Co-occurrence of microcystin and microginin congeners in Brazilian strains ofMicrocystissp.

Abstract

Species of Microcystis are the most common bloom‐forming cyanobacteria in several countries. Despite extensive studies regarding the production of bioactive cyanopeptides in this genus, there are limited data on isolated strains from Brazil. Three Microcystis sp. strains were isolated from the Salto Grande Reservoir (LTPNA01, 08 and 09) and investigated for the presence of mcy genes, microcystins and other cyanopeptides. Microcystin and microginin production was confirmed in two isolates using high‐resolution tandem mass spectrometry after electrospray ionization (ESI‐Q‐TOF), and the structures of two new microginin congeners were proposed (MG756 Ahda‐Val‐Leu‐Hty‐Tyr and MG770 MeAhda‐Val‐Leu‐Hty‐Tyr). The biosynthesis profile of the identified cyanopeptides was evaluated at different growth phases via a newly developed HPLC‐UV method. Results demonstrated no substantial differences in the production of microcystins and microginins after data normalization to cell quota, suggesting a constitutive biosynthesis. This study represents the first confirmed co‐production of microginins and microcystins in Brazilian strains of Microcystis sp. and highlights the potential of Brazilian cyanobacteria as a source of natural compounds with pharmaceutical interest.

Growth and Saxitoxin Production by Cylindrospermopsis raciborskii (Cyanobacteria) Correlate with Water Hardness

“…Growth rates were estimated according to Carneiro et al . [40]. Briefly, the exponential growth period was determined by exponential regressions, and the exponential growth phase was considered when the data adherence was higher than 95% ( R 2 ≥ 0.95).…”

Microcystin‐LR Detected in a Low Molecular Weight Fraction from a Crude Extract of Zoanthus sociatus

“…Other cyclopeptides with similar elution time, maximum UV absorbance at 220–274 nm and m / z 995 were previously reported as cyanopeptolin [47]. However, the isomerization [48] and co-elution with another congeners, like cyanopeptolin [47,49] and microginin [50], can produce unusual UV spectra. The co-occurrence of cyanotoxins with other congeners is a common fact supporting the possibility of components co-elution.…”

“…It is noteworthy the presence of putative co-eluting components detected by MS of the peak 2 (Supplementary Figure S3). Unfortunately, the amount of the fraction was limited, and further purification steps based on the gradient elution with phosphoric acid as the mobile phase was not possible to perform as previously reported [50]. …”

Efeito do herbicida glifosato sobre o crescimento e produção de metabólitos secundários em Microcystis aeruginosa e Cylindrospermopsis raciborskii

“…SPC804 de Microcystis, mas a confirmação estrutural destes compostos não foi realizada. No ano seguinte, duas novas moléculas de microgininas foram identificadas na linhagem brasileira Microcystis aeruginosa LTPNA 08(CARNEIRO et al, 2012). Neste mesmo artigo (Anexo 2), mais de 30 variantes de microgininas já descritas são relacionadas (Tabela 7).…”

“…Neste mesmo artigo (Anexo 2), mais de 30 variantes de microgininas já descritas são relacionadas (Tabela 7). Sequência de aminoácidos de algumas microgininas (MG) descritas na literatura CARNEIRO et al, 2012.. Da mesma forma que para as cianotoxinas, desconhece-se o papel que microgininas exercem no metabolismo das cianobactérias.Segundo Neumann et al.…”