• KSBB Journal
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• v.7 no.2
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• pp.139-143
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• 1992

One of the objectives of this work is to obtain information relevant to the industrial production of alcohol from sugar. The fermentation of alcohol by a strain of saccharomycess cerevisiae ATCC 24858 was studied In a continuous single-stage process with recycle of the cells via tangential flow microfiltration membranes. The experimental results reported in this study pertain to continuous cultures with total cell-recycle by varying the dilution rate (D=0.3, 0.5, and 0.7 $hr^{-1}$) and glucose concentration (50, 100, 150, and 200g/l sugar solution). Productivity using a repeated cell recycle system was found extremely high, 1.e., over 10 to 29 times higher than that of a smile batch system. When a sugar concentration of 200g/1 at dilution rate, 0.7 hr-1 was used, 83.9g/l ethanol was formed with an ethanol yield of 0.42(82% of theoretical) based on sugars utilized.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2004.06a
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• pp.278-281
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• 2004

The $\alpha$1,6-mannosyltransferase encoded by Saccharomyces cerevisiae OCH1 plays a key role for the outer chain initiation of the N-linked oligosaccharides. A search for Hansenula polymorpha genes homologous to S. cerevisiae OCHI (ScOCH1) has revealed seven open reading frames (ORF100, ORF142, ORF168, ORF288, ORF379, ORF576, ORF580). All of the seven ORFs are predicted to be a type II integral membrane protein containing a transmembrane domain near the amino-terminal region and has a DXD motif, which has been found in the active site of many glycosyltransferases. Among this seven-membered OCH1 gene family of H. polymorpha, we have carried out a functional analysis of H. polymorpha ORF168 (HpOCH2) showing the highest identity to ScOCH1. Inactivation of this protein by disruption of corresponding gene resulted in several phenotypes suggestive of cell wall defects, including hypersensitivity to hygromycin B and sodium deoxycholate. The structural analysis of N-glycans synthesized in HpOCH2-disrupted strain (Hpoch2Δ) and the in vitro $\alpha$1,6-mannosyltransferase activity assay strongly indicate that HpOch2p is a key enzyme adding the first $\alpha$1,6-mannose residue on the core glycan Man$_{8}$GlcNAc$_2$. The Hpoch2Δ was further genetically engineered to synthesize a recombinant glycoprotein with the human compatible N-linked oligosaccharide, Man$_{5}$GlcNAc$_2$, by overexpression of the Aspergillus saitoi $\alpha$1,2-mannosidase with the 'HDEL” ER retention signal.gnal.

• Journal of Food Hygiene and Safety
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• v.16 no.3
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• pp.188-193
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• 2001

To evaluate antimicrobial activities of chongkukjang slime fermented by different strains, growth characteristics were compared using various standard microorganisms with addition of chongkykjang slime. Chonghkjang slime was prepared by fermenting cooked soybean after inoculating with Bacillus circulans K-1, Baciilus spp N-1 and Bacillus subtilis CH-1, respectively. Significant antimicrobial activity was observed by chongkukjang slime on gram positive bacteria (Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Micrococcus luteus), gram negative bacteria(Escherichia coli O157:H7, Salmonella Typhimurium, Pseudomonas fluorescens), and yeast (Pichia membranaefaciens, Saccharomyces cerevisiae, Candida albicans). In case of B. cereus growth inhibition of 80% was achieved by the addition of chongkukjang slime; on the contrary, to Escherichia coli O157:H7 only 20% inhibition was observed. Slime from Bacillus subtilis CH-1, in particular, inhibition of 40% toward bacteria and yeast, whereas slime from Bacillus circulans K-1, Bacillus spp N-1 showed only 20% inhibition.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.206-211
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• 1999

Volatile antimicrobial compounds, isothiocyanates (ITCs), were compared their antimicrobial activity against 9 strains, Listeria monocytogenes, Bacillus subtilis, Pseudomonas fluorescens, Escherichia coli, Erwinia carotovora, Saccharomyces cerevisiae, Candida albicans, Aspergillus oryzae and Penicillium roqueforti. And synergistic antimicrobial effect of ITCs was examined with acetic acid. Allyl isothiocyanate (AIT), benzyl isothiocyanate (BIT), and ethyl isothiocyanate (EIT) were more effective than other ITCs. MIC (minimum inhibitory concentration) of these compounds was $100{\sim}200\;{\mu}g/dish$ against microorganisms tested and their inhibitory actions were more effective in order of fungi>yeast>Gram-negative bacteria>Gram-positive bacteria. MIC of acetic acid was $50{\sim}500\;{\mu}g/dish$ as lower concentration than ITCs. Using a mixture of volatile antimicrobial compounds and acetic acid, the synergistic effect was increased in $2{\sim}10$ times than ITCs used solely.

