Yu-Kaung Chang

Antiviral effects of Salvia miltiorrhiza (Danshen) against enterovirus 71.

In this study, the antiviral activities of seven different extracts of Salvia miltiorrhiza (danshen) were determined. The first two extracts, SA1 and SA2, isolated at room temperature by ethyl acetate and water extraction, respectively, neutralized the enterovirus 71-induced cytopathic effect in Vero, rhabdomyosarcoma and MRC-5 cells. The other five crude extracts, extracted with warm water (60-70 degrees C) or organic solvents, did not have any protective activity. The 50% inhibitory concentrations for neutralizing the enterovirus 71-induced cytopathic effect were 0.742 +/- 0.042 mg/ml for SA1 and 0.585 +/- 0.018 mg/ml for SA2 in Vero cells. No antiviral activity was observed in the other viruses tested. Antiviral activity was more efficient in cultures treated with SA1 or SA2 during viral infection compared to the cultures treated before or after infection, suggesting that these danshen extracts could interfere with viral entry. SA1 and SA2 were able to inhibit viral RNA synthesis in the infected cells and to abate the apoptotic process in enterovirus 71-infected Vero cells. We conclude that danshen extracts possess antiviral activity and have potential for the development as an anti-enterovirus 71 agent.

Recent Developments on Genetic Engineering of Microalgae for Biofuels and Bio-Based Chemicals

Microalgae serve as a promising source for the production of biofuels and bio‐based chemicals. They are superior to terrestrial plants as feedstock in many aspects and their biomass is naturally rich in lipids, carbohydrates, proteins, pigments, and other valuable compounds. Due to the relatively slow growth rate and high cultivation cost of microalgae, to screen efficient and robust microalgal strains as well as genetic modifications of the available strains for further improvement are of urgent demand in the development of microalgae‐based biorefinery. In genetic engineering of microalgae, transformation and selection methods are the key steps to accomplish the target gene modification. However, determination of the preferable type and dosage of antibiotics used for transformant selection is usually time‐consuming and microalgal‐strain‐dependent. Therefore, more powerful and efficient techniques should be developed to meet this need. In this review, the conventional and emerging genome‐editing tools (e.g., CRISPR‐Cas9, TALEN, and ZFN) used in editing the genomes of nuclear, mitochondria, and chloroplast of microalgae are thoroughly surveyed. Although all the techniques mentioned above demonstrate their abilities to perform gene editing and desired phenotype screening, there still need to overcome higher production cost and lower biomass productivity, to achieve efficient production of the desired products in microalgal biorefineries.

Rapid purification of lysozyme by mixed-mode adsorption chromatography in stirred fluidized bed

The commercial STREAMLINE Direct HST adsorbent was employed to investigate the adsorption characteristics of lysozyme in complex chicken egg white (CEW). The effects of operating parameters, including adsorption pH, ionic strength, and hydrophobicity of liquids on binding capacity, were examined using a well-mixed contactor. To determine the elution strategy, the experiments were carried out in a small packed bed. The lysozyme was completely eluted by 0.5 M NaCl in 40 mM carbonate buffer (pH 12) at a high liquid velocity of 200 cm/h. The effect of rotating speed on fluidization characteristics was further investigated by using a stirred fluidized bed process. Smoother fluidization was observed when the rotating speed reached 200 rpm and lysozyme was directly recovered from highly viscous CEW in a single step with a high yield of 94.3% and a purification factor of 15.7.

Direct recovery of malate dehydrogenase from highly turbid yeast cell homogenate using dye-ligand affinity chromatography in stirred fluidized bed

Dye-ligand affinity chromatography in a stirred fluidized bed has been developed for the rapid recovery of malate dehydrogenase (MDH) from highly turbid bakers yeast cell homogenate in a single step. The most suitable dye, namely Reactive Orange 4, in its optimal immobilized concentration of 8.78 mg/mL was immobilized onto high-density STREAMLINE matrix. To further examine optimal adsorption and elution conditions, the enzyme recovery operation was carried out using unclarified cell homogenates in stirred fluidized bed system. Aiming to develop a non-specific eluent, namely NaCl, to effectively elute the MDH adsorbed, direct recovery of MDH from highly turbid cell homogenate (50% w/v) in a stirred fluidized bed adsorption system was performed. The proposed system successfully achieved a recovery yield of 73.6% and a purification factor of 73.5 in a single step by using 0.6 M NaCl as an eluent at a high liquid velocity of 200 cm/h.

Dye Affinity Nanofiber Membrane for Adsorption of Lysozyme: Preparation and Performance Evaluation

Polyacrylonitrile (PAN) nanofibrous membrane was prepared by an electrospinning technique. After heat treatment and alkaline hydrolysis, the weak ion exchange membrane was grafted with chitosan molecule and then covalently immobilized with a Cibacron Blue F3GA (CB). Fibre diameter, porosity and pore size of the membrane and immobilized dye density were characterized. Furthermore, the membrane was applied to evaluate the binding performance of lysozyme under various operating parameters (pH, chitosan mass per volume ratio, dye concentration, ionic strength and temperature) in batch mode. The experimental results were directly applied to purify lysozyme from chicken egg white by membrane chromatography. The results showed that the capture efficiency, recovery yield and purification factor were 90 and 87%, and 47-fold, respectively, in a single step. The binding capacity remained consistent after five repeated cycles of adsorption-desorption operations. This work demonstrates that the dye-affinity nanofibrous membrane holds great potential for purification of lysozyme from real feedstock.

Isolation of C-phycocyanin from Spirulina platensis microalga using Ionic liquid based aqueous two-phase system

An aqueous two-phase system (ATPS) with ionic liquids (ILs) was used for the isolate of C-phycocyanin (CPC) from Spirulina platensis microalga. Various imidazolium ILs and potassium salts were studied. The effect of ILs-ATPS on the extraction efficiency of CPC was also studied. The experimental parameters like pH, loading volume, algae concentration, temperature, and alkyl chain length of IL were well-covered in this report. The experimental results showed that the extraction efficiency, the partition coefficient, and the separation factor for CPC were 99%, 36.6, and 5.8, respectively, for an optimal pH value of 7 and a temperature of 308 K. The order of extraction efficiency for CPC using IL-ATPS was: 1-octyl-3-methylimidazolium bromide (C8MIM-Br) > 1-hexyl-3-methylimidazolium bromide (C6MIM-Br) > 1-butyl-3-methylimidazolium bromide (C4MIM-Br). The isolation process followed the pseudo second-order kinetic model and the thermodynamic results were obviously spontaneous.