工程技术最新文献

Microbial production of industrially important exopolysaccharide (EPS) from extremophiles has several advantages. In this study, key media components (i.e., sucrose, yeast extract, and urea) were optimized for biomass growth and extracellular EPS production in Haloferax mediterranei DSM 1411 using Box-Behnken design. In a multi-objective optimization framework, response surface methodology (RSM) and genetic algorithm (GA)-optimized artificial neural network (ANN) were used to minimize biomass growth while increasing EPS production. The performance of the selected ANN model for the prediction of biomass and EPS (R²: 0.964 and 0.975, respectively) was found to be better than that of the multiple regression model (R²: 0.818, 0.963, respectively). The main effect of sucrose and its interaction with urea appears to have a significant effect on both responses. The ANN model projects an increase in EPS production from 4.49 to 18.2 g l^-1 while shifting the priority from biomass to biopolymer. The optimized condition predicted a maximum biomass and EPS production of 17.27 g l^-1 and 17.80 g l^-1, respectively, at concentrations of sucrose (19.98 g l^-1), yeast extract (1.97 g l^-1), and urea (1.99 g l^-1). Based on multi-objective optimization, the GA-ANN model predicted an increase in the EPS to biomass ratio for increasing the EPS and associated biomass production. The extracted EPS, identified as Gellan gum through NMR spectroscopy, was further characterized for surface and elemental composition using SEM-EDX analysis.

China is the largest producer and exporter of sweet potato in the world. Sweet potato residue (SPR) separated after starch extraction account for more than 10% of the total dry matter of sweet potatoes. However, large amounts of unutilized SPR can cause environmental pollution. SPR is rich in starch and cellulose, both of which can be converted into glucose, making it a good carbon source for microbial fermentation. Therefore, an efficient SPR enzymatic process needs to be developed. The technological conditions of high-solid enzymatic hydrolysis of SPR by fed-batch was investigated in detail. Cellulase, amylase, and pectinase had synergistic effects on SPR enzymatic digestion. The experiments were first conducted to optimize the total enzyme addition of 15 mg enzyme protein/g substrate. The experiments were designed using Design-Expert (10.0) to optimize the enzyme proportions to 42%, 31.8%, and 26.2% for cellulase, amylase, and pectinase, respectively. The fed-batch enzymatic hydrolysis of SPR was investigated. The feed time and amount were optimized. The results showed that the initial SPR enzymatic hydrolysis concentration was 14% (w/v), 9% (w/v) was added at 3 h, 6 h and 12 h, respectively and the final substrate concentration was 41% (w/v). After 24 h of enzymatic hydrolysis, the glucose concentration obtained was 194.57 g/L and the glucan conversion was 63.58%. The fed-batch enzymatic hydrolysis of SPR described in this study has great potential for the whole chain utilization of sweet potato and in the microbial fermentation industry as it is environmentally friendly, economical and efficient.

The ubiquitous presence of pharmaceuticals and personal care products (PPCPs) in the environment has become a significant concern due to their persistence, bioaccumulation potential in biota, and diverse implications for human health and wildlife. This review provides an overview of the current state-of-the-art in environmental bioremediation techniques for reducing pharmaceutical residues, with a special emphasis on microbial physiological aspects. Numerous microorganisms, including algae, bacteria or fungi, can biodegrade various pharmaceutical compounds such as antibiotics, analgesics and beta-blockers. Some microorganisms are capable of transferring electrons within the cell, and this feature can be harnessed using Bio Electrochemical Systems (BES) to potentiate the degradation of pharmaceuticals present in wastewater. Moreover, researchers are evaluating the genetic modification of microbial strains to improve their degradation capacity and expand list of target compounds. This includes also discuss how environment changes, such as fluctuations in temperature or pH, may affect bioremediation efficiency. Furthermore, the presence of pharmaceuticals in the environment is emphasised as a major public health issue because it increases the chance for antibiotic-resistant bacteria emerging. This review combines existing information and outlines needed research areas for improving bioremediation technologies in the future.

