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

Abstract

Algal–bacterial interactions play a major role in shaping diversity of algal associated bacterial communities. Temporal variation in bacterial phylogenetic composition reflects changes of these complex interactions which occur during the algal growth cycle as well as throughout the lifetime of algal blooms. Viruses are also known to cause shifts in bacterial community diversity which could affect algal bloom phases. This study investigated on changes of bacterial and viral abundances, bacterial physiological status, and on bacterial successional pattern associated with the harmful benthic dinoflagellate Ostreopsis cf. ovata in batch cultures over the algal growth cycle. Bacterial community phylogenetic structure was assessed by 16S rRNA gene ION torrent sequencing. A comparison between bacterial community retrieved in cultures and that one co‐occurring in situ during the development of the O. cf. ovata bloom from where the algal strain was isolated was also reported. Bacterial community growth was characterized by a biphasic pattern with the highest contributions (~60%) of highly active bacteria found at the two bacterial exponential growth steps. An alphaproteobacterial consortium composed by the Rhodobacteraceae Dinoroseobacter (22.2%–35.4%) and Roseovarius (5.7%–18.3%), together with Oceanicaulis (14.2‐40.3%), was strongly associated with O. cf. ovata over the algal growth. The Rhodobacteraceae members encompassed phylotypes with an assessed mutualistic‐pathogenic bimodal behavior. Fabibacter (0.7%–25.2%), Labrenzia (5.6%–24.3%), and Dietzia (0.04%–1.7%) were relevant at the stationary phase. Overall, the successional pattern and the metabolic and functional traits of the bacterial community retrieved in culture mirror those ones underpinning O. cf. ovata bloom dynamics in field. Viral abundances increased synoptically with bacterial abundances during the first bacterial exponential growth step while being stationary during the second step. Microbial trends also suggest that viruses induced some shifts in bacterial community composition.

Analysis of random non-autonomous logistic-type differential equations via the Karhunen–Loève expansion and the Random Variable Transformation technique

“…The prominent role of the logistic differential equation to model problems in different settings as Biology (the dynamics of a population), Economics (the diffusion of a new technology or the growth of an economy), Engineering (the variation of physical properties subject to industrial processes), etc., has been extensively discussed and exhibited in numerous contributions (see for instance [1,2,3], [4,5] and [6,7], respectively). The logistic differential equation was first proposed by Pierre-François Verhulst, in his celebrated papers [8,9], to overcome the shortcomings of Malthusian's model to study the population growth.…”

“…Using this assumption, we get the bound corresponding to term (1). Let F 0 = f P 0 (p 0,1 ), by hypothesis H3:…”

Exploring the Role of Macroalgal Surface Metabolites on the Settlement of the Benthic Dinoflagellate Ostreopsis cf. ovata

“…Among co-occurring species on surfaces colonized by O. cf. ovata, Roseobacter bacteria (Vanucci et al, 2016;Guidi et al, 2018), diatoms of the genera Licmophora, Navicula, and Amphora, and the dinoflagellates Prorocentrum lima, Amphidinium carterae, and Coolia monotis (Accoroni et al, 2015;Marro et al, 2019) have been reported to be the most abundant. Recent evidences of chemically mediated interactions between microalgae and their predators (Ianora et al, 2004;Selander et al, 2015), competitors (Tillmann and Hansen, 2009;Poulson-Ellestad et al, 2014;Ternon et al, 2018), and the bacterial community (Wichard and Beemelmanns, 2018 and references therein) suggest that biotic interactions within members of the epiphytic community may also influence the settlement of O. cf.…”

Chemical Ecology of the Benthic Dinoflagellate Genus Ostreopsis: Review of Progress and Future Directions

“…Pérez-Guzmán et al (2008) identified single species belonging to the Cytophaga-Flavobacter-Bacteroides complex. Vanucci et al (2016) and Guidi et al (2018) found Alphaproteobacteria (83 % relative abundance -genera Ruegeria, Jannaschia and Erythrobacter-), Gammaproteobacteria (13%) and Flavobacteria (7%) during the early O. cf. ovata bloom period, while Alphaproteobacteria (66%) and Flavobacteria (19%) were predominant in peak bloom phases.…”

“…The mucilage, rich in organic carbohydrates, appears also as biologically colonizable surface for the growth of some bacteria (Vanucci et al, 2016;Guidi et al, 2018) including Vibrio (Bellés-Garulera et al, 2016). This positive association for pathogenic bacteria increases the risk of health impacts posed by Ostreopsis to human populations.…”