Isolation And Identification Of Longispora Urticae Sp.nov.and Study On Secondary Metabolite

Actinomycetes have become one of the greatest sources of novel antibiotics,including?-lactams,macrolides,tetracyclines,aminoglycosides,rifamycins,glycopeptides and so on,which are the most significant antimicrobial agents.Up to now,most of the antibiotics people used were discovered a few decades ago.However,all kinds of antibiotics have the problem of drug resistance.Antimicrobial resistance has an impact on the use of antibiotics.Since pathogens have the rapid cross-resistance to antibiotics with similar structures or properties which affects the use of antibiotics,it is urgent to discover novel bioactive compounds.Researchers turned their direction of study to the novel actinomycetes from undeveloped habitats,hoping to discover new natural active substances with funtions.In this study,the habitat with the most frequent interaction between plants and microorganisms,rhizosphere soil,was chosen as the isolation source of actinomycetes.The novel actinomycete was identified to belong to the rare genus(Longispora)in multiple aspect and was analysed the composition of metabolites in order to enrich the actinomycetes resource and the metabolites diversity of Longispora.The results are as follows:(1)The actinomycetes in the rhizosphere soil of Urtica urens L.were screened by using five isolation mediums(HV,GS,CPA,DPA,and SSA),and 112 actinomycetes were obtained finally.The dominant microorganisms belong to Streptomyces,there also exist strains belong to Micromonospora,Nocardia,Rhodococcus,Nonomuraea,Actinomadura and Longispora.(2)Growth inhibition experiment of 12 kinds of fungi and 3 kinds of bacteria was preformed with112 actinomycetes.The results showed that most actinomycetes exhibited antimicrobial activity belong to Streptomyces,33.9 percent of actinomycetes showed the ability to suppress at least 3 kinds of pathogenic fungi and 33 percent of actinomycetes showed the ability to suppress at least one kind of indicator bacteria.Detection of nonribosomal peptide synthetase genes and polyketide synthase genes was tested on 22 actinomycetes,with a broad range of fungi inhibition or superior bacteria inhibition.There were 20 actinomycetes had at least one kind of these three biosynthetic genes,and indicated that these antibacterial strains had the potential to produce natural active substances.(3)Polyphasic taxonomic identification of two strains of actinomycetes NEAU-PCY-3~T and NEAU-PCY-4 was performed.The result of molecular level detection showed that the two strains were most closely to the actinomycetes of Longispora and confirmed they were classified as representatives of a novel species of the genus Longispora,for which the name Longispora urticae sp.nov.is proposed due to their isolation source(Urtica urens L.),by the further comparative analysis of macroscopic and microscopic morphological features,colony color and growth situation on different mediums,physiological and biochemical characteristics and chemical characteristics of the cell components.(4)The metabolites of the rare actinomycete NEAU-PCY-3~T were isolated and identificated to have six compounds:2-phenylacetamide,trans-cinnamic acid,indole-3-carbaldehyde,anthranilic acid,3-hydroxyacetyl-indole and cinnamamide.