Endophytic Bacteria Diversity Of Didymodon Tectorum And The Effects Of Extracts From Strains Fermentation Broth On The Gorwth Of Host Plant

Endophytic bacteria, the presence of healthy plants tissues for a part or the whole of its life cycle, isn’t causing obvious diseases symptom on the host plants. To date, few bryophytes, with simple structure and without transfusion tissue, has been studied, although endophytic bacteria of vascular plants has been addressed in several studies. Bryophytes, the major plant group to prevent soil erosion and water loss in the Loess Hilly Region, constitutes microhabitats is the one of the most abundant types of microorganisms. In this study, Didymodon tectorum, the dominant species in this region, was selected as materials. Based on traditional culture-dependent methods and MiSeq sequencing technology, we explored the diversity of its endophytic bacterial. Moreover, we observed how the extraction of fermentation broth of representative strains effect on host spore germination and protonema growth. The main results were as follows:1. The best method of plants surface sterilization,70% ethanol 3min+2%NaC10 lmin, was obtained.68 endophytic bactieria strains had been isolated from the plants by raditional culture-dependent methods. The strains analysis were based on the detection of 16S rDNA gene, Colony morphology, physiological and biochemical characteristics. The results showed similarity to seven Bacillus species:B. subtilis, B. simplex, B. cereus, B. niacini, B. aryabhattai, B. pumilus, Bacillus sp., B. subtilis was the dominant speices.2. Petroleum ether, ethyl acetate and n-butyl alcohol extracts of Bacillus subtilis DT-1 had no significant effect at 1 μg/ml、10 μg/ml、100 μg/ml three concentrations on host spore germination. Petroleum ether extract at three concentrations were inhibited host protonema growth in different extent. Ethyl acetate extract significantly promoted the protonema growth at 1 μg/ml concentration. N-butyl alcohol extract also played a significant role in promoting at 1μg/ml,10μg/ml concentrations.3. Three kinds of extracts of Bacillus cereus DT-9 had no significant effect at three concentrations on host spore germination. Petroleum ether extract were inhibited host protonema growth in different extent. Ethyl acetate and N-butyl alcohol extracts significantly promoted the protonema growth at different concentrations.4. Using MiSeq sequencing technology investiaged the endophytic bacterial co-mmunity comparison of Didymodon tectorum. The results showed that, endophytic bacterial population composed mainly by 7 phyla,11 classes,16 orders,32 families. The dominant phyla were Proteobacteria and Actinobacteria. The dominant classes were Alphaproteobacteria, Actinobacteria and Betaproteobacteria. The dominant orders were Actinomycetales, Rhizobiales and Sphingomonadales. Sphingomonas belongs to Sphingomonadaceae, was the dominant genus.