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Lee, Gil-Yong,Ha, Suk-Jin,Jung, Jong-Hyun,Seo, Dong-Ho,Park, Jong-Yul,Kim, Su-Rin,Park, Nam-Woo,Kweon, Dong-Keon,Park, Sang-Hoo,Park, Cheon-Seok The Korean Society for Applied Biological Chemistr 2009 Applied Biological Chemistry (Appl Biol Chem) Vol.52 No.3
Hyaluronic acid (HA) is a linear high-molecular-weight polysaccharide with useful biomedical applications. Streptococcus zooepidemicus, a typical HA-producing bacterium, requires an animal-derived nitrogen source such as tryptone, peptone or sheep blood as a nutrient. Sixteen non-animal-derived (NAD) nitrogen sources were tested as a replacement for the expensive animal-derived nitrogen sources, which may have safety issues. Among the sixteen tested NAD nitrogen sources, a yeast-derived nitrogen source (YE 0251) showed the highest HA productivity, which was equivalent to the control HA production medium containing tryptone in a 5-L jar and in 3,000-L industrial fermentations. In the 3,000-L fermentation, YE 0251 increased cell mass (dry cell weight) and HA production by 11% and 8%, respectively, compared with the control HA production medium. The fmal specific volumetric productivity (0.41 g/L h) was improved by about 70% after reducing the fermentation time from 20 h to 12 h, compared to the conventional production medium.
Kim, Soo Rin,Lee, Ki-Sung,Choi, Jin-Ho,Ha, Suk-Jin,Kweon, Dae-Hyuk,Seo, Jin-Ho,Jin, Yong-Su Elsevier 2010 Journal of biotechnology Vol.150 No.3
<P><B>Abstract</B></P><P>Xylose-fermenting <I>Saccharomyces</I> strains are needed for commercialization of ethanol production from lignocellulosic biomass. Engineered <I>Saccharomyces cerevisiae</I> strains expressing <I>XYL1</I>, <I>XYL2</I> and <I>XYL3</I> from <I>Pichia stipitis</I>, however, utilize xylose in an oxidative manner, which results in significantly lower ethanol yields from xylose as compared to glucose. As such, we hypothesized that reconfiguration of xylose metabolism from oxidative into fermentative manner might lead to efficient ethanol production from xylose. To this end, we generated a respiration-deficient (RD) mutant in order to enforce engineered <I>S. cerevisiae</I> to utilize xylose only through fermentative metabolic routes. Three different repeated-batch fermentations were performed to characterize characteristics of the respiration-deficient mutant. When fermenting glucose as a sole carbon source, the RD mutant exhibited near theoretical ethanol yields (0.46gg<SUP>−1</SUP>) during repeated-batch fermentations by recycling the cells. As the repeated-batch fermentation progressed, the volumetric ethanol productivity increased (from 7.5 to 8.3gL<SUP>−1</SUP>h<SUP>−1</SUP>) because of the increased biomass from previous cultures. On the contrary, the mutant showed decreasing volumetric ethanol productivities during the repeated-batch fermentations using xylose as sole carbon source (from 0.4 to 0.3gL<SUP>−1</SUP>h<SUP>−1</SUP>). The mutant did not grow on xylose and lost fermenting ability gradually, indicating that the RD mutant cannot maintain a good fermenting ability on xylose as a sole carbon source. However, the RD mutant was capable of fermenting a mixture of glucose and xylose with stable yields (0.35gg<SUP>−1</SUP>) and productivities (0.52gL<SUP>−1</SUP>h<SUP>−1</SUP>) during the repeated-batch fermentation. In addition, ethanol yields from xylose during the mixed sugar fermentation (0.30gg<SUP>−1</SUP>) were higher than ethanol yields from xylose as a sole carbon source (0.21gg<SUP>−1</SUP>). These results suggest that a strategy for increasing ethanol yield through respiration-deficiency can be applied for the fermentation of lignocellulosic hydrolyzates containing glucose and xylose.</P>
The effect of Helicobacter pylori infection on decline of lung function
( Ha Youn Lee ),( Hye-rin Kang ),( Ye Jin Lee ),( Seung Ho Choi ),( Deog Kyeom Kim ) 대한결핵 및 호흡기학회 2019 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.127 No.-
Introduction: Although H. pylori infection has been associated with many extra-gastric diseases, its effects on the decline of lung function and development of COPD is controversial. We investigated the relationship between H. pylori infection and lung function in health screening population. Methods: A retrospective cohort study was conducted using the Gene-Environment of Interaction and phenotype (GENIE) data had collected from 2004 to 2015 in Seoul National University Gangnam Health Center. The seropositivity for H. pylori and combined clinical information was assessed. The differences in development of COPD and an annual decline rate of FEV1 or FVC reduction were compared according to the positivity of H. pylori-specific IgG adjusting with age, sex, height and smoking (pack-year). Results: A total of 3619 subjects (1849 (51.1%) patients with H. pylori-specific IgG and 1770 (48.9%) patients without seropositivity) were included and their median follow-up period was 7 years. At the first year, 95 (2.6%) patients were diagnosed with COPD, but their seropositivity for H. pylori-specific IgG was not different (p=0.756). During the total follow-up periods, the incidence of COPD was not different according to seropositivity of H. pylori (2.2% in seronegative patients vs. 2.0% in seropositive patients, p=0.728). The decline rate of mean FVC was similar in both groups (35.38 ml/year in seronegative group vs. 34.34 ml/year in seropositive group; p=0.389). Also the decline rate of mean FEV<sub>1</sub> was not different between two groups (39.23 ml/year in seronegative group vs. 37.49 ml/year in seropositive group, p=0.086). The eradication treatment for H. pylori did not affect the rate of decline in the mean FEV1 and FVC in seropositive patients. Conclusions: No significant association was found between H. pylori infection and lung function decline rate and the development of COPD. Also, H. pylori eradication therapy did not affect the rate of lung function decline.