• Microbiology and Biotechnology Letters
• /
• v.27 no.4
• /
• pp.327-332
• /
• 1999

A highly productive fed-batch fermentation process was developed for the production of L-ornithine by using a new stabilized strain, Breviabcterium ketoglutamicum BK52. Fed-batch cultures with a continuous feeding of the complex medium were conducted on various operating conditions. The optimal concentration of phosphate in the complex medium was 2.1g/L. The optimal feeding rate of L-arginine was 0.028g/L/hr. The optimal feeding point of the complex medium was determined to be at 40 OD of the cell mass. The final L-ornithine concentrations within 64hrs of cultivation in 5 and 50 liter fermenters were 73g/L and 71g/L, respectively. The maximum overall L-ornithine productivity was 1.14g/L/hr which was about 2 times higher than that of the conventional fed-batch culture with intermittent feeding. The overall productivity of the fermentation system is remarkably improved by employing the optimized conditions, and it offers a significant potential for industrial application.

• The Korean Journal of Mycology
• /
• v.13 no.3
• /
• pp.185-189
• /
• 1985

This experiment was undertaken to investigate considerable economy of labor for selection of auxotrophs from strains of Lentinus edodes. Various types of auxotrophs of this strain were isolated after treatment of basidiospores with ultraviolet light, and the highest proportion of putative mutants was also obtained from isolates irradiated to give 1.30 % survival.

• Archives of Pharmacal Research
• /
• v.20 no.3
• /
• pp.206-211
• /
• 1997

The optimal conditions for the production and regeneration of the protoplasts from Lentinula edodes were studied. Protoplast formation from the mycelia of L. edodes which were cultured in liquid medium showed a significantly high yield compared with that of the mycelia which were cultured on cellophane covered agar media. A mixture of Novozyme 234 (15 mg/ml) and Cellulase Onozuka R10 (10 mg/ml) in 0.6 M mannitol (pH 4) was optimal lytic enzyme for the protoplast release. The optimal incubation time and mycelia age were 3.5-4 hours at $30^{\circ}C$ and 6-8 days, respectively. Regeneration frequency was 0.18% plated onto a medium containing 0.6 M sucrose, and 0.08% plated onto a medium containing mannitol. But hardly any regeneration was observed in the media containing NaCl, KCl, or $MgSO_{4}$ More than 90% of the protoplasts contained nuclei and the nucleus number per protoplast was 1.1. The DNA content per nucleus was 5.1 pg. The diameter of the protoplast was $3-5{\mu}m$ and it had a well defined cell structure.

• The Plant Pathology Journal
• /
• v.23 no.2
• /
• pp.51-56
• /
• 2007

A plant pathogenic fungus, Gibberella zeae (anamorph: Fusarium graminearum), not only generates economic losses by causing disease on cereal grains, but also leads to severe toxicosis in human and animals through the production of mycotoxins in infected plants. Here, we characterized a histidine auxotrophic mutant of G. zeae, designated Z43R1092, which was generated using a restriction enzyme-mediated integration (REMI) procedure. The mutant exhibited pleiotropic phenotypic changes, including a reduction in mycelial growth and virulence and loss of sexual reproduction. Outcrossing analysis confirmed that the histidine auxotrophy is linked to the insertional vector in Z43R1092. Molecular analysis showed that the histidine requirement of Z43R1092 is caused by a disruption of an open reading frame, designated GzHIS7. The deduced product of GzHIS7 encodes a putative enzyme with an N-terminal glutamine amidotransferase and a C-terminal cyclase domain, similar to the Saccharomyces cerevisiae HIS7 required for histidine biosynthesis. The subsequent gene deletion and complementation analyses confirmed the functions of GzHIS7 in G. zeae. This is the first report of the molecular characterization of histidine auxotrophy in G. zeae, and our results demonstrate that correct histidine biosynthesis is essential for virulence, as well as sexual development, in G. zeae. In addition, our results could provide a G. zeae histidine auxotroph as a recipient strain for genetic transformation using this new selectable marker.

• The Korean Journal of Mycology
• /
• v.16 no.1
• /
• pp.16-20
• /
• 1988

Auxotrophic mutants were obtained by UV-irradiation to mycelium of Ganoderma lucidum. Induction rate of auxotrophs was 5.78%. Interspecific fusion products of protoplasts were obtained by polyethylene glycol induced fusion of protoplasts from auxotrophic mutants of Ganoderma lucidum and Ganoderma applanatum. Fusion products were selected by means of the comparison with the mycelial growth rate and colony morphology. Fusion products were confirmed by mycelial morphology and esterase isozyme pattern. Some segregants were observed and fusion product produced fruit bodies.

