Hwai-Shen Liu

Loofa Sponge as a Scaffold for the Culture of Human Hepatocyte Cell Line

Loofa sponge was investigated as a three‐dimensional scaffold for stationary and perfusion culture of human hepatoblastoma cell line C3A/HepG2. In stationary culture, C3A/HepG2 cells in loofa cubes showed higher α‐fetoprotein and albumin secretion rates than those in polyurethane foam (PU). To use loofa cylinders in a packed‐bed reactor, immobilization of C3A/HepG2 cells by recirculating medium at 26 mL/min (superficial velocity = 51.7 cm/min) resulted in a cell loading density of 5.15 × 107 cells/cm3‐loofa. This cell loading density is higher than values reported in the literature for packed‐bed reactor intended for bioartificial liver. During 9 days of perfusion culture in the reactor, immobilized C3A/HepG2 showed steady synthesis of albumin with an average synthesis rate at 42.2 μg/106 cells/day. These experimental results and observations by SEM suggested that loofa sponge is a suitable scaffold for high‐density culture of human hepatocyte cell line and the immobilized cells could express high levels of liver‐specific functions.

Effect of lard oil, olive oil and castor oil on oxygen transfer in an agitated fermentor

Adding lard oil, olive oil or castor oil into a baffled and agitated fermentor decreased the volumetric oxygen transfer coefficient (KLa) in the low concentration range. However, KLa was increased when concentration reached 0.25% (v/v) at 400 rpm. Experimental results indicated that 1% (v/v) olive oil was as good as 0.1% (v/v) polypropylene glycol when added to a yeast fermentation.

Molecular dynamics simulations to determine the effect of supercritical carbon dioxide on the structural integrity of hen egg white lysozyme.

In this study, various molecular dynamics simulations were conducted to investigate the effect of supercritical carbon dioxide on the structural integrity of hen egg white lysozyme. The analyses of backbone root‐mean‐square deviation, radius of gyration, and secondary structure stability all show that supercritical CO2 exhibits the ability to increase the stability of this protein, probably as a result of the solvent with less polarity, where hydrophobic interactions stabilizing the native structure are weakened and simultaneously the local hydrogen bonds are strengthened, resulting in stabilization of the secondary structures. The hydrophobic cores in the α‐ and β‐domains also play an important role in preventing this protein from thermal unfolding. As supercritical CO2 has been attractive for biomedical applications because of the advantages of mild critical condition, nonflammability, nontoxity, and the purity of the resulting products, the structural stabilizing effect found in this study strongly suggests that it is possible to increase the thermostability of hen egg white lysozyme by pretreatment with supercritical CO2, leading to better industrial applications of this protein.

Alcoholysis of olive oil for producing wax esters by intracellular lipase in immobilized fungus cells

SummaryAlcoholysis of olive oil was carried out with lauryl and palmityl alcohols for producing wax esters. The reaction can be catalyzed efficiently by cell-bound lipase of Rhizopus niveous fungus cells immobilized within cellulose biomass support particles. Influences of reaction conditions such as water content, temperature, and substrate concentrations on reaction rates and yields were investigated.

Comparison of isoamylase immobilization to insoluble and temperature-sensitive reversibly soluble carriers

Isoamylase recovered from the fermentation broth of Pseudomonas amyloderamosa was immobilized onto water-insoluble carriers (chitin, CM-cellulose), and a temperature-sensitive reversibly soluble copolymer (N-isopropylacrylamide-co-N-acryloxysuccinimide). The characteristics and costs of the immobilized enzymes were analyzed. Enzyme coupled to the soluble copolymer showed the best performance among all supports.

Investigation on the immobilization of Pseudomonas isoamylase onto polysaccharide matrices

Abstract This study examined Pseudomonas isoamylase immobilized onto polysaccharide matrices, among which included agarose, cellulose, and raw corn starch. For chemical binding of polysaccharides activated with tosyl chloride, a high specific activity of 23144 U/g-starch was obtained as compared with matrices of cellulose and agarose with 3229 U/g-cellulose and 84 U/g-agarose, respectively.For raw corn starch, isoamylase desorption occurred when the immobilized enzyme by physical adsorption was subjected to 0.05 M acetate buffer with pH 5.2 at 40 °C; this is despite the considerable affinity between the enzyme and the matrix. In contrast, no detectable activity leached from the matrix for chemical binding, regardless of whether maltose, i.e. an affinity species to isoamylase, was added. For immobilized starch-isoamylase, its optimal activity performance was obtained in broader pH ranges of 3.5–5.5 and 5 °C higher than those of the free enzymes. More specifically, the free enzymes activity markedly decreased within five hours while the immobilized starch-isoamylase exhibited a fairly stable behavior over a three day incubation period at 40 °C. After 175 days of storage at 4 °C, the residues of relative activity of 75% and 45% were obtained with respect to immobilized and free isoamylases, respectively.

Olive oil addition in insect cell cultivation

Adding olive oil to an insect cell (Spodoptera frugiperda) cultivation with a TNM-FH medium enhanced cell growth. In the static cultivation, growth with 0.5% oil increased viable cell density by 32%, while cultivation in spinner flasks agitated at 260 rpm increased by 64%. With a gradual increase of agitation from 60 rpm to 500 rpm, the viable cell density was 81% higher than that without the olive oil supplement.