• Microbiology and Biotechnology Letters
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• v.43 no.3
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• pp.219-226
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• 2015

Acetic acid bacteria (AAB) were isolated from vinegar fermented through traditional methods in Namhae county, Gyeongnam, the Republic of Korea. The isolated strains were Gram negative, non-motile, and short-rods. Three selected strains were identified as either Acetobacter pasteurianus or Acetobacter aceti by 16S rRNA gene sequencing. A. pasteurianus NH2 and A. pasteurianus NH6 utilized ethanol, glycerol, D-fructose, D-glucose, D-mannitol, D-sorbitol, L-glutamic acid and Na-acetate. A. aceti NH12 utilized ethanol, n-propanol, glycerol, D-mannitol and Na-acetate. These strains grew best at 30℃ and an initial pH of 3.4. They were tolerant against acetic acid at up to 3% of initial concentration (v/v). The optimum conditions for acetic acid production were 30℃ and pH 3.4, with an initial ethanol concentration of 5%, resulting in an acetic acid concentration of 7.3−7.7%.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.856-862
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• 2015

The objective of this study was to optimize the slurry contents and salt concentrations for ethanol production from hydrolysates of the seaweed Eucheuma spinosum. A monosaccharide concentration of 44.2 g/l as 49.6% conversion of total carbohydrate of 89.1 g/l was obtained from 120 g dw/l seaweed slurry. Monosaccharides from E. spinosum slurry were obtained by thermal acid hydrolysis and enzymatic hydrolysis. Addition of activated carbon at 2.5% (w/v) and the adsorption time of 2 min were used in subsequent adsorption treatments to prevent the inhibitory effect of HMF. The adsorption surface area of the activated carbon powder was 1,400-1,600 m²/g and showed selectivity to 5-hydroxymethyl furfural (HMF) from monosaccharides. Candida tropicalis KCTC 7212 was cultured in yeast extract, peptone, glucose, and high-salt medium, and exposed to 80, 90, 100, and 110 practical salinity unit (psu) salt concentrations in the lysates. The 100 psu salt concentration showed maximum cell growth and ethanol production. The ethanol fermentations with activated carbon treatment and use of C. tropicalis acclimated to a high salt concentration of 100 psu produced 17.9 g/l of ethanol with a yield (Y_EtOH) of 0.40 from E. spinosum seaweed.

• Journal of Life Science
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• v.23 no.10
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• pp.1192-1198
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• 2013

To improve yeast strains for bioethanol production, yeasts with ethanol tolerance, thermotolerance, and ${\beta}$-1,3-glucanase activity were bred using yeast genome shuffling. Saccharomyces cerevisiae $BY4742{\Delta}exg1$/pAInu-exgA, which has extracellular ${\beta}$-1,3-glucanase activity, and the Aspergillus oryzae and S. cerevisiae YKY020 strains, which exhibit ethanol tolerance and thermotolerance, were fused by yeast protoplast fusion. Following cell fusion, four candidate cells (No. 3, 9, 11, and 12 strains) showing thermotolerance at $40^{\circ}C$ were selected, and their ethanol tolerance (7% ethanol concentration) and ${\beta}$-1,3-glucanase activity were subsequently analyzed. All the phenotypes of the two parent cells were simultaneously expressed in one (No. 11) of the four candidate cells, and this strain was called BYK-F11. The BYK-F11 fused cell showed enhanced cell growth, ethanol tolerance, ${\beta}$-1,3-glucanase activity, and ethanol productivity compared with the $BY4742{\Delta}exg1$/pAInu-exgA and YKY020 strains. The results prove that a new yeast strain with different characters and the same mating type can be easily bred by protoplast fusion of yeasts.

