• Asian-Australasian Journal of Animal Sciences
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• v.10 no.5
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• pp.460-470
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• 1997

On an absolute straw diet, the effect of graded levels of green grass supplementation on intake, nutrient digestibility, rumen fermentation pattern and microbial N yield has been studied in cattle. Of the two trials conducted, 16 intact growing bulls of 304 kg weight and 32 months old, randomly allocated to four treatments in a completely randomized design in the 1st trial. While, in the, 2nd trial, four rumen cannulated local bulls of about 60 months old and 400 kg weight were used in a $4{\times}4$ Latin square design with four treatments in four periods. In both the trials, in addition to a mineral mixture, animals were supplemented with graded levels of naturally grown green grass of 0 kg (T1), 2 kg (T2), 4 kg (T3) or 6 kg (T4) to an ad libitum rice straw diet In the 1st trial, measurements were made on intake digestibility, growth rate, N balance and microbial N yield. While in the 2nd trial, in addition to the above parameters (except growth rate), rumen parameters were also studied. All levels of grass supplementation decreased the straw DM intake and increased the substitution rate. The rumen $NH_3-N$ concentration increased with the increase in grass level and ranges from 8-46 mg/l. The rumen pH and the rate and extent of DM degradability of straw were not affeceted by different rumen environments created by different levels of grass inclusion. At 48 h, straw DM degradability were 42, 44, 44 and 43% respectively for 0, 2, 4 and 6 kg grass supplementation daily. The whole gut digestibilities of DM, OM and ADF increased significantly (p < 0.05) only at 6 kg level daily. The microbial N yield was not affected by the levels of grass supplemented. The mean microbial N yield was 10 (SD 3.7) g/kg DOM apparently fermented in the rumen. The estimated minimum N loss and thus the maintenance requirement of tissue protein was 303 mg/kg $W^{0.75}/d$. All the animals lost live weight but 6 kg grass supplementation gave positive energy and N balances. Small amount of green grass supplementation is often recommended for optimization of rumen environment of a straw diet However, under the present experimental condition, no such beneficiary effect observed up to 6 kg (26% of DM intake) level of supplementation.

• KSBB Journal
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• v.21 no.2
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• pp.79-84
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• 2006

In order to minimize the reduction of lysine productivity by accumulation of lysine and byproducts in the end of fed-batch fermentations, a salt-tolerant mutant C14-49-3-15-7-3-20, which could grow at high concentrations of NaCl was isolated through mutagenesis from the Corynebacterium glutamicum mother strain I. In the evaluation of L-lysine productivity by fed-batch fermentations using a 5 L jar fermenter, the salt-tolerant mutant strain C14-49-3-15-7-3-20 produced 130.6 g/L of L-lysine with a 48.6% of yield. The mother strain I produced L-lysine concentration only 104.9 g/L with a yield 41.8%, implying the improvement of L-lysine productivity by introduction of salt-tolerance character.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.606-614
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• 2023

This study was conducted to optimize the size of olive flounder Paralichthys olivaceus (OF) as a material of sikhae and to investigate the quality characteristics. The results on the protease activity of OF meat, protein and ash contents of the bone, and yields and hardness of fish bone during fermentation time suggest that the suitable fish weight for sikhae was less than 250 g. The proximate compositions of the OF sikhae fermented under optimum condition (fermentation for 9 days at 15℃), were 73.0% moisture, 12.0% crude protein, 1.3% crude fat and 2.4% ash. The salinity, titration acidity and amino acid nitrogen contents per 100 g sikhae were 1.7 g, 2.46 g, and 311.3 mg, respectively. The lactic acid bacteria concentration in the sikhae were 8.84 log CFU/g, which were higher than those (5.78-6.62 log CFU/g) of 5 kind of commercial flounder sikhae. The functional properties, such as ACE inhibitory activity (69.0%), antioxidative activity (69.3%), α-glucosidase inhibitory activity (22.7%), xanthine oxidase inhibitory activity (88.2%), and nitrite scavenging activity (96.4%) of the sikhae were superior to those of 5 kind of commercial flounder sikhae.

