Applied Biochemistry and Biotechnology最新文献

Spirulina platensis low-molecular-weight peptides (SP) have been reported to exhibit antioxidant and hepatoprotective properties. However, the limited bioavailability and solubility of SPs limit their potential applications. In this study, to examine the potential anti-obesity effects and underlying mechanisms of SPs, high-fat diet-induced non-alcoholic fatty liver disease (NAFLD) model rats were treated with SPs and SP-loaded nanoliposomes. Furthermore, hepatic biochemical parameters, inflammatory markers, histopathological changes, and genes involved in AMPK signaling were analyzed. SP-loaded nanoliposomes demonstrated a spherical shape with slower and sustained SP release. SP and SP-loaded nanoliposomes mitigated hepatic damage by lowering serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and increasing hepatic antioxidant enzymes, which are manifested in improving histopathological findings. In addition, notably, SP-loaded nanoliposomes downregulated lipogenic fatty acid synthase (FAS) and sterol regulatory element-binding protein-1c (SREBP-1c) in the liver. Meanwhile, an upregulation of phosphorylated AMP-activated protein kinase (P-AMPK), lipid acid oxidation-related genes carnitine palmitoyltransferase-1 (CPT-1), and peroxisome proliferator-activated receptor alpha (PPAR-α) was found in the rat liver. This data implies that SP and SP-loaded nanoliposomes exhibit protective potential in rats against the HFD-induced NAFLD, which is mediated through the activation of the AMPK signaling pathway.

The significance of exopolysaccharides (EPS) in various applications has garnered increasing attention. In this study, two bacteria, Liquorilactobacillus hordei SK6 and Liquorilactobacillus mali SK26, isolated from traditional water kefir grains, produced 8.89 g/L and 7.2 g/L of homopolymeric glucan, respectively. NMR analysis revealed that both glucans were dextrans composed of (1 → 6)-linked α-D-glucose units, with (1 → 3)-linked α-D-glucose units serving as branching points, accounting for 5.3 ± 0.2% in dextran SK6 and 2.7 ± 0.15% in SK26. FTIR and XRD analyses further confirmed the amorphous nature of the dextrans, although dextran SK6 exhibited micro-arranged structures. Thermal characterization using TGA and DSC showed degradation temperatures of 298.5 °C for dextran SK6 and 282.1 °C for dextran SK26. Clear differences in morphological properties were observed using AFM and SEM. These findings provide valuable insights into dextran-producing strains and their potential applications in various industries.

Recurrence is of utmost importance for hepatocellular carcinoma (HCC) after ultrasound-guided microwave ablation (UGMWA) therapy. The fibrosis 4 (FIB-4) index is a valuable predictor of HCC recurrence after surgical resection. However, whether FIB-4 can predict the recurrence of HCC patients receiving UGMWA remains unclear. The FIB-4 index was detected in healthy controls, hepatitis patients, and HCC patients. The predictive value of FIB-4 in HCC occurrence and recurrence following UGMWA therapy was evaluated using receiver operating characteristic analysis. The associated factors of FIB-4 in HCC patients were compared between patients with high and low levels of FIB-4. A Kaplan-Meier plot was used to assess the impact of FIB-4 on overall survival (OS) and recurrence-free survival (RFS). FIB-4 levels were increased in HCC patients and could predict the occurrence of HCC. Meanwhile, it was associated with five factors, including recurrence. Furthermore, FIB-4 levels decreased in HCC patients after UGMWA therapy but increased in recurrent HCC patients following UGMWA therapy. Importantly, FIB-4 could predict recurrence after UGMWA. The HCC patients had shorter OS and RFS. FIB-4 was associated with HCC recurrence after UGMWA therapy. Specifically, it had a predictive value for HCC occurrence and recurrence following UGMWA therapy.

Haloalkane dehalogenase DhaA is a member of the α/β-hydrolase superfamily and can degrade the halogenated compounds. However, the enzyme could not tolerate harsh and extreme environmental conditions, such as high temperature, extreme pH, and hypersaline, which limits its practical applications. Pullulan is a hydrophilic polysaccharide and acts as an additive to improve the enzyme stability. Polyethyleneimine (PEI) is a protein stabilizer and a polymer with a high density of ionizable amino groups. In the present study, DhaA was covalently conjugated with acetylated pullulan and adsorbed with PEI by electrostatic interactions to form nanoparticles (PEI-pullulan-DhaA). As compared with DhaA, PEI-pullulan-DhaA essentially maintained the enzymatic activity of DhaA, along with slight change in the kinetic parameters and enzyme conformation. The conjugated pullulan tends to form a large hydrated layer around DhaA. PEI, a cationic polymer, generated an amphiphilic microenvironment around DhaA. Pullulan conjugation and PEI adsorption could significantly improve the stability of DhaA against high temperature and low pH by structural stabilization of DhaA. PEI-pullulan-DhaA could also tolerate the hypersaline, organic solvents, and long-term storage. Thus, PEI-pullulan-DhaA has a strong environmental stability and is promising for industrial and environmental applications.

