Two-Phase Fermentation Systems for Microbial Production of Plant-Derived Terpenes.

Microbial cell factories, renowned for their economic and environmental benefits, have emerged as a key trend in academic and industrial areas, particularly in the fermentation of natural compounds. Among these, plant-derived terpenes stand out as a significant class of bioactive natural products. The large-scale production of such terpenes, exemplified by artemisinic acid-a crucial precursor to artemisinin-is now feasible through microbial cell factories. In the fermentation of terpenes, two-phase fermentation technology has been widely applied due to its unique advantages. It facilitates in situ product extraction or adsorption, effectively mitigating the detrimental impact of product accumulation on microbial cells, thereby significantly bolstering the efficiency of microbial production of plant-derived terpenes. This paper reviews the latest developments in two-phase fermentation system applications, focusing on microbial fermentation of plant-derived terpenes. It also discusses the mechanisms influencing microbial biosynthesis of terpenes. Moreover, we introduce some new two-phase fermentation techniques, currently unexplored in terpene fermentation, with the aim of providing more thoughts and explorations on the future applications of two-phase fermentation technology. Lastly, we discuss several challenges in the industrial application of two-phase fermentation systems, especially in downstream processing.

TMT-Based Quantitative Proteomic Analysis Reveals Downregulation of ITGAL and Syk by the Effects of Cycloastragenol in OVA-Induced Asthmatic Mice.

Background: Cycloastragenol (CAG) has been reported to alleviate airway inflammation in ovalbumin- (OVA-) induced asthmatic mice. However, its specific mechanisms remain unclear. Objective: This study is aimed at investigating the effects of CAG on asthma, comparing its efficacy with dexamethasone (DEX), and elucidating the mechanism of CAG's regulation. Methods: The asthma mouse model was induced by OVA. CAG at the optimal dose of 125 mg/kg was given every day from day 0 for 20-day prevention or from day 14 for a 7-day treatment. We observed the preventive and therapeutic effects of CAG in asthmatic mice by evaluating the airway inflammation, AHR, and mucus secretion. Lung proteins were used for TMT-based quantitative proteomic analysis to enunciate its regulatory mechanisms. Results: The early administration of 125 mg/kg CAG before asthma happened prevented asthmatic mice from AHR, airway inflammation, and mucus hypersecretion, returning to nearly the original baseline. Alternatively, the administration of CAG during asthma also had the same therapeutic effects as DEX. The proteomic analysis revealed that the therapeutical effects of CAG were associated with 248 differentially expressed proteins and 3 enriched KEGG pathways. We then focused on 3 differentially expressed proteins (ITGAL, Syk, and Vav1) and demonstrated that CAG treatment downregulated ITGAL, Syk, and Vav1 by quantitative real-time PCR, western blot analysis, and immunohistochemical staining. Conclusion: These findings suggest that CAG exerts preventive and protective effects on asthma by inhibiting ITGAL, Syk, and the downstream target Vav1.

Insight into the Mechanical Performance of the UHPC Repaired Cementitious Composite System after Exposure to High Temperatures.

In this paper, the mechanical performance of an ultra-high-performance concrete (UHPC) repaired cementitious composite system, including the old matrix and the new reinforcement (UHPC), under various high temperature levels (20 °C, 100 °C, 300 °C, and 500 °C) was studied. In this system, UHPC reinforced with different contents of steel fibers and polypropylene (PP) fibers was utilized. Moreover, the physical, compressive, bonding, and flexural behaviors of the UHPC repaired system after being exposed to different high temperatures were investigated. Meanwhile, X-ray diffraction (XRD), baseline evaluation test (BET), and scanning electron microscope (SEM) tests were conducted to analyze the effect of high temperature on the microstructural changes in a UHPC repaired cementitious composite system. Results indicate that the appearance of the bonded system changed, and its mass decreased slightly. The average percentage of residual mass of the system was 99.5%, 96%, and 94-95% at 100 °C, 300 °C, and 500 °C, respectively. The residual compressive strength, bonding strength, and flexural performance improved first and then deteriorated with the increase of temperature. When the temperature reached 500 °C, the compressive strength, bonding strength, and flexural strength decreased by about 20%, 30%, and 15% for the UHPC bonded system, respectively. Under high temperature, the original components of UHPC decreased and the pore structure deteriorated. The cumulative pore volume at 500 °C could reach more than three times that at room temperature (about 20 °C). The bonding showed obvious deterioration, and the interfacial structure became looser after exposure to high temperature.

Interface Characterization Between Polyethylene/ Silica in Engineered Cementitious Composites by Molecular Dynamics Simulation.

Polyethylene is widely adopted in engineered cementitious composites to control the crack width. A clearer knowledge of the PE/concrete interfacial properties is important in developing engineered cementitious composites, which can lead to a limited crack width. Tensile failure and adhesion properties of the amorphous polyethylene/silica (PE/S) interface are investigated by molecular dynamics to interpret the PE/concrete interface. The influence of the PE chain length, the PE chain number and coupling agents applied on silica surface on the interfacial adhesion is studied. An increase of the adhesion strength of the modified silica surface by coupling agents compared with the unmodified silica is found. The failure process, density profile and potential energy evolutions of the PE/S interface are studied. The thermodynamic work of adhesion that quantifies the interfacial adhesion of the PE/S interface is evaluated. The present study helps to understand the interfacial adhesion behavior between ECC and PE, and is expected to contribute to restricting the crack width.

Effective Properties of Composites with Periodic Random Packing of Ellipsoids.

The aim of this paper is to evaluate the effective properties of composite materials with periodic random packing of ellipsoids of different volume fractions and aspect ratios. Therefore, we employ computational homogenization. A very efficient MD-based method is applied to generate the periodic random packing of the ellipsoids. The method is applicable even for extremely high volume fractions up to 60%. The influences of the volume fraction and aspect ratio on the effective properties of the composite materials are studied in several numerical examples.