Fig. 1

Effect of GlcNAc addition on the fermentation characteristics of S. verticillus in chemically defined medium and schematic diagram of GlcNAc metabolism. a Bleomycin productions in modified ISP4 with 5 g/L mannose and modified ISP4 medium with 5 g/L GlcNAc (medium I). The HPLC spectrum of standard bleomycins was showed in cyan curve, and the peak times of bleomycin A2 and B2 had been marked by black dotted lines. b Metabolic pathway and enzymes in GlcNAc metabolism and GDP-mannose synthesis. c Length and organization of the gene sequences of the dasR, dasA, dasBCD, nagB and nagKA operons; the dre elements located in the promote region of dasA, nagB and nagK are indicated in red columns. d WebLogo of the dre element, and nucleotide sequence of dre motifs in S. verticillus. The DNA binding sequences of DasR were collected from literatures [10, 42], and were deposited to WebLogo to create sequence logos. The dre sequence was proposed by Rigali et al. [10]. Based on MAST analysis, the DNA sequences of the dre motif in the promoter region of dasA, nagB and nagK were shown, in which the red font indicated similarity with the dre consensus sequence