Grazing-resistance, antibiotic production and internal carbon cycling are characteristics for bacteria that prevail in long-term enclosure experiments

ABSTRACT: Enclosure experiments are frequently used to investigate the impact of changing environmental conditions on microbial assemblages. Yet, the question how individual members of bacterial communities respond to challenges posed by the incubation itself remained unanswered. We used metaproteomic profiling, 16S rRNA gene analysis and high nucleic acid content analysis to monitor bacterial communities during long-term incubations (55 days) under marine (M1), mesohaline (M2) and oligohaline (M3) conditions with and without the addition of terrestrial dissolved organic matter. Our results showed that early in the experiment (after one week, T2), bacterial communities were highly diverse and their composition differed significantly between marine, mesohaline and oligohaline conditions. Controls (BS) and tDOM-treated samples (FKB) showed notable differences at this stage. In contrast, in the late phase of the experiment (after 55 days, T6), bacterial communities in both, manipulated and untreated marine and mesohaline enclosures were quite similar to each other and were dominated by gammaproteobacterial Spongiibacter. In the oligohaline enclosure, the actinobacterial hgc-I clade was very abundant in this phase. Our findings suggest that individual capacities, e.g. grazing-resistance, antibiotics production, and the ability to access alternative carbon sources may enable Spongiibacter and hgc-I clade members to successfully prevail during long-term incubations. Bacterial community composition in enclosure experiments thus seems to be strongly influenced by the individual inherent bacterial strategies to cope with the incubation as such. Researchers intending to investigate the effects of manipulation on complex microbial communities may therefore want to use short incubation periods or sophisticated systems that avoid these unspecific effects of long-term experiments.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Bacteria Viruses Eukaryota (eucaryotes)

SUBMITTER: Frank Unfried  

LAB HEAD: Stephanie Markert

PROVIDER: PXD011160 | Pride | 2019-07-09

REPOSITORIES: Pride