Permanent residents or temporary lodgers: characterizing intracellular bacterial communities in the siphonous green algaBryopsis

Abstract

The ecological success of giant celled, siphonous green algae in coastal habitats has repeatedly been linked to endophytic bacteria living within the cytoplasm of the hosts. Yet, very little is known about the relative importance of evolutionary and ecological factors controlling the intracellular bacterial flora of these seaweeds. Using the marine alga Bryopsis (Bryopsidales, Chlorophyta) as a model, we explore the diversity of the intracellular bacterial communities and investigate whether their composition is controlled by ecological and biogeographic factors rather than the evolutionary history of the host. Using a combination of 16S rDNA clone libraries and denaturing gradient gel electrophoresis analyses, we show that Bryopsis harbours a mixture of relatively few but phylogenetically diverse bacterial species. Variation partitioning analyses show a strong impact of local environmental factors on the presence of Rickettsia and Mycoplasma in their association with Bryopsis. The presence of Flavobacteriaceae and Bacteroidetes, on the other hand, reflects a predominant imprint of host evolutionary history, suggesting that these bacteria are more specialized in their association. The results highlight the importance of interpreting the presence of individual bacterial phylotypes in the light of ecological and evolutionary principles such as phylogenetic niche conservatism to understand complex endobiotic communities and the parameters shaping them.

Invasion Is a Community Affair: Clandestine Followers in the Bacterial Community Associated to Green Algae, Caulerpa racemosa, Track the Invasion Source

“…In light of these very new findings, we suggest that a more complete sampling including these newly identified native and invaded ranges would add further important information to more precisely identify the origin of Mediterranean invasion. However, our results, allied to other recent studies [32,33], suggest that our understanding of biological invasions need to evolve from a focus on the competitive capacities of the invasive species, to consideration of the ‘meta-organism’, or ‘holobiont’ including the synergies between the host and associated bacterial communities determining their adaptation to their new environment and their capacity to outcompete native organisms.…”

“…This demonstrates the stability of bacterial communities during the course of transport and invasion, also indicating their potential to trace the origin of invasion. These results add to recent evidence that the bacteria flora of macro-organisms, including human, is unique, even at the level of individual, and provides an important potential as a tool in identification of taxonomic entities and pathways of migration [15,32,33,36,44]. …”

“…racemosa (Table S2) both in its native and in its invasive range, reaching or exceeding the already high level of diversity reported for exceptional holobionts such as coral or sponges systems [24]. Also, the diversity of the bacterial community found in this study, overcomes the already large diversity found for another siphonous alga – Bryopsis – [31,32,33]. However, the use of DGGE in this study like for the majority of studies aiming to characterize bacterial endophytes thus far may have led to underestimation of the bacterial diversity.…”

Large-scale seaweed cultivation diverges water and sediment microbial communities in the coast of Nan'ao Island, South China Sea

“…Recent reports on the epiphytic and endophytic microbial communities of various seaweeds (green alga, red alga and brown alga) based on varying methods such as scanning electron microscope, restriction fragment length polymorphism (RFLP), catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH), denaturing gradient gel electrophoresis (DGGE) fingerprinting, and 16S rRNA gene sequencing (Falkowski and De Vargas, 2004;Pennisi, 2006) have revealed that seaweed-associated bacteria are host-specific and temporally-variable (Campbell et al, 2015;Hollants et al, 2013b;Hollants et al, 2011;Lachnit et al, 2009;Lachnit et al, 2011;Mancuso et al, 2016). Also, the taxonomically diverse microbial communities associated with seaweed (Armstrong et al, 2001;Burke et al, 2011a) performed important functions for their hosts (Egan et al, 2013).…”

The Effect of Thermal Stress on the Bacterial Microbiome of Exaiptasia diaphana

“…The relative abundance of an indicator species from the family Rhizobiaceae increased as bleaching progressed. Bacteria in the family Rhizobiaceae may be intracellular associates of marine alga [99,100]. However, the increase of this ASV alongside a diminishing Symbiodiniaceae population may indicate that increasing temperature was a stronger promoter of growth than Symbiodiniaceae association.…”