A novel rhythm of microcystin biosynthesis is described in the cyanobacterium Microcystis panniformis Komarek et al.

Author(s)

Kujbida, Paula ; Cardozo, Karina Helena Morais ; Carvalho, Valdemir Melechco ; Moura, Ariadne do Nascimento ; Colepicolo, Pio ; Pinto, Ernani ^[6] ; Bittencourt-Oliveira, Maria do Carmo ^[7]

• Document type: Journal article
• Source: Biochemical and Biophysical Research Communications; v. 326, n. 3, p. 687-694, Jan. 2005.
• Field of knowledge: Biological Sciences - Microbiology

Abstract

The presence of microcystins (MCY) in the cyanobacteria Microcystis panniformis Komarek et al. is reported for the first time. This strain of cyanobacterium has been isolated from Barra Bonita, an eutrophicated water reservoir in S (a) over tildeo Paulo state, Brazil. The identification of M. panniformis was confirmed by both traditional morphological analysis and the phycocyanin intergenic spacer sequences. MCY-LR and [Asp(3)]-MCY-LR were identified in this strain after HPLC purification and extensive ESI-MS/MS analysis. Their levels in this strain were determined by HPLC and ranged from 0.25 to 2.75 and 0.08 to 0.75 fmol/cell, respectively. Analyzing the levels of MCY-LR and [Asp(3)]-MCY-LR in different times during the light:dark (L:D) cycle, it was found that levels of MCYs per cell were at least threefold as high during the day-phase than during the night-phase. This may be associated to the biological clock since prokaryotic cyanobacteria express robust circadian (daily) rhythms under the control of a timing mechanism that is independent of the cell division cycle. Our findings also showed the same pattern under light:light (L:L) cycle. (AU)