• Journal of Microbiology and Biotechnology
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• v.34 no.4
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• pp.838-845
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• 2024

Excessive alcohol consumption can have serious negative consequences on health, including addiction, liver damage, and other long-term effects. The causes of hangovers include dehydration, alcohol and alcohol metabolite toxicity, and nutrient deficiency due to absorption disorders. Additionally, alcohol consumption can slow reaction times, making it more difficult to rapidly respond to situations that require quick thinking. Exposure to a large amount of ethanol can also negatively affect a person's righting reflex and balance. In this study, we evaluated the potential of lactic acid bacteria (LAB) to alleviate alcohol-induced effects and behavioral responses. Two LAB strains isolated from kimchi, Levilactobacillus brevis WiKim0168 and Leuconostoc mesenteroides WiKim0172, were selected for their ethanol tolerance and potential to alleviate hangover symptoms. Enzyme activity assays for alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) were then conducted to evaluate the role of these bacteria in alcohol metabolism. Through in vitro and in vivo studies, these strains were assessed for their ability to reduce blood alcohol concentrations and protect against alcohol-induced liver damage. The results indicated that these LAB strains possess significant ethanol tolerance and elevate ADH and ALDH activities. LAB administration remarkably reduced blood alcohol levels in rats after excessive alcohol consumption. Moreover, the LAB strains showed hepatoprotective effects and enhanced behavioral outcomes, highlighting their potential as probiotics for counteracting the adverse effects of alcohol consumption. These findings support the development of functional foods incorporating LAB strains that can mediate behavioral improvements following alcohol intake.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2060-2065
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• 2016

Characteristics of E. coli O157:H7-specific infection bacteriophages (O157 coliphages) and broad-host-range bacteriophages for other E. coli serotypes (broad-host coliphages) were compared. The burst sizes of the two groups ranged from 40 to 176 PFU/infected cell. Distributions of the virulence factors stx1, stx2, ehxA, and saa between the two groups were not differentiated. Broad-host-range coliphages showed lower stability at $70^{\circ}C$, in relation to O157 coliphages. However, O157 coliphages showed high acid and ethanol tolerance by reduction of only 22% and 11% phages, respectively, under pH 3 and 70% ethanol for 1 h exposure. Therefore, these results revealed that the O157 coliphages might be more stable under harsh environments, which might explain their effective infection of the acid-tolerant E. coli O157:H7.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1159-1165
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• 2011

Biodiesel is methyl and ethyl esters of long-chain fatty acids produced from vegetable oils or animal fats. Lipase enzymes have occasionally been used for the production of this biofuel. Recently, biodiesel production using immobilized lipase has received increased attention. Through enhanced stability and reusability, immobilized lipase can contribute to the reduction of the costs inherent to biodiesel production. In this study, methanol-tolerant lipase M37 from Photobacterium lipolyticum was immobilized using the cross-linked enzyme aggregate (CLEA) method. Lipase M37 has a high lysine content (9.7%) in its protein sequence. Most lysine residues are located evenly over the surface of the protein, except for the lid structure region, which makes the CLEA preparation yield quite high (~93%). CLEA M37 evidences an optimal temperature of $30^{\circ}C$, and an optimal pH of 9-10. It was stable up to $50^{\circ}C$ and in a pH range of 4.0-11.0. Both soluble M37 and CLEA M37 were stable in the presence of high concentrations of methanol, ethanol, 1-propanol, and n-butanol. That is, their activities were maintained at solvent concentrations above 10% (v/v). CLEA M37 could produce biodiesel from olive oil and alcohols such as methanol and ethanol. Additionally, CLEA M37 generated biodiesel via both 2-step methanol feeding procedures. Considering its physical stability and reusability, CLEA M37 may potentially be used as a catalyst in organic synthesis, including the biodiesel production reaction.

