Diversity Of Culturable Endophytic Bacteria Of Cymbidium Goeringii Potted Inside Greenhouse

In this study, we investigated the community diversity of the culturable endophytic bacteria of Cymbidium goeringii potted inside greenhouse, and the community diversity of IAA-producing endophytic bacteria in the roots of C. goeringii by using cultured-dependent method, amplified DNA restriction analysis (ARDRA) and 16S rDNA sequencing.Different organs of C. goeringii were surface sterilized by different concentrations of sodium hypochlorite solution. The best method of surface sterilization of roots and pseudobulbs was as following: 75% ethanol for 3.0 min, 3.0% sodium hypochlorite for 2.0 min, and 75% ethanol for 30 s, and the best method of leaves was 75% ethanol for 1.0 min, 2.0% sodium hypochlorite for 2.0 min, and 75% ethanol for 30 s.The endophytic bacteria in the roots of C. goeringii were isolated by three media, R2A, TSA and Doberener N-free medium. The numbers of endophytic bacteria were 2.5×10~5 cfu / g fw on R2A, 1.9×10~5 cfu / g fw on TSA, and 0.9×10~5 cfu / g fw on Doberener N-free medium. Based on ARDRA and 16S rDNA sequences, 211 isolates were grouped into six phyla, including Alphaproteobacteria (50.9%), Gammaproteobacteria (34.6%), Betaproteobacteria (6.7%), Firmicutes (5.2%), Actinobacteria (1.9%) and Bacteroidetes (0.7%). The dominant genera were Rhizobium (48.3%) and Dyella (25.8%). Twenty-one genera, 11 genera and 12 genera were obtained from R2A, TSA, and D?berener N-free medium, respectively. The results showed that endophytic bacteria can be isolated efficiently by R2A from C. goeringii roots.The endophytic bacteria in roots, pseudobulbs and leaves of C. goeringii were isolated by R2A and TSA. Pseudobulbs samples had the highest number of endophytic bacteria (2.80×10~3 cfu/g fw), roots had the middle number (2.08×10~3 cfu/g fw), whereas leaves had the lowest values (0.22×10~3 cfu/g fw). A total of 123 strains of endophytic bacteria were isolated from three organs of C. goeringii. Based on ARDRA and 16S rDNA sequences, 57 strains isolated from the roots were grouped into five phyla and 14 known genera, the dominant genus was Bacillus (45.79%); 55 strains isolated from the pseudobulbs were grouped into five phyla and 15 known genera, the dominant genera were Burkholderia (42.67%) and Sphingomonas (21.33%); 11 strains isolated from the leaves were grouped into four phyla and 7 known genera, and there was no obvious dominant genus. The results suggested that endophytic bacteria have the organ specificity. Our results revealed diverse and abundant communities of endophytic bacteria of C. goeringii.We investigated the diversity of IAA-producing endophytic bacteria in the roots of C. goeringii. A total of 57 IAA-producing isolates were obtained from 256 strains isolated from the interior roots of C. goeringii. Based on amplified ribosomal DNA restriction analyses (ARDRA) and 16S rDNA sequences, 57 isolates were divided into 25 groups. The IAA-producing endophytic bacteria were grouped into six phyla, Alphaproteobacteria (35.1%), Firmicutes (33.3%), Gammaproteobacteria (14.0%), Betaproteobacteria (8.8%), Actinobacteria (7.0%) and Bacteroidetes (1.8%). The dominant groups were Alphaproteobacteria and Firmicutes, and the dominant genus, Paenibacillus, produced relatively high levers of IAA.To our knowledge, it is the first report that Altererythrobacter, Brachybacterium, Chitinophaga, Cellulosimicrobium, Dyella, Labrys, Pandoraea and Porphyrobacter are isolated as endophytic bacteria from plants. Fourteen potential novel taxonomic units were isolated from C. goeringii.