Discovery Of Natural Products Derived From Two Streptomyces Strains And Metagenomic Library

Natural products are an important source of drugs,and most of the antibiotics and anti-tumor drugs currently used in clinics are derived from natural products and their derivatives.As the largest resources for novel natural products,research on microbial secondary metabolism still have great prospects.The methods of mining microbial secondary metabolites vary according to whether the microbes could be directly separated and cultured under traditional conditions.The cultivation conditions of cultivable microorganisms were mature,and the discovery of corresponding natural products had a history of more than 100 years.While under the guidance of current bioinformatics,it was expected to obtain new discoveries from cultured microbes.Non-cultivable microorganisms were relatively lacking in research on their natural products due to their limited culture conditions.With the development of metagenomics technology,it provided an opportunity to tap the natural products of non-cultivable microorganisms.In this subject,we selected cultivable Streptomyces sp.F5650 and Streptomyces sp.F1521 for routine fermentation and genome mining;for non-cultivable microorganisms study,7 halogenase gene containing clones from a metagenomic library were selected and sequenced.The sequences of the clones were analyzed to reveal whether they contained halide biosynthesis gene cluster for expression of novel halogenase and halide compounds.Anti SMAH was used to predict the natural product biosynthetic gene clusters in Streptomyces sp.F5650 and Streptomyces sp.F1521,and 41 and49 gene clusters related to the synthesis of secondary metabolites were identified,respectively.The clusters were predicted for their products,and the Streptomyces stains were fermented and the compounds from the fermentation broth were isolated.Finally,enterocin(main ingredient)was obtained from the fermentation broth of Streptomyces sp F5650.The fermentation of Streptomyces F1521 failed to determine its main component structure,but the separation method has been successfully determined and optimized.For non-cultured microorganisms study,7halogenase containing clones were sequenced and the sequencing analysis revealed the clone ZF1418 contained non-ribosomal peptide(NRPS)biosynthetic genes which have the potential to produce novel halide compound.In summary,based on the bioinformatics,the potential of producing natural products of two Streptomyces strains were analyzed,and compound enterocin was isolated and identified form Streptomyces sp F5650.From a metagenomic library,a halogenase containing NRPS biosynthetic gene cluster was idnetified.It showed not only a new idea of obtaining novel microbial natural products,but also provided a basis for both the subsequent studies on the Streptomyces secondary metabolites and the activation and expression of halogenase gene clusters.