• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1403-1412
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• 2013

Ethanol fuel production from lignocellulosic biomass is emerging as one of the most important technologies for sustainable development. To use this biomass, it is necessary to circumvent the physical and chemical barriers presented by the cohesive combination of the main biomass components, which hinders the hydrolysis of cellulose and hemicellulose into fermentable sugars. This study evaluated the hydrolytic capacity of enzymes produced by yeasts, isolated from the soils of the Brazilian Cerrado biome (savannah) and the Amazon region, on sugarcane bagasse pre-treated with $H_2SO_4$. Among the 103 and 214 yeast isolates from the Minas Gerais Cerrado and the Amazon regions, 18 (17.47%) and 11 (5.14%) isolates, respectively, were cellulase-producing. Cryptococcus laurentii was prevalent and produced significant ${\beta}$-glucosidase levels, which were higher than the endo- and exoglucanase activities. In natura sugarcane bagasse was pre-treated with 2% $H_2SO_4$ for 30 min at $150^{\circ}C$. Subsequently, the obtained fibrous residue was subjected to hydrolysis using the Cryptococcus laurentii yeast enzyme extract for 72 h. This enzyme extract promoted the conversion of approximately 32% of the cellulose, of which 2.4% was glucose, after the enzymatic hydrolysis reaction, suggesting that C. laurentii is a good ${\beta}$-glucosidase producer. The results presented in this study highlight the importance of isolating microbial strains that produce enzymes of biotechnological interest, given their extensive application in biofuel production.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.675-683
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• 2016

One osmotolerant strain from among 44 yeast isolates was selected based on its growth abilities in media containing high concentrations of sucrose. This selected strain, named SK-ENNY, was identified as Meyerozyma guilliermondii by sequencing the internal transcribed spacer regions and partial D1/D2 large-subunit domains of the 26S ribosomal RNA. SK-ENNY was utilized to produce high-fructose glucose syrup (HFGS) from sucrose-containing biomass. Conversion rates to HFGS from 310-610 g/l of pure sucrose and from 75-310 g/l of sugar beet molasses were 73.5-94.1% and 76.2-91.1%, respectively. In the syrups produced, fructose yields were 89.4-100% and 96.5-100% and glucose yields were 57.6-82.5% and 55.3-79.5% of the theoretical values for pure sucrose and molasses sugars, respectively. This is the first report of employing M. guilliermondii for production of HFGS from sucrose-containing biomass.

• Microbiology and Biotechnology Letters
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• v.6 no.4
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• pp.155-159
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• 1978

Phenol utilizing yeast No. 558 isolated from soil sewage sediment was able to use substantial amount of phenol as the sole carbon source, and the biomass productivity by this organism was very excellent. This organism could grow well in 1000 ppm of phenol concentration, the maxim-um specific growth rate obtainable at pH 5.0, 3$0^{\circ}C$ was 0.27/hr., and the biomass yield coefficient Y vs. consumed phenol was 3.2. Maximum production rate of biomass was observed at 35$^{\circ}C$, pH 3.5 to pH 4.5, and the addition of the 0.005~0. 01% yeast extract was the most effective. Addition of HgCl$_2$ and phenyl hydrazine, inhibitors of oxide-reductase, in the phenol containing cultural liquid caused this organism no-growth at the concentration of 10$^{-5}$ M, 10$^{-3}$ M respectively. This organism could utilize not only phenol but catechol, resorcinol and benzidine.

• Journal of Microbiology and Biotechnology
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• v.24 no.10
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• pp.1427-1437
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• 2014

Enzymatic hydrolysis of lignocellulosic biomass into fermentable sugars is a key step in the conversion of agricultural by-products to biofuels and value-added chemicals. Utilization of a robust microorganism for on-site production of biomass-degrading enzymes has gained increasing interest as an economical approach for supplying enzymes to biorefinery processes. In this study, production of multi-polysaccharide-degrading enzymes from Aspergillus aculeatus BCC199 by solid-state fermentation was improved through the statistical design approach. Among the operational parameters, yeast extract and soybean meal as well as the nonionic surfactant Tween 20 and initial pH were found as key parameters for maximizing production of cellulolytic and hemicellulolytic enzymes. Under the optimized condition, the production of FPase, endoglucanase, ${\beta}$-glucosidase, xylanase, and ${\beta}$-xylosidase was achieved at 23, 663, 88, 1,633, and 90 units/g of dry substrate, respectively. The multi-enzyme extract was highly efficient in the saccharification of alkaline-pretreated rice straw, corn cob, and corn stover. In comparison with commercial cellulase preparations, the BCC199 enzyme mixture was able to produce remarkable yields of glucose and xylose, as it contained higher relative activities of ${\beta}$-glucosidase and core hemicellulases (xylanase and ${\beta}$-xylosidase). These results suggested that the crude enzyme extract from A. aculeatus BCC199 possesses balanced cellulolytic and xylanolytic activities required for the efficient saccharification of lignocellulosic biomass feedstocks, and supplementation of external ${\beta}$-glucosidase or xylanase was dispensable. The work thus demonstrates the high potential of A. aculeatus BCC199 as a promising producer of lignocellulose-degrading enzymes for the biomass conversion industry.

