• Journal of Microbiology and Biotechnology
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• 제16권4호
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• pp.543-549
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• 2006

DNA microarray was used to study the transcription profiling of Escherichia coli adapting to acetate as a sole carbon source. Bacteria grown in glucose minimal media were used as a reference. The dynamic expression levels of 3,497 genes were monitored at seven time points during this adaptation. Among the central metabolic genes, the glycolytic and glucose phosphotransferase genes were repressed as the bacteria entered stationary phase, whereas the glyoxylate pathway, TCA cycle, and gluconeogenic genes were induced. Distinct induction or repression patterns were recognized among different pathway genes. For example, the repression of glycolytic genes and the induction of gluconeogenic ones started immediately after glucose was depleted. On the other hand, the regulation of the pentose phosphate pathway genes and glyoxylate genes gradually responded to the glucose depletion or was more related to growth in acetate. When the whole genome was considered, many of the CRP, FadR, and Cra regulons were immediately responsive to the glucose depletion, whereas the $\sigma^s$, Lrp, and IHF regulons were gradually responsive to the glucose depletion. The expression profiling also provided differential regulations between isoenzymes; for example, malic enzymes A (sfcA) and B (maeB). The expression profiles of three genes were confirmed with RT-PCR.

• Journal of Microbiology and Biotechnology
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• 제30권12호
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• pp.1944-1949
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• 2020

Mutant sugar transporter ScGAL2-N376F was overexpressed in Kluyveromyces marxianus for efficient utilization of xylose, which is one of the main components of cellulosic biomass. K. marxianus ScGal2_N376F, the ScGAL2-N376F-overexpressing strain, exhibited 47.04 g/l of xylose consumption and 26.55 g/l of xylitol production, as compared to the parental strain (24.68 g/l and 7.03 g/l, respectively) when xylose was used as the sole carbon source. When a mixture of glucose and xylose was used as the carbon source, xylose consumption and xylitol production rates were improved by 195% and 360%, respectively, by K. marxianus ScGal2_N376F. Moreover, the glucose consumption rate was improved by 27% as compared to that in the parental strain. Overexpression of both wild-type ScGAL2 and mutant ScGAL2-N376F showed 48% and 52% enhanced sugar consumption and ethanol production rates, respectively, when a mixture of glucose and galactose was used as the carbon source, which is the main component of marine biomass. As shown in this study, ScGAL2-N376F overexpression can be applied for the efficient production of biofuels or biochemicals from cellulosic or marine biomass.

• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.1949-1954
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• 2007

A simple way to prevent protein hyperglycosylation in Hansenula polymorpha was found. When glucose oxidase from Aspergillus niger and carboxymethyl cellulase from Bacillus subtilis were expressed under the control of an inducible methanol oxidase (MOX) promoter using methanol as a carbon source, hyperglycosylated forms occurred. In contrast, MOX-repressing carbon sources (e.g., glucose, sorbitol, and glycerol) greatly reduced the extent of hyperglycosylation. Carbon source starvation of the cells also reduced the level of glycosylation, which was reversed to hyperglycosylation by the resumption of cell growth. It was concluded that the proteins expressed under actively growing conditions are produced as hyperglycosylated forms, whereas those under slow or nongrowing conditions are as short-glycosylated forms. The prevention of hyperglycosylation in the Hansenula polymorpha expression system constitutes an additional advantage over the traditional Saccharomyces cerevisiae system in recombinant production of glycosylated proteins.

• Mycobiology
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• 제39권1호
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• pp.1-6
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• 2011

Isolates of Ophiocordyceps heteropoda (Kobayasi) collected from Mt. Halla on Jeju-do, Korea were tested for mycelial growth on different agar media and in the presence of different carbon and nitrogen sources. Similarly, isolates were also incubated at different temperatures as well as under continuous light and dark conditions. Growth was better on Hamada agar, basal medium, and malt-yeast agar, but poor on Czapek-Dox agar. Different carbon sources such as dextrin, saccharose, starch, lactose, maltose, fructose, and dextrose resulted in better growth. Complex organic nitrogen sources such as yeast extract and peptone revealed the most effective growth. Mycelial growth was best at $25^{\circ}C$. The growth rate was faster in the dark than the light, but mycelial density was less compact in the dark.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.317-320
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• 2000

The optimal temperature and pH for both mycelial growth and exe-biopolymer production by Cordyceps millitaris in shake flask culture were found to be $20^{\circ}C$ and 6.0, respectively. Sucrose (4%) and corn steep powder (1%) were the most suitable carbon and nitrogen source for mycelial growth and exo-biopolymer production. The maximum specific growth rate $(0.142h^{-1})$ was achieved when sucrose was used as the sole carbon source. Exo-biopolymer production was increased with the increase in C/N molar ratio concentration, probably due to the facilitated carbon uptake. Under the optimal culture conditions, the maximum mycelial growth exe-biopolymer concentration were reached to around 13.3 g dry cell weigh/l and 3.33 g/l, respectively.

