Enslavement in the Water Body by Toxic Aphanizomenon ovalisporum, Inducing Alkaline Phosphatase in Phytoplanktons

Abstract

The hepatotoxin cylindrospermopsin (CYN) produced by certain cyanobacteria, including Aphanizomenon ovalisporum (hereafter Aphanizomenon) [1], seriously affects lake water quality [2], but its biological role is not known. Strong correlation between Aphanizomenon abundance in Lake Kinneret, Israel, and alkaline phosphatase (APase) activity suggests that inorganic phosphate (Pi) limitation induces the PHO regulon and APase secretion [3]. Staining lake samples with DAPI [4] revealed a high level of polyphosphate bodies (PPB) in Aphanizomenon. Application of enzyme-labeled fluorescence (ELF-APase) [5] showed APase in various organisms, but not in Aphanizomenon. ELF-APase signals and extracellular APase activity in Aphanizomenon were detected only after exploiting PPB under prolonged Pi deprivation in cultures or toward the end of its autumn bloom. Pi deprivation of Aphanizomenon induces CYN production, high-affinity Pi uptake, and an internal, not external, APase. Addition of Aphanizomenon spent media or CYN to various phytoplanktons, including Chlamydomonas reinhardtii, induced genes typically upregulated under Pi limitation and a rise in extracellular APase activity, despite ample surrounding Pi. Coculturing Aphanizomenon with Chlamydomonas or with Debarya sp. showed positive ELF-APase signals, but not in Aphanizomenon. CYN producers promote Pi supply by inducing APase secretion by other phytoplanktons, possibly explaining their increased abundance despite reduced Pi supply from watersheds.

Transcriptional response of Prochlorococcus to co-culture with a marine Alteromonas: differences between strains and the involvement of putative infochemicals

“…Taken together, these results rule out nutrient or carbon starvation as major mechanisms underlying the inhibition of MIT9313 strain by high cell densities of Alteromonas HOT1A3. They also suggest that the inhibitory effect of large cell concentrations of HOT1A3 on MIT9313 is not due to interference with nutrient uptake or sensing (Bar-Yosef et al, 2010).…”

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

“…In lakes, where physico-chemical factors are relatively stable, allelopathy is thought to play a nonnegligible role in the alternating successions of algae species and in the formation and ending of blooms (Kearns and Hunter, 2001;Takano et al, 2003;Vardi et al, 2002). Previous studies have revealed the occurrence of interspecific allelopathy among cyanobacteria (Bar-Yosef et al, 2010;e Mello et al, 2012;Gantar et al, 2008;Rzymski et al, 2014;Schagerl et al, 2002). However, the population dynamics of cyanobacteria blooms have rarely been considered in light of the chemical interactions occurring among the dominant cyanobacteria species.…”

Constitutive Cylindrospermopsin Pool Size in Cylindrospermopsis raciborskii under Different Light and CO 2 Partial Pressure Conditions

“…The difference from other cyanobacterial species may be related to the different role(s) attributed to cyanobacterial toxins (45). For instance, the presence of dissolved dCYN in the water column could be beneficial for C. raciborskii growth through allelopathic effects on other phytoplankton species (e.g., inducing alkaline phosphatase secretion) (46)(47)(48) and zooplankton grazers (49). Their toxicities to mammals would then be seen as an inadvertent secondary effect.…”