• KSBB Journal
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• 제19권5호
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• pp.410-414
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• 2004

Fed-batch cultures of Enterococcus faecalis RKY1 were performed to maximize the L(+)-Iactic acid concentration in the bioreactor. The highest lactic acid concentration was obtained at around 225 g/L by intermittent feeding the concentrated glucose media containing 500 g/L of glucose and 15 g/L (or 75 g/L) of yeast extract. However, in all fed-batch cultures, volumetric productivities of lactic acid gradually decreased due to the inhibitory effect of lactic acid produced during the fermentation. The highest value of lactic acid concentration obtained in this work corresponded to around 1.5-fold increase compared with conventional batch fermentation.

• 한국미생물·생명공학회지
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• 제24권3호
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• pp.331-335
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• 1996

Characteristics of ethanol fermentation were investigated during the stationary culture of a killer yeast, Saccharomyces cerevisiae B15-1. Specific ethanol production rate reached the maximum level, 1.203 g-EtOH/g-cell-hr, at 150 g/l of the initial glucose concentration. No big differences were obtained in ethanol fermentability based on the initial sugar concentration below 150 g/l. When 200 g/l of sugar was used, fermentability dropped significantly. Although the final cell mass and the amount of ethanol produced were increased, their increase rates were declined according to the increase of initial sugar concentration. It was found that most of the sugar used below 150 g/l of concentration could be changed to ethanol. However, when 200 g/l of sugar was used, some of them remained in the media even after increase of cell mass and fermentation stopped. The ethanol yield was decreased when initial sugar concentration was high, and were increased when the amount of ethanol produced was increased and finally reached the plateau over 60 g/l of ethanol concentration.

• Journal of Microbiology and Biotechnology
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• 제21권5호
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• pp.470-476
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• 2011

A potent fungus for amylase production, Chrysosporium asperatum, was isolated from among 30 different cultures obtained from wood samples collected in the Junagadh forest, India. All of the isolated cultures were screened for their ability to produce amylase by submerged fermentation. Among the selected cultures, C. asperatum (Class Euascomycetes; Onygenales; Onygenaceae) gave maximum amylase production. In all of the different media tested, potato starch was found to be a good substrate for production of amylase enzyme at $30^{\circ}C$ and pH 5.0. Production of enzyme reached the maximum when a combination of starch and 2% xylose, and organic nitrogen (1% yeast extract) and ammonium sulfate were used as carbon and nitrogen sources, respectively. There was no significant effect of metal ions on enzyme activity. The enzyme was relatively stable at $30^{\circ}C$ for 20 min, and no inhibitory effect of $Ca^{+2}$ ions on amylase production was observed.

• 한국축산시설환경학회지
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• 제14권1호
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• pp.1-8
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• 2008

This study was conducted to solve the problem of public grievance owing to odor of a pig farm. Odor emissions from pig production systems mainly originate from liquid manure storage and solid manure fermentation. The low-cost odor abatement system (OAS) for application at liquid manure storage tank and solid manure fermentation facilities was developed in this study. The OAS adapted odor removing principles of a biofilter and biotrickling filter. The OAS is very simplified in structure. The appearance of the OAS had a form of cylindrical or cubical shape. The system performance was monitored for about one year after stabilization. A 7 seconds empty bed contact time for the OAS was adapted to achieve the odor reduction levels. The commercial type of OAS was constructed with media comprised of wood chips. Moisture content always remained above 50% wet basis. Average ammonia removal efficiency for the developed design was 89% at the liquid manure storage tank. Also, the removal efficiency at a solid manure fermentation facility was 86% on ammonia.

• Journal of Microbiology and Biotechnology
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• 제14권4호
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• pp.665-672
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• 2004

D-Ribose is a five-carbon sugar used for the commercial synthesis of riboflavin, antiviral agents, and flavor enhancers. Batch fermentations with transketolase-deficient B. subtilis JY1 were carried out to optimize the production of D-ribose from xylose. The best results for the fermentation were obtained with a temperature of $37^{\circ}C$ and an initial pH of 7.0. Among various sugars and sugar alcohols tested, glucose and sucrose were found to be the most effective for both cell growth and D-ribose production. The addition of 15 g/l xylose and 15 g/l glucose improved the fermentation performance, presumably due to the adequate supply of ATP in the xylose metabolism from D-xylulose to D-xylulose-5-phosphate. A batch culture in a 3.7-1 jar fermentor with 14.9 g/l xylose and 13.1 g/l glucose resulted in 10.1 g/l D-ribose concentration with a yield of 0.62 g D-ribose/g sugar consumed, and 0.25 g/l-h of productivity. Furthermore, the sugar utilization profile, indicating the simultaneous consumption of xylose and glucose, and respiratory parameters for the glucose and sucrose media suggested that the transketolase-deficient B. subtilis JY1 lost the glucose-specific enzyme II of the phosphoenolpyruvate transferase system.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권2호
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• pp.115-121
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• 2005

