Disentangling the relative influence of bacterioplankton phylogeny and metabolism on lysogeny in reservoirs and lagoons

Abstract

Previous studies indicate that lysogeny is preponderant when environmental conditions are challenging for the bacterial communities and when their metabolism is reduced. Furthermore, it appears that lysogeny is more frequent within certain bacterial phylogenetic groups. In this comparative study from 10 freshwater reservoirs and 10 coastal lagoons, we aim to disentangle the influence of these different factors. In eight reservoirs and four lagoons, lysogeny was detected by induction assays with mitomycin C, and induction significantly modified the bacterial community composition (BCC), whereas community composition remained constant in ecosystems in which lysogeny was not observed. Among the phylogenetic groups studied, the most abundant ones were Bacteroidetes and a-proteobacteria in lagoons, and b-proteobacteria and Bacteroidetes in reservoirs. These dominant groups comprised the highest proportions of inducible lysogens. In order to unravel the effects of bacterial metabolism from phylogeny on lysogeny, we measured bacterial community physiology and the specific activities of selected phylogenetic groups. The proportion of inducible lysogens within the a-and the b-proteobacteria decreased with increasing group-specific metabolism in lagoons and reservoirs, respectively. In contrast, this relationship was not observed for the other lysogen-containing groups. Hence, both host physiology and phylogeny are critical for the establishment of lysogeny. This study illustrates the importance of lysogeny among the most abundant phylogenetic groups, and further suggests its strong structuring impact on BCC.

Oxygen minimum zones harbour novel viral communities with low diversity

“…We hypothesize that the viruses tend towards lysogeny in the anoxic core regardless of season consistent with considering the ETSP OMZ as an extreme environment. Consistent with this hypothesis, the number of inducible prophage was found to decrease with increasing bacterial metabolism in lagoons and reservoirs (Maurice et al ., ). Last, the microbes of the anoxic core may have been particle associated and not been sampled because of the pre‐filtering steps.…”

“…In addition, low microbial abundances have been correlated with a greater frequency of lysogeny in deeper low oxygen marine waters (Ram et al ., ; Corinaldesi et al ., ; Magagnini et al ., ). A higher abundance of lysogeny‐associated domains were identified in marine‐vent viromes compared with surface water viromes, leading to the hypothesis of higher levels of lysogeny in extreme environments (Maurice et al ., ; Anderson et al ., ). A similar switch in viral lifestyle may occur the anoxic core of the ETSP OMZ.…”

Tropical freshwater ecosystems have lower bacterial growth efficiency than temperate ones

“…Alternatively, strong grazing control might likely maintain bacterial communities in a rapid growth condition (e.g., as in the exponential growth phase), resulting in high-energy metabolic expenditure (such as in the ATP paradox, see discussion above). Concerning viral infection, there is almost no information available on how viral infection varies with latitude or temperature, but it has been suggested that higher bacterial metabolic rates are usually associated with low viral induced lysogeny (Maurice et al, 2010). …”

Epibiotic bacterial community of Sphaeroma serratum (Crustacea, Isopoda): relationship with molt status

“…This high taxonomic diversity within the Proteobacteria coincides with a high degree of morphological diversity. Although the bacterioplankton community of the surrounding water was not investigated in the present study, Proteobacteria, Bacteroidetes and Actinobacteria are frequently reported from coastal waters (Fuhrman & Ouverney 1998, Longnecker et al 2005, Bouvier & Del Giorgio 2007, Maurice et al 2011. Surprisingly, neither Bacteroidetes nor Actinobacteria could be detected on the spherom cuticle.…”