• Applied Biological Chemistry
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• v.36 no.5
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• pp.332-338
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• 1993

For the production of riboflavin, strain development of Ashbya gossypii NRRL Y-1056 was attempted by NTG(N-methyl-N'-nitro-N-nitrosoguanidne) treatment. The optimum composition of culture medium and other culture conditions for the production of riboflavin by selected mutant Ashbya gossypii JAG-13 were determined. The optimum composition of medium was 9% of corn oil, 3% of gellatone, 4% of CSL, 0.3% of glycine, 0.2% of S770. The optimum culture temperature and initial pH of medium was $28^{\circ}C$ and 6.5, respectively. oxygen was essential for the production of riboflavin, but excess oxygen inhibit the production of riboflavin. When Ashbya gossypii JAG-13 was cultured under above conditions for 12 days with a bioreactor, 6.9 mg/ml of riboflavin was produced.

• Genomics & Informatics
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• v.4 no.2
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• pp.80-86
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• 2006

It is clear that the construction of large insert DNA libraries is important for map-based gene cloning, the assembly of physical maps, and simple screening for specific genomic sequences. The bacterial artificial chromosome (BAC) system is likely to be an important tool for map-based cloning of genes since BAC libraries can be constructed simply and analyzed more efficiently than yeast artificial chromosome (YAC) libraries. BACs have significantly expanded the size of fragments from eukaryotic genomes that can be cloned in Escherichia coli as plasmid molecules. To facilitate the isolation of molecular-biologically important genes in Ashbya gossypii, we constructed Ashbya chromosome-specific BAC libraries using pBeloBAC11 and pBACwich vectors with an average insert size of 100 kb, which is equivalent to 19.8X genomic coverage. pBACwich was developed to streamline map-based cloning by providing a tool to integrate large DNA fragments into specific sites in chromosomes. These chromosome-specific libraries have provided a useful tool for the further characterization of the Ashbya genome including positional cloning and genome sequencing.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.2
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• pp.75-88
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• 2001

In this paper, the microbial production of riboflavin is reviewed and includes descriptions of riboflavin overproducers, and the biosynthesis and details of the key-enzyme genes related to riboflavin. There kinds of riboflavin overproducers are known; Bacillus subtilis and Candida famate utilize glucose as a carbon source, but the fungus Ashbya gossypii requires plant oil as its sole carbon source. The starting material in ribofalvin biosynthesis is guanosine triphospate (GTP), which is converted to riboflavin through six enzymatic reactions. Though Bacillus subtilis, Candida famate, and Ashbya gossypii operate via different pathways until GTP, they follow the same pathway from GTP to riboflavin. From the metabolic viewpoint, with respect to improved riboflavin production, the supplementation of GTP, aprocess-limiting precursor must be considered. The GTP fluxes originate from three sources, serine, threonine and glyoxylate cycles. The development of pathways to strengthen GTP supplementation using biotechnological techniques remains an issue fro future research.

• Microbiology and Biotechnology Letters
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• v.21 no.6
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• pp.615-621
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• 1993

In order to maximize the riboflavin production by a mutant strain Ashbya gosspyii, the optimization of medium and fed-batch fermentation were performed. As carbon sources, glucose and soybean oil were necessary for the riboflavin overproduction. Optimal concentrations of glucose and soybean oil in the flask cultures were found to be 3.0% and 0.5%, respectively, in a complex medium containing corn steep liquor(CLS) 1%. Among the various organic nitrogen sources tested, CSL was the most effective one both for the cell growth and riboflavin overproduction.

• Korean Journal of Microbiology
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• v.23 no.3
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• pp.167-171
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• 1985

In order to investigate the origin of the ribityl froup of riboflavin and the involvement of GTP cyclohydrolase II in the riboflavin pathway, we studied the incorporation of $^{14}C-labeled$ guanosine using a well known riboflavin over producer, Ashbya gossypii.Cells were grown in a media containing $(U- ^{14}C)$ guanosine and the riboflavin and GMP were isolated and purifired by column chromatography. The isolated compounds, riboflavin and GMP were labeled in the ribityl and ribosyl side chain and the isoalloxazine and guannine moiety. By comparing the specific radioactivity of each compound we reached a conclusion that the ribose of guanosine is converted directly to the rivityl moiety of riboflavin. The results indicate that biosynthesis of the vitamin begins at the level of a guanosine compound and also suppory the involvement of GTP cyclohydrolase II in one of the early steps in the biosynthetic pathway.