Chitin is the second most abundant biopolymer present in soils and is utilized by antibiotic-producing Streptomyces species. Its monomer, N-acetylglucosamine (NAG), regulates the developmental program of the model organism Streptomyces coelicolor. NAG blocks differentiation when growing on rich medium whilst it promotes development on poor culture media. We report here the negative effect of NAG on tacrolimus (FK506) production in Streptomyces tsukubaensis NRRL 18488 growing on a defined rich medium. Using microarrays technology, we found that GlcNAc represses the transcription of fkbN, encoding the main transcriptional activator of the tacrolimus biosynthetic cluster, and of ppt1, encoding a phosphopantheteinyltransferase involved in tacrolimus biosynthesis. On the contrary, NAG stimulated transcription of genes related to amino acid and nucleotide biosynthesis, DNA replication, RNA translation, glycolysis, pyruvate metabolism, and key gene members of the PHO regulon. The results obtained support those previously reported for S. coelicolor, but some important differences were observed
Overall design: The transcriptomic experiment is composed of 16 samples from two time series named NAG (culture medium containing N-acetylglucosamine) and CTL (control condition: the culture medium without addition). Each time series was replicated once. Streptomyces tsukubaensis spores (10e9) were inoculated into 0.5-L flasks containing 100 mL of MGm-2.5 medium (PMID 22990582) and cultivated at 28 ºC, 220 rpm. Samples for RNA extraction were taken from flask cultures at 70 h, 70.5 h, 71 h and 72 h (4 timepoints × 4 cultures = 16 samples). The final concentration of N-acetylglcuosamine was 22.6 mmol/L (i. e., 0.5 % w/v).
Less...