| Marine actinomycetes play an important role in pharmacy development, because some of them can excrete abundant unique novel bioactive compounds. In this research, 96 strains of marine actinomyces were investigated on the scope of pesticide science. The research focused on isolating and screening of strains, mutations induced by antibiotics, optimization of the fermentation conditions, assessment of antimicrobial activities, identification of taxonomical status and bioactive compounds. The main results are as follows:On the basis of assessment of fungicidal activities, 96 strains of actinomycetes were isolated from marine samples. Metabolite of strain B3 showed antibiotic activity to some target bacteria and pathogenic fungi. Fermentation filtrate of strain B3 inhibited the mycelium growth of Macrophoma kawatsukai and Alternaria longipes, and the EC50 values were all less than 10 mL·L-1; it also exhibited antibacterial activities against Bacillus cereus, Staphylococcus aureus and Escherichia coli, and the diameters of inhibition zone were 22.7mm,23.9 mm and 19.7mm, respectively. The results of the pot tests showed that the fermentation products exhibited 98.67% of protective efficacy and 76.93% of therapeutic efficacy against Blumeria graminis. Compared with the curves of classical antibiotics in Doskochilova system, the active components in the fermentation filtrate might be some identified as alkaline and water soluble compounds. The total of 4 compounds were identified by ESI-MS/MS as N-acetyl Streptothricin D, Streptothricin F, N-acetyl Streptothricin C and Streptothricin D.Twelve actinomycetes, which didn't exhibit antibiotic activity or exhibited weak antibiotic activity, were mutation induced by Streptomycin, Gentamycin, Rifampicin in the models of mono- and multi-drug resistance, respectively. The total of 858 mutants of resistant mutation were obtained, finally. The antimicrobial activities of the mutants'metabolites against 6 species of plant pathogenic fungi and 5 species of bacteria were tested by means of mycelium growth rate and the double-layer method, respectively. Fermentation filtrate of J22-G6, E6-S6, and E7-G1 exhibited obvious antibacterial activities. The result of continuous passage culture showed that the antibacterial activity of metabolites was not changed obviously, even when strain J22-G6 was sub-cultured for 10 generations.The wild strain J22 and its mutant strain J22-G6 were identified by the way of morphological, cultural, physiological, chemotaxonomy, 16SrDNA gene techniques. The morphological characteristics of them were similar in different Culture medium, but the mycelium color and growth rate in medium were different. All physiological and biochemical characteristics of J22 were similar with J22-G6 expect for no utilizing inositol as carbon source. The type of wild strain and mutant strain were belonged to cell wall type I, cell sugar pattern C. In addition, the wild strain and mutant strain showed no differences in 16SrDNA sequences gene. The 16SrDNA sequences showed that the homology between strain J22 and Streptomyces anulatus 173897 was 99%, so the strain J22 was identified as Streptomyces anulatus, which the name Streptomyces anulatus J22 was proposed.The fermentation conditions for stain J22-G6 were optimized by response surface methodology, which included the components of liquid medium, culture period, the pH value of medium, inoculate concentration and the volume of liquid medium of strains. The study results of strain J22-G6 showed that the suitable liquid medium was composed of 10 g·L-1 millet, 20g·L-1 Lactose, 3 g·L-1 beef extract, 2.5 g·L-1 NaCl,2 g·L-1 CaCO3 and distilled water, and the suitable cultivated condition was 145h, 6×107cfu·mL-1 and 50mL liquid medium in 250mL flask, pH 7.0.The active component of metabolites from strain J22-G6 was studied. Compared with the curves of classical antibiotics in Doskochilova system, the active components in the fermentation filtrate might be a water-soluble antibiotic. A active compound, F4, was isolated from the fermentation of J22-G6 by macroporous adsorption resin, CM-Sephadex-C25 and pre-HPLC. Compound F4 could inhibit some gram-positive bacteria. The compound F4 was identified preliminarily as Polyether, on the basis of spectral data(MS, 1H-NMR, 13C-NMR).
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