Open AccessInfluence of depth and time on diversity of free‐living microbial community in the variably saturated zone of a granitic aquifer
Author(s) -
Bougon Nolwenn,
Aquilina Luc,
Molénat Jérome,
Marie Dominique,
Delettre Yannick,
Chancerel Emilie,
Vandenkoornhuyse Philippe
Publication year - 2012
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2011.01273.x
Subject(s) - biology , vadose zone , aquifer , microbial population biology , 16s ribosomal rna , groundwater recharge , ecology , groundwater , soil water , bacteria , geology , paleontology , geotechnical engineering
We investigated the temporal and vertical changes in the microbial communities related to hydrological variations an aquifer ( B rittany, F rance). Five water samplings were carried out, spanning three hydrological cycles in the variably and the permanently saturated zones. Seasonal variations in the major anion concentrations (NO 3−,SO 42 − and Cl − ) indicated that different physical processes occurred during the recharge process in the two zones. The variably saturated zone is mainly dominated by diffusion and advection processes from the soil, whereas the permanently saturated zone is controlled by moderate advective transfer from the variably saturated zone. Bacterial diversity was investigated by flow cytometry, 16 S rRNA and narG genes analyses. Part of this diversity was new in that 6 of the 27 16 S rRNA gene sequence phylotypes were unknown even at the class or phylum level. The narG gene analysis did not reveal any clear variation in time or depth within the nitrate reducers’ community. In contrast, 16 S rRNA gene analyses showed modifications of community composition that could be related to the hydrologic and chemical contrast between the two zones. It was concluded that the physical processes of water transfer could influence bacterial diversity at the soil–aquifer interface.