Consistency in microbiomes in cultures of Alexandrium species isolated from brackish and marine waters

Abstract

Summary Phytoplankton and bacteria interactions have a significant role in aquatic ecosystem functioning. Associations can range from mutualistic to parasitic, shaping biogeochemical cycles and having a direct influence on phytoplankton growth. How variations in phenotype and sampling location, affect the phytoplankton microbiome is largely unknown. A high‐resolution characterization of the bacterial community in cultures of the dinoflagellate Alexandrium was performed on strains isolated from different geographical locations and at varying anthropogenic impact levels. Microbiomes of Baltic Sea Alexandrium ostenfeldii isolates were dominated by Betaproteobacteria and were consistent over phenotypic and genotypic Alexandrium strain variation, resulting in identification of an A. ostenfeldii core microbiome. Comparisons with in situ bacterial communities showed that taxa found in this A. ostenfeldii core were specifically associated to dinoflagellate dynamics in the Baltic Sea. Microbiomes of Alexandrium tamarense and minutum, isolated from the Mediterranean Sea, differed from those of A. ostenfeldii in bacterial diversity and composition but displayed high consistency, and a core set of bacterial taxa was identified. This indicates that Alexandrium isolates with diverse phenotypes host predictable, species‐specific, core microbiomes reflecting the abiotic conditions from which they were isolated. These findings enable in‐depth studies of potential interactions occurring between Alexandrium and specific bacterial taxa.

Biosynthesis of Saxitoxin in Marine Dinoflagellates: An Omics Perspective

“…The alteration or substitution of local microbial community was demonstrated to cause noteworthy changes in saxitoxin production by the athecate dinoflagellate G. catenatum [118]. This outcome is in agreement with the discovery of a later investigation, in which a few groups of bacteria were found to be present consistently among several strains of A. ostenfeldii, A. minutum, and A. tamarense [119]. The fascinating coexistence of dinoflagellates and bacteria in their phycosphere even led to the formulation of theories of saxitoxin biosynthesis by symbiotic bacteria living within the dinoflagellates.…”

Microbiome Associated With Gambierdiscus balechii Cultures Under Different Toxicity Conditions

“…This notion is similar to previous work on Prorocentrum (Wang et al, 2017;Kim et al, 2021), Alexandrium spp. (Sörenson et al, 2019), and Symbiodiniacean species (Lawson et al, 2018;Nitschke et al, 2020). In the present study, we found that Labrenzia and Muricauda were the most abundant and common bacteria shared across all cultures.…”

Metabolic relationships of uncultured bacteria associated with the microalgae Gambierdiscus

“…This study also showed that algal‐attached communities in seawater are different from bulk particle‐associated communities, indicating that phycosphere communities are specific and distinct from the regional species pool. The Rhodobacteraceae and Flavobacteriaceae reported here are common members of dinoflagellate microbiomes, whereas Planctomycetes are rare or absent in dinoflagellate microbiome sequence sets (Hasegawa et al ., ; Severin and Erdner, ; Sörenson et al ., ). Crenn and colleagues () compared microbiomes of diatoms from cultures and environmental samples, and reported lower diversity in the former.…”