• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.337-343
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• 2020

In this study, the medium optimization for cell growth and metabolite formation of Haematococcus sp. under mixotrophic cultivation was investigated. As a result, modified MS medium was selected as the basal medium; glucose was selected as the carbon source, with an optimum concentration of 10 g/l, and potassium nitrate was chosen as the nitrogen source, with an optimum concentration of 1.9 g/l. Under optimum conditions, Haematococcus sp. demonstrated an increase in biomass concentration from 0.18 gDW/l to 5.58 gDW/l in 14 days, after which there was a 31-fold increase in its growth. At the same time, the concentrations of chlorophyll and carotenoids were 172.16 mg/l and 42.33 mg/l, respectively. This work will contribute to the basic data for mass cultivation of microalgae.

• Microbiology and Biotechnology Letters
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• v.16 no.4
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• pp.287-292
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• 1988

The interaction between Lactobacillus acidophilus and Kluyveromyces fragilis on the utilization of amino acids in soymilk was investigated. K. fragilis assimilated relatively well various amino acids such as Met., ILe., Phe., Leu., Thr., Lys., Val., Arg., Tyr., Ser., Asp., Ala. and Glu. that existed only in trace amounts in soymilk. K. fragilis did not utilized Gly., while hi accumulated His. L. acidophilus hydrolyzed soyprotein to liberate various amino acids. Among various amino acids, it utilized Met., ILe., Thr., Tyr., Ser., Val. and His. as growth factors and accumulated Leu., Phe., Lys., Arg., Glu., Asp. and Ala. among the essential amino acids required by K. fragilis and Gly. These results implied that K. fragilis grew on amino acids that existed only in trace amounts in soymilk, but it's growth was stimulated by amino acids such as Leu., Phe., Lys., Arg., Glu., Asp. and Ala. ac-cumulated by L. acidophilus.

• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.335-343
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• 1992

A Streptomyces strain No. 182-27, which produced amino acid antimetabolite, was isolated from soil. During the course of screening for new amino acid antimetabolites from the culture broths of Actinomycetes, we found that the strain produced a substance active against Gram-positive bacteria and its activity was reversed by L-Ieucine on the synthetic minimal agar medium in the culture broth. The morphological and cultural characteristics serve to identify the producing organism strain 182-27 as the Streptomyces, although the species of this strain should be resolved in further studies. Fermentation was carried out in the synthetic medium at $28^{\circ}C$ for 78 hours. The fermentation yield reached about 2 mg per liter of the broth. Purification was done by ion exchange resin, active carbon, silica gel column chromatography and obtained 20 mg of pure active substance from the 20 $\ell$ culture broth. The 182-27 substance was obtained as white powder, mp 18SoC. From the physicochemical characteristics of the substance, it was amino acid like substance but unknown about its chemical structure. It is active against some Gram-positive bacteria and reversed by L-Ieucine.

• Microbiology and Biotechnology Letters
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• v.5 no.1
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• pp.36-45
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• 1977

A piscicidal substance was isolated from the culture medium of Streptomyces umbrosus by avicel column chromatography and avicel thin layer chromatography after extration with chroloform. Bluegreen fluorescence was emitted under UV irradiation. Factors which govern toxin production and nutrition requirement for high toxin titres were observed. Nutritional uptake for toxin production was not curresponded with that for cell growth. Alanine, valine, serine asparagine, arginine, histidine, urea and sodium nitrate as a carbon source and glucose, mannose, rhamnose, xylose, arabitol and starch as a carbon source were recognized as a favorable nutrient for high toxin production. Magnesium was essential factor whereas vitamins were not of effective. Most of toxin was formed simultaneously with cell growth in esponential phase. Maximal production was observed for six day culture at 3$0^{\circ}C$. Tissues of gill, kidney and pnacreas in Cyprinus carpio were denatured extreamly after treating with the substance. Atrophied nucleous, indented membrane and degradated cytoplasm with necrotic affectness were noted on each tissue. The chemical formula of the substance was designated as $C_{38}$ $H_{66}$ $NO_4$.

• Microbiology and Biotechnology Letters
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• v.15 no.2
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• pp.104-111
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• 1987

As a trial method of breeding L-lysine producing strains, the intraspecific protoplast fusion bet-ween Brevibacterium flavum ATCC 21528R and Brevibacterium flavum ATCC 21529S and the intergeneric protoplast fusion between Brevibacterium flavum ATCC 21528R and Corynebacterium glutamicum ATCC 13058S were performed. The optimum conditions for protoplast formation of these strains were examined and the effect of plasma expander on regeneration and/or fusion was also observed. Both fusants No. CH23 and No. CH4l showed higher productivity of L-lysine than those of parental cells under the optimum cultural conditions at a rate of 21％ and 8.9％, respectively. And, activity of several enzymes in L-lysine biosynthetic pathway including aspartokinase, a rate-limiting enzyme, was determined. Besides, metabolic control mechanism of L-lysine biosynthesis in fusant No. CH23 and in No. CH41 was investigated to compare with that of parental strains.

