Journal of Hunan Ecological Science

【Objective】This study aimed to isolate and identify endophytic nitrogen fixing bacteria from Sedum emarginatum and explore their growth promoting characteristics, providing new resources for the development of biofertilizers and green ecological agriculture. 【Method】Endophytic bacteria from S. emarginatum were used as materials. The nitrogenase activity was determined by acetylene reduction as- say, and the endophytic nitrogen fixing bacteria were isolated and identified by IS-PCR fingerprint cluste- ring, 16S rRNA gene phylogenetic analysis, and physicochemical property identification. Additionally, the effect of the isolated strains on the growth of maize seedlings was evaluated through pot tests. 【Result】 A total of 20 endophytic nitrogen fixing bacterial strains were successfully isolated from S. emarginatum, belonging to five taxonomic groups, including Klebsiella pneumoniae subsp. ozaenae, Proteus mirabilis, Providencia rettgeri, Klebsiella quasipneumoniae subsp. quasipneumoniae, and Phytobacter diazotrophicus. Among them, K. pneumoniae subsp. ozaenae and P. diazotrophicus possessed not only nitrogen fixing abil- ity but also multiple growth promoting characteristics such as phosphorus solubilization, potassium disso- lution, siderophore production, and auxin production. Pot tests showed that JSR1 and JSR21 could sig- nificantly promote the growth of maize seedlings. The longest root length of maize seedlings treated with JSR21 increased by 48. 4% compared with the control, while JSR1 increased the shoot growth of maize seedlings by 27. 2% compared with the control. 【Conclusion】The endophytic nitrogen fixing bacteria in S. emarginatum are diverse and possess multiple growth promoting characteristics, making them potentially valuable for applications in the development of green ecological agriculture and biofertilizer.

Sedum emarginatum; endophyte bacteria; nitrogen fixing bacteria; growth promoting characteristics; associated nitrogen fixation