Effect of a transient perturbation on marine bacterial communities with contrasting history

Abstract

Aims: To evaluate the importance of the bacterial composition on the resilience of the organic matter assimilation in the sea. Methods and Results: Chemostats were inoculated with coastal and offshore bacterial communities. Bacterial density and protein synthesis increased before stabilizing, and this response to confinement was more marked in the offshore chemostats. Before the toluene perturbation the community structure in the coastal chemostats remained complex whereas the offshore chemostats became dominated by Alteromonas sp. After the perturbation, bacterial protein synthesis was inhibited before peaking briefly at a level fivefold to that observed before the perturbation and then stabilizing at a level comparable to that before the perturbation. Alteromonas dominated both the coastal and the offshore communities immediately after the perturbation and the coastal communities did not recover their initial complexity. Conclusions: Cell lysis induced by the toluene perturbation favoured the growth of Alteromonas which could initiate growth rapidly in response to the nutrient pulse. Despite their different community structure in situ, the resilience of protein synthesis of coastal and offshore bacterial communities was dependent on Alteromonas, which dominated in the chemostats. Significance and Impact of the Study: Here we show that although Alteromonas sp. dominated in artificial offshore and coastal communities in chemostats, their response time to the shock was different. This suggests that future perturbation studies on resilience in the marine environment should take account of ecosystem history.

Transcriptional responses of surface water marine microbial assemblages to deep‐sea water amendment

“…1B). Since A. macleodii has been observed to commonly respond to perturbation experiments (Schäfer et al ., 2000; Zemb et al ., 2010), as seen here in both DSW and DOM treatments (but not the control), we then explored potential differences in the genomic composition and transcriptome responses of A. macleodii populations between the two treatments (see below in the section of Alteromonas ‐centric analysis).…”

Genomes of surface isolates of Alteromonas macleodii: the life of a widespread marine opportunistic copiotroph

“…AltDE-like sequences were also detected, although at much lower abundance. This data illustrate by a totally different methodology the relevance of this microbe as an r- strategist that blooms under conditions of sudden increase in the availability of resources (probably DOM released or exudated by the phytoplankton)121314.…”

Homogeneity and Synchronous Dynamics of Microbial Communities in Particulate Biofilms: from Major Populations to Minor Groups

“…1) ensures good mixing conditions throughout the whole reactor, not only for the liquid but also for the solid phase, with a constant rate of particle attrition (21). If each particle is considered an individual ecosystem in ITBR, the bacterial community composition may change independently over time, as shown in replicated bioreactors without a physical link (6, 7, 13, 23, 32). Thus, this question of heterogeneity or homogeneity in a homogeneous environment was never a central concern in previous studies.…”

“…In particular, the behavior of replicated communities evolving in distinct ecosystems with similar environmental conditions may diverge over time (4, 7, 23, 32). The make-up of the microbial communities results from the balance of two opposite shaping forces, one leading to convergence while the other to divergence.…”