title: [Effect of flooding time on community structure and abundance of Geobacteraceae in paddy soil].
abstract: OBJECTIVE
  The dynamic characteristics of community structure and relative abundance of Geobacteraceae were investigated to understand their response to microbial iron (III) reducing in flooded paddy soil.
  
  
  METHODS
  The paddy soil was incubated anaerobically and the amount of Fe(II) was determined during the flooding incubation. We retrieved Geobacteraceae sequences from clone libraries constructed for different time points (1 h and day 1, 5, 10, 20 and 30) after flooding of the paddy soil. The diversity and community structure were analyzed by using RFLP method, and the relative abundance of Geobacteraceae was detected by real-time PCR.
  
  
  RESULTS
  Microbial reduction of iron (III) changed greatly in early time and was stable after incubated for 20 d in paddy soil. The largest iron reduction potential was 10.16 mg/g with a Vmax of 1.064 mg/(g x d) at the time of 4.84 d whereas this process achieved plateau after 20 days flooding. Diversity of Geobacteraceae, given by alpha indices, fluctuated during the flooding incubation. Two peaks of diversity were observed in treatments of 5 d and 20 d respectively, while significant low diversity appeared in samples of 10 d and 30 d. Beta indices described the differences between community structures of Geobacteraceae and hence reflected the variation of the flooding situation over time. In all samples, 10 RFLP-based preponderant types were found, which fell into clade 1 and clade 2 of Geobacteraceae. The relative abundance of Geobacteraceae was the lowest in 1 d (1.20% ) and the highest in 20 d (4.54%).
  
  
  CONCLUSIONS
  The dynamic variation of Geobacteraceae diversity, community structure and abundance are closely related to microbial iron (III) reducing in flooding paddy soil.
authors.affiliation: College of Life Sciences, Northwest A & F University, Yangling 712100, China. youjiaohua403@yahoo.com.cn
authors.forename: Jiaohua
authors.initials: J
authors.lastname: You
authors.forename: Shuhong
authors.initials: S
authors.lastname: Xia
authors.forename: Baoli
authors.initials: B
authors.lastname: Wang
authors.forename: Dong
authors.initials: D
authors.lastname: Qu
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics; D020564:Deltaproteobacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D017753:Ecosystem; D055868:Floods; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D013997:Time Factors
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012987:Soil