title: Microbial population dynamics in the sediments of a eutrophic lake (Aydat, France) and characterization of some heterotrophic bacterial isolates.
abstract: The bacterial populations of anoxic sediments in a eutrophic lake (Aydat, Puy-de-Dôme-France) were studied by phospholipid fatty acid analysis (PLFA) and also by culturing heterotrophic bacteria under strictly anaerobic conditions. The mean PLFA concentrations of prokaryotes and microeukaryotes were 5.7 +/- 2.9 mgC g(-1) DS and 9.6 +/- 6.7 mgC g(-1) DS, respectively. The analysis of bacterial PLFA markers was used to determine the dynamics of the Gram-positive and Gram-negative species of anaerobic bacteria, Clostridiae, and sulfate-reducing bacteria. Throughout the sampling period the concentrations of i15:0 (from 20 nmol g(-1) DS to 130 nmol g(-1) DS), markers of Gram-positive bacteria, were higher than those for Gram-negative bacteria. The dynamics of Clostridiae (Cy15:0) paralleled those of sulfate-reducing bacteria that were marked by i17:1omega7. Partial 16S rDNA sequencing and the physiological study of the various fermenting strains, whose abundance in the superficial sediment layer was 1.1 +/- 0.4 x 10(6) cells mL(-1), showed that all the isolates belonged to the Clostridiae and related taxa ( Lactosphaera pasteurii, Clostridium vincentii, C. butyricum, C. algidixylanolyticum, C. puniceum, C. lituseburense, and C. gasigenes). All the isolates were capable of metabolizing a wide range of organic substrates.
authors.affiliation: Laboratoire de Biologie des Protistes, UMR CNRS 6023, Université Blaise Pascal, 63177 Aubière cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Mallet
authors.forename: M
authors.initials: M
authors.lastname: Basset
authors.forename: G
authors.initials: G
authors.lastname: Fonty
authors.forename: C
authors.initials: C
authors.lastname: Desvilettes
authors.forename: G
authors.initials: G
authors.lastname: Bourdier
authors.forename: D
authors.initials: D
authors.lastname: Debroas
mesh_terms: D000693:Anaerobiosis; D001483:Base Sequence; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D003013:Clostridium / Q000166:cytology / Q000235:genetics* / Q000502:physiology*; D017931:DNA Primers; D005227:Fatty Acids / Q000378:metabolism; D005602:France; D005618:Fresh Water; D019015:Geologic Sediments / Q000382:microbiology*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism; D011157:Population Dynamics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013696:Temperature
chemical_list: D017931:DNA Primers; D005227:Fatty Acids; D010743:Phospholipids; D012336:RNA, Ribosomal, 16S; D002244:Carbon