• Journal of Microbiology and Biotechnology
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• v.15 no.4
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• pp.749-755
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• 2005

The ccpA gene encoding catabolite control protein A (CcpA) of Leuconostoc mesenteroides SYl, a strain isolated from kimchi, was cloned, sequenced, analyzed for transcript, and overexpressed in Escherichia coli. The ccpA ORF (open reading frame) is 1,011 bp in size, which can encode a protein of 336 amino acid residues with a molecular mass of 36,739 Da. The transcription start site was mapped at a position 49 nucleotides upstream of the start codon, and promoter sequences were also identified. The putative cre site overlapped with the -35 promoter sequence. The deduced amino acid sequence of the CcpA contained the helix-turn-helix motif found in many DNA-binding regulatory proteins. CcpA from 1. mesenteroides SY1 had $54.6\%$ identity with CcpA from Lactobacillus casei. The Northern blot experiment showed that ccpA was transcribed as a single 1.1 kb transcript, and transcription was repressed when grown on media containing glucose. CcpA was overproduced in E. coli BL21(DE3) cells using the pET expression vector, and purified to an apparent homogeneity. Gel Mobility Shift Assay with purified CcpA and a DNA fragment containing the ere sequence of the $\alpha$-galactosidase gene (aga) from L. mesenteroides SY1 revealed that CcpA bound specifically to the cre site of aga.

• Microbiology and Biotechnology Letters
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• v.2 no.1
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• pp.29-35
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• 1974

We have studied the applicability of the principles and inherent advantages of the two-stage dontinuous uclture technique to an enzyme process for the purpose of improving and optimizing the productivity of 3-ketosteroid-delta-1-dehydrogenase. By using a two-stage continuous culture system, the growth st ageand enzyme produdtion stage are separated. In each stage an optimal set of toperaing conditions was determined, and this was tested for feasibility for the period of 10 days. During this period, at least 70％ of the maximum enzyme productivity could be maintained. The important design parameters studied are: (1) optimal specific growth rate in the first stage which corresponds to the maximal cell productivity, (2) the optimal dilution rate in the second stage which in turn determines the size of second stage fermentor and the mean residence time of cells in the second stage, (3) cell concentration in both stages, add (4) the specific enzyme productivity and enzyme productivity of the second stage. In addition, by using two-stage continuous culture system we have been able to reduce or eliminate the effect of catabolite repression due to high medium concentration and the adverse effect of the solvent used to dissolve the inducer. We have found the balance between the opposing effects of induction and repression in the second stage judging from the observation that the enzyme productivity goes through a maximum.

• 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.

• Microbiology and Biotechnology Letters
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• v.19 no.1
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• pp.21-24
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• 1991

The promoter isolated from an alkali-tolerant Hwillus sp. chromosomal DNA was subcluned. The activity of promoter in B, subtilis and alkali-tolerant Bacillus sp. began to increase at the early stage. of spore formation. In the presence of 1% glucose, the promotcr activity repressed and was recovered by ;tddition of c-GMP in the medium.

• Journal of Microbiology and Biotechnology
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• v.1 no.4
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• pp.256-260
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• 1991

In B. subtilis, $\alpha$-amylase synthesis is regulated by amyR located directly on the upstream of amyE. Three different amyR alleles have been reported, amyR1, amyR2 and amyR3. Strains bearing the gra-10 mutation which confers derepression for catabolite repression has GlongrightarrowA transition mutation at ＋5 of amyR1. S1 nuclease mapping demonstrated that transcription initiated at 8 bases downstream from the -10 region of putative E$\sigma^{A}$ promoter P1 in amyR1 and gra-10. In amyR2, the major transcription initiatd at the same place and the minor, 10 bases downstream from -10 of P2. The transcript from P2 contributed approximately 15-20% of total amyE mRNA. S1 nuclease protection experiment indicated that amyE mRNA levels corresponded to the rate of synthesis assumed by specific activities of $\alpha$-amylase in culture supernatants, suggesting that $\alpha$-amylase synthesis is regulated at the level of transcription.n.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.587-592
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• 2005

