Isolation Of Endophytic Actinobacteria From Several Crops And Identification Of A Novel Actinomycete

Endophytic actinobacteria, which exist in the inner tissues of living plants, have attractedincreasing attention among taxonomists, ecologists, agronomists, chemists and evolutionarybiologists. Numerous studies have indicated that these prolific actinobacteria appear to have acapacity to produce an impressive array of secondary metabolites exhibiting a wide variety ofbiological activity, such as antibiotics, antitumor and anti-infection agents, plant growth promotersand enzymes. Isolation, antimicrobial activity, identification and screening bioactive compoundfrom the root of four crops which collected from Harbin.This study used special sampling and separation methods of our laboratory. A total of45endophytic actinomycetes strains were isolated from four kinds of crop roots. The plate methodand cross method were used respectively to determine bacteriostatic activity of extract offermentation broth of45endophytic actinomycetes strains, including two kinds of bacteria andeight kinds of fungi. According to morphological comparison and its antibacterial activity analysis,The16S rRNA gene sequence of X8, X17and NEAU-Z6were sequenced and analysed. Theresults showed that X8and X17belonged to the genus Streptomyces, and NEAU-Z6was a memberof the genus Nonomuraea. Strain NEAU-Z6was subjected to polyphasic taxonomy study.Strain NEAU-Z6was characterized using a polyphasic approach. Phylogenetic analysis basedon the16S rRNA gene showed that strain NEAU-Z6belonged to the genus Nonomuraea, withhighest sequence similarity to Nonomuraea monospora PT708~T(98.83%), Nonomuraea rosea GW12687~T(98.55%) and Nonomuraea rhizophila YIM67092~T(98.02%). Sequence similaritiesbetween strain NEAU-Z6~Tand other species of the genus Nonomuraea were lower than98%.Theneighbour-joining phylogenetic tree based on16S rRNA gene sequences showed that strainNEAU-Z6formed a distinct phyletic line with N. monospora PT708~T, N. rosea GW12687~T and N.rhizophila YIM67092~T, This branching pattern was also supported by the tree constructed with themaximum-likelihood method. Based on DNA-DNA relatedness and comparative analysis ofphysiological, biochemical as well as chemotaxonomic data allowed genotypic and phenotypicdifferentiation of strain NEAU-Z6from closely related species, also confirmed that this strainconstitutes a novel Nonomuraea taxon. Thus, strain NEAU-Z6represents a novel species of the genus Nonomuraea, for which the name Nonomuraea solani sp. nov. is proposed. The type strain isNEAU-Z6~T(=CGMCC4.7037~T=DSM45729~T).