title: Ecological niche separation in the Polynucleobacter subclusters linked to quality of dissolved organic matter: a demonstration using a high sensitivity cultivation-based approach.
abstract: The free-living, cosmopolitan, freshwater betaproteobacterial bacterioplankton genus Polynucleobacter was detected in different years in 11 lakes of varying types and a river using the size-exclusion assay method (SEAM). Of the 350 strains isolated, 228 (65.1%) were affiliated with the Polynucleobacter subclusters PnecC (30.0%) and PnecD (35.1%). Significant positive correlations between fluorescence in situ hybridization and SEAM data were observed in the relative abundance of PnecC and PnecD bacteria to Polynucleobacter communities (PnecC + PnecD). Isolates were mainly PnecC bacteria in the samples with a high specific UV absorbance at 254 nm (SUVA(254) ), and a low total hydrolysable neutral carbohydrate and amino acid (THneutralCH + THAA) content of the dissolved organic matter (DOM) fraction, which is known to be correlated with a high humic content. In contrast, the PnecD bacteria were abundant in samples with high chlorophyll a and/or THneutralCH + THAA concentrations, indicative of primary productivity. With few exceptions, differences in the relative abundance of PnecC and PnecD in each sample, determined using a high-sensitivity cultivation-based approach, were due to DOM quality. These results suggest that the major DOM component in the field, which is allochthonously or autochthonously derived, is a key factor for ecological niche separation between PnecC and PnecD subclusters.
authors: National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan. watanabe.keiji@nies.go.jp
authors: Keiji
authors: K
authors: Watanabe
authors: Nobuyuki
authors: N
authors: Komatsu
authors: Tatsumi
authors: T
authors: Kitamura
authors: Yuichi
authors: Y
authors: Ishii
authors: Ho-Dong
authors: HD
authors: Park
authors: Ryo
authors: R
authors: Miyata
authors: Naohiro
authors: N
authors: Noda
authors: Yuji
authors: Y
authors: Sekiguchi
authors: Takayuki
authors: T
authors: Satou
authors: Mirai
authors: M
authors: Watanabe
authors: Shigeki
authors: S
authors: Yamamura
authors: Akio
authors: A
authors: Imai
authors: Seiji
authors: S
authors: Hayashi
mesh_terms: D042521:Burkholderiaceae / Q000502:physiology*; D002734:Chlorophyll / Q000032:analysis; D017753:Ecosystem; D005618:Fresh Water / Q000737:chemistry* / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D014871:Water Microbiology
chemical_list: D002734:Chlorophyll