Fig. 1

TetR1 acts as a positive regulator of acarbose synthesis. a The expression of 65 TFRs was derived from transcriptome information. TPM (Transcripts Per Million reads): Number of read sections from a transcript of transcripts per million reading segments. b Schematic diagram of the strategy used for deletion of TetR1 in SIPI12-34. TetR1-V1 and TetR1-V1 were primer pairs used for PCR validation and pSET-ΔTetR1 was knockout plasmid used for deletion of TetR1. c PCR validation of SIPI12-34, RM strain and ΔTetR1. RM strain: strain with no genome changes after double crossover recombination. ΔTetR1: mutant strain with deletion of TetR1 (627 bp) in the chromosome of SIPI12-34. d Acarbose production profiles of SIPI12-34 and other mutant were analyzed by HPLC. ΔTetR1/TetR1: mutant strain with complement of TetR1 under the control of native promoter. SIPI12-34/pSET152: SIPI12-34 with pSET152 plasmid acted as a control strain. Error bars show standard deviations, ***P < 0.001 ns: no significant. e Transcriptional analysis of acarbose BGC in SIPI12-34 and ΔTetR1 during the fermentation process by quantitative real-time PCR. RNA samples were isolated from SIPI12-34 and ΔTetR1 at 48 h and 72 h in shake flask culture. At each time point, the expression levels of each transcriptional unit in SIPI12-34 were taken as 1 to quantify the relative expression levels in ΔTetR1, respectively. Each strain has 3 replicates at different time points