and pharmaceutical industries. However, large-scale microbial production is constrained by insufficient precursor supply and limited strain tolerance to high product concentrations. In this study, modular metabolic engineering was first employed to enhance the availability of key precursors, including shikimate, serine, and glutamine, yielding strain TRPJ-13 with a 34.6% increase in L-tryptophan titer. To enhance strain tolerance, an indigo-based high-throughput reporter system was constructed and coupled with genome-scale overexpression library screening, leading to the identification of soxS as a tolerance-conferring target. Mechanistic analysis demonstrated that soxS upregulated lpxC to enhance lipopolysaccharide biosynthesis, thereby reinforcing membrane integrity and improving L-tryptophan tolerance. Combinatorial engineering of soxS and lpxC generated strain TRPJ-23, which increased L-tryptophan tolerance by 74.8% and L-tryptophan titer by 10.3%. Furthermore, YicL was identified as a novel transmembrane protein involved in L-tryptophan transport that effectively promoted L-tryptophan efflux, further increasing the titer by 9.0%. After fermentation optimization, strain TRPJ-28 produced 74.3 g/L L-tryptophan in a 5-L bioreactor, with a yield of 0.26 g/g and a productivity of 1.24 g/L/h. In a 1000-L pilot-scale bioreactor, TRPJ-28 reached a titer, yield, and productivity of 70.4 g/L, 0.25 g/g, and 1.17 g/L/h, respectively. This study provides new engineering insights for developing industrially promising L-tryptophan-producing strains.

Genome-scale overexpression screening↗

PubMed2026

Multistrategy metabolic engineering of Talaromyces pinophilus for α-amylase production from lignocellulosic biomass.

Filamentous fungi are important hosts for industrial enzyme production. Growing demand for α-amylase has increased reliance on food-derived carbon substrates, necessitating fungal strains that efficiently utilize nongrain biomass. In this study, Talaromyces pinophilus Y117 was metabolically engineered to produce α-amylase from lignocellulosic biomass. A strong cellobiohydrolase I gene (cbh1) promoter (Pcbh1Tru) was identified to drive expression. Multiple rounds of multilocus integration of the α-amylase gene were performed using homologous multicopy genomic sequences as recombination arms with a Cre/loxP-based recyclable selection system, yielding the multicopy strain Tp4, which achieved 4124.5 U/mL α-amylase activity in shake-flask fermentation with corncob powder as the sole carbon source. To minimize enzyme degradation, the protease gene 8538 was deleted using the Cre/lox2272 system, generating Tp4Δp. This strain showed a 50% increase in shake-flask α-amylase activity (6208.4 U/mL). In 3-L bioreactor cultivation, Tp4Δp exhibited excellent production performance, achieving 26 712.2 U/mL α-amylase activity. When corncob powder was used as the sole substrate, the cellulose and hemicellulose degradation rates reached 90.00% and 70.01%, respectively, and the enzyme yield reached 213 697.5 U per gram of corncob powder. This engineered strain demonstrates strong potential for industrial applications. The synthesis-degradation synergistic optimization strategy provides a practical approach for engineering filamentous fungal cell factories to produce enzymes directly from lignocellulosic biomass. One sentence summary Metabolic engineering of Talaromyces pinophilus through promoter optimization, multicopy integration, and protease deletion enables efficient α-amylase production from lignocellulosic biomass, achieving 26 712 U/mL in bioreactor fermentation.

Talaromyces↗

PubMed2026

Whole-Genome Analysis of Bacillus Licheniformis Ali5 and Synthesis of Lichenysin via Genome Shuffling.

Whole-genome sequencing of Bacillus licheniformis Ali5 was performed via MGI-seq PE150 and Nanopore single-molecule real-time sequencing. The strain has a 4,114,664 bp circular genome encoding 4030 protein-coding genes. Functional annotation across NR, COG, GO, KEGG, CARD, BacMet, and CAZy databases identified 4025, 2812, 988, 1242, 72, 69, and 94 corresponding genes, respectively, and antiSMASH 6.0 revealed multiple antimicrobial biosynthetic gene clusters, including intact lichenysin and lichenicidin VK21 A1/A2 gene clusters. Three rounds of recursive protoplast fusion-based genome shuffling, paired with a dual-index screening system, significantly improved strain growth and lichenysin biosynthesis. Recombinants exhibited shortened lag phase, enhanced proliferation, improved stationary-phase stability, and higher diauxic peak biomass. PP3-176 and PP3-186 showed 4.6%-8.1% higher 12-h shake-flask titer and 3.1%-4.0% higher maximum titer than the parental average, with excellent fermentation stability. 1-L bioreactor validation confirmed strong scale-up potential. PP3-186 achieved 27.2% and 31.6% titer increases at 12 h and 20 h, while PP3-176 yielded 20.4% and 14.6% improvements with robust metabolic performance. This study validates genome shuffling as an effective strategy for enhancing lichenysin production, providing candidate strains and technical support for industrial application.

