The Influence Of Light On Growth、Conidiation And Mevastatin Biosynthesis In Penicillium Citrinum

Background:Light represents a major carrier of information in nature. Light regulates several aspects of the biology of many organisms, including the balance between asexual and sexual development in some fungi. In Aspergillus nidulans, light inhibits sexual reproduction as well as secondary metab olism.VeA, which play an important role in the light-responding progress.The a-import in KapA supports the entry of the VeA-VelB dimer into the nucleus in the dark.In the nucleus, the VelB-VeA dimer can interact with LaeA, forming the heterotrimeric velvet complex that regulates secondary metabolism and development. The LaeA could represse the VeA-VelB dimer depolymerization in the dark.VelB can also form homodimers and is part of another heterodimer, VosA-VelB. VosA-VelB represses asexual development and is required for the viability of spores by activating trehalose biogenesis. Light decreases the cellular levels of VosA and VelB and allows asexual sporulation. In the dark, VosA-velB is present and negatively regulates asexual conidiation and still supports trehalose biosynthesis. VeA interacts with the red light receptor FphA that is associated with the blue light receptors LreA and LreB.So the light could regulate the development and metabotites by reduced biosynthesis or decreased stability or both and an additional impaired import of VeA into the nucleus in Aspergillus nidulans. In recent year, the research on the homologous of laeA and veA cloned from Aaspergillus fumigatus、 Neurospora crassa and Penicillium chrysogenum play the same function role in regulation development and metabolic pathways。The Penicllium citrinum has been used for the commercial production of ML-236B (Compactin\Mevastatin). Studying on the molecular regulation mechanism of Penicllium citrinum is meaningfull.The homologous of laeA and veA in Penicllium citrinum has been cloned by our lab.Wehter laeA and veA in Penicillium citrinum has the similar function on regulation of development and metabolic pathways is worth researching.Obejective:To understand the mechemism of light-responding regualtion in Penicillium citrinum,the relative expression of pcialeA、pciveA and mlcR were detected by RT-qPCR and difference between the phenotype,conidiation and the biosynthesis of secondary metabolites of ML-236-B of Penicillium citrinum was researched under light and dark condition.Method:1.The Penicillium citrinum were cultured on PGA medium each under illumination and dark.The phenotype were seen by SEM (scanning electron microscope)2. The production of ML-236B were decteced by HPLC.3.the RT-qPCR were usd to analyse the expression of pcilaeA,pciveA,mlcR.4.The pcilaeA (CDS) was inserted into Penicillium citrinum ATCC38065by ATMT.The production of Penicillium citrinum::pcilaeA(CDS) were detected by HPLC.Result:1.The Penicillium citrinum show abundant conidiation under light which is contrary to that under dark.There is much more pigments in the strain under light than dark.2.The production of ML-236B under light was lower than dark at last.3.The expression of pciveA/pcilaeA and mlcR were lower than under dark.4.The production of ML-236B from Penicillium citrinum::pcilaeA(CDS) was higher than from wilde type Penicillium citrinum. And there were new peak appeared in the prodcution of Penicillium citrinum::pcilaeA(CDS).Conclusion:The light could affect the phenotype and conidiation on Penicillium citrinum. the production of ML-236B produced by Penicillium citrinum IMB002under light is lower than the production under dark from3d to7d.Combining with the analysis of gene expression I infer that the PcilaeA and PciveA in Penicillium citrinum could regulate secondary metabolism and conidiation during the light-responding.