Preliminary Detection Of Culturable Myxobacteria And Their Antibiotic Activities In Eastern Inner Mongolia

Myxobacteria are a class of Gram-negative,aerobic,and unicellular bacteria,which can produce secondary metabolites with novel structure,rich variety,and unique mechanism and serve as an important resource for the development of new drugs or their lead compounds.Therefore,myxobacteria have great application and development value in agriculture,ecology and medicine.In this study,150 soil samples were collected from eastern Inner Mongolia.Firstly,the environmental parameters of the samples were measured.The results showed that the soil samples were generally neutral and acidic and in a drought state of varing degrees.The content of soil organic matter,available potassium,hydrolyzed nitrogen,and available phosphorus were low and the soil fertility was poor overall.Myxobacteria were isolated from 150 soil samples by rabbit dung pellets inducing method,Escherichia coli inducing method and filter paper inducing method and purified by picking fruiting bodies directly combined with antibiotic treatment.A total of 150 strains of myxobacteria were obtained.These strains belonged to five genera,including Myxococcus,Corallococcus,Pyxidicoccus,Cystobacter,and Archangium.Myxococcus was the most dominant myxobacteria in eastern Inner Mongolia.The abundance of myxobacteria were the highest in the Chifeng area and the poorest in the Hulunbeier area.Myxobacteria were more abundant in cultivated land and grassland,but less in woodland and unused land.Myxobacteria isolated from Castanozems,aeolian sandy soils and meadow soils were more aboundant and less in brown earths,brown coniferous forest soils and gray forest soils.The distribution of culturable myxobacteria were positively correlated with pH value and negatively correlated with organic matter content.In the detection of the antibiotic activity of myxobacteria in the eastern region,94.67%of the strains showed different levels of inhibitory effect on Phytophthora infestans,of which 7.75% of the strains had very strong activity.The positive detection rate of myxobacteria of Myxococcus,Corallococcus,Pyxidicoccus and Archangium were 100%.The active substances of these myxobacteria and their antibiotic mechanism need to be explored in the future.In this study,the preservation methods of myxobacteria,including filter paper preservation method,distilled water preservation method,glycerol-physiological saline preservation method,and direct glycerol preservation method,were tested initially.The results showed that the viability of myxobacteria could be detected in all methods.The four methods had no significant effects on the morphological,physiological and biochemical characteristics of different species of myxobacteria.The effects of the four methods on the antibiotic activity of myxobacteria were species-specific.Considering contamination rate,recovery rate,growth rate and other factors,the filter paper preservation method at-80? was the best for all the tested strains and the 20% glycerol method was the second.The storage effect of the distilled water preservation method at 4? and the 20% glycerol-physiological saline preservation method were slightly poor.The strains of different species should be preserved by several different methods to ensure their stability.The distribution and antibiotic activities of culturable myxobacteria in eastern Inner Mongolia were analyzed for the first time in this study.The completion of this work not only enriched the myxobacterium resource bank in Inner Mongolia region,but also laid the foundation for the development and utilization of myxobacteria in the future.