Isolation,Identification And Morphological Differentiation Of Facultative Oligotrophic Kitasatospora

The cultivation of oligotrophic microorganisms is of irreplaceable significance.In this study,the in-situ soil environment was determined,the oligotrophic microorganisms were isolated and screened by dilution plate method,and the strains with facultative oligotrophic growth were obtained.The results of PCR amplification and sequencing were compared by primer amplification and identified at the level of molecular biology.The identification medium was used to confirm the culture characteristics and colony characteristics,and the micromanipulation technique was used to record the morphological characteristics of mycelium and sporophyte.According to the results of comprehensive identification,the strain was identified to species.Through the starvation stress treatment of the strain,the response of morphological differentiation to hunger stress was recorded,and the results were statistically analyzed.The results are as follows:1.With the increase of soil depth,the contents of organic matter,humus,total carbon and available nitrogen in soil changed significantly?P<0.05?.The concentration of CO₂ in deep soil was significantly higher than that in surface soil.The content of actinomycetes in the in-situ soil was abundant and the difference was significant?P<0.05?.In summary,the concentration of CO₂ in simulated culture was determined to screen oligotrophic microorganisms,and the screening direction of Actinomycetes as target strains was determined.2.Three strains of Streptomyces could be subcultured on AMS medium and Bennett medium.Among them,strain 10 was stable in shape in Bennett liquid medium,and its growth curve could be determined by eutrophication in the form of short spore chain.The colony number was counted by dilution plate method,and the standard curve and growth curve were drawn according to the absorbance value of bacterial suspension.It can grow on AMS oligotrophic medium and the colony is white,which is similar to Streptomyces.The results showed that the PCR products of DNA were positive to Ks Pr specific primers.According to the analysis and comparison of the PCR sequencing results of its 16s r DNA,the similarity between strain 10 and Kitasatospora phosalacinea was the highest.According to the results of microscopic examination,its morphology was consistent with that of Kitasatospora,and it was temporarily named K.phosalacinea 10.3.K.phosalacinea 10 has a response to starvation stress in terms of morphological differentiation.In AMS liquid medium,K.phosalacinea 10 survived in the mode of oligotrophic metabolism and belonged to the shape of amorphous mycelium.Under nitrogen stress,K.phosalacinea 10 grew and survived in the form of fusiform mycelium.In eutrophication culture,K.phosalacinea 10 was in the form of short spore silk chain and there was no mycelium.K.phosalacinea 10,which is in the form of short spore silk chain and no mycelium in Bennett liquid medium,can be used to determine the stable growth curve.This is helpful to detect its growth status in real time and has application value in industrial fermentation.