Current Issue
March 2024
Volume 39, No.1
pISSN 1225-7117
eISSN 2288-8268
Articles
Most Read
Abstract : Makgeolli, one of Korean alcoholic beverages, have been increased market size since 2017 with the permission of online purchases. Several functional makgeolli by the addition of functional substances such as lactic acid from lactic acid bacteria(LAB) attracted the attention of consumers. We therefore studied the functional makgeolli in circulation which have been added both LAB as a probiotics and galactooligosacchride(GOS) as a prebiotics. Out of several combinations of LAB, mixture(S3) of Lactobacillus sakei(probiotics) and Lactobacillus sakei(parabiotics) added the GOS was shown the highest in the total bacterial cells. The GOS represented to the extent of positive effect for the growth and survival of LAB. The makgeolli with a high amount of total acid and lactic acid content improved quality due to the increase of sourness. Also, lactic acid increase from GOS addition induced proportionally antioxidative effect and received good reviews in the sensory evaluation without any deterioration of quality. These results indicated that the addition of LAB to makgeolli in circulation evaluated both the taste quality and functionality.
Abstract : Non-canonical amino acids (ncAAs) have shown considerable potential in enzyme engineering to improve catalytic activity, modulate enzyme active sites, probe complex enzyme mechanisms, create new to nature enzymes, and enhance thermostability. In this study, we report site-specific incorporation of the photocrosslinking ncAA: p-benzoyl-phenylalanine (pBpA) at the dimeric interface of the transaminase from Vibrio fluvialis (TAVF) and the effect of bulky ncAA incorporation on its functionality has been evaluated. Incorporating the pBpA at selected sites of TAVF led to the destabilization of the functional dimer and improper folding of variants. Two mutants, V31pBpA and K73pBpA, were isolated in the soluble form. The incorporation of bulky pBpA showed detrimental effects on the enzyme activity. Also, we determined the photocrosslinking efficiency of the incorporated pBpA, which showed a cross-linked variant with only 31pBpA highlighting the importance of the precise selection of the incorporation site for ncAA incorporation. Here we demonstrated the ncAA incorporation at a single site of the enzyme and its effects on the enzyme activity.
Abstract : The free fatty acid (FFA) content in the feedstock lipids of microalgae (MA), sewage sludge (SS), and waste coffee grounds (WCGs) were 7.6%, 38.5%, and 1.7%, respectively. For a single feedstock lipid, the maximum biodiesel conversion was about 70% for MA lipids using acid or alkaline catalysts, 29.6% for SS lipids using acid catalysts, and 93.5% for WCG lipids using alkaline catalysts. For a mixture of MA and SS lipids, the maximum biodiesel conversion was only 38.6% in the experimental range tested. In contrast, for mixtures of WCG and MA lipids and WCG and SS lipids, where WCG lipids accounted for three-fourth of the mixtures, the biodiesel conversions using an alkaline catalyst were 89.5% and 70.0%, respectively. When MA, SS, and WCG lipids were mixed in equal proportions, 71.8% biodiesel conversion was obtained with 3.0 wt% of an alkaline catalyst. This study shows that WCG lipids, when used with lipids having high FFA content, are crucial for improving the conversion of lipids into biodiesel. In addition, by manipulating the proportion of WCG lipids in the mixture, we were able to use an alkaline catalyst, which has several advantages over an acid catalyst, to produce biodiesel at a relatively high biodiesel conversion.
Abstract : There is an urgent need to elucidate how the introduction of cavitation bubbles or gas bubbles during precipitation improves the precipitation efficiency. In this study, the role of the bubble surface according to the gas flow rate and air sparger pore size in the gas bubble-based fractionation of (+)-dihydromyricetin, a natural bioactive compound, was investigated. As the gas flow rate increased and the air sparger pore size decreased, the bubble surface increased. At gas flow rates of 0.5 to 1.5 L/min, the yield and rate constant increased to be 1.7 to 1.9 and 2.6 to 5.5 times (air sparger pore size 10 μm), 1.4 to 1.8 and 1.9 to 4.7 times (30 μm), and 1.3 to 1.8 and 1.4 to 4.2 times (43 μm) higher than those obtained in the conventional precipitation. In addition, the changes in activation energy decreased as the bubble surface increased. The mechanism, by which nucleation could be induced seems to be heterogeneous due to the bubble surface provided.
Abstract : Molecular docking method helps predict the protein-ligand binding conformation, but its prediction accuracy is still limited and varies depending on the target ligand's structure and physicochemical properties. Therefore, understanding the ligand-dependent prediction accuracy is crucial in efficiently using the docking tool. In this study, we investigated how the prediction accuracy of AutoDock, a popular molecular docking tool, is affected by the aromaticity of the target ligand structure, ligand torsion number, and ligand hydrophobicity. The ligands with an aromatic ring showed substantially lower prediction accuracy than those without an aromatic ring. The ligands with lower torsion number showed higher prediction accuracy in the ligands with and without an aromatic ring. The hydrophobicity of ligands did not significantly influence the prediction accuracy in the case of ligands with an aromatic ring structure. However, the ligands without ring structure showed a clear difference in prediction accuracy depending on their hydrophobicity. These results are expected to be employed as a reference in molecular docking studies using AutoDock.
