Host-specific adaptation governs the interaction of the marine diatom, Pseudo-nitzschia and their microbiota

Abstract

The association of phytoplankton with bacteria is ubiquitous in nature and the bacteria that associate with different phytoplankton species are very diverse. The influence of these bacteria in the physiology and ecology of the host and the evolutionary forces that shape the relationship are still not understood. In this study, we used the Pseudo-nitzschia-microbiota association to determine (1) if algal species with distinct domoic acid (DA) production are selection factors that structures the bacterial community, (2) if host-specificity and co-adaptation govern the association, (3) the functional roles of isolated member of microbiota on diatom-hosts fitness and (4) the influence of microbiota in changing the phenotype of the diatom hosts with regards to toxin production. Analysis of the pyrosequencing-derived 16S rDNA data suggests that the three tested species of Pseudo-nitzschia, which vary in toxin production, have phylogenetically distinct bacterial communities, and toxic Pseudo-nitzschia have lower microbial diversity than non-toxic Pseudonitzschia. Transplant experiments showed that isolated members of the microbiota are mutualistic to their native hosts but some are commensal or parasitic to foreign hosts, hinting at co-evolution between partners. Moreover, Pseudo-nitzschia host can gain protection from algalytic bacteria by maintaining association with its microbiota. Pseudo-nitzschia also exhibit different phenotypic expression with regards to DA production, and this depends on the bacterial species with which the host associates. Hence, the influences of the microbiota on diatom host physiology should be considered when studying the biology and ecology of marine diatoms.

Microbial dynamics during harmful dinoflagellate Ostreopsis cf. ovata growth: Bacterial succession and viral abundance pattern

“…A deep knowledge on phylogenetic composition and successional dynamics of bacterial communities associated with HABs is therefore recognized as a crucial step for unveiling relevant and recurrent algal‐bacterial associations underpinning the different bloom phases (Bagatini et al., ; Mayali et al., ; Tada, Taniguchi, Sato‐Takabe, & Hamasaki, ; Yang et al., ), and in parallel with complementing laboratory‐based studies, it will allow to elucidate the functional significance of these complex interactions (Bagatini et al., ; Buchan et al., ; Kazamia, Helliwell, Purton, & Smith, ; Sison‐Mangus et al., ). Indeed, although 16S rRNA gene phylogenetic surveys do not directly decode bacterial functionality, they still provide insights on how the different bacterial groups correlate within the assemblages and with the microalgal partner, considering certain metabolic characteristics significant to the groups and to the associated organism (Amin et al., ; Buchan et al., ; Gifford, Sharma, & Moran, ; Newton et al., ).…”

Biosynthesis of the neurotoxin domoic acid in a bloom-forming diatom

“…Although abiotic (12) and biotic (13) factors have been shown to affect toxicity in culture, the biological and physicochemical mechanisms underlying DA production in Pseudo-nitzschia are unclear. Moreover, not all Pseudo-nitzschia blooms produce DA (12).…”

Analysis of raw and pre-treated seawater for potential biofouling precursors

“…In this study, the high quantity of TEP measured in seawater and the microbial community composition for each water sources contributed to the difference in TEP formation observed on the RO membrane from both experiments. Bacteria and diatoms were observed on all biofouled membranes and this along with the observed TEP and nutrients would have formed a microbiota which has been proven to contribute to biofilm formation and its regulation [53].…”