Biotechnology and Bioprocess Engineering最新文献

The mammalian target of rapamycin (mTOR) is known to regulate cell growth, protein stability and cell-cycle progression, and many human tumors result from the dysregulation of mTOR signaling. Although various mTOR inhibitors have been developed, effective delivery systems are still needed to enhance the anti-cancer effects of mTOR inhibitors. In this study, we developed the Tat-fused mTOR inhibitor binding domain (Tat-MBD/TMBD) for the enhancement of the anti-cancer effect of mTOR inhibitors, due to the improvement of intracellular uptake. A TMBD/mTOR inhibitors complex spontaneously formed by biological affinity between MBD and mTOR inhibitors without chemical conjugation and modification. We constructed that a recombinant fusion protein expression vector composed of Tat (protein transduction domain) and mTOR inhibitor-binding domain (Tat-MBD) to deliver the mTOR inhibitors. The MBD spontaneously bound with mTOR inhibitors including sirolimus, everolimus, and temsirolimus, resulting in the formation of a TMBD/mTOR inhibitors complex. The enhancement of the delivery efficacy of mTOR inhibitors into various breast cancer cells was confirmed and improved anti-cancer efficacy was observed. We demonstrated the effective delivery systems of mTOR inhibitors without chemical conjugation of mTOR inhibitors.

This study addresses the challenge of separating bacteria with similar structures such as Escherichia coli and Aeromonas hydrophila. This approach employs pulsed field dielectrophoresis assisted by laminar flow fractionation in a lab-on-a-chip system with integrated optical detection. Bacterial cells passed through 30-µm microelectrodes subjected at 1 MHz and 14 V peak-to-peak in pulsed mode, while fluid flow carried bacteria towards the chamber’s end. The on-and-off electric field at specific pulse intervals expose bacterial cells to diverse forces, including kinetics, dielectrophoresis, gravity, drag, and diffusion, resulting in a net force facilitating their movement. Variations of pulsing time, flow rates, and voltage were investigated to identify the optimal combination for efficient separation. Next, the bacteria were detected using an optical fibre based on their absorbance. Results demonstrated a 30% separation efficiency in 90 min at 9.6 μL min⁻¹ flow rates, 4 s pulsing time, and 40 μS cm⁻¹ medium conductivity. A. hydrophila aggregates experienced greater DEP force and retained at microelectrodes during electric field application compared to E. coli, which moved faster towards optical detection. The separation mechanism with and without electric field was different, and precise control of cell movement during field-off periods is important to minimize uncontrolled diffusion. While the optical detection part has been successful, longer time and separation length are recommended for better separation. A carefully tuned combination of pulsing time, flow rates, voltage, and microelectrode design is crucial for this integrated lab-on-chip system to be efficient for separating and detecting closely related microorganisms.

Non-conventional yeasts are promising cell factories to produce lipids and oleochemicals, metabolites of industrial interest (e.g., organics acids, esters, and alcohols), and enzymes. They can also use different agro-industrial by-products as substrates within the context of a circular economy. Some of these yeasts can also comprise economic and health burdens as pathogens. Genome-scale metabolic models (GEMs), networks reconstructed based on the genomic and metabolic information of one or more organisms, are great tools to understand metabolic functions and landscapes, as well as propose engineering targets to improve metabolite production or propose novel drug targets. Previous reviews on yeast GEMs have mainly focused on the history and the evaluation of Saccharomyces cerevisiae modeling paradigms or the accessibility and usability of yeast GEMs. However, they did not describe the reconstruction strategies, limitations, validations, challenges, and research gaps of non-conventional yeast GEMs. Herein, we focused on the reconstruction of available non-Saccharomyces GEMs, their validation, underscoring the physiological insights, as well as the identification of both metabolic engineering and drug targets. We also discuss the challenges and knowledge gaps and propose strategies to boost their use and novel reconstructions.