Abstract : A series of biological processes were developed to extract fermentable sugars from barley straw and produce succinic acid (SA), a microbial metabolite. For selectively removal of lignin with the alkali-catalyzed organosolv, process parameters such as NaOH concentration (w/w, %), ethanol concentration (v/v, %) and reaction temperature (oC) were investigated using the response surface method. As a result, the cellulose content of pretreated materials was increased about 63% and lignin was removed about 80% compared to the raw materials. For obtaining the high amount of SA, separate hydrolysis and fermentation (SHF) process was performed with high amount (113.9 g/L) of pretreated materials in a 5 L bioreactor. Through employing the fed-batch mode with enzyme feeding, the saccharification could be carried out effectively despite the low concentration (5 FPU cellulase/gglucan) of enzyme, resulting in the fermentable sugars of 58.76 g/L and glucose conversion rate of 63.35%. Actinobacillus succinogenes consumed glucose and xylose simultaneously, the main carbon sources of saccharified solution, at the rates of 0.71 and 0.49 g/L/h, respectively, and the phenomenon of catabolite repression was not observed. SA of 32.58 g/L was produced with a production yield of 0.56 SA g/total sugars g. Finally, it was turned that the A. succinogenes has metabolic capacities that could effectively utilize the carbohydrates of the lignocellulosic biomass, and the saccharified solution derived from barley straw was suitable as fermentation substrate.
Abstract : Mitochondria are the powerhouse of a cell that produces cellular energy, especially adenosine triphosphate (ATP), to fuel cell biosynthesis and protein production. In this study, we aim at inducing mitochondrial biogenesis in Chinese hamster ovary (CHO) cells to increase cellular ATP levels as well as recombinant protein productivity. Focusing on the culture process engineering, we tested two chemical additives, resveratrol and nicotinamide adenine dinucleotide (NAD), in CHO cell cultures to reinforce mitochondrial biogenesis. Resveratrol and NAD treatment resulted in an increase in specific productivity (qp) by 10-30% and 40-50% compared to the control, respectively. In addition, NAD exhibited an increase in viable cell densities, culture longevity and specific lactate uptake rates. Moreover, along with an increase in the ATP level, mitochondrial DNA (mtDNA) copy number and mRNA expression of the mitochondrial biogenesis-related genes were also up-regulated compared to the control. In conclusion, although there might be varied cell line-specific impacts on cell growth, inducing mitochondrial biogenesis using chemical additives would be an effective strategy for improving recombinant proteins productivity in CHO cells culture.
Abstract : To achieve a high viability by minimizing thawing damage, ice crystallization must be reduced in the process of thawing. Thermophysical properties of suspensions of Porphyra seriata, Undaria pinnatifida, and Sargassum fulvellum were measured to determine the optimal thawing conditions in the thawing process for species conservation of sea algae. The range of final thawing temperature was –2.49 ~ –0.50°C at thawing speed 1.25°C/min and 2~3°C at 1.5~2.0°C/min, and thawing was completed at temperatures above 3.0°C, enabling the removal process of cryoprotectant. The optimum thawing speed with the minimum thawing time was 0.75~1.0°C/min, and the latent heat of thawing was Undaria pinnatifida 128.37 J/g, Porphyra seriata 118.53 J/g, and Sargassum fulvellum 94.42 J/g, which can be useful for the design and manufacture of algae cryopreservation system. From the change of enthalpy, entropy and free energy according to each thawing rate, the optimum thawing rate for recrystallization temperature pan and viability improvement is suitable over Porphyra seriata, Sargassum fulvellum, Undaria pinnatifida 0.75°C/min, 1.0°C/min, 1.5°C/min respectively. From the results of the thawing process, the optimal method of freezing-thawing process of seedlings for aquaculture will be set up to increase the viability and contribute to the aquaculture industry by being used for growth in the farm. In addition, the results of this study will contribute to the establishment of gene bank, seed bank, and seed vault for various kinds of sea algae.
Abstract : The advanced clinical stage of breast cancer causes a lower survival rate even though the survival rate in the early stages is relatively high. Thus, the development of a rapid and easy-to-access diagnostic method is needed. In this study, a single chain Fv (scFv)-type antibody fragment that binds to HER2, a transmembrane protein overexpressed on breast cancer cells, was generated. The scFv was converted to a Quenchbody by site-specifically labeling the scFv using fluorescent dye through a maleimide-thiol reaction. The Quenchbody could detect a picomolar order of HER2 in a few minutes, and its signal-to-background ratio of fluorescence intensity was higher than a fluorescence scFv generated through a conventional fluorescent dye-conjugating method. The Quenchbody can be used as a probe for detecting and imaging of breast cancer cells for point-of-care diagnosis of breast cancer.
You-Chan Jeon, Deok-Ho Kwon, Yoojin Lee, Sanghoon Lee, Sung-Hun Kwon, Hyung-Moo Jung, Suk-Jin Ha
Korean Society for Biotechnology and Bioengineering Journal 2023; 38(3): 188-193
https://doi.org/10.7841/ksbbj.2023.38.3.188
Ho-Seong Im, Gyung-Sik You, Yong-Hyeon Jung, and Hyun-Jae Shin
Korean Society for Biotechnology and Bioengineering Journal 2023; 38(3): 153-161
https://doi.org/10.7841/ksbbj.2023.38.3.153
Hye-Jin Kim, Kyung June Yim, Hyun-Jin Jang, Seong-Joo Hong, Ji Young Jung, Seung Won Nam, Young-Jin Ryu , Choul-Gyun Lee, Su-Hwan Cheon, and Z-Hun Kim
Korean Society for Biotechnology and Bioengineering Journal 2023; 38(2): 127-134
https://doi.org/10.7841/ksbbj.2023.38.2.127
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