We propose to isolate novel natural products from under-explored microorganisms and provide them to the Molecular Libraries Screening Center Network (MLSCN).  The bacterial strains that will be investigated include: (i) endophytes, (ii) actinomycetes, and (iii) extremophiles from under-explored ecological niches in various parts of China.  The criteria for strain selection are: (i) the uniqueness and richness of biodiversity, (ii) symbiosis with traditional Chinese medicinal plants, (iii) morphological and taxonomical distinctiveness, and (iv) bias towards actinomycetes.  We will (i) optimize natural product production, (ii) prepare extracts and subject them to TLC and HPLC for chemical profiling and titer estimation followed by LC-MS and 1H NMR dereprelication for strain prioritization, (iii) isolate and determine the structures of the novel natural products, and (iv) provide them to MLSCN.  Our hypotheses are: (i) bacteria that are morphologically distinctive and taxonomically new are likely to produce novel natural products, (ii) assay-blind and TLC- and HPLC-based chemical profilings allow the detection of all natural products, (iii) LC-MS and 1H NMR followup analyses permit rapid dereplication of the extracts, allowing prioritization of the strains for subsequent isolation and structural elucidation, and (iv) quantities of the natural products can be produced by scaleup microbial fermentation.  The specific alms are: (i) to evaluate 600 strains, including approximately 200 endophytes, 300 actinomycetes, and 100 extremophiles, provided by Prof. Cheng-Lin Jiang of the Yunnan Institute of Microbiology, Yunnan University, China, by fermentation optimization, extract preparation, TLC- and HPLC-based chemical profiling and titer estimation, and LC-MS and 1H NMR analyses to identify 15 hit strains annually;(ii) to dereplicate the natural products in the 15 hit strains by natural product isolation and structural elucidation to identify one to five novel natural products per strain to yield a total of 15-75 compounds annually;and (iii) to scale up fermentation of the hit strains and to provide a 15-75-member library of the resultant novel natural products, each of which will be HPLC and NMR pure and in quantities weighing minimally 10 mg, to MLSCN annually.  PUBLIC HEALTH RELEVANCE: Natural products have inspired ~75% of the drugs approved for human use and are evolutionarily optimized to serve as modulators of biologically important processes.  This application seeks to discover natural products from new microorganisms, isolated from previously untapped and carefully selected ecological niches, for use as biochemical tools by which to understand fundamental and applied biology.