Abstract

γ-Aminobutyric acid (GABA) is a non-proteinogenic amino acid with important physiological functions, which has been widely used in food, pharmaceuticals, and polyamides production. The fermentative GABA production by Corynebacterium glutamicum was recognized as one of the most promising methods. However, the problems of low catalytic activity of the heterologously expressed glutamate decarboxylase (GAD) and the imbalanced carbon flux between cell growth and GABA synthesis severely limited the GABA production by C. glutamicum. This study applied combinational metabolic engineering and catalytic condition optimization strategies to solve these two major obstacles. The secretory expression of GAD was enhanced using a bicistronic-designed expression cassette. This bicistronic expression cassette was further triply inserted into the genome by substituting the ldhA, pqo, and ack genes, thus stabilizing the expression of GAD and reducing the accumulation of by-products of lactate and acetate. A growth-regulated promoter P_{CP_2836} was applied to dynamically control the expression of odhA, thus controlling the α-oxoglutarate dehydrogenase complex activity for balanced cell growth and GABA production. The glutamate precursor synthesis and pyridoxal 5′-phosphate supply were also strengthened by promoter substitution. Finally, through a two-stage pH-controlled fed-batch fermentation under optimized conditions, the engineered strain reached GABA titer of 81.31 ± 1.31 g/L with a yield and productivity of 0.50 ± 0.01 g/g and 1.36 ± 0.23 g L⁻¹ h⁻¹, which was 4.8%, 13.6%, and 11.2% higher than that of the original strain. This study laid a solid foundation for industrial fermentative GABA production by engineered C. glutamicum.

In the present work, the possibility to grow the strain Synechococcus nidulans CCALA 188 on Mars using a medium mimicking a one obtainable using in situ available resources, i.e. the so-called Martian medium, under an atmosphere obtainable by pressurization of Mars CO₂, is investigated. The goal is to obtain a biomass with high-value products to sustain a crewed mission to Mars. The results show that the replacement of 40% vol of Z-medium with the same volume of Martian medium does not affect the cultivation and leads to a slight improvement of biomass productivity. Under an atmosphere consisting of pure CO₂ the growth rate was reduced but the strain managed to adapt by modifying its metabolism. Total proteins and carbohydrates were significantly reduced under Mars-like conditions, while lipids increased when using CO₂. A balanced diet rich in antioxidants is crucial for the wealth of astronauts, and in our case, radical scavenging capacities range from 15 to 20 mmol_TEAC/kg were observed. Under CO₂, a reduction in antioxidant power is observed likely due to a decrease in photosynthetic activity. The lipidome consisted of sulfoquinovosyldiacylglycerol, monogalactosyldiacylglycerol, digalactosyldiacylglycerol, phosphatidylcholine, phosphatidylglycerol, and triacylglycerol. A significant increase in the latter ones was observed under Mars simulated atmosphere.

Bacillus pumilus, a bacterial strain was isolated from agricultural soil and used for xylanase enzyme (Xy) production under the submerged fermentation technique. The (Xy) enzyme had an optimum temperature at 50℃ (maximum activity from 45–60 °C) and was active at broad pH range (5.0–8.0) with an optimum pH at around 6.3 as evaluated from response surface methodology studies. This enzyme after purification (purification; 2.87 folds, specific activity; 64.3 U/mg) was immobilized onto MOF_Cu-BTC (a copper ion-based metal organic framework) and was used for clarification of freshly squeezed fruit juice (pineapple and pomegranate). The study revealed an improved catalytic efficiency (V_max from 1.252.5 to 1.361 U/mL/mg of support) and greater half-life of the immobilized system (77–99 min). The activation energy decreased from that required for the free system (37.59–25.63 kJ/mol). The reusability of the enzyme improved after immobilization where 61% of the enzyme’s activity was retained after 21 cycles of usage. The MOF_Xy-Cu-BTC system showed improved clarification (47.58–57.97% for pineapple, and 15.34–18.3 for pomegranate) thereby showing its effectiveness in commercial juice clarification process.

Biofoundries represent advanced automation facilities pivotal for streamlining the Design-Build-Test-Learn (DBTL) paradigm in biomanufacturing and synthetic biology, suitable for both academic research and industrial applications. Nonetheless, establishing such a platform demands significant financial and temporal resources while maintaining a forward-looking perspective on automation, equipment compatibility, and operational efficiency. Despite its challenges, international collaborations between global biofoundries may offer solutions. The automated DBTL framework in biofoundries has transformed the production of bioproducts using engineered microbes. As the field advances, biofoundries are essential for streamlining and standardizing biotechnological processes, addressing efficiency, cost, and consistency challenges.