title: Bacterial succession in glacial forefield soils characterized by community structure, activity and opportunistic growth dynamics.
abstract: The succession of bacterial communities inhabiting the forefield of the Dammaglacier (Switzerland) was investigated in soils ranging in successional age from 0 to 100 years since deglaciation. Overall activity per bacterial cell was estimated by the amount of fluorescein diacetate (FDA) hydrolyzed per DAPI-stained cell, and an index of "opportunism" was determined from the ratio of culturable to total cells (C:T ratio). Ribosomal intergenic spacer analysis (RISA) was used to estimate the richness of dominant phylotypes and to construct rank-abundance plots of the dominant populations. We observed a biphasic trend in specific cellular activity, which exhibited minima in the 0- and 100-year-old soils while a maximum activity per cell was reached in the 70-y soil. On average, the C:T ratio showed the same trend as the specific activity, although we observed some differences between the two sampling transects. RISA revealed a decrease in dominant phylotype richness as successional age increased, and rank-abundance plots indicated that the evenness of the dominant bacterial phylotypes significantly decreased with successional age. The combination of specific cellular activity and C:T ratio results suggested the presence of an r-K continuum of bacteria while RISA showed that richness and evenness of dominant phylotypes decreased with successional age. We conclude that bacterial succession in the glacier forefield was a dynamic process with adaptation to the differing stages of succession occurring on both the individual and community levels.
authors.affiliation: Institute for Terrestrial Ecology, Soil Biology, Swiss Federal Institute of Technology, 8952-Schlieren, Switzerland. sigler@ito.umnw.ethz.ch
authors.forename: W V
authors.initials: WV
authors.lastname: Sigler
authors.forename: S
authors.initials: S
authors.lastname: Crivii
authors.forename: J
authors.initials: J
authors.lastname: Zeyer
mesh_terms: D001419:Bacteria; D017753:Ecosystem; D005452:Fluoresceins / Q000737:chemistry; D006868:Hydrolysis; D011157:Population Dynamics; D012270:Ribosomes; D012988:Soil Microbiology; D014197:Trees
chemical_list: D005452:Fluoresceins; C018506:diacetylfluorescein