• Proceedings of the Korean Society of Crop Science Conference
• /
• 2006.04a
• /
• pp.598-599
• /
• 2006

• 한국약용작물학회:학술대회논문집
• /
• 2008.05a
• /
• pp.267-268
• /
• 2008

• Proceedings of the Microbiological Society of Korea Conference
• /
• 2005.05a
• /
• pp.15-15
• /
• 2005

• Proceedings of the PSK Conference
• /
• 2001.10a
• /
• pp.284.1-284.1
• /
• 2001

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2020.06a
• /
• pp.103-103
• /
• 2020

• Microbiology and Biotechnology Letters
• /
• v.44 no.4
• /
• pp.409-419
• /
• 2016

Filamentous Aspergillus spp. are the most common fungi in our environment and can be beneficial and/or pathogenic to humans. Many Aspergillus spp. reproduce by forming asexual spores and can synthesize various secondary metabolites. A series of studies has revealed that Velvet regulators are fungus-specific transcription factors coordinating fungal growth, development, and secondary metabolism in the model fungus Aspergillus nidulans. Proteins of the Velvet family form various complexes that play diverse roles in the life cycle of A. nidulans. In other Aspergillus spp., proteins of this family are highly conserved and coordinate asexual development and secondary metabolism. This review summarizes the functions of Velvet proteins in Aspergillus spp.

• Journal of Microbiology and Biotechnology
• /
• v.10 no.2
• /
• pp.169-175
• /
• 2000

The filamentous soil bacterium Streptomyces coelicolor is known to produce four distinct antibiotics. The simultaneous global regulation for the biosynthesis of those four antibiotics was previously confirmed by absA and absB mutations that blocked all four antibiotics' biosynthesis without influencing their morphological differentiation. To study the complex regulatory cascade that controls the secondary metabolism in Streptomyces, a new abs-like mutation was characterized. namely absR, which is slightly leaky on a complete R2YE medium, yet tight on a minimal medium. A genetic analysis of the absR locus indicated that it is located at 10 o'clock on the genetic map, near the site of absA. A cloned copy of the absA gene that encoded bacterial two-component regulatory kinases did not restore antibiotic biosyntheis to the absR mutant. Accordingly, it is proposed that absR is another abs-type mutation which is less tight than the previously identified absA or absB mutations income medium conditions, and can be used to characterize another global regulatory gene for secondary metabolete formation in S. coelicolor.

• KSBB Journal
• /
• v.13 no.2
• /
• pp.203-208
• /
• 1998

We investigated the effects of dissolved oxygen (D.O.) and fructose (C-source) on cell growth and biosynthesis of cyclosporin A (CyA) produced as a secondary metabolite by a wild-type filamentous fungus, Tolypocladium inflatum. This was performed by controlling the level of D.O. and the residual C-source, as required, through adjustment of medium flow rate, medium concentration and agitation rate in fed-batch cultures. CyA production was furned out to be maximal, when D.O. level was controlled around 10% saturated D.O. and concentration of the C-source was maintained sufficiently low (below 2 g/L) not to cause carbon catabolite repression. Under this culture condition, we obtained the highest values of CyA concentration (507.14 mg/L), Qp (2.11 mg CyA/L/hr), $Y_x/s$ (0.49 g DCW/g fructose), $Y_p/s$<(22.56 mg CyA/g fructose), and YTEX>$_p/x$ (48.31 mg CyA/g DCW), but relatively lower values of cell concentration (11.98 g DCW/L) and cell productivity (0.043 g DCW/L/hr), in comparison with other parallel fed-batch fermentation conditions. These results implied that, in the carbon-limited culture with 10% saturated D.O. level, the producer microorganism utilized the C-source more efficiently for secondary metabolism.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.41 no.spc1
• /
• pp.123-144
• /
• 1996

This review deals briefly with the various medicinal components(mainly saikosaponins), their biological activities and the variation of their contents by different cultivation environment and plant parts in Bupleurum species. Bupleuri radix, a crude drug, is the root of Bupleurum falcatum L. (Korea, Japan), B. chinense(China), and their related species (Umbelliferae). There are over 120 species in Bupleurum genus throughout world, mainly Asian area, and over 5 species in Korea, investigated up to now. These plants contain many physiological active compounds and the principal components are saikosaponins. Major activities of this crude drug and saikosaponins are the anti-inflammatory and antihepatotoxic activities. Saikosaponins and their derivatives in Bupleurum spp. have been chemically studied, isolated and identified over 70 compounds in over 50 species. Other components, physiologically active ones, also have been investigated, which are the groups of lignan, flavonoid, essential oil, polyacetylene, polysaccharide, etc. Saikosaponins belong to the group of triterpenoid saponin chemotaxonomically and occur the accumulation and turnover in plant tissues through secondary metabolism, mevalonic acid pathway. The contents and kinds of saikosaponins and other components in Bupleurum spp. plants are various due to different species and growing environments, as the plant growth characters and yield are various. Most of medicinal plants as well as Bupleurum species are very useful as agricultural products and traditional medicines, and also are very valuable as genetic resources and natural products. So we need to collect, evaluate, preserve, and utilize various medicinal plants, and also to under-stand secondary metabolism and improve the breeding and cultivation techniques for the safe production of crude drugs with high quality and yielding.

• Journal of Microbiology and Biotechnology
• /
• v.8 no.4
• /
• pp.325-332
• /
• 1998

In vitro phosphorylation experiments with a cell extract of Streptomyces coelicolor A3(2) M130 in the presence of ${\gamma}-[^32P]$]ATP revealed the presence of multiple phosphorylated proteins, including the AfsR/AfsK kinases which control the biosynthesis of A-factor, actinorhodin, and undecylprodigiosin. Phosphorylation of AfsR by a cell extract as an AfsK source was significantly inhibited by Ser/Thr protein kinase inhibitors, staurosporine and K-252a, at concentrations giving 50% inhibition ($IC_50$) of $1{\mu}M\;and\;0.1{\mu}M$, respectively. Further in vitro experiments with the cell extracts showed that phosphorylation of multiple proteins was inhibited by various protein kinase inhibitors with different inhibitory profiles. Manganese and calcium ions in the reaction mixture also modulate phosphorylation of multiple proteins. Manganese at 10 mM greatly enhanced the phosphorylation and partially circumvented the inhibition caused by staurosporine and K-252a. A calcium-activated protein kinase(s) was little affected by these inhibitors. Herbimycin and radicicol, which are known as tyrosine kinase inhibitors, did not show any significant inhibition of AfsR phosphorylation. Consistent with the in vitro effect of the kinase inhibitors, they inhibited aerial mycelium formation and pigmented antibiotic production on solid media. On the contrary, when assayed in liquid culture, the amount of actinorhodin produced was increased by staurosporine and K-252a and greatly decreased by manganese. All of these data clearly show that the genus Streptomyces possesses several protein kinases of eukaryotic types which are involved in the regulatory network for morphogenesis and secondary metabolism.