Vertical Distribution of Functional Potential and Active Microbial Communities in Meromictic Lake Kivu.
The microbial community composition in meromictic Lake Kivu, with one of the largest CH4 reservoirs, was studied using 16S rDNA and ribosomal RNA (rRNA) pyrosequencing during the dry and rainy seasons. Highly abundant taxa were shared in a high percentage between bulk (DNA-based) and active (RNA-based) bacterial communities, whereas a high proportion of rare species was detected only in either an active or bulk community, indicating the existence of a potentially active rare biosphere and the possible underestimation of diversity detected when using only one nucleic acid pool. Most taxa identified as generalists were abundant, and those identified as specialists were more likely to be rare in the bulk community. The overall number of environmental parameters that could explain the variation was higher for abundant taxa in comparison to rare taxa. Clustering analysis based on operational taxonomic units (OTUs at 0.03 cutoff) level revealed significant and systematic microbial community composition shifts with depth. In the oxic zone, Actinobacteria were found highly dominant in the bulk community but not in the metabolically active community. In the oxic-anoxic transition zone, highly abundant potentially active Nitrospira and Methylococcales were observed. The co-occurrence of potentially active sulfur-oxidizing and sulfate-reducing bacteria in the anoxic zone may suggest the presence of an active yet cryptic sulfur cycle.
Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Brussel, Belgium. oezguel@gmail.com.
Özgul
Ö
İnceoğlu
Laboratory of Freshwater Ecology, Université de Namur, Namur, Belgium.|Department of Genetics and Microbiology, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Marc
M
Llirós
Departments of Microbiology and Immunology, and Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, Canada.
Sean A
SA
Crowe
Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Brussel, Belgium.
Tamara
T
García-Armisen
Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.
Cedric
C
Morana
Chemical Oceanography Unit, Université de Liège, Liège, Belgium.
François
F
Darchambeau
Chemical Oceanography Unit, Université de Liège, Liège, Belgium.
Alberto V
AV
Borges
Laboratory of Freshwater Ecology, Université de Namur, Namur, Belgium.
Jean-Pierre
JP
Descy
Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Brussel, Belgium.
Pierre
P
Servais
D001105:Archaea / Q000235:genetics / Q000502:physiology*; D019843:Archaeal Proteins / Q000235:genetics; D001419:Bacteria / Q000235:genetics; D018407:Bacterial Physiological Phenomena; D001426:Bacterial Proteins / Q000235:genetics; D015023:Democratic Republic of the Congo; D060106:Lakes / Q000382:microbiology*; D064307:Microbiota; D010802:Phylogeny; D019642:RNA, Archaeal; D012329:RNA, Bacterial; D060888:Real-Time Polymerase Chain Reaction; D012432:Rwanda; D012621:Seasons; D017422:Sequence Analysis, DNA; D017423:Sequence Analysis, RNA
D019843:Archaeal Proteins; D001426:Bacterial Proteins; D019642:RNA, Archaeal; D012329:RNA, Bacterial
Abundant and rare; Active; Archaea; Bacteria; Bulk; Meromictic lake; Network; Pyrosequencing; qPCR