Identification Of Three Rare Actinomycetes And Primary Research On Activity Of Isolated Strains

Actinomycetes as a microorganisms group which have a variety of genes encoding for many bioactive compouds. At first, the study of metabolites from actinomycetes mainly revolves around the members of the genus Streptomyces. But now the frequency of the new compounds discovered from Streptomyces is reduced. Due to the development of the rare actinomycetes is relatively late, and the new species can increase the possibility of discovery of a new compound. Hence, this study aimed at looking for new species of rare actinomycetes, in order to getting strains which produced compound with new structure.In this experiment, to screen actinomycetes from6kinds of mud sample collected from Harbin, Daqing, Qiqihaer, Shanghai and Guangzhou, gause1medium and humic acid medium were adopted as separation medium, nalidixic acid, cycloheximide and potassium dichromate were used as inhibitor, a total of86actinomycetes were obtained.The plate method and cross method were used respectively to determine bacteriostatic activity of extract of fermentation broth of86actinomycetes, including two kinds of bacteria and eight kinds of fungi.12actinomycetes showed the inhibition zone diameter above15mm against Bacillus subtilis or Micrococcus luteus, the inhibition zone diameter of strain yn10could reach more than20mm for both of bacteria. We got the active substances actinomycin D from yn10.9actinomycetes had good inhibiting effect for at least two kinds of fungi, the inhibition zone diameter of strain ZJ12could be up to20mm for four kinds of fungi.Through the colony morphology observation and microscope morphology observation of86actinomycetes, we selected eight special actinomycetes to sequence their16s rRNA. Comparison of sequencing results using EzTaxon-e server showed that the distribution of8actinomycetes were belong to5genera in actinomycete, including Streptomyces, Micromonospora, Nonomuraea, Saccharothrix and Catellatospora. Strains NEAU-ZJ3and NEAU-yn31were most closely related to Nonomuraea salmonea DSM43678T (98.27%), Nonomuraea endophytica YIM65601T (98.23%), Nonomuraea cadida HMC10T (98.05%), and Nonomuraea ferruginea IFO14094T (99.08%), Nonomuraea Candida HMC10T (98.01%), respectively. Their taxonomic positions determined by a polyphasic approach showed that they were consistent with Nonomurea and could also be distinguished from the menbers of Nonomuraea in morphological characteristics, chemical taxonomy and molecular classification characteristics. Thus, strains NEAU-ZJ3and NEAU-yn31represent two novel species of the genus Nonomuraea, for which the names Nonomuraea guanghzouensis sp. nov. and Nonomurae harbinensis sp. nov. are proposed. The type strains are NEAU-ZJ37(=CGMCC4.7101T=DSM45889T) and NEAU-yn31T (=CGMCC4.7106T=DSM45887T), respectively. The16S rRNA gene sequence of another strain NEAU-yn17showed it most closely related to Saccharothrix saharensis SA152T (99.52%) and Saccharothrix xinjiangensis NBRC101911T (99.04%). Howere, DNA hybridization values were55.6%and55.6%with them (these values are below the threshold value of70%for the assignment of strains to the same genomic species). In addition, strain NEAU-yn17could also be differentiated from them based on cultural characteristics. Therefore, NEAU-yn17represents a new species of the genus Saccharothrix, for which the name Saccharothrix carnea sp. nov. is proposed. The type strain is NEAU-yn17T (=CGMCC4.7097T=DSM45878T).