Secondary Metabolites Produced By Two Streptomyces Spp.and Identification Of Streptomyces Montanus Sp.nov

Antibiotic are bioactive secondary metabolites produced by microorganisms through the metabolic process,which are widely used in clinical treatment,such as tuberculosis and anthrax.The secondary metabolites of the genus Streptomyces are important sources of antibiotic research and development.Therefore,it has important implications to study the secondary metabolites o f the genus Streptomyces.In this research,60 actinomycetes were screened by two fungi(Sclerotinia sclerotiorum,Fusarium head blight)and two bacteria(Ralstonia solanacearum,Bacillus subtilis)as indicator strains.14 actinomycetes showed the ability to suppress fungi,10 actinomycetes showed the ability to suppress bacteria.The secondary metabolites of two Streptomyces spp.(NEAU-C151 and NF-1451)with better activity among those actinomycetes were isolated and identified.In addition,NEAU-C151 was a novel species of the genu Streptomyces.The results are as follows:(1)The strain NF-1451 showed definite antimicrobial activity.According to the culture medium screening,H9 as the fermentation media had the best antibacterial activity,so the medi a was used to ferment 30 L.The five monomer compounds were isolated and purified from the fermentation broth by silica gel column,Sephadex LH-20 column and HPLC.Then,their structure was identified by using ESI-MS,1D and 2D NMR,IR,UV and HRESIMS.Compared with the literature,compound 3 was a novel compound which was identified as N-(2-(1-hydroxy-4-oxocyclohexyl)ethyl)acetamide,the other componuds were homononactic acid(4),nonactyl homononactate(5),homononactyl homononactate(6)and germacradienol(7),respectively.(2)NEAU-C151 was fermented for 20 L,the treatment for fermentation is the same as above.After purification,two tricyclic polymeric compounds were isolated.The NMR and ESI-MS data compared with the literature indicated that compound 2 was a novel compound to be named isolucknolide A and another known compound was 1-ethyl-streptazolin.(3)The activity of the seven compounds were detected.The results showed that compounds 1 and 6 had certain inhibitory activity against Staphylococcus aureus,and compound 5 also had inhibitory activity against Escherichia coli.Compound 2 has weak antibacterial activity and moderate antitumor activity.(4)After 16 S r RNA gene detection,it was found that NEAU-C151 might be a novel species of the genus Streptomyces,and its similarity with the closest species as low as 97.58%.Therefore,a number of polyphasic taxonomy identification,including identification of morphological,identification of chemotaxonomic characteristics,identification of physiological and biochemical characteristics,and identification of molecular characteristics,were carried out.The results showed that Streptomyces sp.NEAU-C151 was indeed a novel species of the genus Streptomyces,for which the name Streptomyces montanus sp.nov.is proposed.