title: [Comparison of daily alkaline phosphatase activity of a cyanobacterium (Microcystis aeruginosa) and a diatom (Synedra capitata)].
abstract: Alkaline phosphatase activity (ALP) (EC: 3.1.3.1) presents a nycthemeral variation in both Microcystis aeruginosa (cyanobacterium) and Synedra capitata (diatom) species. Nevertheless, a comparative study reveals differences between the enzymatic behaviour of these two species. ALP is 33 times higher in cyanobacteria than in diatoms under similar experimental conditions. Microcystis aeruginosa presents therefore a larger capacity for mineralizing organic phosphorus per unit of biomass. Under LD (16:8) conditions, diatoms show a higher enzymatic activity during the day time (around 0.12 mumol pNPP/mn/mg); on the contrary, cyanobacterial enzymatic activity is rather low during the day time and rises at the beginning of night time (around 3.5 mumol pNPP/mn/mg). Finally, the mean of ALP of Synedra capitata is maximal (around 0.12 mumol pNPP/mn/mg) under total darkness (DD) while the mean of enzymatic activity is maximal (around 3.58 mumol pNPP/mn/mg) under permanent light (LL) for the cyanobacteria. These observed differences in the alkaline phosphatase activity between Microcystis aeruginosa and Synedra capitata might, to some extent, explain the observed alternances within the planktonic settlements between algae and cyanobacteria in hypereutrophic lakes such as the Grangent reservoir (Loire).
authors.affiliation: Laboratoire de biologie animale et appliquée, faculté des sciences et techniques, université Jean-Monnet, Saint-Etienne France.
authors.forename: H
authors.initials: H
authors.lastname: Giraudet
authors.forename: J L
authors.initials: JL
authors.lastname: Berthon
authors.forename: B
authors.initials: B
authors.lastname: Buisson
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D000704:Analysis of Variance; D002940:Circadian Rhythm; D017377:Diatoms / Q000201:enzymology*; D008029:Lighting; D046931:Microcystis / Q000201:enzymology*
chemical_list: D000469:Alkaline Phosphatase
vernacular_title: Comparaison de l'activité phosphatase alcaline quotidienne d'une cyanobactérie (Microcystis aeruginosa) et d'une diatomée (Synedra capitata).