The Taxonomic Identification Of Rare Endophytic Actinomycetes From Dianthus Chinensis L And The Primary Exploration Of Antimicrobial Activity About Isolated Strains

Plant-associated endophytic actinomycetes that colonize host plants do not interfere the growth and reproduction of plants. Although both colonize in the plant tissues, endophytic actinomycetes are not equal to morbigenous microorganism. Researchs show that many endophytic actinomycetes bebefit to growth and reproduction of plants. This is because the endophytic actinomyces is prokaryotic organisms that secret multitudinous bioative compounds. These secondary metabolites have the effect to inhibit pathogenic bacteria breeding and promote plant growth, so as to improve the survival rate of plants. Plant-associated endophytic actinomycetes has attracted largely attention among microbiologist, ecologists and agriculture experts. The active substances produced by actinomycetes can be widely applied in the various industries, such as pharmaceutical industry, agriculture, chemical industry, animal husbandry and so on. Dianthus chinensis L has 2 history of nearly thousands years as a medicinal plant in China. The plants species can synthesize a variety of active natural substances. Current research of endophytic actinomyces from Dianthus chinensis L is still few. So the research about endophytic actinomyces from Dianthus chinensis L is significant.This experiment devoted to investigating the diversity and distribution of actinomyces in the Dianthus samples, at the same time endophytic actinomyces were evaluated their potential of active material production through fungus or bacteria resistant assays. We isolated 64 strains of actinomycetes from different tissues of Dianthus samples growing in the different conditions. The study found that the isolated effect varied with different plant tissue and various selected mediums. The roots of Dianthus samples contained much endophytic actinomyces. The effect of HV mediums and GS mediums were best, which contained the most isolated actinomyces.21 strains of endophytic actinomycetes showed resistance to pathogenic fungi. Among them 5 strains resisted to more than eight pathogenic fungi. The inhibition rates of 7 strains were about 15%on average.5 isolated strains’ fermentation showed resistance to pathogenic bacteria. There were extracted sediments of three endophytic actinomycetes (CY23, CY60, CY64) that has obvious antibacterial activitives to Bacillus subtilis, of those average inhibition rate was about 10%.We choosed four strains whose Morphological properties were rare among 64 actinomyces strains for 16sRNA sequeaces analysis. According to the result of 16sRNA sequences analysis, we found that CY10 belonged to Micromonospora genera, CY13 was subordinate to Streptosporangium genera, CY12 and CY18 were affiliated to Sphaerisporangium genera. It is concluded that a novel actinomycete, designated strain NEAU-CY18T, was isolated from the root of Dianthus chinensis L and subjected to a polyphasic taxonomic study. The novel strain developed spherical sporangia with non-motile spores on aerial mycelium. The main composition of cell-wall peptidoglycan was meso-diaminopimelic acid. The whole-cell sugars were madurose, mannose, ribose, galactose and glucose. The phospholipid profile contained diphosphatidylglycerol, phosphatidylmethylethanolamine. phosphatidylethanolamine, hydroxy-phosphatidylmethylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides and an unidentified phospholipid. The predominant menaquinones were MK-9(H4), MK-9(H2) and MK-9(H6). The major fatty acids were C17;0 10-roetbyl, iso-C16:0 and Ci6:0. EzTaxon-e analysis of the 16S rRNA gene sequence manifested that the strain NEAU-CY181 was a member of genus Sphaerisporangium, and was most closely related to Sphaerisporangium cinnabarinum JCM 3291T (98.9%) and Sphaerisporangium melleum JCM 13064; (98.3%). The association was supported by a bootstrap value of 97% in the neighbour-joining tree and also recovered with the maximum-likelihood algorithm. Comparisons of some phenotypic properties and low DNA-DNA relatedness values enabled the strain to be differentiated from S. cinnabarinum JCM 3291T and S. melleum JCM 13064T. Therefore, it is proposed that strain NEAU-CY181 represents a novel Sphaerisporangium species, Sphaerisporangium dianthi sp. nov.