title: Isolation of endophytic diazotroph Pantoea agglomerans and nondiazotroph Enterobacter asburiae from sweetpotato stem in Japan.
abstract: OBJECTIVE
  To isolate and identify diazotrophic endophytes in the stem of Japanese sweetpotato cv. Koganesengan.
  
  
  RESULTS
  Surface-sterilized and thinly sliced (1-2 mm) sweetpotato stem samples were incubated in test tubes with semi-solid modified Rennie (MR) medium. The test tubes were assayed for acetylene reduction activity (ARA) 5 days after incubation at 30 degrees C. Twelve isolates were obtained from MR plates inoculated with a loop of semi-solid MR medium from ARA+ tubes. However, ARA test showed that only nine isolates were diazotrophic and three were nondiazotrophic strains. Using the API 20E diagnostic kit, four diazotrophic isolates were identified as strains of Pantoea spp. and five isolates as Klebsiella spp. The nondiazotrophic bacteria were strains of Enterobacter spp. A diazotrophic isolate Pantoea sp. MY1 and nondiazotrophic isolate Enterobacter sp. MY2 were identified to the species level by full sequence analysis of 16S rRNA gene. The results showed that MY1 had 99.2% similarity to Pantoea agglomerans ATCC 27155 and MY2 had 99.5% similarity to Enterobacter asburiae ATCC 35953.
  
  
  CONCLUSIONS
  The stem of sweetpotato cv. Koganesengan was colonized by diazotrophic endophyte P. agglomerans and nondiazotrophic endophyte E. asburiae.
  
  
  CONCLUSIONS
  This study is an essential step toward understanding the ecology and interaction between endophytic bacteria and sweetpotato.
authors.affiliation: Department of Upland Farming Research, National Agricultural Research Center for Kyushu Okinawa Region, Miyazaki, Japan. cajr@monbusho.org
authors.forename: C A
authors.initials: CA
authors.lastname: Asis
authors.forename: K
authors.initials: K
authors.lastname: Adachi
mesh_terms: D015373:Bacterial Typing Techniques; D004275:DNA, Ribosomal / Q000737:chemistry / Q000302:isolation & purification; D004754:Enterobacter / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism; D027723:Ipomoea batatas / Q000382:microbiology*; D007564:Japan; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010084:Oxidation-Reduction; D020636:Pantoea / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism; D010641:Phenotype; D018547:Plant Stems / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013559:Symbiosis
chemical_list: D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S