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species! have! been! carried! out! successfully! (39?41).! ! However,! most! of! water!
supply! enterprises! analyze! phytoplankton! composition! from! reservoirs! through!
optical!microscopy!regulated!by!European!legislation!(Directive!2000/60/EC)!(42)!
as! a! routine! technique.! Consequently,! a! search! for! alternative! methods! based! on!
microscope!procedures!to!differentiate!between!toxin?producing!and!non?toxic!M.)
aeruginosa!strains!is!vital.!

Lectins! are! carbohydrate?binding! proteins! or! glycoprotein! of! non?immune!
origin,! which! specifically! conjugates! with! monosaccharides! or! simple!
oligosaccharides!(43).!Lectins!are!important!reagents!for!analyzing!cell!surface!and!
cell!components!in!bacteria,!yeast,!protozoa!and!higher!microorganisms!(reviewed!
by! 44,! 45).! They! play! a! role! in! biological! recognition! phenomena! and! the!
interaction!of!lectins!with!the!surfaces!of!microorganisms!has!been!widely!applied!
for!typing!bacteria!and!protists!(reviewed!by!46,!47).!In!a!pioneer!paper,!Costas!&!
López?Rodas! (1994)! (48)! demonstrated! that! different! species! and! strains! of!
marine! dinoflagellates! could! be! identified! microscopically! using! fluorescent!
lectins.! This! lectin?binding! procedure! is! also! able! to! discriminate! between! toxin?
producing! and! non?toxic! strains! of! marine! dinoflagellates! of! genus! Gymnodinium.!
This!ability!of!lectins!to!bind!non?covalently!to!sugars!of!surface!cells!has!received!
early! attention! in! phycological! studies.! Lectins! have! been! used! to! differentiate!
species! and! strains! of! several! microalgal! species! (49?51)! including! toxic!
dinoflagellates!(52,!53)!and!domoic?acid!producing!diatoms!(54).!Lectins!were!also!
effective! probes! for! differentiating! between! different! species! and! strains! of!
Microcystis) sp! (55,! 56)! and! other! toxic! cyanobacteria! species! (57).! These! results!
indicate! that! lectins!could!be!useful!tools!in!discriminating!species!and!strains!of!
toxic!cyanobacteria.!!

In! this! regard,! Kehr! et! al.! (2006)! (58)! report! the! discovery! of! a! new! lectin,!
microvirin! (MVN),! isolated! from! M.) aeruginosa! strain! PCC7806,! which! is! involved!
in! cell?cell! attachment! of! M.) aeruginosa.! Apparently,! MVN! lectin! is! differentially!
expressed! in! microcystin?producing! wild! type! genotypes! and! mutants! lacking! the!
microcystin.!

In!this!study,!we!analyze!the!usefulness!of!fluorescent?labeled!lectin!assays!
to!microscopically!differentiate!strains!of!M.)aeruginosa!that!occurs!simultaneously!
within!the!same!and!between!blooms.!Three!M.)aeruginosa!blooms!in!water!supply!
reservoirs! of! Spain! as! well! as! one! bloom,! which! caused! mass! mortality! of! wildlife!
in! Doñana! National! Park! (Spain)! were! analysed.! The! results! suggest! that!
fluorescent! lectins! are! a! rapid! procedure! to! microscopically! characterize! strains!
and!to!discriminate!between!toxic!and!non?toxic!strains!of!M.)aeruginosa.!

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