• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.571-575
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• 2005

A simple, but effective on-line method for estimating the mycelial cell mass concentration from agitation speed data, a most readily-available process variable, has been developed for DO-stat cultures of Agaricus blazei. The dynamic change of dissolved oxygen concentration (DOC) in the initial transient period and the change in yield were considered in the development of the estimation algorithm or estimator. Parameters in the estimation algorithm were calculated from the agitation speed data at 20% of DOC. The proposed estimator could accurately predict the cell mass concentration regardless of DOC levels in the tested range of $10{\sim}40%$, showing a good extrapolation capability.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.4
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• pp.227-233
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• 2000

Although filamentous fungi are used extensively for protein expression, their use for the production of heterologous glycoproteins is constrained by the types of N-glycan structures produced by filamentous fungi as compared to those naturally found on the glycoproteins. Attempts are underway to engineer the N-glycan synthetic pathways in filamentous fungi in order to produce fungal expression strains which can produce heterologous glycoproteins carrying specific N-glycan structures. To fully realize this goal, a detailed understanding of the genetic components of this pathway in filamentous fungi is required. In this review, we discuss the characterization of the $\alpha$-mannosidase gene family in filamentous fungi and its implications for the elucidation of the N-glycan synthetic pathway.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.5
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• pp.462-465
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• 2006

An important issue in the oxidation of pentachlorophenol (PCP) by the enzyme horseradish peroxidase (HRP) is enzyme inactivation during the reaction. This study was initiated to investigate the ability of two nonionic surfactants (Tween 20 and Tween 80) to mitigate HRP inactivation. The surfactants were tested at concentrations below and above their critical micelle concentrations (CMCs). Enhancement of PCP oxidation was observed at sub-CMCs, indicating effective protection of HRP by the two surfactants. Maximum levels of PCP removal were observed when the concentrations of Tween 20 and Tween 80 were 40 and 50% of the CMCs, respectively At supra-CMCs, both surfactants caused a noticeable reduction in the extent of PCP removal.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.954-957
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• 2007

Gelation mechanism of xanthan-carob mixture (X/C) was investigated based on thermorheological behavior. Three X/C ratios (1:3, 1:1, and 3:1) were studied. Small amplitude oscillatory shear tests were performed to measure linear viscoelastic behavior during gelation. Temperature sweep ($-1^{\circ}C/min$) experiments were conducted. Using a non-isothermal kinetic model, activation energy (Ea) during gelation was calculated. At 1% total concentration, the Ea for xanthan fraction (${\phi}_x$)=0.25, 0.5, and 0.75 were 178, 159, and 123 kJ/mol, respectively. However, a discontinuity was observed in the activation energy plots. Based on this, two gelation mechanisms were presumed-association of xanthan and carob molecules and aggregation of polymer strands. The association process is the primary mechanism to form 3-D networks in the initial stage of gelation and the aggregation of polymer strands played a major role in the later stage.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.345-349
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• 2000

To easily separate chitosanoligosaccharides by size exclusion, an coencapsulating technology of substrate and enzyme was developed. The membrane was composed of alginate and a divalent cation such as calcium. Chitosan and chitosanase were enveloped in this membrane and the product released to medium by size exclusion. The capsule was stabilized in a 2% acetic acid solution (pH 5.0) containing 0.145 M CaCO$_3$. The leakage of substrate caused by the agitation speed was controlled by increasing alginate and CaCO$_3$concentrations. The lower limit of the alginate concentration and the agitation speed were 0.5% and 49rpm, respectively. Membrane thickness and capsule diameter were 10$\mu\textrm{m}$ and 2.5mm, respectively. By TLC analysis, the composition of chitosanoligosaccharides were mainly 3-6 mers. The molecular weight distribution of the released oligosaccharides ranged from 262 to 3624 Da by GPC.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.5
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• pp.291-293
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• 2003

Batch reactors were employed to investigate the kinetics of cellulose hydrolysis under extremely low acid (ELA) and high temperature condition. The sawdust was pretreated by Auto-hydrolysis prior to the batch reaction. The maximum yield of glucose obtained from the batch reactor experiment was about 70% for the pretreated sawdust, this occurred at 210 and 22$0^{\circ}C$. The maximum glucose yield from the untreated sawdust was much lower at these temperatures, about 55%. The maximum yields of glucose from the lignocellulosics were obtained between 15th and 20th minutes after which gradual decrease was observed.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.313-319
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• 2000

A crucial and causative role in the pathogenesis of atherosclerosis is believed to be the oxidative modification of low density lipoprotein (LDL). The oxidation of LDL involves released free radical driven lipid peroxidation. Several lines of evidence support the role of oxidized LDL in atherogenesis. Epidemiologic studies have demonstrated an association between an increased intake of dietary antioxidant vitamins, such as vitamin E and vitamin C and reduced morbidity and mortality from coronary artery diseases. It is thus hypothesized that dietary antioxidants may help prevent the development and progression of atherosclerosis. The oxidation of LDL has been shown to be reduced by antioxidants, and, in animal models, improved antioxidants may offer possibilities for the prevention of atherosclerosis. The results of several on going long randomized intervention trials will provide valuahle information on the efficacy and safety of improved antioxidants in the prevention of atherosclerosis. This review a evaluates current literature involving antioxidants and vascular disease, with a particular focus on the potential mechanisms.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.6-10
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• 1998

A plasmid vector containing two reporter genes, mer-lux and lac-GFP, was transformed to both Escherichia coli and Pseudomonas putida. Their cellular activities and biofilm characteristics were investigated in flow-cell units by measuring bioluminescent lights and fluorescent levels of GFP. Bioluminescence was effective to monitor temporal cell activities, whereas fluorescent level of GFP was useful to indicate the overall cell activities during biofilm development. The light production rates of E. coli and P. putida cultures were dependent upon concentrations of HgCl2. Mercury molecules entrapped in P. putida biofilms were hardly washed out in comparison with those in E. coli biofilms, indicating that P. putida biofilms may have higher affinity to mercury molecules than E. coli biofilms. It was observed that P. putida expressed GFP cDNA in biofilms but not in liquid cultures. This may indicate that the genetic mechanisms of P. putida were favorably altered in biofilm conditions to make a foreign gene expression possible.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.4
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• pp.221-226
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• 2003

With the current rapid development of nanotechnology and synthesis technology for designed oligonucleotides or oligonucleotide-modified nanoparticle conjugates, the combined strategies have become one of the most valuable methods in detection technology for DNA analysis. Using the uniquely recognizable interactions of pre-designed DNA molecules in assembling nanoparticles, various novel approaches have been recently developed towards detecting specific DNA sequences. Here we describe the key fundamentals and issues of this promising strategies ranging from the initial findings of rationally designed DNA-based assembly of nanoparticles to the extended chip-based detection system. Some limitations of these new strategies and possible approaches will be also discussed for the practical application in the area of DNA microarray detection.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.4
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• pp.213-220
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• 2003

Polymerase chain reaction (PCR) is one of the most widely used analytical tool and is an important module that would benefit from being miniaturized and integrated onto diagnostic or analytical chips. There are potentially two different approaches for the miniaturization of the PCR module: chamber-type and flow-type micro-PCR. These miniaturized PCRs have distinct characteristics and advantages. In this article, we review the necessity of micro-PCR, the materials for the chip fabrication, the surface modification, and characteristics of the two types of micro-PCR. The motivation underlying the development of micro-PCR, the advantages and disadvantages of the various materials used in fabrication and the surface modification methods will be discussed. And finally, the precise features of the two different types of micro-PCR will be compared.