title: Identification of growing bacteria during litter decomposition in freshwater through H218O quantitative stable isotope probing.
abstract: Identification of microorganisms that facilitate the cycling of nutrients in freshwater is paramount to understanding how these ecosystems function. Here, we identify growing aquatic bacteria using H218O quantitative stable isotope probing. During 8 day incubations in 97 atom % H218O, 54% of the taxa grew. The most abundant phyla among growing taxa were Proteobacteria (45%), Bacteroidetes (30%) and Firmicutes (10%). Taxa differed in isotopic enrichment, reflecting variation in DNA replication of bacterial populations. At the class level, the highest atom fraction excess was observed for OPB41 and δ-Proteobacteria. There was no linear relationship between18O incorporation and abundance of taxa. δ-Proteobacteria and OPB41 were not abundant, yet the DNA of both taxa was highly enriched in18O. Bacteriodetes, in contrast, were abundant but not highly enriched. Our study shows that a large proportion of the bacterial taxa found on decomposing leaf litter grew slowly, and several low abundance taxa were highly enriched. These findings indicating that rare organisms may be important for the decomposition of leaf litter in streams, and that quantitative stable isotope probing with H218O can be used to advance our understanding of microorganisms in freshwater by identifying species that are growing in complex communities.
authors.affiliation: Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA.
authors.forename: Michaela
authors.initials: M
authors.lastname: Hayer
authors.affiliation: Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA.|Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86001, USA.
authors.forename: Egbert
authors.initials: E
authors.lastname: Schwartz
authors.affiliation: Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA.|Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86001, USA.
authors.forename: Jane C
authors.initials: JC
authors.lastname: Marks
authors.affiliation: Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Koch
authors.affiliation: Division of Plant and Soil, West Virginia University, Morgantown, WV, 26506, USA.
authors.forename: Ember M
authors.initials: EM
authors.lastname: Morrissey
authors.affiliation: Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA.|Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86001, USA.
authors.forename: Alexa A
authors.initials: AA
authors.lastname: Schuettenberg
authors.affiliation: Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA.|Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86001, USA.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Hungate
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000254:growth & development* / Q000378:metabolism; D005618:Fresh Water / Q000382:microbiology*; D007553:Isotope Labeling; D018515:Plant Leaves / Q000382:microbiology*