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Authors Bagwell, CE; Dantzler, M; Bergholz, PW; Lovell, CR
Author Full Name Bagwell, CE; Dantzler, M; Bergholz, PW; Lovell, CR
Title Host-specific ecotype diversity of rhizoplane diazotrophs of the perennial glasswort Salicornia virginica and selected salt marsh grasses
Source AQUATIC MICROBIAL ECOLOGY
Language English
Document Type Article
Author Keywords diazotrophs; rhizoplane; physiological specialization; rhizosphere ventilation
Keywords Plus SPRING MICROBIAL MAT; SPARTINA-ALTERNIFLORA LOISEL; ACETYLENE-REDUCTION; NITROGEN-FIXATION; RHIZOSPHERE; COMMUNITY; POPULATIONS; SEDIMENTS; BACTERIA; GRADIENT
Abstract The degree of host specificity of most plant root associated bacteria is poorly understood. In this study we examined the physiological diversity of oxygen utilizing, culturable diazotrophs from the rhizoplane of the high marsh perennial glasswort Salicornia virginica and compared them to diazotrophs from other salt marsh plants (tall and short Spartina alterniflora, Juncus roemerianus, and Spartina patens) from the same ecosystem. Forty-six pure culture strains were recovered from the rhizoplane of S. virginica by stab inoculating freshly collected roots into combined nitrogen-free semi-solid media, followed by streak plating of clonal outgrowths. The majority of these strains were Gram-negative obligately aerobic or microaerophilic rods, but 3 Gram-positive strains were also isolated and characterized. API 20NE test strips were used for preliminary characterization of all strains, yielding 22 physiologically different API strain groups. One representative strain was selected from each API group and tested for the presence of nifH, denoting strains capable of Nz-fixation. Seventeen strains (14 Gram-negative, 3 Gram-positive) were nifH-positive and were characterized further using BIOLOG test plates. Four well-supported strain clusters were identified by bootstrapped cluster analysis of the BIOLOG substrate utilization profiles. These clusters differed in utilization of carbohydrates, carboxylic acids, and amino acids. S. virginica diazotrophs were physiologically quite different from rhizoplane diazotrophs from the low marsh plants S, alterniflora and J. roemenianus, but much more similar to diazotrophs from another high marsh plant, S. patens. We hypothesize that the observed physiological differentiation between high marsh and low marsh diazotrophs reflects differences in selection pressures in the rhizoplane microenvironment produced by plants with differing abilities to ventilate the rhizosphere. In addition, high and low marsh branches were further resolved into host-specific strain clusters, which also implies a strong impact of other host features, such as the suite of carbon exudate compounds produced, on the distributions of specific diazotroph strains. These findings imply endemic, host-specific distributions of salt marsh diazotrophs and are consistent with the great diversity of diazotrophs that have been observed in this ecosystem to date.
Author Address Univ S Carolina, Dept Biol Sci, Columbia, SC 29208 USA
Reprint Address Lovell, CR (corresponding author), Univ S Carolina, Dept Biol Sci, Columbia, SC 29208 USA.
ResearcherID Number Bergholz, Peter/C-1293-2010
Times Cited 37
Total Times Cited Count (WoS, BCI, and CSCD) 38
Publisher INTER-RESEARCH
Publisher City OLDENDORF LUHE
Publisher Address NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY
ISSN 0948-3055
29-Character Source Abbreviation AQUAT MICROB ECOL
ISO Source Abbreviation Aquat. Microb. Ecol.
Publication Date FEB 28
Year Published 2001
Volume 23
Issue 3
Beginning Page 293
Ending Page 300
Digital Object Identifier (DOI) 10.3354/ame023293
Page Count 8
Web of Science Category Ecology; Marine & Freshwater Biology; Microbiology
Subject Category Environmental Sciences & Ecology; Marine & Freshwater Biology; Microbiology
Document Delivery Number 413XH
Unique Article Identifier WOS:000167636500009
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