Effects of differences in organic supply on bacterial diversity subject to viral lysis

• Published in: FEMS microbiology ecology Vol. 83; no. 1; pp. 202 - 213
• Main Authors: Töpper, Birte, Thingstad, Tron Frede, Sandaa, Ruth-Anne
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2013; Blackwell; Oxford University Press
• Subjects: 16S rRNA gene; Alphaproteobacteria - growth & development; Alphaproteobacteria - virology; Animal, plant and microbial ecology; Bacteria; bacterial diversity; Bacteriolysis; Bacteriophages - growth & development; Batch Cell Culture Techniques; Biodiversity; Biological and medical sciences; Community composition; DNA, Bacterial - isolation & purification; Ecology; Food Chain; Fundamental and applied biological sciences. Psychology; Gammaproteobacteria - growth & development; Gammaproteobacteria - virology; Genetic diversity; Glucose - metabolism; Microbial ecology; Microbiology; Niches; organic carbon composition; Organic matter; Phaeocystis pouchetii; Phytoplankton; Phytoplankton - growth & development; Phytoplankton - metabolism; Population Dynamics; Replicative cycle, interference, host-virus relations, pathogenicity, miscellaneous strains; Seawater - microbiology; Seawater - virology; Substrates; Thalassiosira; Thalassiosira sp; Various environments (extraatmospheric space, air, water); Virology; virus control; Water Microbiology; bacterial diversity; sp; virus control; 16S rRNA gene; organic carbon composition; Organic carbon; Composition; Phaeocystis pouchetii; Algae; Ribosomal DNA; Thalassiosira sp; Biodiversity; Haptophyta; Virus; Heterokontophyta; Species diversity; Bacillariophyta; Lysis; 16S-RNA
• ISSN: 0168-6496; 1574-6941; 1574-6941
• DOI: 10.1111/j.1574-6941.2012.01463.x

Abstract Bacterial diversity is believed to be controlled both by bottom-up and top-down mechanisms such as nutrient competition, predation and viral lysis. We hypothesise that lytic viruses create trophic niches within bacterial communities, and thus primarily control richness and evenness, while substrate composition primarily controls community composition, that is, the inhabitants of these niches. To investigate this, we studied diversity of mixed bacterial communities subject to viruses under different regimes of organic matter supply. From a predator-free inoculum, bacterial communities were allowed to develop in batch cultures where the organic substrate was either a single compound [glucose (G)] or more complex mixtures produced by phytoplankton [Phaeocystis pouchetii (P) or Thalassiosira sp. (T)]. Throughout the experiment, c. 98% of the sequences in treatment G belonged to the Gammaproteobacteria class, which dominated also in the initial phase of the other treatments [T (c. 87%) and P (62%)]. In treatment T, the composition shifted to a dominance of Alphaproteobacteria (c. 37%), while in P, the proportion of Gammaproteobacteria remained stable. Richness increased with increasing substrate complexity, while evenness remained similar in the different treatments. The results suggest that both substrate composition (bottom-up) and viral lysis (top-down) operate simultaneously in the control of bacterial diversity. Despite the reduction in factors supposed to influence prokaryote diversity, the system was still complex if taken into account the potential synergistic interactions within and between the remaining factors.