Isolation And Identification Of Endophytic Bacteria In Eleven Landscape Plants And Taxonomic Analysis Of A Novel Bacterium

Endophytic bacteria are a kind of bacteria that colonize in healthy plant cells or intercellular space and have no obvious influence on host plants.They are widely distributed in various plants and become an important component of plant microecosystem.Some endophytic bacteria play a positive role in promoting plant growth,antagonizing plant pathogens,alleviating plant stress response under stress,and promoting plant tolerance and absorption of toxic and harmful pollutants.In this study,endophytic bacteria isolated from various garden plant tissues were identified,and the bacterial diversity and potential biological functions were analyzed;polyphasic taxonomy was used to clarify the classification status of a potential new bacteria isolated from the bulb tissue of Lilium pumilum.(1)100 strains of endophytic bacteria were isolated from 11 species of garden plant(Cymbidium goeringii,Phragmites australis,Sabina vulgaris,Metaplexis japonica,Artemisia sphaerocephala,Lilium pumilum,Artemisia ordosica,Hylotelephium erythrostictum,Typhonium giganteum,Cynodon dactylon and Ephedra minuta)tissue samples collected from mountain area of Fuping,Baoding City,Hebei Province,the sandy land of Wushen Banner,Ordos City,Inner Mongolia,and the greenhouse of the Chinese Academy of Forestry.After16S r DNA gene sequence alignment,it was found that these strains were divided into 37bacteria genera,83 species,among which Pseudomonas and Bacillus were the most abundant.(2)In these isolated endophytic bacteria,CL11-2,SDB6-1,LW4-1,GYG1-1,JT4-1 were found to have beneficial biological effects on plants in some ways.In addition,there are 13strains may have some potential functions.(3)A novel gram-negative,aerobic,non-spore-forming,rod-shaped and non-nitrogen fixing bacterium named strain 24NR^T was isolated from wild Lilium pumilum bulbs.Based on phenotypic,phylogenetic,and genotypic data,strain 24NR^T is considered to represent a novel species of the genus Neorhizobium,for which the name Neorhizobium lilium sp.nov.is proposed.The size of strain 24NR^T is about(0.3-0.5)×(0.7-1.7)?m,milky white colonies were formed on YMA plate with neat edges.The strain could grow normally in the Na Cl concentration range of 0-2%(w/v),the temperature range of 15-42?and the p H range of6.0-9.0.The optimal Na Cl concentration,p H and temperature were 0%,p H 7.0-8.0 and 30?,respectively.The test of contact enzyme and catalase showed positive,and the test of nitrate reduction reaction showed negative.The major cellular fatty acids were summed feature 8(C_18:1?7c and/or C_18:1?6c)and C_19:0 cyclo?8c.The G+C content was 60.3 mol%.