Comparative analysis of bacterioplankton assemblages from Karenia brevis bloom and nonbloom water on the west Florida shelf (Gulf of Mexico, USA) using 16S rRNA gene clone libraries

Abstract

The brevetoxin-producing dinoflagellate, Karenia brevis, forms nearly annual blooms off the Florida west coast, severely impacting the region's ecology and economy. Bacteria are often cited as either promoting or interfering with the development of algal blooms, and thus a detailed study of the bacterioplankton assemblages associated with K. brevis was undertaken. We developed sixteen 16S rRNA gene clone libraries from K. brevis bloom and adjacent nonbloom water to determine the bacterial groups present and assess the influence of K. brevis cell number and/or depth on bacterioplankton community composition. Most notably, bacterial groups such as Rhodobacterales (Alphaproteobacteria) and Cytophagales/Sphingobacteriales (Bacteroidetes), reported previously to be associated with other harmful algal species, were often abundant in the presence of K. brevis. Cyanobacteria frequently dominated surface samples containing no detectable K. brevis, consistent with earlier work suggesting that these photosynthetic organisms may be important in promoting the proliferation of these blooms by conditioning the water. Moreover, differences in the abundance/diversity of traditionally more rare and often undocumented phylogenetic groups (e.g. Betaproteobacteria, Deltaproteobacteria, Chloroflexus, Firmicutes) were apparent in bloom vs. nonbloom water. This is the first study to document the association of these phylogenetic groups with natural K. brevis populations and suggests a potential role for these microorganisms in K. brevis bloom dynamics.

Dynamics of bacterial community structure during blooms of Cochlodinium polykrikoides (Gymnodiniales, Dinophyceae) in Korean coastal waters

“…11B) indicated that Rhodobacterales had statistically positive correlation with the C. polykrikoides populations (p 0.01). Previous reports have indicated that this order was closely correlated with other dinoflagellate blooms formed by Akashiwo sanguinea, Alexandrium spp., Gymnodinium catenatum, Karenia mikimotoi, and Prorocentrum lima (Lafay et al, 1995;Garcé s et al, 2007;Green et al, 2004;Jasti et al, 2005;Jones et al, 2010;Yang et al, 2015). Rhodobacterales is the second most abundant bacterial group in marine environments Rappé et al, 2000).…”

“…Interestingly, large physio-chemical changes may not be essential to initiate blooms of C. polykrikoides as this species has significant ecophysiological tolerance for changes in temperature, salinity, and nutrients (Kudela et al, 2008;Gobler et al, 2012). Recent studies of dinoflagellates have reported that blooms can be closely related to the characteristics of the associated bacteria (Jones et al, 2010 and references therein) with algicidal bacteria perhaps contributing to bloom demise (Mayali and Azam, 2004). The single study to consider bacteria and C. polykrikoides blooms to date reported 10-fold higher bacterial densities associated with C. polykrikoides blooms and used terminal restriction fragment length polymorphisms (T-RFLP) to demonstrate that blooms were associated with a bacterial flora that differed significantly from nearby non-bloom algal populations (Koch et al, 2014).…”

Evolutionary Ecology of the Marine Roseobacter Clade

“…Indeed, modern lineages of roseobacters are abundant and consistent components of the phycosphere community of these phytoplankton groups (12,(15)(16)(17)(64)(65)(66)(67). The predicted occurrence of genes involved in motility and chemotaxis in the ancestor of the Roseobacter clade would have potentially allowed cells to sense and swim toward phytoplankton (41), enabled by a cell size of red-plastid-lineage phytoplankton large enough to be detected by chemotaxis (68); earlier-evolving phytoplankton groups dominated by the cyanobacteria and green algal lineages were considerably smaller.…”

“…Roseobacter clade members not only grow on these carbohydrates (e.g., Planktotalea frisia) but also may grow better on exudates produced by certain species (85), raising the possibility of an adaptive association of roseobacters with specific phytoplankton lineages. The organic sulfur compound dimethylsulfoniopropionate (DMSP) is produced in abundance by dinoflagellates and coccolithophorids (12,17,67), two phytoplankton groups often found associated with roseobacters in ocean waters (15,16,(64)(65)(66). DMSP acts as a specific chemical cue that attracts motile and chemotactic bacteria, including roseobacters (86).…”

Evidence against fluvial seeding of recurrent toxic blooms of Microcystis spp. in Lake Erie's western basin

“…The UniFrac web interface has been previously utilized to successfully study dynamics of microbial populations in diverse environments such as hot springs, the mammalian intestinal tract and marine phytoplankton blooms (Lozupone et al, 2007;Jones et al, 2010), and we chose this method to differentiate the cyanobacterial populations herein. UniFrac was applied to the ITS sequences from the Maumee River, Maumee Bay, and the western basin of Lake Erie to examine the similarities in the entire cyanobacterial community between the different locations.…”