title: Presence does not imply activity: DNA and RNA patterns differ in response to salt perturbation in anaerobic digestion.
abstract: BACKGROUND
  The microbial community in anaerobic digestion is mainly monitored by means of DNA-based methods. This may lead to incorrect interpretation of the community parameters, because microbial abundance does not necessarily reflect activity. In this research, the difference between microbial community response on DNA (total community) and RNA (active community) based on the 16S rRNA (gene) with respect to salt concentration and response time was evaluated.
  
  
  RESULTS
  The application of higher NaCl concentrations resulted in a decrease in methane production. A stronger and faster response to salt concentration was observed on RNA level. This was reflected in terms of microbial community composition and organization, as richness, evenness, and overall diversity were differentially impacted. A higher divergence of community structure was observed on RNA level as well, indicating that total community composition depends on deterministic processes, while the active community is determined by stochastic processes.Methanosaetawas identified as the most abundant methanogen on DNA level, but its relative abundance decreased on RNA level, related to salt perturbation.
  
  
  CONCLUSIONS
  This research demonstrated the need for RNA-based community screening to obtain reliable information on actual community parameters and to identify key species that determine process stability.
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.|Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, Rúa Lope Gomez de Marzoa s/n, E-15782 Santiago de Compostela, Spain.
authors.forename: Jo
authors.identifier: 0000-0001-9365-8896
authors.initials: J
authors.lastname: De Vrieze
authors.affiliation: Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, Rúa Lope Gomez de Marzoa s/n, E-15782 Santiago de Compostela, Spain.
authors.forename: Leticia
authors.initials: L
authors.lastname: Regueiro
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
authors.forename: Ruben
authors.initials: R
authors.lastname: Props
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
authors.forename: Ramiro
authors.initials: R
authors.lastname: Vilchez-Vargas
authors.affiliation: Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research (HZI), Brunswick, Germany.|AgResearch, Tennent Drive, Palmerston North, 4442 New Zealand.
authors.forename: Ruy
authors.initials: R
authors.lastname: Jáuregui
authors.affiliation: Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research (HZI), Brunswick, Germany.
authors.forename: Dietmar H
authors.initials: DH
authors.lastname: Pieper
authors.affiliation: Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, Rúa Lope Gomez de Marzoa s/n, E-15782 Santiago de Compostela, Spain.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Lema
authors.affiliation: Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, Rúa Lope Gomez de Marzoa s/n, E-15782 Santiago de Compostela, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Carballa
keywords: Archaea; Biogas; Illumina sequencing; Methanogenesis; Salinity