• Journal of Applied Biological Chemistry
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• v.53 no.3
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• pp.126-131
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• 2010

In order to maximize the growth of Bifidobacterium lactis BL 740 and soy isoflavone agycones production, we investigated the optimization of a culture medium containing soy hypocotyls, which are the byproducts of the soy manufacturing process, and soy proteins. The ingredients of the medium containing soy materials (S-medium) were selected by fractional factorial design (FFD) and central composite design (CCD) within a desirable range. The FFD was applied by six factors: glucose, cellobiose, fructooligosaccharide, soy peptone, soy protein, and soy hypocotyl. Soy protein, soy peptone, and soy hypocotyl were found to be significant factors from the result of FFD for both the growth of B. lactis BL 740 and aglycone production. The CCD was then applied with three variables found from FFD at five levels each and the optimum values were determined for the three variables: soy peptone, soy protein, and soy hypocotyl. In the case of the growth of B. lactics BL740, the proposed optimal media contained 12.73 g/L of soy protein, 29.55 g/L of soy peptone, and 130.67 g/L of soy hypocotyl. To produce isoflavone aglycones, optimized media was composed of 2.06 g/L, soy protein, 1.25 g/L of soy peptone, and 60.02 g/L of soy hypocotyl.

• Journal of Life Science
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• v.21 no.8
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• pp.1083-1093
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• 2011

A microorganism utilizing rice hulls as a substrate for the production of carboxymethylcellulase (CMCase) was isolated from seawater and identified as Bacillus lincheniformis by analyses of its 16S rDNA sequences. The optimal carbon and nitrogen sources for production of CMCase were found to be rice hulls and ammonium nitrate. The optimal conditions for cell growth and the production of CMCase by B. lincheniformis LBH-52 were investigated using the response surface method (RSM). The analysis of variance (ANOVA) of results from central composite design (CCD) indicated that a highly significant factor ("probe>F" less than 0.0001) for cell growth was rice hulls, whereas those for production of CMCase were rice hulls and initial pH of the medium. The optimal conditions of rice hulls, ammonium nitrate, initial pH, and temperature for cell growth extracted by Design Expert Software were 48.7 g/l, 1.8 g/l, 6.6, and 35.7$^{\circ}C$, respectively, whereas those for the production of CMCase were 43.2 g/l, 1.1 g/l, 6.8, and 35.7$^{\circ}C$. The maximal production of CMCase by B. lincheniformis LBH-52 from rice hulls under optimized conditions was 79.6 U/ml in a 7 l bioreactor. In this study, rice hulls and ammonium nitrate were developed to be substrates for the production of CMCase by a newly isolated marine microorganism, and the time for production of CMCase was reduced to 3 days using a bacterial strain with submerged fermentation.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.840-845
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• 2011

Degradation products of agarose are biologically active and thus used as an ingredient in pharmaceuticals or functional cosmetics. Furthermore, it has been strongly considered as a substrate for bio-ethanol fermentation. Recently, we isolated new agarase-producing microorganism, Pseudoalteromonas sp. from south sea of Korea. In this study, we aimed to separate and purify the agarase from culture broth of this strain. Separation of agarase was performed by ion- exchange chromatography on DEAE-Sepharose resin. Equilibrium pH and volume ratio of resin to the amount of protein were optimized for the efficient adsorption of protein. 410 ${\mu}g$ of protein was completely adsorbed to 3 mL of resin at pH 7.5. The total amount of eluted protein increased as NaCl concentration increased to 400 mM at isocratic elution. Agarase was separated by linear gradient elution of NaCl (0~1,000 mM). Three major protein peaks were observed and the presence or absence of agarase in these eluted proteins was measured by Lugol's staining technique. Only six eluted protein fractions showed strong agarase activity.