Herein, we explored an effective method for preparing silver nanoparticles (Ag NPs)-coated antibacterial silk fabrics. In particular, using amino acids and cellulose from silk as reducing agents and silver nitrate as a precursor, Ag NPs were synthesised in situ on the surface of silk without requiring additional reducing agents and catalysts. The surface morphology and chemical composition of the involved samples were characterised using techniques such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Notably, silk and silk precursors (silkworm cocoons, silk fibers and sericin) could be used for in situ Ag NPs synthesis. Furthermore, the antibacterial properties of the samples were evaluated against Escherichia coli-a Gram-negative bacterium-as a model, demonstrating an impressive antibacterial rate of up to 99.91%. In addition, we investigated the water absorption behaviour of the samples at 25 °C by assessing their moisture regain, water retention value and vertical wick height. The results indicated that the Ag NPs coating did not damage the water absorption performance of the involved silk. Finally, we compared the fabric performance before and after treatment using a universal testing machine and colorimeter. The results showed that the mechanical properties of the fabrics with the Ag NPs coating did not substantially change with treatment, but the fabrics became more yellowish. Overall, this research has notable application potential in the field of antibacterial fabrics.

In this study, we present a hybrid dynamic flux balance analysis (DFBA) model, combined with Partial Least Squares (PLS) regression, to simulate cell culture behavior in response to variations in media composition. DFBA models typically incorporate a stoichiometric matrix representing metabolic reactions, leveraging the pseudo-stationarity assumption to reduce the number of parameters, which in turn minimizes the risk of overfitting. Here, PLS regression is employed to define kinetic rate constraints within the DFBA model, capturing the dynamic and non-linear nature of reaction rates over different culture phases. An optimization approach identifies the minimal number of kinetic constraints required, ensuring model accuracy without excessive complexity. Our hybrid model is validated through simulation case studies using an E. coli system, demonstrating its effectiveness in adjusting to changes in initial media composition. The case studies reveal that the model's accuracy improves with a more detailed stoichiometric matrix, particularly when larger networks or more varied metabolic environments are present. Additionally, the hybrid DFBA-PLS approach provides a robust and scalable modeling framework adaptable to other bioprocesses, offering insights into medium composition effects and highlighting its potential for bioprocess optimization.

Blockage of the interaction between programmed death receptor-1 (PD-1) and programmed death ligand-1 (PD-L1) can restore T-cell activity and enhance antitumor immunity. PD-1/PD-L1 pathway inhibitors have promising applications in the treatment of advanced prostate cancer (PCa). We successfully developed a peptides-functionalized gold nanoconstruct (P-AuNS) consisted of PD-L1-binding peptide (PD-L1pep, P) and gold nanostar (AuNS), which could bind to cell-surface PD-L1 specifically and deliver PD-L1 into PCa cells with high efficiency. In PCa cells, P-AuNS can efficiently degrade PD-L1 in a lysosomal-dependent manner. In the co-culture system of Jurkat cells and DU145 cells, P-AuNS restored the proliferative capacity and interferon-gamma (IFN-γ) secretion level of Jurkat cells inhibited by co-cultured DU145 cells, indicating that P-AuNS effectively hampered the interaction between PD-1 and PD-L1. In addition, in PCa-bearing mice, P-AuNS can effectively inhibit tumor growth and down-regulate PD-L1 protein levels, and in vivo experimental results show that P-AuNS has no systemic toxicity. P-AuNS block the interaction between PD-1 and PD-L1 by efficiently degrading PD-L1, thus restoring the antitumor activity of T cells and inhibiting tumor progression of PCa. In all, P-AuNS has great promise as a potential immunotherapy strategy in the treatment of advanced PCa and even other solid tumors.

In this study, a bio-based vinylidene monomer, itaconic acid (IA), produced by a fungus Aspergillus terreus NBRC 6123 was polymerized in the culture. The inhibition of IA polymerization by the culture components was eased by extraction with 4-methyltetrahydropyran (4mTHP). The extraction with 4mTHP for 4 days under aerobic condition resulted in IA production at 67.9 g/L (522 mM) in the organic phase from 180 g/L glucose. Interestingly, 4mTHP did not affect to the glucose consumption and respiration of A. terreus. IA polymerization in 4mTHP for 72 h using 400 mM IA and 1 mM 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) as a radical initiator under anaerobic condition by N₂ gas purging resulted in that the IA conversion, and the weight-averaged molecular weight (Mw) and the molecular weight distribution (MWD) of the synthesized polyitaconic acid (polyIA) were 11.5%, 79.8 × 10³ g/mol, and 1.26, respectively. The respiration by the IA producer itself was used to remove the residual oxygen in the flask by sealing after the IA production. Colorimetric evaluation with a redox indicator, resazurin, revealed that an anaerobic condition which is suitable for the IA polymerization can be accomplished by just incubation for 1 day after the sealing. The synthesis of polyIA from glucose in the same flask with 4mTHP was demonstrated, resulting in that the IA conversion, and Mw and MWD of the synthesized polyIA were 13.8%, 9.1 × 10³ g/mol, and 1.24, respectively, when 47.1 g/L (362 mM) IA was produced by the extraction for 3 days. To our knowledge, this is the first demonstration of radical polymerization of vinylidene monomer in microbial cultures.

