The Studies On Isolation, Identification And Antibacterial Activity Of Myxococcus Fulvus

Myxobacteria could produce a wealth of secondary metabolites, which had astrong anti-tumor, anti-fungal, anti-virus and anti-bacteria activity. Their structure ofactive substance was novel, mechanism of action was unique. They had a wide rangeof potential applications in medicine, agriculture and environment, which was of greatvalue in the research and development. The main purpose of this paper was in orderto study the rich resources of Myxobacteria and obtained strains with high biologicalactivity.In this paper, Myxobacteria was enriched from the soil and rotten wood inZhengzhou suburb by cell induction and cellulose induction method. A high activityhg59was obtained with anti-bacteria experiment, which had antibacterial activity onGram positive and negative bacteria, but the effect was significant on positive bacteria.The stain was Gram negative, early colony was light yellow and becameorange-yellow gradually, thin to the edge of the expansion, there are signs of sliding.Vegetative cells were rod-shaped, slightly pointed ends, willow-like, the size is5-8μm×0.3-0.6μm, sticky spores were oval or elliptical; Congo red test and catalase testwere positive, the other tests were negative;16S rDNA homology analysis showedthat the strain had the closest relationship with Myxococcus fulvus, the similarity wasmore than99%. According to the morphological, physiological and biochemicalcharacteristics and16S rDNA gene sequence, the strain could be initially identified asMyxococcus fulvus, eventually named Myxococcus fulvus hg59.Eight factors influencing antibacterial activity were evaluated byPlackett-Burman design which contained yeast power, CaCl2, VB12, initial pH,inoculation volume, temperature, rotation speed and incubation time. Power yeast,inoculation volume and incubation time were selected as the main factors; Themaximum response region and center point of response surface were determined bysteepest ascent experiment; The optimum level of important factors were determinedby Box-Behnken design and response surface analysis. Optimum conditions were asfollows: yeast power was6.20g/L, inoculation volume was12.20%, incubation timewas175.00h, the maximum estimated value of Y was18.79mm, the effect wasconsistent with the theoretical prediction by the model experiment. The active metabolite of the strain was studied by active tracking method. Theactive substances were found mainly in ethyl acetate phase by different polarity of theorganic solvent extraction; Thin Layer Chromatography with extracted substanceshowed the effect was better when CHCl3:C2H5OH was5:3by many experiments;The highest activity was used for color reaction test through silica gel columnchromatography, the results showed that contained the lactone ring and alkaloidsubstances, the effect was consistent with IR analysis results.