Allelopathy in freshwater cyanobacteria

Abstract

Freshwater cyanobacteria produce several bioactive secondary metabolites with diverse chemical structure, which may achieve high concentrations in the aquatic medium when cyanobacterial blooms occur. Some of the compounds released by cyanobacteria have allelopathic properties, influencing the biological processes of other phytoplankton or aquatic plants. These kinds of interactions are more easily detectable under laboratory studies; however their ecological relevance is often debated. Recent research has discovered new allelopathic properties in some cyanobacteria species, new allelochemicals and elucidated some of the allelopathic mechanisms. Ecosystem-level approaches have shed some light on the factors that influence allelopathic interactions, as well as how cyanobacteria may be able to modulate their surrounding environment by means of allelochemical release. Nevertheless, the role of allelopathy in cyanobacteria ecology is still not well understood, and its clarification should benefit from carefully designed field studies, chemical characterization of allelochemicals and new methodological approaches at the "omics" level.

Dissolved organic matter (DOM) release by phytoplankton in the contemporary and future ocean

“…In contrast, the raphidophyte Heterosigma akashiwo releases a high molecular weight polysaccharide-protein complex (> 1 000 000 Da) that inhibits the growth of the diatom Skeletonema costatum by binding to the surface of the cells (Yamasaki et al, 2009). There is an extensive and rapidly growing literature on allelopathy associated with phytoplankton, which is beyond the scope of this review (see reviews by Gross, 2003;Legrand et al, 2003;Leão et al, 2009). …”

“…The most common effects of allelochemicals are cell lysis and growth inhibition (Legrand et al, 2003). Being defined by function, allelochemicals have diverse chemical structures and molecular weights (Leão et al, 2009). Karenia brevis produces multiple small (500 to 1000 Da) allelochemicals containing aromatic groups that inhibit the growth of the diatom Asterionellopsis glacialis (Prince et al, 2010).…”

Growth inhibitory effect of Microcystis on Aphanizomenon flos-aquae isolated from cyanobacteria bloom in Lake Dianchi, China

“…This may occur via allelopathy which is defined as direct or indirect effect of one plant (including micro-organisms) on another through the emission of chemicals into the environment (Rice, 1984). Cyanobacteria produce a wide range of allelochemicals, which are involved in inter-specific interactions including inhibiting the growth of competitors, and some of these allelochemicals are identified as inter alia, cyclic and non-cyclic peptides, polyketides, alkaloids, phenols and chlorinated aromatic compounds Leão et al, 2009).…”

Synergistic allelochemicals from a freshwater cyanobacterium

“…17), and the allelopathic potential of these organisms was described through field-derived observations in the 1970s (18,19). Since then, several genera of cyanobacteria have been implicated in allelopathic phenomena, with targets ranging from other cyanobacteria to higher plants; unfortunately, only a very limited number of allelochemicals have been identified and mainly from freshwater cyanobacteria (20). These include cyanobacterin, a chlorinated γ-lactone produced by Scytonema hofmanni that inhibits other cyanobacteria and green microalgae (21); fischerellin A, an enediyne-containing photosystem II inhibitor produced by Fischerella muscicula (22); the hapalindoles, small metabolites that have been isolated from Hapalosiphon and Fischerella spp.…”