• Food Science and Biotechnology
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• v.17 no.3
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• pp.587-593
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• 2008

Microbial exopolysaccharide (EPS) is a biothickener that can be added to a wide variety of food products, where it serves as a viscosifying, stabilizing, emulsifying, and gelling agent. The objective of this study was to investigate the optimum conditions of pH, incubation temperature, and whey protein concentration (WPC) for EPS production by Lactobacillus rhamnosus ATCC 9595. We found that maximal EPS production was achieved at a pH of 5.5 and temperature of $37^{\circ}C$. At the same fermentation conditions, EPS production was affected by the addition of L. rhamnosus GG (a weak-EPS producer). After growth for 24 hr, total EPS production was $583{\pm}15.4mg/L$ in the single culture system, and $865{\pm}22.6\;mg/L$ in the co-culture system with L. rhamnosus GG. Based on the presence of WPC, EPS production dramatically increased from $583{\pm}15.4$ (under no WPC supplementation) to $1,011{\pm}14.7\;mg/L$ (under supplementation with 1.0% WPC). These results suggest that WPC supplementation and the co-culture systems coupled with small portions of weak-EPS producing strain can play an important role in the enhancement of EPS production.

• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.95-104
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• 2018

Biosurfactants or microbial surfactants are surface-active biomolecules that are produced by a variety of microorganisms. Biodegradability and low toxicity have led to the intensification of scientific studies on a wide range of industrial applications for biosurfactants in the field of environmental bioremediation as well as the petroleum industry and enhanced oil recovery. However, the major issues in biosurfactant production are high production cost and low yield. Improving the bioindustrial production processes relies on many strategies, such as the use of cheap raw materials, the optimization of medium-culture conditions, and selecting hyperproducing strains. The present work aims to obtain a mutant with higher biosurfactant production through applying mutagenesis on Bacillus subtilis SPB1 using a combination of UV irradiation and nitrous acid treatment. Following mutagenesis and screening on blood agar and subsequent formation of halos, the mutated strains were examined for emulsifying activity of their culture broth. A mutant designated B. subtilis M2 was selected as it produced biosurfactant at twice higher concentration than the parent strain. The potential of this biosurfactant for industrial uses was shown by studying its stability to environmental stresses such as pH and temperature and its applicability in the oil recovery process. It was practically stable at high temperature and at a wide range of pH, and it recovered above 90% of motor oil adsorbed to a sand sample.

• Korean Journal of Food Science and Technology
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• v.47 no.6
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• pp.687-697
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• 2015

With the shortage of edible fats and oils and depletion of fossil fuels in many countries, microbial lipids is emerging as one of the most promising sources of fats and oils in the global market. Oleaginous microorganisms, also called single cell oils (SCOs), can accumulate lipids more than 25% in the cell volume. Triacylglycerols are the major storage lipids. SCOs offer several advantages for lipid production as follows: SCOs have short life span which would shorten production time, cultivation conditions are not affected by climate and place; the production process is easy to control. There are a number of oleaginous yeasts, molds, and microalgae. Furthermore, the lipid productivity of SCOs can be enhanced through strain improvement and the optimization of cultivation conditions. The new strains developed using recent advanced biotechnical methods showed greatly improved oleaginicity. Further, hydrolysates of lignocellulosic materials can be used as carbon sources for economic production of SCO.

• KSBB Journal
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• v.15 no.3
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• pp.268-273
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• 2000

A microbiological hydrogen production process was optimized. Anaerobic photosynthetic bacteria like Rhodospirillum rubrum which is known to produce hydrogen from carbon monoxide efficiently and remove sulfur was used. To evaluate the potenital of this microorganism the optimization of media fermentation condition light intensity and light requirement for CO conversionwas tried in batch cultures and the continuous fermenter was also applied for this process. The gas residence time on CO conversion was sought out to get high conversion of carbon monoxide to hydrogen. Through this study the possibility of microbial synthtics gas concersion process was proposed.