Bacillus licheniformis↗

PubMed2026

Enhanced Production of Recombinant Thermophilic Xylanase X11P in Ogataea polymorpha via In-Silico Signal Peptide Discovery and Fed-Batch Fermentation.

Efficient secretion of heterologous proteins is essential for advancing yeast-based bioprocesses, yet signal peptide (SP) optimization in the thermotolerant methylotrophic yeast Ogataea polymorpha remains limited. This study integrates in-silico SP discovery, experimental validation, and bioprocess engineering to enhance secretion of the thermophilic xylanase X11P under sucrose-inducible expression. Genome-wide screening of 5184 O. polymorpha proteins using SignalP, Phobius, DeepLoc, WoLF PSORT, and ProP identified 11 high-confidence SP candidates. Comparative analysis with Komagataella phaffii endogenous proteins guided selection of seven SPs for experimental evaluation. Among these, the novel O. polymorpha α-mating factor-like peptide FUN_005010 exhibited strong secretion-promoting activity, with its prepro-sequence yielding the highest extracellular xylanase levels and outperforming the classical Saccharomyces cerevisiae α-MF. To evaluate industrial applicability, sucrose-based fermentation strategies were systematically optimized in a 5-L bioreactor. Controlled sucrose feeding and balanced C/N ratios were found to be critical for maximizing maltase (MAL) promoter-driven expression. A stepwise increasing sucrose feed combined with induction at 30°C enabled X11P titers up to 770 U/mL, representing a 15-fold improvement over shake-flask cultures. This work demonstrates that the combination of SP evaluation and optimized sucrose-inducible fed-batch operation significantly enhances X11P production in O. polymorpha. The identified FUN_005010-prepro SP and the refined process framework provide valuable tools for developing O. polymorpha as a high-performance industrial expression platform.

Fermentation↗

PubMed2025

A comprehensive analysis of supermere, exomere, and extracellular vesicle isolation and cargo in colorectal cancer.

Biofluids contain a heterogeneous mixture of extracellular vesicles and non-vesicular nanoparticles (including exomeres and supermeres) that transport a diverse array of proteins, RNA, and lipids. Our previous efforts to characterize the contents of these carriers in colorectal cancer relied on 2D culture systems requiring large-scale setups and time-consuming ultracentrifugation-based isolation. To streamline this process, we have combined 3D hollow-fiber bioreactor production and fast-protein liquid chromatography-based size-exclusion chromatography. Here, we compare the impact of culture methods and purification strategies on small extracellular vesicle, exomere, and supermere cargo. Proteomic analyses show consistently distinct profiles for extracellular vesicles, exomeres, and supermeres regardless of culture conditions or isolation method. In contrast, these two variables influence small RNAs, their base modifications, and lipidomic profiles. We present an online tool to query these and future secretome datasets (https://superomics.shinyapps.io/browse).

Humans↗

PubMed2026

Reprogrammed Komagataella phaffii for enhanced secretory expression of human lactoferrin.

Human lactoferrin (hLF) is a multifunctional glycoprotein of the transferrin family derived from milk and mucosal secretions, which exhibits antibacterial, anti-tumor, and immunomodulatory functions, and is an important component of infant formula. Conventional methods for lactoferrin expression are often inefficient, primarily due to inadequate protein synthesis capabilities and poor stability within microbial hosts. Herein, a Komagataella phaffii yeast strain capable of high-level secretory expression of hLF was constructed by reprogramming the endoplasmic reticulum (ER) and vacuole using CRISPR/Cas9 technology. A dual-expression cassette containing the AOX1 promoter, an α-secretion signal peptide, the hLF gene, and a terminator was integrated into three different sites of the K. phaffii genome. The stepwise strategy combining expansion of the ER membrane involved in protein synthesis with knockout of vacuolar proteases further enhanced hLF production. Subsequently, 0.1 g/L FeCl₃ was added to the medium to reduce the toxicity of hLF and improve its stability. After high-density cultivation of K. phaffii through optimization of cultivation conditions in shake flasks and a 5 L bioreactor, the secretory intact hLF titer reached 2214 mg/L, representing a 76.3-fold increase achieved through these engineering strategies. In addition, antibacterial experiments demonstrated that this secretory hLF had a significant inhibitory effect on Escherichia coli, Staphylococcus aureus, and yeast. Overall, the developed K. phaffii protein expression platform enabled efficient production of lactoferrin, demonstrating its potential for expressing other lactoproteins.

Lactoferrin↗

PubMed2025

Unveiling the genetic basis of the low pH response in the acidophilic yeast Maudiozyma bulderi as a potential host for biorefinery.