Using a general Saccharomyces cerevisiae as a model strain, continuous ethanol fermentation was carried out in a stirred tank bioreactor with a working volume of 1,500 mL. Three different gravity media containing glucose of 120, 200 and 280 g/L, respectively, supplemented with 5 g/L yeast extract and 3 g/L peptone, were fed into the fermentor at different dilution rates. Although complete steady states developed for low gravity medium containing 120 g/L glucose, quasi-steady states and oscillations of the fermented parameters, including residual glucose, ethanol and biomass were observed when high gravity medium containing 200 g/L glucose and very high gravity medium containing 280 g/L glucose were fed at the designated dilution rate of $0.027\;h^{-1}$. The observed quasi-steady states that incorporated these steady states, quasi-steady states and oscillations were proposed as these oscillations were of relatively short periods of time and their averages fluctuated up and down almost symmetrically. The continuous kinetic models that combined both the substrate and product inhibitions were developed and correlated for these observed quasi-steady states.

• Journal of Microbiology and Biotechnology
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• 제32권11호
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• pp.1479-1484
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• 2022

Bacterial cellulose (BC) is gaining attention as a carbon-neutral alternative to plant cellulose, and as a means to prevent deforestation and achieve a carbon-neutral society. However, the high cost of fermentation media for BC production is a barrier to its industrialization. In this study, chestnut shell (CS) hydrolysates were used as a carbon source for the BC-producing bacteria strain, Gluconacetobacter xylinus ATCC 53524. To evaluate the suitability of the CS hydrolysates, major inhibitors in the hydrolysates were analyzed, and BC production was profiled during fermentation. CS hydrolysates (40 g glucose/l) contained 1.9 g/l acetic acid when applied directly to the main medium. As a result, the BC concentration at 96 h using the control group and CS hydrolysates was 12.5 g/l and 16.7 g/l, respectively (1.3-fold improved). In addition, the surface morphology of BC derived from CS hydrolysates revealed more densely packed nanofibrils than the control group. In the microbial BC production using CS, the hydrolysate had no inhibitory effect during fermentation, suggesting it is a suitable feedstock for a sustainable and eco-friendly biorefinery. To the best of our knowledge, this is the first study to valorize CS by utilizing it in BC production.

• 한국산업융합학회 논문집
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• 제2권1호
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• pp.77-83
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• 1999

Grown in the secondary broth of production media, the strain Streptomyces albulus has increased more the production of its metabolite ${\varepsilon}$-poly-L-lysine, one of poly(amino acid)s used as disinfecting food additives, than the strain in the primary culture of growth nutrients. Having the strain removed, the large concentrate obtained by ultrafiltrating the secondary culture broth. The concentrated production broth exchanged into followed by detecting in UV flowcell at 220nm the peptide bond of the components eluting the adsorbed proteins and polylysine with NaCl salt of gradient concentration, and has separated into five components. Among them the component in the fourth peak fraction has proved to be the pure ${\varepsilon}$-poly-L-lysine after the portion being hydrolyzed the fraction with HCl into amino acid followed by being the composing amino acid analysis.

• 한국미생물·생명공학회지
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• 제25권2호
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• pp.207-211
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• 1997

Media optimization for the production of thermostable protease specifically hydrolyzing defatted soybean meal (DSM) from Bacillus licheniformis NS70 was performed by two methods, one-at-a-time method and response surface methodology (RSM). The best carbon source and nitrogen source for the protease production were lactose and DSM, respectively. The maximum protease production estimated by RSM was 606 U/L at 1.11% lactose and 0.43% DSM, the value of which was nearly consistent to the experimental value of 599 U/L. Yeast extract suppressed the protease production. The medium pH was slightly increased at the beginning stage of fermentation, and it tended to decrease after 8 hours. The optimal pH for the protease production was 7.2 in the batch fermentation.