• Journal of Microbiology and Biotechnology
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• v.5 no.3
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• pp.158-162
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• 1995

The effect of carbon and nitrogen sources on the production of novel aminopeptidase M inhibitors MR-387A and B by Streptomyces sp. SL-387 has been studied. High D-glucose and ammonia concentrations (5$\%$ and 1$\%$, respectively) exerted a negative influence on the inhibitor formation. The suppressive effect of glucose on the inhibitor formation is probably caused by an effect of medium pH rather than that of cyclic AMP. To establish the optimum conditions for inhibitor overproduction, various nitrogen sources and ammonium ion-trapping agents were examined. The use of ammonia slow-releasing nitrogen sources such as soybean meal and fish meal, or ammonium ion-trapping agents such as kaoline, celite, and natural zeolite achieved the enhancement of inhibitor production. These results also indicate that inhibitor formation is affected by ammonium ion repression.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.207-212
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• 1992

An anti-inflammatory agent, serratiopeptidase, was produced from the culture of the Serratia marcescens. The effects of carbon sources, nitrogen sources and inducers on the production were investigated. Citrate was found to be inhibitory in the production of serratiopeptidase. The enzyme was synthesized in the synthetic medium without inducers, albeit low level of synthesis. But the synthesis was increased by the addition of proteinaceous substrate and leucine. Induction of extracellular proteinase by its end-product was discovered, which is not common in the proteinase synthesis in the bacteria. By the glucose fed-batch culture, we found the possible catabolite repression on the production of serratiopeptidase.

• Journal of Microbiology and Biotechnology
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• v.31 no.5
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• pp.659-666
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• 2021

After Candida albicans, Candida glabrata is one of the most common fungal species associated with candidemia in nosocomial infections. Rapid acquisition of nutrients from the host is important for the survival of pathogens which possess the metabolic flexibility to assimilate different carbon and nitrogen compounds. In Saccharomyces cerevisiae, nitrogen assimilation is controlled through a mechanism known as Nitrogen Catabolite Repression (NCR). NCR is coordinated by the action of four GATA factors; two positive regulators, Gat1 and Gln3, and two negative regulators, Gzf3 and Dal80. A mechanism in C. glabrata similar to NCR in S. cerevisiae has not been broadly studied. We previously showed that in C. glabrata, Gln3, and not Gat1, has a major role in nitrogen assimilation as opposed to what has been observed in S. cerevisiae in which both factors regulate NCR-sensitive genes. Here, we expand the knowledge about the role of Gln3 from C. glabrata through the transcriptional analysis of BG14 and gln3Δ strains. Approximately, 53.5% of the detected genes were differentially expressed (DEG). From these DEG, amino acid metabolism and ABC transporters were two of the most enriched KEGG categories in our analysis (Up-DEG and Down-DEG, respectively). Furthermore, a positive role of Gln3 in AAA assimilation was described, as was its role in the transcriptional regulation of ARO8. Finally, an unexpected negative role of Gln3 in the gene regulation of ABC transporters CDR1 and CDR2 and its associated transcriptional regulator PDR1 was found. This observation was confirmed by a decreased susceptibility of the gln3Δ strain to fluconazole.

• Microbiology and Biotechnology Letters
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• v.28 no.6
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• pp.341-348
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• 2000

Selection of high producer strain, optimization of production medium and cultivation in bioreactor system were carried out in order to produce an antifungal substance, PAFS in large amounts which sources and 41 kinds of nitrogen sources, a synthetic medium consisting of fructose(70 g/1) and ammonium sulfate (10g/l) and a complex medium including galactose(30g/l), fructose(20g/l) and cottonseed flour(35g/l) were determined as opti-mized media for PAFS production. In bioreactor studies examining physiological characteristics of the pro- ducer microorganism with the complex medium, typical pattern of diauxic growth was observed as demonstrated by the result that fructose was not used before almost exhaustion on readily utilizable carbon source, galactose. When galactose was supplemented additionally during the fermentation period. PAFS pro-ductivity did no increases any more, indicating that large portion of the added galactose was used for cell growth instead of biosynthesis of the secondary metabolite. It was deduced that PAFS production could be enhananced by employing fed-batch operation in order to overcome the apparent phenomenon of catabolite repression and /or inhibition.

• Microbiology and Biotechnology Letters
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• v.31 no.2
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• pp.157-164
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• 2003

An alkali-tolerant bacterium producing the xylanase was isolated from soil and identified as Bacillus alcaiophilus. This strain, named B. alcalophilus AX2000, was able to grow and produce xylanase optimally at pH 10.5 and $37^{\circ}C$. The maximum xylanase production was obtained when 0.5%(w/v) birchwood xylan and 0.5%(w/v) polypeptone and yeast extract were used as carbon source and nitrogen source, respectively. The biosynthesis of xylanase was under the catabolite repression by glucose in the culture medium, and inhibited in the presence of high concentration of xylose. The maximum activity of xylanase was observed at pH 10.0 and $50^{\circ}C$ and the enzyme activity remained was over 80% at $60^{\circ}C$ and from pH 5.0 to 11.0.

• Microbiology and Biotechnology Letters
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• v.27 no.5
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• pp.370-377
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• 1999

Thermo-tolerant bacterium producing the xylanase was isolated from soil and identified as Bacillus pumilus. This strain, named Bacillus pumilus TX703, was able to grow ad produce xylanase at the culture temperature of 5$0^{\circ}C$. The maximum xylanase production was obtained when 1%(w/v) birchwood xylan and 1% (w/v) soytone were used as carbon source and nitrogen source, respectively. The biosynthesis of xylanase was under the catabolite repression induced by glucose in the culture medium, and it was completely inhibited in the presence of 0.2% (w/v) glucose. The maximum activity of xylanase was observed from pH8.0 to 9.0 and from 50 to 6$0^{\circ}C$ and the enzyme was highly heat-stable, whose activity remained was over 50% at 8$0^{\circ}C$, and was quite stable from pH5.0 to 10.0.

• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.349-354
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• 2000

Abstract A facultative alkalophilic gram-negative Vibrio metschnikovii strain RH530, isolated from the wastewater, produced several alkaline proteases (VAP) including six alkaline serine proteases and a metalloprotease. From this strain, high yielding YAP mutants were isolated by NTG treatment. The isolated mutant KS1 showed nine times more activity than the wild-type after optimization of the culture media. The production was regulated by catabolite repression when glucose was added to the medium. The effects of several organic nitrogen sources on the production of the YAP were investigated to avoid catabolite repression. The combination of 4% wheat gluten meal (WGM), 1.5% cotton seed flour (eSF), and 5% soybean meal (SBM) resulted in the best production when supplemented with 1% NaCl. The YAP showed a resistance to surfactants such as $sodium-{\alpha}-olefin$ sulfonate (AOS), polyoxy ethylene oxide (POE), and sodium dodecyl sulfate (SDS), yet not to linear alkylbenzene sulfonate (LAS). However, the activity of the YAP was restored completely when incubated with LAS in the presence of POE or $Na_2SO_4$. The YAP was stable in a liquid laundry detergent containing 6.6% SLES (sodium lauryl ether sulfate), 6.6% LAS, 19.8% POE, and stabilizing agents for more than two weeks at $40^{\circ}C$, but the stability was sharply decreased even after 1 day when incubated at $60^{\circ}C$. A washing performance test with the YAP exhibited it to be a good washing power by showing 51 % and 60% activity at $25^{\circ}C{\;}and{\;}40^{\circ}C$, respectively, thereby indicating that the YAP also has a good detergency at a low temperature. All the results suggest that the YAP produced from the mutant strain KSI has suitable properties for use in laundry detergents.rgents.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.259-262
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• 2000

The production of pullulan by Aureobasidium pullulans HP-2001 was investigated under various ratios of glucose as carbon source and yeast extract as the nitrogen source, Highest conversion rate (productivity) of glucose to pullulan was 40.0% when concentrations of glucose and yeast extract were 5% and 0.15%, respectively. Maximal production of pullulan was 29.3g/1 when the concentration of glucose was 8%(w/v) and that of yeast extract was 40:1. On basis of the result that production of pullulan was found in a medium which concentration of glucose as carbon source was up to 20%(w/v), Aureobasidium pullulans HP-2001 seemed to overcome the catabolite repression. Conversion rate of pullulan from 20%(w/v) of glucose was 11.1%.

• Applied Biological Chemistry
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• v.34 no.4
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• pp.327-333
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• 1991

This study was carried out to determine the effects of media compositions on cell growth and casein hydrolysis for cell production in order to add Micrococcus sp. LL3 as a potential agent for industrial application for the shortening of ripening period. Monosaccharides like glucose, mannose and fructose were mare excellent as carbon source, but arabinose and xylose markedly inhibited cell growth and caseinolysis. Among the organic nutrients, yeast extract was more effective for cell growth and for caseolysis. However, inorganic nitrogen sources were less effective than organic sources. Urea inhibited cell growth severely. Cell growth and caseinolysis were rather increased a little in the broth containing 1% NaCl, and the organism tolerated and grew in relatively high concentrations of NaCl up to 9%. Addition of vitamin did not affect cell growth and caseolysis in level of $0.1\;{\mu}g/ml$ concentration. Cell growth and caseinolysis were stimulated by addition of glutamic acid and $MgSO_4$ with concentration of 0.2% and 0.05% respectively.

• Journal of Life Science
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• v.7 no.1
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• pp.30-38
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• 1997

For screening thermostable $\alpha$-amylase from thermophiles, various samples from extreme environments such as hot spring and sewage near them, and compoat, wereexamined microbial growth in enrichment culture medium at 55$\circ$C on the assumption that enzymes from thermophiles are inevitable thermostable. One strain showing higher $\alpha$-amylase activity was pure cultured and designated as Bacillus sp. TR-25 from the results of morphological, cultural and physiological characteristics. The most important carbon sourses for the enzyme production were soluble starch, dextrin, potato starch and corn starch. Glucose and fructose had a catabolite repression on the enzyme production. The good nitrogen sources for the enzyme production were yeat extract, nutrient broth, tryptone, corn steep liquor and ammonium sulfate. The enzyme production was accelerated by addition of CaCl$_{2}$. $\cdot $ H$_{2}$O. The optimal medium composition for the enzyme production was soluble starch 2.0%, yeast extract 0.55, CaCl$_{2}$ $\cdot $ 2H$_{2}$O 0.015, Tween 80 0.001%, pH8.0, respectively. In jar fermenter culture, this strain shows a rapid growth and required cheaper carbon and nitrogen source. These properties are very useful to fermentation industry. The $\alpha$-amylase of this strain demonstrated a maximum activity at 80$\circ$C, pH 5.0, respectively. And calcium ion did not improve thermostability of the enzyme. At 10$0^{\circ}C$, this enzyme has 235 of relative activity. Transformation was carried out by thermophilic Bacillus sp. TR-25 genomic DNA. As a result, the transformant has increased thermostable $\alpha$-amylase activity.