Studies On Antimicrobial Activities From Fermentation Broth Of Actinomycete NYS-4and553

Actinomycetes NYS-4and553, which were isolated from a soil sample of the Qinlingmountain of Shaanxi province and pesticides pollution of Shandong Peninsula, were selectedin this thesis. The identification of taxonomy, evaluation of the antimicrobial activity,seperation and identification of the active ingredients were studied in the period of thesis forMaster’s degree. The primary results are as follows:l. Based on the results of morphologic observation, cultural characteristics, physiologicaland biochemical characteristics and the analysis of16S rDNA of strains NYS-4and553.Strain NYS-4was identified as Streptomyces griseus NYS-4and strain553was identified asNocardiopsis albirubida553, respectively.2. The results of bioassay in vitro indicated that the broth of NYS-4exhibited strongantimicrobial activities against several plant pathogens. The mycelial growth inhibition rate ofthe broth of NYS-4could more than95%against Fusarium oxysporum f. sp. niveum,Alternaria alternate, Sclerotinia sclerotiorum and more than80%against Colletotrichumgloesporioides, Eggplant Verticillium dahliae and Gibberella zeae, respectively. However, themycelial growth inhibition rate were only20%against Drupe anthrax, Botrytis cinerea.Additional, the broth has not protective effect against Blumeria giamiais.The results of bioassay in vitro showed the broth of553exhibited stronger antibacterialactivities against Bacillus subtilis, Staphylococcus aureus and Bacillus cereus, but noinhibitory activity against pathogenic fungi was observed.3. Guided by the result of the bioassay in vitro,15streptothricins, including5newcompounds, N-acetyl streptothricin A, N5-methy-N16-acetyl streptothricin A, N-acetylstreptothricin B, N-acetyl streptothricin B acid and streptothricin B acid, were isolated andidentified from the fermentation broth of NYS-4by macroporous resin, silica gel columnchromatography, RP-HPLC and HPLC-ESI-MS/MS. Three compounds, WZ-01, WZ-02andWZ-03were isolated from the fermentation broth of553. Compound WZ-01was identified asN-(2-hydroxyphenyl) acetamide, and the structures of compounds WZ-02and WZ-03will beidentified in the furture.