• Journal of Microbiology and Biotechnology
• /
• v.2 no.4
• /
• pp.243-247
• /
• 1992

The thr operon of Escherichia coli TF427, an $\alpha$-amino-$\beta$-hydroxyvaleric acid (AHV)-resistant threonine overproducer, was cloned in a pBluescriptII $KS^＋$ plasmid by complementation of E. coli mutants. All clones contained a common 8.8 kb HindIII-generated DNA fragment and complemented the thrA, thrB, and thrC mutants by showing that these clones contained the whole thr operon. This thr operon was subcloned in the plasmid vectors pBR322, pUC18, and pECCG117, an E. coli/Corynebacterium glutamicum shuttle vector, to form recombinant plasmids pBTF11, pUTF25 and pGTF18, respectively. The subcloned thr operon was shown to be present in a 6.0 kb insert. A transformant of E. coli TF125 with pBTF11 showed an 8~11 fold higher aspartokinase I activity, and 15~20 fold higher L-threonine production than TF125, an AHV-sensitive methionine auxotroph. Also, it was found that the aspartokinase I activity of E. coli TF125 harboring pBTF11 was not inhibited by threonine and its synthesis was not repressed by threonine plus isoleucine.

• The Korean Journal of Mycology
• /
• v.25 no.3 s.82
• /
• pp.233-237
• /
• 1997

A PABA auxotroph of Pleurotus sajor-caju were transformed to prototrophy by using a plasmid containing pab 1 gene from Coprinus. The efficiencies of transformation of Pleurotus sajor-caju was five transformants per ${\mu}g$ of plasmid DNA. Southern blot analysis of DNA extracted from transformants demonstrated that plasmid DNA was integrated into the chromosomal DNA in multiple tandem copies. Progenies of heterokaryons between transformants of PABA and other auxotropic strains produced pab-progeny, which indicated that integration occurred at a site(s) other than the resident pab biosynthetic gene.

• Applied Biological Chemistry
• /
• v.28 no.2
• /
• pp.92-97
• /
• 1985

UV irradiation method was applied to Agrobacterium tumefaciens A 136 to obtain arginine auxotrophic mutant which is applicable as a host of Ti-plasmid. When the bacterial growth was measured at 600 nm, it showed the exponential phase between 7 and 16 hours after 2% inoculation (v/v) in TY medium and the generation time of 4.8 hours. Survival rate of $1{\sim}0.1%$ was reserved when irradiated at the intensity of $800\;{\mu}w/cm^2$ for $30{\sim}50sec$. Fifteen mutants were selected among 5,000 colonies after UV irradiation. Two of them were identified as arginine auxotrophs, three of them as asparagine auxotrophs, ana the other not as arginine, asparagine, glycine nor cysteine auxotrophs.

• Microbiology and Biotechnology Letters
• /
• v.16 no.5
• /
• pp.407-412
• /
• 1988

In order to increase the tryptophan productivity of E. coli SB1007, a mutant resistant to sulfanilamide was isolated and then a tyrosine auxotroph TY-90 was derived from the sulfanilamide-resistant mutant SA3-39-16. In the test-tube culture a quantitative amount of tryptophan was accumulated in strain TY-90 but in a jar fermentor culture the productivity was lower as compared to the level obtained by the parent strain. From the double auxotrophic mutant SB2756, a revertant resistant to 2, 000$\mu\textrm{g}$/$m\ell$ of $\beta$-thienylalanine, TA 40-10, was selected and then phenylalanine auxotrophs were derived from the revertant strain TA-40-10. One of the phenylalanine auxotrophs, TP-4, accumulated 3.7g/$\ell$ of L-tryptophan after 71-hr cultivation in a jar fermentor experiment.

• The Korean Journal of Mycology
• /
• v.26 no.1 s.84
• /
• pp.103-107
• /
• 1998

The trp2 gene encoding trifunctional enzyme in Coprinus cinereus was investigated the expression in the heterothallic mushroom species. To identify the homology of trp2 gene to Schizophyllum commune and Pleurotus ostreatus, southern hybridization was performed with plasmid pHIONA8 containing C. cinereus trp2 gene as a probe, which resulted in a strong signal indicating an homologous sequence to the chromosomal DNA of S. commune. About 50 transformants per dish was appeared in the complementation test by pHIONA8 using S. commune tryptophan auxotroph as host. In the mating test between transformants and other mating type alleles, the fruiting body of S. commune was formed at $30^{\circ}C$ in $2{\sim}3$ weeks.