Nonconventional yeasts represent a great genetic and phenotypic diversity with potential for industrial strain development in the bio-production of green chemicals. In recent years, mass genome sequencing of nonconventional yeasts has opened avenues to improved understanding of transcriptional networks and phenotypic plasticity and gene function, including the discovery of novel genes. Here, we investigated the expressional and morphological changes at low-pH in three strains of the acidophilic yeast Maudiozyma bulderi (previously Kazachstania bulderi and Saccharomyces bulderi): CBS 8638, CBS 8639, and NRRL Y-27205. The comparison of the transcriptome of cells growing in a bioreactor at pH = 5.5 vs pH = 2.5, primarily showed dysregulation of genes involved in cell wall integrity, with NRRL Y-27205 the least acidophilic strain, showing the largest transcriptional response when compared to the other strains. We identified four uncharacterized genes, unique to M. bulderi, and predicted function as transporters, upregulated at low pH. Microscopy studies showed that M. bulderi cell wall is not damaged in acidic environment, and the membrane lipid composition remains stable at low pH, unlike Saccharomyces cerevisiae. Overall, our data on transcriptional variability in M. bulderi highlights genes and cellular pathways involved in the acidophilic adaptation of this species and can aid further strain development.

Hydrogen-Ion Concentration↗

PubMed2026

Characterisation of metabolic burden in Pseudomonas putida reveals precursor limitation in heterologous lycopene production.

BACKGROUND: The introduction of heterologous pathways into microbial hosts often imposes a metabolic burden on the cell, arising from three major physiological constraint layers: competition for gene expression resources, limited precursor availability and flux distribution, and insufficient energy and redox supply. Although Pseudomonas putida KT2440 is considered a robust and metabolically versatile production host, it remains unclear which of these constraint layers primarily limits heterologous terpenoid production in this organism. Here, lycopene biosynthesis was used as a model system to systematically dissect these three potential sources of metabolic burden. RESULTS: A capacity-monitoring system revealed no clear reduction in transcriptional or translational capacity across the tested strains and cultivation conditions, indicating that general gene expression capacity was not the primary limiting factor. Instead, lycopene production depended strongly on promoter architecture and plasmid backbone, showing that regulatory design shaped pathway performance. Enhancing precursor supply by introducing a heterologous mevalonate (MVA) pathway substantially increased product titres, identifying precursor availability from the native MEP pathway as the dominant bottleneck. This conclusion was independently supported by exogenous mevalonate supplementation, which further increased lycopene accumulation but also revealed saturation at higher concentrations, suggesting that downstream pathway balance or enzyme capacity became limiting once precursor supply was relieved. Under controlled bioreactor conditions, lycopene titres increased from approximately 1 mg/L to nearly 25 mg/L, indicating that process conditions further modulate production performance, suggesting an additional contribution of process-dependent energy and redox constraints. CONCLUSION: Metabolic burden during heterologous lycopene production in P. putida is governed primarily by precursor availability rather than by limitations in general gene expression capacity. Regulatory properties of the vector system strongly influence pathway performance, while controlled cultivation conditions can further improve production by alleviating additional process-dependent constraints. Together, these findings provide a systematic framework for distinguishing constraint layers and guiding the optimisation of heterologous terpenoid production systems.

Lycopene↗

PubMed1977

The tubular loop fermentor: oxygen transfer, growth kinetics, and design.

Oxygen transfer measurements using a dynamic method and evaluated with an appropriate mathematical model have been made on a tubular loop bioreactor, Correlations of the type used in tank systmes are used to describe the influence of power and aeration rate on the mass transfer coefficient. Yeast cultures grown on hydrocarbon and glucose substrates show growth characteristics similar to conventional tank results. Model considerations for large-scale tubular fermentors allow for the prediction of the steady-state oxygen profiles and maximum reactor length. Combination with two-phases flow and oxygen transfer correlations yields a design procedure for commercial scale tubular loop fermentors.

Absorption↗

PubMed1977

Electric field control of lipase membrane activity.

Lipase (EC 3.1.1.3., from Pseudomonas sp.) was entrapped in collagen membrane containing liquid crystal (4-methoxybenzilidene-4'-n-butylaniline). The activity of the lipase-liquid crystal membrane at an applied voltage of 4 V was 3.4 compared to a membrane tested without imposition of an external electric field. A linear relationship was observed between the activity of the lipase-liquid crystal membrane and the current. The apparent Michaelis constant (K'm) of the lipase-liquid crystal membrane under electric field was identical to that of the membrane under ordinary condition. Activation of the lipase-liquid crystal membrane was observed repeatedly, i.e., activation in the presence of an electric field and reversion to a basal level upon removal of the field occurred cyclically. Activity control of immobilized enzymes is desirable for switching devices of a bioreactor. Possible mechanisms of the lipase activation by electric field are discussed.

Collagen↗