Hydrolyzates from lignocellulosic biomass contain a mixture of simple sugars; the predominant ones being glucose, cellobiose and xylose. The fermentation of such mixtures to ethanol or other chemicals requires an understanding of how each of these substrates is utilized. Candida lusitaniae can efficiently produce ethanol from both glucose and cellobiose and is an attractive organism for ethanol production. Experiments were performed to obtain kinetic data for ethanol production from glucose, cellobiose and xylose. Various combinations were tested in order to determine kinetic behavior with multiple carbon sources. Glucose was shown to repress the utilization of cellobiose and xylose. However, cellobiose and xylose were simultaneously utilized after glucose depletion. Maximum volumetric ethanol production rates were 0.56, 0.33, and 0.003 g/L h from glucose, cellobiose and xylose, respectively. A kinetic model based on cAMP mediated catabolite repression was developed. This model adequately described the growth and ethanol production from a mixture of sugars in a batch culture.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.568-571
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• 1999

Aspergillus oryzae U1521, which was a genetically engineered strain, produced 1,000,600 U per g . glucose of extracellular alkaline protease within 72 h in a submerged fermentation. However, the alkaline protease was not detected during the first 24 h. Northern blot analysis indicated that the enzyme synthesis was repressed at the transcriptional level during the lag period. Both catabolite repression and pH of the growth medium significantly affected the enzyme production. Use of this enzyme as a silver recovery agent from used X-ray film was confirmed by experiments in the shake-flask scale.

• Microbiology and Biotechnology Letters
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• v.21 no.3
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• pp.239-246
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• 1993

Producing an extracellular alkaline lipase, this isolate JM123 was identified as a Pseudomonas aeruginosa strain from the results of the analyses of its morphological, biochemical and physiological properties. This strain showed the highest productivity of alkaline lipase when grown at pH 9.0 and 30C for 13-20 hours in the medium of 2% starch, 1% soytone, 0.5% peptone and 1% MgSO4.7H2O. However, this enzyme was greatly repressed when grown in the glucose containing medium. The culture broth was fractionated by the order of the ammonium sulfate precipitation, Sephadex G-200 gel filtration, DEAE-cellulose column chromatography, and Sephadex G-150 gel filtration.

• The Korean Journal of Mycology
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• v.24 no.3 s.78
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• pp.206-213
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• 1996

Talaromyces luteus 2004, a thermophilic mutant of T. luteus 6112 was obtained by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. T. luteus 2004 produced thermophilic carboxymethylcellulase (CMCase), and other polysaccharide enzymes: avicellase, xylanase, and ${\beta}-glucosidase$. Induction of CMCase production was shown at the highest level in 3% carboxymethylcellulose (CMC) minimal broth, indicating that CMC could work as an inducer. However, glucose and D-cellobiose showed catabolite repression for CMCase production which was under the control of CMC utilization. Optimal conditions for CMCase activity were at $70^{\circ}C$ and pH 4.0, suggesting that CMCase of T. luteus 2004 was a thermophilic enzyme.

• Microbiology and Biotechnology Letters
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• v.19 no.5
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• pp.464-469
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• 1991

An $\alpha$-amylase producing bacterium, strain 2B, was isolated from soil and identified to genus Bacillus. To enhance $\alpha$-amylase productivity, strain 2B was mutagenized successively with nitrosoguanidine. For an efficient selection of a-amylase hyperproducers, mutants which produced $\alpha$-amylase in the presence of glucose were isolated. The resultant mutant HG4, which was classified as constitutive and catabolite derepressed hyperproducer of a-amylase, produced about 30 folds more $\alpha$-amylase than parental strain in medium containing lactose as carbon source. The strain HG4 grew rapidly and produced enzyme in parallel with cell growth. Moreover, its cell lysis did not occur until time of maximal yield of enzyme, which was considered to be a favorable characteristic for the production and purificiation of enzyme in industrial scale. The enzymatic properties of parental strain 2B and mutant strain HG4 were almost the same. The optimal temperature and pH for enzyme reaction was $70^{\circ}C$ and pH 6.0, respectively, in 'the presence of 0.6mM $Ca^[2+}$ as an effective stabilizer.