• 미생물학회지
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• 제29권6호
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• pp.371-379
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• 1991

Effects of freshwater red tide of Peridinium bipes (dinoflagellate) in August of 1991 on the carbon flux through the microbial loop were studied in Soyang Reservoir. Chlorophyll a and primary production, bacterial production in red tide area were 22, 18 and 400 times higher, respectively, than other sites. Phytoplandton biomass comprised 97% and 20% of food source of zooplankton grazing within and without red tide, respectively. The percent bacterial production supported by phytoplankton exudate was 14% within red tide and >100% without red tide. In laboratory experiments, more than 85% organic carbon of Peridinium biomass was released or degraded by heterotrophic bacteria within 14 days. As results of red tide of Peridinium with sudden influx of organic carbon in water column, the main food source of zooplankton and dependency of bacteria on phytoplankton exudate were changed. Therefore, the relative importance of microbial loop to grazing food web was changed.

• 미생물학회지
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• 제16권1호
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• pp.21-29
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• 1978

In the fed-batch fermentation of penicillin specific uptake rates of carbon source and ammonia nitrogen, and specific production rate of penicillin as the most important process variables were evaluated over the fermentation course and their effects on the productivity studied. As the results, glucose and lactose each as a major carbon source showed the following values, respectively ; the specific uptake rates of 47-93 mg hexose per gm-DCW per he and 37-44 mg hexose per gm-DCW per hr, the specific uptake rates of 4.6-6.8 mg $NH_3-N$ per gm-DCW per hr, and 1.2 mg $NH_3-N$ per gm-DCW per he and the specific production rates of 32-42 arbitrary unit per gm-DCW per hr and 46-50 arbitrary unit per gm-DCW per hr. The productivity of penicillin could be improved by controlling the feed rates of glucose and ammonia nitrogen to meet the uptake rates.

• KSBB Journal
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• 제25권3호
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• pp.230-238
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• 2010

A microbial strain having high keratinase activity was isolated from the soil of poultry factories of Gyeonggi or Chungcheong-do. The isolated strain was identified as Bacillus sp. based on its morphological and biochemical characteristics. In this study, the optimal conditions for the production of keratinase by this strain were investigated. The optimal medium composition for the keratinase production was determined to be 3.5% chicken feather as carbon source, 1.0% tryptone as organic nitrogen source, 1.0% $KNO_3$ as inorganic nitrogen source and 0.05% KCl, 0.05% $KH_2PO_4$, 0.03% $K_2HPO_4$ as mineral source and 0.01% yeast extract as growth factor. The optimal temperature and pH was $40^{\circ}C$ and 8.5 with shaking culture (200 rpm), respectively. The maximum keratinase production reached to 123 units/ml after 42 hr of cultivation under the optimal condition. When the hair was used as the sole carbon source, the maximum enzyme activity was 88 units/ml after 120 hr and in this case, the hair added in the medium was not degraded completely but got thinner than the control by 20%.

• 한국유기농업학회지
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• 제5권1호
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• pp.87-99
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• 1996

Cultural conditions for mass production of the antagonistic bacteria, Bacillus subtills CAP134 against pathogens causing major airborne diseases to apple tree, effect of temperature, pH, carbon and nitrogen source in the culture broth were investigated. The bacterial growth was most vigorous when the temperature and pH of the culture broth was 30~$35^{\circ}$C, and 7, respectively. As for carbon source, dextrose was best followed in order by dextrose(monosaccharides)>sucrose(disaccharides)$\geq$saccharose(di-saccharides)>starch (polysaccharides). Among different sugars, bacterial growth was favored by in the order of brown, black and white sugars, indicating that the bacterial growth might be promoted by the minor elements presented as impurities in the less purified sugars. As for nitrogen source, organic forms were better to bacterial growth than inorganic forms, that is polypeptone was best followed in order by soy sauce, soybeen milk and inoganic nitrogens. Differences in bacterial growth among different forms of inorganic nitrogen were negligible.

• 미생물학회지
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• 제16권4호
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• pp.141-147
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• 1978

In order to increase the productivity of cellulolytic enzymes, medium composition and culture conditions were studied. When cellulose powder (Avicel) supplemented with rice straw was used as carbon source, productivity of ${\beta}-glucosidase$ was increased by about 3 times compared with the runs with only cellulose powder as a carbon source. In this case no negative effects on the production of CMC enzyme activity and filter paper activity was found. For the production of celulolytic enzymes using T. reesei QM 9414, casitone was found to be a good nitrogen source compared with other sources studied, such as peptone, yeast extract, tryptone, and casein. The highest cellulase activity was attained when 0.3% glucose and 0.01% Tween 80 were supplemented to the standard medium of Rese. An adequate oxygen transfer rate was also found to be important to the cellulase fermentation and about 50 mmole of oxygen/liter/hour supported good cellulase biosynthesis during cellulase fermentation.