Open AccessMolecular Analysis of Diazotroph Diversity in the Rhizosphere of the Smooth Cordgrass, Spartina alterniflora
Author(s) -
Charles R. Lovell,
Yvette M. Piceno,
Joseph M. Quattro,
Christopher E. Bagwell
Publication year - 2000
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.66.9.3814-3822.2000
Subject(s) - diazotroph , rhizosphere , biology , spartina , spartina alterniflora , botany , proteobacteria , salt marsh , temperature gradient gel electrophoresis , halophyte , nitrogen fixation , ecology , marsh , bacteria , 16s ribosomal rna , genetics , salinity , wetland
N2 fixation by diazotrophic bacteria associated with the roots of the smooth cordgrass,Spartina alterniflora , is an important source of new nitrogen in many salt marsh ecosystems. However, the diversity and phylogenetic affiliations of these rhizosphere diazotrophs are unknown. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplifiednifH sequence segments was used in previous studies to examine the stability and dynamics of theSpartina rhizosphere diazotroph assemblages in the North Inlet salt marsh, near Georgetown, S.C. In this study, plugs were taken from gel bands from representative DGGE gels, thenifH amplimers were recovered and cloned, and their sequences were determined. A total of 59 sequences were recovered, and the amino acid sequences predicted from them were aligned with sequences from known and unknown diazotrophs in order to determine the types of organisms present in theSpartina rhizosphere. We recovered numerous sequences from diazotrophs in the γ subdivision of the divisionProteobacteria (γ-Proteobacteria ) and from various anaerobic diazotrophs. Diazotrophs in the α-Proteobacteria were poorly represented. None of theSpartina rhizosphere DGGE band sequences were identical to any known or previously recovered environmentalnifH sequences. TheSpartina rhizosphere diazotroph assemblage is very diverse and apparently consists mainly of unknown organisms.