title: [Screening, identification and antagonistic activity of a siderophore-producing bacteria G-229-21T from rhizosphere of tobacco].
abstract: OBJECTIVE
  To screen antagonistic bacteria from rhizosphere of tobacco against Phytophthora parasitica var. nicotianae (Breda de Hann) Tucker and to analyze its antagonistic activity.
  
  
  METHODS
  The antagonistic bacteria were screened by dual culture with P. parasitica var. nicotianae (Breda de Hann) Tucker on low iron (2 micromol/L FeCl3) Sucrose-L-Asparagine (SA) plate. The chrome azurol S (CAS) assay was used to detect the siderophore production and its affinity to ferric ion. The strain was identified by using morphological, biochemical and physiological characteristics, 16S rRNA sequence homology, phylogenetics and specific species molecular analysis. The siderophore was isolated by column chromatography on Amberlite XAD-2 and analyzed by spectrophotometer. Antagonistic activity of the siderophore was confirmed by incubation of P. parasitica var. nicotianae (Breda de Hann) Tucker in liquid SA medium with different concentration of siderophore and FeCl3.
  
  
  RESULTS
  We obtained an antagonistic bacterium G-229-21T against P. parasitica var. nicotianae (Breda de Hann) Tucker. The strain produced high-affinity siderophore under low iron conditions and was identified as Pseudomonas mediterranea. This strain produced carboxylate-type siderophore against P. parasitica var. nicotianae (Breda de Hann) Tucker. The suppression ratio was up to 92.3% under low iron conditions (0.16 micromol/L-10 micromol/L FeCl3). However, it was only 2.0% under Fe-replete conditions (100 micromol/L FeCl3).
  
  
  CONCLUSIONS
  P. mediterranea G-229-21T could produce high-affinity carboxylate-type siderophore against P. parasitica var. nicotianae (Breda de Hann) Tucker under low iron conditions.
authors.affiliation: College of Life Sciences, Shandong Agricultural University, Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an 271018, China. tianfang2001@126.com
authors.forename: Fang
authors.initials: F
authors.lastname: Tian
authors.forename: Yanqin
authors.initials: Y
authors.lastname: Ding
authors.forename: Hui
authors.initials: H
authors.lastname: Zhu
authors.forename: Liangtong
authors.initials: L
authors.lastname: Yao
authors.forename: FengLi
authors.initials: F
authors.lastname: Jin
authors.forename: Binghai
authors.initials: B
authors.lastname: Du
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D007501:Iron / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D010802:Phylogeny; D010838:Phytophthora / Q000187:drug effects; D018517:Plant Roots; D011549:Pseudomonas / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D017262:Siderophores / Q000032:analysis / Q000096:biosynthesis* / Q000494:pharmacology; D014026:Nicotiana / Q000033:anatomy & histology* / Q000166:cytology / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D017262:Siderophores; D007501:Iron