This study successfully constructs a tumor-targeting α-lipoic acid-loaded hollow mesoporous prussian blue nanozyme (AHPRzyme) for targeted therapy of nasopharyngeal carcinoma in mice. In these nanozymes, Arg-Gly-Asp (RGD) acts as a targeting ligand, enabling effective targeting of tumor cells. Additionally, AHPRzyme exhibits multiple anti-tumor mechanisms: ① The prussian blue nanozymes in AHPRzyme have catalase (CAT) activity, which decomposes H₂O₂ in human nasopharyngeal carcinoma CEN2 cells into non-toxic H₂O, reducing H₂O₂ levels and minimizing damage to normal cells. The released O₂ helps alleviate the hypoxic environment of the tumor, inhibiting lactate production due to hypoxia and consequently suppressing tumor growth. ② The prussian blue nanozymes also have peroxidase (POD) activity, which catalyzes H₂O₂ in tumor cells to generate ·OH, a reactive oxygen species, leading to tumor cell apoptosis. ③ The α-lipoic acid structure in AHPRzyme contains disulfide bonds that react with GSH, depleting excess glutathione (GSH) in tumor cells, disrupting the oxidative stress balance within the cells, and making them more sensitive to reactive oxygen species, thereby increasing tumor cell apoptosis. In summary, AHPRzyme can inhibit tumor cell growth and promote tumor cell apoptosis by improving the tumor microenvironment, achieving the goal of anti-nasopharyngeal carcinoma therapy.

Tylvalosin (TAT) is a widely used veterinary antibiotic whose residual contaminants promote antibiotic resistance and pose potential risks to human health and ecosystems. This study successfully isolated and identified a TAT-degrading bacterial strain, Providencia vermicola strain CT1, through 16S rRNA analysis and biochemical tests. Under optimized conditions (30 °C, pH = 6, initial TAT concentration of 300 mg/L, and bacterial culture volume of 50 mL), strain CT1 achieved a TAT degradation percentage of 97.1%. The degradation process followed a first-order kinetic model and was primarily driven by extracellular metabolites. GC-MS analysis identified that strain CT1 degrades TAT to produce small molecules such as 3-methylbutanoic acid, ethyl acetate, and 3-iminopentan-2-one. Strain CT1 effectively degraded TAT in actual wastewater samples, achieving 95% degradation within 60 h, and significantly reduced the COD, BOD₅, and NH₄⁺-N concentrations. These findings provide theoretical guidelines for removing TAT and other macrolide antibiotic contaminants from the environment.

Natamycin, a natural antifungal compound produced by Streptomyces, possesses antibacterial activity against yeast and mold. However, its low yield hinders widespread application in the food and pharmaceutical industries. This study aims to enhance natamycin production of Streptomyces gilvosporeus through engineering strain and optimization bioprocess. A high-yield strain exhibiting robust genetic stability was bred, yielding a 19.8% increase in shake flask fermentation and a 26.3% increase in fed-batch fermentation compared to the starting strain. The influence of temperature on high-yield strains was examined separately through batch fermentation and fed-batch fermentation. Subsequently, based on comprehensive analysis of fermentation kinetic parameters, a two-stage temperature control strategy was proposed. Specifically, the temperature was maintained at 30 ℃ for the first 18 h to shorten the lag phase, followed by a reduction to 26 ℃ and maintaining this temperature until the end of fermentation. Under this strategy, the natamycin production reached 14.4 g·L^-1, representing a 25.2% increase compared to constant temperature fermentation at 28 ℃. This study provided an efficient production strategy for natamycin.