The preparation of value-added chemicals from carbon dioxide (CO₂) can act as a way of reducing the greenhouse gas from the atmosphere. Industrially significant C1 chemicals like methanol (CH₃OH), formic acid (HCOOH), and formaldehyde (HCHO) can be formed from CO₂. One sustainable way of achieving this is by connecting the reactions catalyzed by the enzymes formate dehydrogenase (FDH), formaldehyde dehydrogenase (FALDH), and alcohol dehydrogenase (ADH) into a single cascade reaction where CO₂ is hydrogenated to CH₃OH. For this to be adaptable for industrial use, the enzymes should be immobilized in materials that are extraordinarily protective of the enzymes, inexpensive, stable, and of ultra-large surface area. Metal-organic frameworks (MOFs) meet these criteria and are expected to usher in the much-awaited dispensation of industrial biocatalysis. Unfortunately, little is known about the molecular behaviour of MOF-immobilized FDH, FALDH, and ADH. It is also yet not known which MOFs are most promising for industrial enzyme-immobilization since the field of reticular chemistry is growing exponentially with millions of hypothetical and synthesized MOF structures reported at present. This review initially discusses the properties of the key enzymes required for CO₂ hydrogenation to methanol including available cofactor regeneration strategies. Later, the characterization techniques of enzyme-MOF composites and the successes or lack thereof of enzyme-MOF-mediated CO₂ conversion to CH₃OH and intermediate products are discussed. We also discuss reported multi-enzyme-MOF systems for CO₂ conversion cognizant of the fact that at present, these systems are the only chance of housing cascade-type biochemical reactions where strict substrate channelling and operational conditions are required. Finally, we delve into future perspectives.

An important factor in the development of diabetes and its associated consequences is prolonged chronic hyperglycemia, which weakens the antioxidant defense system and produces reactive oxygen species. Phytochemicals have been found to scavenge free radicals and exhibit antioxidant effects necessary to increase insulin sensitivity and reduce the development of diabetes-related complications. Current treatments for managing diabetes and diabetic nephropathy are often not very effective and come with several limitations and side effects. Resveratrol, for example, has shown therapeutic potential in mitigating kidney damage induced by high glucose levels, but its short bioavailability is a significant limitation. This accentuates the need for alternatives that not only improve the disease but also reduce the side effects associated with treatment. To enhance the therapeutic efficacy of resveratrol, we investigated the protective effects of liposomal resveratrol (LR) in a streptozotocin-induced diabetic rat model at doses of 20 and 40 mg/kg. We compared the impact of LR to that of resveratrol alone (at a dose of 40 mg/kg) on various parameters, including serum levels of biochemical markers, tissue levels of pro-inflammatory cytokines, nuclear transcription factor, oxidative stress indices, and apoptotic markers. LR, as a highly absorbable and metabolized form of resveratrol, has demonstrated beneficial effects in diabetic rats. Administered at both 20 mg/kg and 40 mg/kg dosages over a 5-week period, it demonstrated notable efficacy in alleviating inflammation. This was accomplished by diminishing the levels of pro-inflammatory mediators, TNF-α and IL-6, through the inhibition of NF-κB translocation. Additionally, LR influenced apoptotic markers, specifically caspase, BCL-2, and BAX. Furthermore, it enhanced the expression of key antioxidant enzymes such as catalase and glutathione peroxidase while significantly lowering malondialdehyde levels. These significant biochemical and immunological protective effects correlated with improved histological integrity and overall kidney architecture. Notably, resveratrol alone was not as effective as LR in restoring kidney function, highlighting its potential as a therapeutic candidate for the treatment of diabetic nephropathy. However, more in-depth studies are needed to explore its mechanism of action and improved bioavailability.