• Korean Journal of Food Science and Technology
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• v.20 no.1
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• pp.28-33
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• 1988

The optimum conditions for growth and lipid production of Rhodotorula marina IFO 0879 were investigated. The optimum temperature and pH of cultivation was $30^{\circ}C$ and pH 6.0-7.0, respectively. During shaking of the culture for 8 days at $30^{\circ}C$, the maximum cell biomass of Rh. marina was 9.82g per liter of the medium, and the lipid content obtained was 35.4(w/w) of the dry cell biomass. Lactose and glucose were the most effective carbon sources for the lipid production. Ammonium sulfate was found to be the most effective nitrogen in culture medium the growth of the yeast was retarded, whereas its growth was favored at high concentrations with decreased lipid yield. When lacose was added during fermentation, in the initial stage cell biomass and lipid production were lower than those of the control, but in the later stage the trend were reversed. The major fatty acids of yeast lipid were palmitic acid(20.3%), oleic acid(46.6%) and linoleic acid(16.2%)

• KSBB Journal
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• v.23 no.6
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• pp.463-469
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• 2008

During the last decade, monacolin-K biosynthesized by fermentation of red yeast rice (Monascus strains) was proved to have an efficient cholesterol lowering capability, leading to rapid increase in the market demand for the functional red yeast rice. In this study, the production medium composition and components were optimized on a shake flask scale for monacolin-K production by Monascus pilosus (KCCM 60160). The effect of three different soybean flours on the monacolin-K production were studied in order to replace the nitrogen sources of basic production medium (yeast extract, malt extract and beef extract). Among the several experiments, the production medium with dietary soybean flour to replace a half of yeast extract was very good for monacolin-K production. Plackett-Burman experimental design was used to determine the key factors which are critical to produce the biological products in the fermentation. According to the result of Plackett-Burman experimental design, a second order response surface design was applied using yeast extract, beef extract and $(NH_4)_2SO_4$ as factors. Applying this model, the optimum concentration of the three variables was obtained. The maximum monacolin-K production (369.6 mg/L) predicted by model agrees well with the experimental value (418 mg/L) obtained from the experimental verification at the optimal medium. The yield of monacolin-K was increased by 67% as compared to that obtained with basic production medium in shake flasks.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.287-290
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• 2000

To examine effects of agitation and aeration as well as adding of glucose and yeast extract on cell growth and polysaccharide production by Paecilomyces japonica, batch culture was carried out at 5L jar fermenter at $27^{\circ}C$ with the initial pH 7 for 7 days cultivation(innoculum size 2%, working volume 3L). Media compositions(g/L) were 30 glucose, 20 yeast extract, 0.5 $KH_2PO_4$, $0.1\;CuCl_2\;{\cdot}\;2H_2O$. Optimum culture conditions of agitation and aeration in batch culture were 400 rpm and 1.0 vvm, resulting in 23.1 g/L biomass and 2.5 g/L polysaccharide. Additional feeding of glucose and yeast extract with a pulse mode conferred an advantage on cell growth and polysaccharide production with showing the results of 29.2 g/L and 3.3 g/L, respectively.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.295-298
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• 2000

In order to maximize the RNA accumulation and biomass production in Saccharomyces cerevisiae MTY62, a high-content RNA yeast strain, fed-bach cultures were performed with optimized industrial medium including molasses and corn steep liquor. Among the feeding modes examined, the constant feeding mode resulted in the cell concentration of 35.7 g-DCW/L and the RNA concentration of 5434 ${\mu}g-RNA/mL$, which were about 2-fold increased levels, compared to the results of bach culture. However, the RNA content (153 mg-RNA/g-DCW) in the fed-batch cultures was lower than that in the batch culture (171 mg-RNA/g-DCW).

• Korean Journal of Food Science and Technology
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• v.15 no.1
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• pp.51-55
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• 1983

It was investigated under several cultural conditions to produce biomass directly from starch by an strictly aerobic and amylolytic yeast, Sporobolomyces holsaticus FRI Y-5. Its optimal temperature and initial pH of medium for growth were $23^{\circ}C$ and 6.9, respectively. Activation energy, Ea, for growth was calculated to be 17.33 Kcal/mole from the Arrhenius relationship. When each of 13 nitrogen sources was added to the basal medium, $(NH_2)_2CO$ had the best effect, on which concentration of cell after 3 day incubation was 10.6 g/l and cell yield was 0.451. The yeast growth was affected by $MgSO_4,\;K_2SO_4\;and\;ZnSO_4$ as a mineral source and was best on the medium containing all of them. The addition of yeast extract (5g/l) could enhance the production of biomass and cell yield to 77% and 32%, respectively.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.3
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• pp.173-178
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• 2001

Food yeast, Saccharomyces cerevisiae, is a safe organism with a long history of use for the production of biomass rich in high quality proteins and vitamins. AmA1, a seed storage albumin from Amaranthus hypochondriacus, has a well-balanced amino acid composition and high levels of essential amino acids and offers the possibility of further improving food animal feed additives. In order to find an effective means of expressing AmA1 in yeast, the gene was cloned into an episomal shuttle vector. Four different promoters were tested: the glyceraldehyde-3-phosphate dehydrogenase promoter, galactose dehydrogenase 10 promoter, alcohol dehydrogenase II promoter, and a hybrid ADH2-GPD promoter. The recombinant AmA1 genes were then introduced into the yeast Saccharomyces cerevisiae 2805. Northern and Western blot analyses of the yeast under appropriate conditions revealed that AmA1 was expressed by all four promoters at varying levels. An enzyme-linked immunosorbent assay demonstrated that the amount of AmA1 protein in the recombinant yeast was 1.3-4.3% of the total soluble proteins. The highest expression level was obtained from the hybrid ADH2-GPD promoter.