Physiological responses of Raphidiopsis raciborskii (Cyanobacteria) strains to water conductivity: effect of sodium and magnesium ions

• Published in: Hydrobiologia Vol. 847; no. 11; pp. 2449 - 2464
• Main Authors: de Lima, Daniel Vinícius Neves, Pacheco, Ana Beatriz Furlanetto, Goulart, Carolina Lage, e Azevedo, Sandra Maria Feliciano de Oliveira
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-06-2020; Springer; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Blooms; Carbohydrates; Conductivity; Cyanobacteria; Ecology; Electric properties; Ethylenediaminetetraacetic acid; Freshwater & Marine Ecology; Growth; Life Sciences; Magnesium; Magnesium chloride; Marine toxins; Photosynthesis; Physiological aspects; Physiological effects; Physiological responses; Physiology; Primary Research Paper; Profiles; Raphidiopsis raciborskii; Salinity; Salt; Salts; Saxitoxin; Semi arid areas; Semiarid lands; Sodium; Sodium chloride; Tropical climate; Water; Water conductivity; Zoology; Halotolerance; Saxitoxin; Ecophysiology; Harmful algae blooms; Nostocales
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-020-04265-3

Cyanobacterial blooms dominated by
Raphidiopsis raciborskii
, a potential producer of saxitoxin (STX), are commonly reported in continental water bodies of semiarid regions with high conductivity (> 1000 µS cm
−1
). STX production is proposed as a cellular protection mechanism against salt stress. Here, we test the hypothesis that high conductivity favors
R. raciborskii
growth and that STX is advantageous under this condition. We included four tropical strains (two STX
+
and two STX
−
) cultured for 12 days in control (450 µS cm
−1
) or in media with NaCl (10 mM) or MgCl
2
(5 mM) (1500 µS cm
−1
). High conductivity (either NaCl or MgCl
2
) had neutral or positive effects on growth for all strains. Total STX content did not differ in response to salt concentrations. All strains could tolerate higher conductivity without signals of stress, as noted for stable photosynthetic parameters and protein expression profiles. For the strain with higher growth in salt, accumulation of intracellular carbohydrates occurred in early times (3 days). In conclusion, high conductivity is a favorable condition for
R. raciborskii
, with no clear relation with the ability to produce STX. Pronounced intraspecific variability was observed, a fact that must be considered for a better understanding of this species.