Utilization of kelp-derived carbon sources by kelp surface-associated bacteria

Abstract

The surfaces of kelp are covered with bacteria that may utilize kelp-produced carbon and thereby contribute significantly to the carbon flux in kelp forest ecosystems. There is scant knowledge about the identity of these bacteria and about which kelp-derived carbon sources they utilize. An enrichment approach, using kelp constituent carbon sources for bacterial cultivation, was used to identify bacterial populations associated with the kelp Laminaria hyperborea that degrade kelp components. In order to assess whether the cultured bacteria are significant under natural conditions, partial 16 rRNA gene sequences from the cultured bacteria were compared to sequences obtained from the indigenous bacterial communities inhabiting natural kelp surface biofilms. The results identify different members of the Roseobacter clade of Alphaproteobacteria in addition to members of Gammaproteobacteria that are involved in kelp constituent degradation. These bacteria are observed sporadically on natural kelp surfaces and may represent opportunistic bacteria important in degradation of dead kelp material. Many of the cultured bacteria appear to be generalists that are able to utilize different kelp carbon sources. This study is the first to link culturable kelpassociated bacteria with their occurrence and possible roles in the natural environment.

Bacterial diversity in relation to secondary production and succession on surfaces of the kelp Laminaria hyperborea

“…It is closely related to the roseobacter Tateyamaria pelophila (Sass et al, 2010), an isolate from tidal flat sediment that is capable of degradation of laminaran, a brown algal storage polysaccharide. Cultivation experiments using laminaran as a carbon source yielded highly similar strains from L. hyperborea surfaces (Bengtsson et al, 2011). Thus, OTU 90 possibly represents a bacterial species of the genus Tateyamaria that utilizes laminaran as a carbon source on kelp surfaces.…”

Isotopic evidence and consequences of the role of microbes in macroalgae detritus-based food webs

“…Refractory material, such as dissolved organic carbon (DOC), is utilized by bacteria, which form aggregates large enough to be consumed by zooplankton and filter feeders, thus introducing previously inaccessible carbon into the food web (Fenchel 2008). Although recent studies have found extensive and specific microbial communities on kelp blades (Staufenberger et al 2008, Bengtsson et al 2010, little work has been conducted on the microbial utilization of large fragmentary algal detritus (Bengtsson et al 2011).…”

Untangling Genomes of Novel Planctomycetal and Verrucomicrobial Species from Monterey Bay Kelp Forest Metagenomes by Refined Binning

“…Along the central coast of California the kelp forest is of tremendous importance for coastal biodiversity, productivity, and the human economy and kelp-surface-associated bacteria are believed to be important players in carbon and nitrogen turnover in this food web (Linley and Field, 1982; Graham, 2004). While this habitat has been intensively researched for decades, still little is known about the microorganisms associated and interacting with the kelp, as only recently molecular techniques have become available to study biofilm species composition and abundance (Bengtsson et al, 2010, 2011, 2012; Hollants et al, 2013; Michelou et al, 2013). …”