Identification Of An Antagonistic Actinomycete TGBSA5Against Pseudomonas Syingae Pv. Actinidiae And Study On Its Bioactive Components

Kiwifruit bacterial canker disease, caused by a pathogenic variant Pseudomonas syingaepv. actinidiae (Abbreviation Psa) is a devastating disease of a serious threat to kiwiproduction. At present, the main prevention and treatment method of the disease is the use ofchemicals, whereas serious pollution exists. Consequently, the study of applying bio-controlmethod and developing pollution free biogenic pesticides are becoming heat issues. Previousresearch found that, an endophytic actinomycete strain TGNBSA5, isolated from Arctiumlappa stem, has strong inhibitory activity against Pseudomonas syringae pv. actinidiae. Inorder to further exploit the biocontrol application of the actinomycete, the taxonomic status ofstrain TGNBSA5, and its fermentation condition of producing bioactive substances againstPsa plus the elucidation of bioactive compound were studied in this research.Physiological and biochemical characterization, morphological, and16S rDNA sequenceanalysis were conducted to identify the strain TGNBSA5. The results showed that theactinomycete performed black grey colony, raisin substrate mycelia, flat lawn surface. Thespores were long ovoid in shape with smooth surface and0.5μm×0.7μm in size.16S rDNAsequence and its Phyloenetic N-J tree analysis showed that the strain was very close to thegene sequence of Streptomyces sporovirgulis, which was99%homology. Nevertheless, strainTGNBSA5did not produce melanin. Therefore, strain TGNBSA5was identified andnominated as Streptomyces sporovirgulis var. arctium.The optimization of TGNBSA5seed culture trial showed that the optimized ingredientswere: starch2.4%, beef extract0.3%, glucose0.1%, yeast extract powder0.5%, petptone0.3%, and CaCO30.4%. In addition, the optimized culture condition was28,36h, rotationspeed150r/min, and culture pH7.0.The optimization of TGNBSA5fermentation culture trial showed that the optimizedingredients were: starch2%, sucrose2%, peptone1%, yeast extract powder2%and CaCO30.4%. In addition, the optimized fermentation condition was28,5d, rotation speed180r/min, and culture pH7.0. Bioassay-guided method was conducted using the bacterial pathogen Psa as target.Bioactive compounds from ethyl acetate were isolated and purified by chromatographictechnology, and HPLC detection. NMR and UV spectra analysis indicated that one of thebioactive compounds was benzyl alcohol.