Fig. 4

The relative abundances of various intracellular metabolites in different fermentation period. Metabolites were analyzed to investigate the differences during the whole fermentation process of S. nodosus, including metabolism of amino acid, sugar, fatty acid, terpenoid backbone, folate biosynthesis and the other secondary metabolites. a Amino acid metabolism, b sugar metabolism and central metabolic pathway, c fatty acid biosynthesis, d terpenoid backbone biosynthesis, e folate biosynthesis and one carbon pool by folate, f secondary metabolites and antibiotics. Metabolites annotation have been checked by authentic standards (Glucose 6-phosphate, Glycerol, serine, cysteine, SAM, Farnesol, THF-polyglutamate, Amphotericin), Red * indicates authentic standards. The error bars represent standard deviations of five values