Regulation Mechanism Of Energy Metabolism For Single-producing Extracellular Yellow Pigment Of Monascus Purpureus BWY-5

As a natural food colourant of microbial source,Monascus red pigment has been produced industrially,but,due to the lack of genetically stable strains of Monascus and the lack of clarity on the mechanisms regulating the anabolism of Monascus yellow pigment during bioprocessing process,causing the Monascus yellow pigment with strong protein ability,good stability and health effect has not been produced industrially so far.The study was based on Monascus purpureus BWY-5 that single-producing extracellular yellow pigment obtained by 12C6+heavy ion beam irradiation.The study used the research methods of the omics(transcriptomics and proteomics)and modern enzymology to analyse the changes in energy metabolism of Monascus during the bioprocessing process of single-producing extracellular yellow pigment,to explore the relationship between the changes in energy metabolism and the metabolism and synthesis in extracellular yellow pigment.Consequently,to elucidate the regulation mechanism of energy metabolism for single-producing extracellular yellow pigment of Monascus purpureus BWY-5.The details are as follows:1.Based on the glycolytic pathway,gluconeogenic pathway and tricarboxylic acid cycle,the regulation mechanism of energy metabolism for Monascus purpureus BWY-5 was elucidated.The expression of genes and proteins in glycolytic pathway was down-regulated of Monascus purpureus BWY-5,but the activities of hexokinase and phosphofructokinase were increased,which promoted glycolytic pathway;The gluconeogenic pathway and the tricarboxylic acid cycle improved related enzyme activity due to the positive regulation of genes and proteins,the tricarboxylic acid cycle was promoted,the content of pyruvate and oxaloacetic acid was increased,the energy and precursor substance for growth of the Monascus and pigment synthesis were provided.By analyzing the level of genes and proteins,the gene of phosphofructokinase may be the key gene inhibiting of the glycolytic pathway;the genes of phosphoenolpyruvate carboxykinase and pyruvate carboxylase could be the key genes enhancing the gluconeogenic pathway;genes such as citrate synthase,succinate CoA ligase[ADP]subunit,succinate dehydrogenase,malate dehydrogenase and isocitrate dehydrogenase[NAD]subunit might be the key genes promoting the tricarboxylic acid cycle.2.By analyzing the changes in energy metabolism of the mitochondrial respiratory chain,the mechanism of its metabolic regulation for extracellular yellow pigment synthesis was elucidated.Monascus purpureus BWY-5 improved the expression level of genes and proteins associated with mitochondrial respiratory chain complex,while the Monascus was mainly the succinate oxidative respiratory chain due to the decreased activity of complex I and produced a large amount of ATP.The Monascus utilized ATP by improving the activity of ATPase so that it could maintain normal growth,increase its biomass and facilitate the accumulation of yellow pigment.What’s more,the Monascus changed the ratios of the NAD+/NADH and NADP+/NADPH providing the reducing power for the production of yellow pigments.By analyzing the level of genes and proteins,it was found that genes such as NADH:ubiquinone oxidoreductase,cytochrome b-c1 complex subunit 7,cytochrome c oxidase subunit 5,ATP synthase 4 and ATP synthase 6 might be the key genes affecting the oxidative phosphorylation pathway.3.The regulation mechanism of amino acids for extracellular yellow pigment synthesis was elucidated from the perspective of energy by analyzing the effect of amino acids for the synthesis of yellow pigment by Monascus purpureus BWY-5.Firstly,13 amino acids were used as nitrogen sources;It was found that glycogenic amino acids were beneficial to the production of Monascus yellow pigment,while glycogenic and ketogenic amino acids were opposite.Secondly,7 amino acids were selected as nitrogen sources to analyze their effects on the energy metabolism of Monascus;It was found that the addition of most amino acids inhibited the mitochondrial respiratory chain of Monascus purpureus BWY-5.The required energy for normal growth of Monascus,required precursor substance for synthesis of yellow pigment and required reducing power for production of yellow pigment were mainly derived from substrate level phosphorylation pathway.The key enzymes affecting the energy metabolism of Monascus purpureus BWY-5 could be the hexokinase,phosphofructokinase,and pyruvate kinase.