• Microbiology and Biotechnology Letters
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• v.24 no.3
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• pp.327-330
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• 1996

An amino acid antimetabolite named YS-460 was isolated from the culture filtrate of a newly isolated Actinomycetes identified as Streptomyces sp. Fermentation was carried out in the synthetic medium at 30$\circ$C for 5 days. Purification was done by ion exchange resin, active carbon, silica gel column chromatography and obtained 38 mg of pure active substance per liter of the broth. YS-460, an amino acid like substance, has the molecular formula of C$_{7}$H$_{11}$NO$_{3}$- Its structure determined to be furanomycin by spectral analysis. It is active against some bacteria on a chemically defined medium and reversed competitively by L-isoleucine and non-competitively by L-leucine and L-valine.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.24-30
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• 1995

The effects of amino acids in growth media on the biosynthesis of Serratia marcescens biodegradative threonine dehydratase activity were examined. The enzyme activity was decreased by 44 and 34% by 10 mM isoleucine and valine, respectively, whereas it was increased approximately by 20% by 10 mM threonine. Among several metabolites tested, pyruvate increased the enzyme activity by 60% at 5 mM, but decreased the enzyme activity approximately by 20 to 70% above 20 mM. The enzyme activity was increased by 64% by 5 mM glyoxylate, whereas it decreased the enzyme activity approximately by 40 to 70% above 20 mM glyoxylate. The thiamine, monopyrrole derivative, also increased the enzyme activity by 84% at 50 $\mu $g/ml, but did not affected the enzyme activity above 300 $\mu $g/ml. cAMP increased the enzyme activity by 58% at 0.5 mM, but decreased the enzyme activity by 15% at 2 mM. These data suggested that the biosynthesis of Serratia marcescens biodegradative threonine dehydratase is regulated by concentrations of pyruvate, glyoxylate and cAMP.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.81-86
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• 1995

A Streptomyces strain YS-943, which produced amino acid antimetabolite, was isolated from soil. During the course of screening for new amino acid antimetabolites from the culture broth of Actinomycetes, we found that the strain produced a substance active against Gram-positive bacteria and its activity was reversed by L-methionine and L-histidine on the synthetic minimal agar medium in the culture broth.The morphological and cultural characteristics serve to identify the producing organism strain YS-943 as the genus Streptomyces. Fermentation was carried out in the synthetic medium at 28$\CIRC$C for 48 hours. The fermentation yield reached about 12 mg per liter of the broth. The YS-943 substance was obtained as white powder, mp 194$\CIRC$C and has the molecular formular of C$_{4}$H$_{8}$N$_{2}$O$_{4}$. Its structure was determined to be o-carbamyl-D-serine by spectroscopic data. It is active against some Gram-positive bacteria and reversed by L-methionine and L-histidine.

• Microbiology and Biotechnology Letters
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• v.28 no.1
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• pp.21-25
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• 2000

We have got several clones from Serratia marcescens which stimulated the cells to use maltose as a carbon source in Escherichia. coli TP2139 ( lac, crp). One of the cloned genes, pCKB17, was further analyzed. In order to find whether the increased expression of the gent was under the direction of maltose metabolism, we constructed several recombinant subclones. We have found that the clone, pCKB17AV, codes maltose metabolism stimulation(mms) gene. E. coli transformed with the cloned gene showed increase in the activity of maltose utilzation, The recombinant proteins expressed by multicopy and induction with IPTG, one polypeptide of 29-kDa, was confirmed by SDS-PAGE. The overexpression of maltose-binding proter protein in the presence of mms gene was confirmed by Western blot analysis. Southern hybridization analysis confirmed that the cloned DNA fragment was originated from S. marcescens chromosomal DNA.

• Microbiology and Biotechnology Letters
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• v.37 no.4
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• pp.333-339
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• 2009

Using a novel pine needle agar, fifteen bacterial species were isolated from pine litter. These bacteria were able to degrade aromatic hydrocarbons derived from lignin and utilize the ortho-cleavage of the $\beta$-ketoadipate pathway to degrade protocatechuate or catechol. A different utilization array of aromatic hydrocarbons by these bacteria was also determined. This study provides the information on bacterial species living in pine litter and suggests that these bacteria have metabolic abilities to utilize aromatic hydrocarbons derived from lignin biodegradation.