Derepression of carbon catabolite repression in an extractive liquid-surface immobilization (Ext-LSI) system

Discovery of secondary metabolites in an extractive liquid-surface immobilization system and its application to high-throughput interfacial screening of antibiotic-producing fungi

“…The latter is a 6PP-producing mutant prepared with N-methyl-N-nitso-Nnitrosoguanidine. 26,29,30 Both strains were inoculated in F-1 medium consisted of 20.0 g of potato starch, 10.0 g of glucose, 20.0 g of soy protein (Soypro; Inui Co., Ltd, Osaka, Japan), 1.0 g of KH 2 PO 4 , 0.5 g of MgSO 4 ·7H 2 O and 1.0 liter of reverse osmosis water, pH 6.0 for the preparation of seed broth. Construction, operation and product recovery for Ext-LSI system.…”

“…49 Although the production of 6PP by T. atroviride AG2755-5NM398 was completely inhibited by adding over 10% (w/v) of glucose and fructose in the SmC, the CCR was effectively derepressed even in the presence of 25% (w/v) glucose and fructose in the Ext-LSI system. 30 Thus, the derepression of CCR in the Ext-LSI system may be favorable to the production of hydrophobic secondary metabolites.…”

Relationship between Interfacial Hydrophobicity and Hydroxylation Activity of Fungal Cells Located on an Organic–Aqueous Interface

“…A Liquid-liquid interface bioreactor (L-L IBR), which consists of a hydrophobic organic solvent (an upper phase), a layer of fungal cellballooned polyacrylonitrile microsphere (diameter, 20-40 μm; density, 0.03-0.20; a middle phase), and a liquid medium (a lower phase), is a unique and effective cultivation system for the microbial transformation with fungi [1]. The system has some interesting and practically important characteristics, i.e., alleviation of toxicity of poisonous substrate and/or product solubilized in the organic phase, excellent productivity of valuable hydrophobic chemicals, efficient supply of oxygen from the organic phase to fungal cells, control and management of pH and nutrients in the liquid medium, depression of catabolize repression caused by easily metabolizable carbon sources [2], and easy recovery of product without troublesome solvent extraction. The system has been applied to various microbial reactions, such as hydrolysis of an acetate ester [1,3], asymmetric reduction of an aromatic dike tone [4], and regio-and stereo selective epoxidation ofcaryophyllene to (-)-β-caryophyllene oxide so far [5].…”

Solid–liquid Interface Screening SystemーApplication to the Screening of Antibiotic and Cytotoxic Substance-producing Fungi

“…It is known that fungal secondary metabolism is affected by many environmental factors, such as light Babitha et al, 2008, medium composition Hewage et al, 2014and pH Miao et al, 2006, temperature and moisture Bacon et al, 1973, CO 2 El-Sabbagh et al, 2008 and O 2 concentrations Lai et al, 2005 , and agitation rate Kim et al, 2002 besides fungal morphology such as pelleted, filamentous, and clump forms Du et al, 2003 . Moreover, while the style of cultivation system, i.e., submerged cultivation SmC , liquid-surface cultivation LSC and solid-state cultivation SSC systems, also affects on the production of fungal metabolites Asaff et al, 2006 , carbon catabolite repression drastically decrease the production of enzymes and secondary metabolites only in the SmC Aguilar et al, 2001 . Recently, the authors have reported that fungal cells growing on an interface between a hydrophobic organic solvent and a liquid medium can produce characteristic hydrophobic secondary metabolites which are not produced in the SmC Oda et al, 2015 . The interface cultivation system, an extractive liquid-surface immobilization Ext-LSI system comprising a hydrophobic organic solvent upper phase , a fungal cell-microsphere mat middle phase , and a liquid medium lower phase , has also some unique and practically important characteristics, such as derepression of carbon catabolite repression Oda et al, 2012a and remarkably high productivity of lipophilic secondary metabolites Oda et al, 2009;Oda et al, 2012b . On the other hand, many microorganisms containing FIG. 1 Strategy for the estimation of secondary metabolite profiles among submerged and agar-solvent interfacial cultivation, and extractive liquid-surface immobilization system.…”