title: Competing factors of compost concentration and proximity to root affect the distribution of streptomycetes.
abstract: Streptomycetes are important members of soil microbial communities and are particularly active in the degradation of recalcitrant macromolecules and have been implicated in biological control of plant disease. Using a streptomycetes-specific polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (PCR-DGGE) methodology coupled with band excision and sequence analysis, we examined the effect of grape marc compost amendment to soil on cucumber plant-associated streptomycetes community composition. We observed that both compost amendment and proximity to the root surface influenced the streptomycetes community composition. A strong root selection for a soil-derived Streptomycete, most closely related to Streptomyces thermotolerans, S. iakyrus, and S. thermocarboxydus, was independent of compost amendment rate. However, while the impact of compost amendment was mitigated with increasing proximity to the root, high levels of compost amendment resulted in the detection of compost-derived species on the root surface. Conversely, in rhizosphere and non-rhizosphere soils, the community composition of streptomycetes was affected strongly even by modest compost amendment. The application of a streptomycetes-specific PCR primer set combined with DGGE analysis provided a rapid means of examining the distribution and ecology of streptomycetes in soils and plant-associated environments.
authors.affiliation: Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Ehud
authors.initials: E
authors.lastname: Inbar
authors.forename: Stefan J
authors.initials: SJ
authors.lastname: Green
authors.forename: Yitzhak
authors.initials: Y
authors.lastname: Hadar
authors.forename: Dror
authors.initials: D
authors.lastname: Minz
mesh_terms: D001673:Biodegradation, Environmental; D018553:Cucumis sativus / Q000382:microbiology; D015180:Electrophoresis, Gel, Two-Dimensional; D005308:Fertilizers; D018517:Plant Roots / Q000382:microbiology; D016133:Polymerase Chain Reaction; D013306:Streptomycetaceae / Q000254:growth & development*
chemical_list: D005308:Fertilizers