Enhanced FK506 production in Streptomyces tsukubaensis by rational feeding strategies based on comparative metabolic profiling analysis

ABSTRACT FK506, a widely used immunosuppressant, is produced by industrial fermentation processes using various Streptomyces species. However, the low titer becomes a bottleneck for its application and industrialization. It urgently required a full understanding of the biological mechanisms for FK506 overproduction. Towards this end, comparative metabolomics approach was employed to analyze metabolite concentrations difference of Streptomyces tsukubaensis cultivated in two media with low and high productivities. Initially, 98 intracellular metabolites were identified and 13 metabolites involved in five pathways were determined to be directly correlated with FK506 biosynthesis. Then in‐depth analysis elucidated how those key factors exerted influence on FK506 biosynthesis. Many previously unreported metabolites were shown to play an important role in FK506 biosynthesis and provided potential regulation points for external manipulation. Based on such key information, rationally designed feeding strategy was carried out. Results showed that the FK506 yield increased from 251 to 405 mg/L, whereas, by‐products FK520 and 37,38‐dihydro‐FK506 decreased by 31% and 39%, respectively, compared with the values of control. To our knowledge, it is the first study to apply the comparative metabolomics method to identify key metabolites to promote the FK506 production. The strategies developed here can easily be extended to titer improvement of other important microbial natural products and process optimization. Biotechnol. Bioeng. 2013;110: 2717–2730. © 2013 Wiley Periodicals, Inc. The present work provided a valuable method for debottlenecking low‐yield microbial natural product. Based on comparative metabolic profiling analysis, the metabolites associated closely with FK506 production were identified. By in‐depth analysis on the metabolic relevance between these key metabolites and FK506 biosynthesis, vital regulation points for FK506 overproduction were uncovered. Rational feeding strategies were then proposed which finally resulted in a 61.4% increase in target product.