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.529-534
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• 2016

Bioethanol was produced using the separate hydrolysis and fermentation (SHF) method with macroalgal polysaccharides from the seaweed, Undaria pinnatifida as biomass. This study focused on the pretreatment, enzymatic saccharification, and fermentation of yeasts in co-culture. Ethanol fermentation with 14.5% (w/v) seaweed hydrolysate was performed using the yeasts, Saccharomyces cerevisiae KCTC 1126 alone, Pichia angophorae KCTC 17574 alone, and their co-cultures with the yeasts either adapted to mannitol or not. Among the combinations, the co-culture of non-adapted S. cerevisiae and P. angophorae adapted to mannitol showed high bioethanol production of 12.2 g/l and an ethanol yield ($Y_{EtOH}$) of 0.41. Co-culture in the SSF process was employed in this study, to increase the ethanol yields of 35.2% and reduction of 33.3% in fermentation time. These results provide suitable information on ethanol fermentation with marine seaweeds for bioenergy production.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.1977-1988
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• 2015

β-1,3-glucanosyltransferases play essential roles in cell wall biosynthesis in yeast. Kluyveromyces lactis has six putative β-1,3-glucanosyltransferase genes. KlGAS1-1 and KlGAS1-2 are homologs of Saccharomyces cerevisiae gene GAS1. RT-qPCR indicated the transcription level of KlGAS1-1 was significantly reduced while heterologous protein (thermostable xylanase B) secretion was enhanced during medium optimization. To evaluate if these two events were related, and to improve xylanase B secretion in K. lactis, we constructed KlGAS1-1 and KlGAS1-2 single deletion strains and double deletion strain, respectively. KlGAS1-1 gene deletion resulted in the highest xylanase B activity among the three mutants. Only the double deletion strain showed morphology similar to that of the GAS1 deletion mutant in S. cerevisiae. The two single deletion strains differed in terms of cell wall thickness and xylanase B secretion. Transcription levels of β-1,3-glucanosyltransferase genes and genes related to protein secretion and transport were assayed. The β-1,3-glucanosyltransferase genes displayed transcription complementation in the cell wall synthesis process. KlGAS1-1 and KlGAS1-2 affected transcription levels of secretion- and transport-related genes. Differences in protein secretion ratio among the three deletion strains were associated with changes of transcription levels of secretion- and transport-related genes. Our findings indicate that KlGAS1-1 deletion is an effective tool for enhancing industrial-scale heterologous protein secretion in K. lactis.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.242-247
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• 2008

In the fungal pathogen Candida albicans, the yeast-to-hyphal transition occurs in response to a broad range of environmental stimuli and is considered to be a major virulence factor. To address whether the zinc homeostasis affects the growth or pathogenicity of C. albicans, we functionally characterized the zinc-finger protein Csr1 during filamentation. The deduced amino acid sequence of Csr1 showed a 49% similarity to the zinc-specific transcription factor, Zap1 of Saccharomyces cerevisiae. Sequential disruptions of CSR1 were carried out in diploid C. albicans. The csr1/csr1 mutant strain showed severe growth defects under zinc-limited growth conditions and the filamentation defect under hypha-inducing media. The colony morphology and the germ-tube formation were significantly affected by the csr1 mutation. The expression of the hyphae-specific gene HWP1 was also impaired in csr1/csr1 cells. The C. albicans homologs of ZRTl and ZRT2, which are zinc-transporter genes in S. cerevisiae, were isolated. High-copy number plasmids of these genes suppressed the filamentation defect of the csr1/csr1 mutant strain. We propose that the filamentation phenotype of C. albicans is closely associated with the zinc homeostasis in the cells and that Csr1 plays a critical role in this regulation.

• Korean Chemical Engineering Research
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• v.44 no.1
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• pp.81-86
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• 2006

This study was carried out to investigate the antimicrobial and antioxidant activities for applications of food additives and medicine using Rumex crispus which widely grown in domestic area. Antimicrobial activities of extract fractions were observed in all microbial species except for Pseudomonas areuginosa. Especially, Vibrio vulificus and Saccharomyces cerevisiae presented obvious antimicrobial activity. Antioxidant activities of the fractions of R. crispus extract were determined by DPPH radical scavenger activity. The fraction of ethyl acetate was presented similar antioxidant activities compared with that of BHA and ascorbic acid. Also, ethyl acetate fraction contained higher phenolic compounds than that of others. The antioxidant activity in the fractions of R. crispus extract was closely related with the content of phenolic compounds in that.

• Journal of Life Science
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• v.18 no.6
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• pp.871-877
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• 2008

Onions are considered to be a promising source of the alcoholic drink because they are rich in sugar, amino acids and various nutrients. To isolate strains of Saccharomyces cerevisiae producing ethanol of higher concentration, 19 strains were subjected to screening. Among them, the strain producing the highest concentration of ethanol was OJ-8 strain. Onion's oder was effectively removed by treatment for 30 min with 10% (w/v) charcoal against medium and then heat treatment of onion extract for 40 min at $100^{\circ}C$. The optimum conditions for alcoholic fermentation was investigated in medium containing the onion extract. The optimal conditions for ethanol production was obtained by standing culture for 5 days at $25^{\circ}C$ with 5% inoculum volume.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.443-450
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• 1984

Chemical and microbial changes during Kimchi (a group of Korean seasoned pickles) fermentation were carried out at various temperatures and salt concentrations. The time reaching optimum ripening of Kimchi varied depending upon fermentation temperature and salt concentration. At high temperature and low salt content Kimchi fermentation was faster than at low temperature and high salt content. The ratio of volatile to non-volatile acids reached its maximum at the optimum ripening time of Kimchi and decreased thereafter. Leu. mesenteroids, Lac. brevis, Lac. plantarum, Ped. cerevisiae, Str. faecalis and low acid producing Lactobacilli were isolated from Kimchi samples. However, the main microorganism responsible for Kimchi fermentation was Leu. mesenteroides and Lac. plantarum was the main acidifying organism. Total viable count increased rapidly in the beginning of fermentation and reached its maximum number at optimum ripening time and then decreased slowly as the acidity of Kimchi increased. While the total aerobic bacteria and fungi decreased during Kimchi fermentation, the yeast increased significantly at lower temperature.