• The Korean Journal of Mycology
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• v.46 no.3
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• pp.307-314
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• 2018

The goal of this study was to investigate the microbiological characteristics of the ethanol-producing wild yeast, Aureobasidium pullulans P-1, isolated from flowers growing near the Yedang reservoir, Chungnam province, Korea, and in addition, to optimize its fermentation ability for the production of Makgeolli. A. pullulans P-1 was oval-shaped, and formed ascospores and pseudomycelium. The P-1 strain was a halophilic and sugar tolerant yeast which grew in 15% NaCl and 50% glucose-containing yeast extract-peptone-dextrose media. The P-1 strain was also resistant to 20% ethanol. Changes of the physicochemical properties during Makgeolli fermentation by A. pullulans P-1 were investigated. A maximum of 8.45% ethanol was obtained when a mixture of cooked rice, 150% water, and 35% ipguk per cooked rice was fermented by 5% A. pullulans P-1 culture broth at $25^{\circ}C$ for 10 days. Antihypertensive angiotensin I-converting enzyme inhibitory activity in the Makgeolli ferment produced by A. pullulans P-1 reached a high of 71.1% after 10 days.

• KSBB Journal
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• v.21 no.6 s.101
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• pp.451-455
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• 2006

An efficient pilot scale (10 ton) three-stage methane fermentation system to digest food waste has been developed in this laboratory. This system consisted of three stages: semianaerobic hydrolysis, anaerobic acidogenesis and strictly anaerobic methanogenesis. From the secondary acidogenesis reactor, a novel strain KA4 responsible for alcohol fermentation was isolated and characterized. The cell was oval and its dimension was $5.5-6.5{\times}3.5-4.5\;{\mu}m$. This strain was identified as Saccharomyces cerevisiae KA4 by 26S rDNA D1/D2 rDNA sequence. Optimal culture temperature was $30-35^{\circ}C$. Cells were tolerant to 5% (v/v) ethanol concentration, however, were inhibited significantly by higher ethanol concentration up to 7%. The strain could grow well up to 50% (w/v) initial glucose concentration in the YM liquid medium, however, optimal concentration for ethanol fermentation was 10%. It could produce ethanol in a broad initial pH range from 4 to 10, and optimal pH was 6. In this condition, the strain converted 10% glucose to 7.4% ethanol during 24 hr, and ethanol yield was estimated to be 2.87 moi EtOH/mol glucose.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.707-712
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• 1994

Yeast screening for effective production of alcohol from Jerusalem artichoke tubers as an alternative energy source was performed. Inulin assimilative strains with high alcohol tolera- nce were isolated from wild sources and cultured in the liquid media of Jerusalem artichoke powder varying its concentraion from 15 to 30%. As a result, four strains of 2,445 isolates showing the inulin assimilation were selected as alcohol fermentative and alcohol tolerant yeasts. These strains were assignated to be Kluyveromyces marxianus F043 and Kluyveromyces sp. F173, E040, and F334, respectively, by their cultural and physiological characteristics. The F043 strain produced ethanol of 98.1 g/l in the 25% Jerusalem artichoke medium for 3 days.

• KSBB Journal
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• v.11 no.1
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• pp.77-85
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• 1996

The optimal initial pH for the ethanol production by Saccharomyces K35 was found to be 5.0, and about 80% of yield was obtained when 200g/$\ell$ of glucose was used as a substrate, which showed sugar tolerant. As the additives and cross-linking agent, the addition of 1.67%(w/v) Celite R-634 together with 0.33%(v/v) of glutaraldehyde(ACG bead) resulted in better stability, ethanol productivity and cell viability than Ca-alginate bead. Also, ACG bead seemed to be more resistant to phosphate ion than Ca-alginate bead, considering outgrowing cell concentration in the media. Scanning electron microscopic observation depicted that the surface of ACG bead was almost similar to the original state but not for Ca-alginate bead. When repealpd-batch culture was performed with Ca-alginate bead for 60 days in a 500m1 Erlenmeyer flask, ethanol and cell concentration were maintained about 138g/$\ell$-gel and 29~30g/$\ell$-gel, respectively, up to 40 days(7th run number), and then both were rapidly decreased. In the case of ACG bead, ethanol and cell concentration were maintained about 130~150g/$\ell$-gel and 32~35g/$\ell$-gel, respectively, up to 60days(10th run number). Cell viability was maintained about 70%, and outgrowing cell concentration was below 5.8% of total cell concentration.