Raoultella sp. strain L03 fixes N2 in association with micropropagated sugarcane plants

• Published in: Journal of basic microbiology Vol. 56; no. 8; pp. 934 - 940
• Main Authors: Luo, Ting, Ou-Yang, Xue-Qing, Yang, Li-Tao, Li, Yang-Rui, Song, Xiu-Peng, Zhang, Ge-Min, Gao, Yi-Jing, Duan, Wei-Xing, An, Qianli
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 01.08.2016
• Subjects: air; antibiotic resistance; Biomass; China; chlorophyll; cultivars; Endophytes - isolation & purification; Endophytes - metabolism; Endophytic bacteria; Enterobacteriaceae - isolation & purification; Enterobacteriaceae - metabolism; fluorescence microscopy; host plants; isotope dilution technique; micropropagation; nitrogen; nitrogen content; Nitrogen fixation; Nitrogen Fixation - physiology; nitrogen-fixing bacteria; Plant growth-promoting bacteria; Plant Roots - microbiology; plant tissues; plantlets; Raoultella; roots; Saccharum - growth & development; Saccharum - metabolism; Saccharum - microbiology; signs and symptoms (plants); stable isotopes; Sugarcane; Symbiosis; China; Nitrogen fixation; Plant growth-promoting bacteria; Endophytic bacteria; Raoultella; Sugarcane
• ISSN: 0233-111X; 1521-4028
• DOI: 10.1002/jobm.201500738

N2‐fixing bacteria belonging to the genus Raoultella of the family Enterobacteriaceae are widely associated with plants. Raoultella sp. strain L03 was isolated from surface‐sterilized sugarcane roots. In this study, we inoculated the strain L03 to microbe‐free micropropagated plantlets of the main sugarcane cultivar ROC22 grown in Guangxi, China and determined N2‐fixation and association between strain L03 and sugarcane plants. Inoculation of strain L03 increased plant biomass, total N, N concentration and chlorophyll, and relieved N‐deficiency symptoms of plants under an N‐limiting condition. An 15N isotope dilution assay revealed 15N isotope dilution in the inoculated sugarcane plants and incorporation of the fixed 14N from air into chlorophyll. Moreover, a gfp‐tagged and antibiotic‐resistant L03 strain was reisolated from surface‐sterilized sugarcane plants and was detected in plant tissues by fluorescent microscopy. This study for the first time demonstrates that a Raoultella bacterium is able to fix N2 in association with the plant host.