Background The filamentous fungus Trichoderma reesei is an important host organism

Background The filamentous fungus Trichoderma reesei is an important host organism for industrial enzyme production. between biosynthetic pathways of 78246-49-8 IC50 amino acids in T. reesei and yeast Saccharomyces cerevisiae. In contrast to S. cerevisiae, however, mitochondrial rather than cytosolic biosynthesis of Asp was observed under all studied conditions. The relative anaplerotic flux to the TCA cycle was low and thus characteristic to respiratory metabolism in both strains and independent of the carbon source. Only minor differences were observed in the flux distributions of the 78246-49-8 IC50 wild type and cre1 deletion strain. Furthermore, the induction of the hydrolytic gene expression did not show altered flux distributions and did not affect the relative amino acid requirements or relative anabolic and respirative activities of the TCA cycle. Conclusion High similarity between the biosynthetic pathways of amino acids in T. reesei and yeast S. cerevisiae was concluded. In vivo flux distributions confirmed that T. reesei uses primarily the respirative pathway also when growing around the repressive carbon source glucose in contrast to Saccharomyces cerevisiae, which substantially diminishes the respirative pathway flux under glucose repression. Background The industrially important protein producer, the filamentous fungus Trichoderma reesei, a clonal derivative of the ascomycete Hypocrea jecorina, is usually adapted to growth in nutrient poor environments, where it is able to use complex plant material as carbon source. T. reesei and a number of other filamentous fungi and cellulolytic bacteria produce and secrete herb polymer hydrolyzing enzymes, such as cellulases and Mouse monoclonal to BNP hemicellulases, into their surroundings to break down the polymers into easily metabolizable monomers [1]. Because of its ability to synthesize and secrete large amounts of proteins, T. reesei has gained industrial importance in production of enzymes of native and heterologous origin. Carbon catabolite repression (CCR) of T. reesei negatively regulates the powerful production machinery of the hydrolytic enzymes when a favored carbon source, such as glucose, is usually available. Inducers of hydrolytic enzyme expression are often small oligosaccharides or derivative parts of the polymers from the environment of the fungus. The inductive signaling leads to synthesis of specific sets of enzymes [2,3]. In T. reesei, D-xylose, xylobiose, sophorose, and lactose have been observed to trigger production of particular enzyme sets [4,5]. Sophorose, a molecule of two beta-1,2-linked glucose units, is an efficient inducer of cellulose gene expression at low concentration (1-2 mM) when T. reesei is usually growing on a non-repressing carbon source, such as sorbitol or glycerol [6]. However, in high glucose concentrations CCR overrules the inductive signals in T. reesei [6]. Sorbitol as a carbon source neither provokes CCR nor triggers the cellulase gene expression in T. reesei [6]. Nevertheless, cellulase production is usually positively correlated with the ability of different T. reesei strains to grow on D-sorbitol [7], which could be converted to L-sorbose [8] that induces cellulase expression in T. reesei [9]. In T. reesei L-arabinitol 4-dehydrogenase (Lad1) is usually involved in the initial oxidization of D-sorbitol at C2 to convert it to D-fructose [10]. A 78246-49-8 IC50 specific sorbitol dehydrogenase converts sorbitol to fructose in Aspergilli fungi [11,2]. Cre1 is the key mediator protein of CCR in T. reesei [12,13]. Trichoderma Cre1 has a 95% sequence similarity with Aspergillus CreA in regions of the zinc-finger and proline-serine-threonine-rich domain name and the complete.