The development of an efficient lactose biosensor employing cellobiose dehydrogenases (CDHs) for monitoring and precise control of the lactose levels in dairy-based products is extremely important for the health of lactose-intolerant population. In this study, the mesophilic (Nc_CDH) and thermophilic (Ct_CDH-A, Ct_CDH-B) CDHs were successfully obtained by heterologous expression and treated with α-1,2-mannosidase and endoglycosidase H to prepare the deglycosylated forms (Nc_dCDH, Ct_dCDH-A, and Ct_dCDH-B); then, the effects of deglycosylation on the catalytic activity in solution and electrochemical performance on electrodes for lactose detection were systematically investigated. In solution, Nc_dCDH was more stable and had a higher V_max value and lower K_M value than Nc_CDH at different temperatures and pH values. In contrast, deglycosylation had adverse effects on the stability of Ct_CDH-A and Ct_CDH-B. When the CDHs mixed with multi-walled carbon nanotubes were dropped and immobilized on electrodes, with regard to Nc_CDH, in the presence of the same concentration of lactose, the detection current of the electrode modified with Nc_dCDH was higher than that of the electrode modified with Nc_CDH, and it had a lower detection limit (2.006 mM) and higher sensitivity (39.37 μA.mmol.L^-1.cm^-2). However, with respect to the thermophilic CDHs, the sensitivity was lowered and the detection limit was increased after deglycosylation. The discrepancy may result from two reasons: N-glycosylation may play a more crucial role in thermostability and structural stability of thermophilic CDHs, and the distribution sites of glycosylated residues may affect the electron transfer kinetics. This study is a step toward using CDH as an electron transfer-based lactose biosensor.

Due to their properties, numerous polyphenols and a static magnetic field could have therapeutic potential. Therefore, the aim of our research was to investigate the effect of caffeic acid (CA), a moderate-strength static magnetic field (SMF) and their simultaneous action on human fibroblasts in order to determine the molecular pathways they affect, which might contribute to their potential use in therapeutic strategies. The research was conducted using normal human dermal fibroblasts (NHDF cells) that had been treated with caffeic acid at a concentration of 1 mmol/L and then exposed to a moderate-strength static magnetic field. The RNA that had been extracted from the collected cells was used as a template for next-generation sequencing (NGS) and an RT-qPCR reaction. We identified a total of 1,006 differentially expressed genes between CA-treated and control cells. Exposure of cells to a SMF altered the expression of only 99 genes. Simultaneous exposure to both factors affected the expression of 953 genes. It has also been shown that these genes mainly participate in cellular processes, including apoptosis. The highest fold change value were observed for HSPA6 and HSPA7 genes. In conclusion, the results of our research enabled the modulators, primarily caffeic acid and to a lesser extent a static magnetic field, of the apoptosis signaling pathway in human fibroblasts to be identified and to propose a mechanism of their action, which might be useful in the development of new preventive and/or therapeutic strategies. However, more research using other cell lines is needed including cancer cells.

This study was to establish an efficient strategy based on inoculum-morphology control for the submerged mycelial fermentation of an edible and medicinal fungus, Inonotus hispidus. Two major morphological forms of the mycelial inoculum were compared, dispersed mycelial fragments versus aggregated mycelial clumps. The dispersed one was more favorable for the fermentation, starting with a shorter lag period and attaining a higher biomass yield and more uniform mycelium pellets in shake flasks. The mycelial pellets taken from the shake flask culture on day 6 were fragmented at 26,000 rpm in a homogenizer, and a shear time of 3 min provided the optimal inoculum. The inoculum and culture conditions were further verified in 5-L stirred tank fermenters and then the fermentation was scaled-up in a 100-L stirred tank. With the optimized inoculum and process conditions plus a fed-batch operation, much higher productivities, including 22.23 g/L biomass, 3.31 g/L EPS, and 5.21 g/L IPS, were achieved in the 100-L fermenter than in the flask culture. A composition analysis showed that the I. hispidus mycelium produced by the fermentation was rich in protein, dietary fiber, and polysaccharides which may be beneficial to health. Overall, the results have shown that the inoculum characteristics including age, morphology, and state of aggregation have significant impact on the productivity of mycelial biomass and polysaccharides in a submerged mycelial fermentation of the I. hispidus fungus.

This work describes the development of a novel biosensor obtained by immobilizing laccase from Pleurotus ostreatus Florida onto a glassy carbon electrode platform modified with zinc oxide quantum dots. For enzyme immobilization, the exopolysaccharide botryosphaeran from Botryosphaeria rhodina MAMB-05 was used. Although both biomaterials are from different fungal sources, laccase immobilization was guaranteed, which was demonstrated by the excellent stability of the fabricated biosensor device for the voltammetric determination of 2,6-dimethoxyphenol (2,6-DMP). Under the optimal experimental conditions, the cathodic current from the square-wave voltammograms presented a linear dependence on the 2,6-DMP concentration within the range of 10-400 nmol L^-1, with a limit of detection of 9 nmol L^-1. This bioanalytical device exhibited excellent repeatability and long-term storage stability.