Bioactive Potential of Two Marine Picocyanobacteria Belonging to Cyanobium and Synechococcus Genera

Abstract

Coccoid cyanobacteria produce a great variety of secondary metabolites, which may have useful properties, such as antibacterial, antiviral, anticoagulant or anticancer activities. These cyanobacterial metabolites have high ecological significance, and they could be considered responsible for the widespread occurrence of these microorganisms. Considering the great benefit derived from the identification of competent cyanobacteria for the extraction of bioactive compounds, two strains of picocyanobacteria (coccoid cyanobacteria < 3 µm) (Cyanobium sp. ITAC108 and Synechococcus sp. ITAC107) isolated from the Mediterranean sponge Petrosia ficiformis were analyzed. The biological effects of organic and aqueous extracts from these picocyanobacteria toward the nauplii of Artemia salina, sea urchin embryos and human cancer lines (HeLa cells) were evaluated. Methanolic and aqueous extracts from the two strains strongly inhibited larval development; on the contrary, in ethyl acetate and hexane extracts, the percentage of anomalous embryos was low. Moreover, all the extracts of the two strains inhibited HeLa cell proliferation, but methanol extracts exerted the highest activity. Gas chromatography–mass spectrometry analysis evidenced for the first time the presence of β-N-methylamino-l-alanine and microcystin in these picocyanobacteria. The strong cytotoxic activity observed for aqueous and methanolic extracts of these two cyanobacteria laid the foundation for the production of bioactive compounds of pharmacological interest.

Microcystins and Cyanobacterial Contaminants in the French Small-Scale Productions of Spirulina (Limnospira sp.)

“…The absence of Microcystis in our samples is consistent with the difficulty for M. aeruginosa to develop under the spirulina culture conditions previously highlighted [ 50 ]. Nevertheless, according to the literature, eight of the cyanobacterial contaminant taxa identified in our study are potential producers of MCs: Aphanocapsa [ 51 ], Cyanobium [ 28 , 30 ], Geitlerinema [ 52 , 53 , 54 ], Leptolyngbya [ 54 , 55 , 56 ], Merismopedia [ 55 ], Phormidium [ 52 , 53 , 54 ], Pseudanabaena [ 52 ] and Spirulina [ 52 ]. This information must be interpreted with caution because the taxonomy of cyanobacteria is continuously evolving with the consequence of a possible confusion of the identification of the species studied in terms of toxin production.…”

“…Potential toxin-producing cyanobacteria identified to date include species belonging to the following genera: Microcystis, Planktothrix , Dolichospermum ( Anabaena ), Anabaenopsis , Fischerella , Geitlerinema , Leptolyngbya , Merismopedia , Phormidium, Nostoc and Synechocystis —and others species: Annamia toxica , Aphanocapsa cumulus , Calothrix parietina , Hapalosiphon hibernicus , Radiocystis fernandoi , Cyanobium bacillare , Arthrospira fusiformis , Limnothrix redekei and Trichormus variabilis [ 27 , 28 , 29 , 30 , 31 , 32 ]. Some of these possibly toxin-producing cyanobacteria ( Calothrix , Phormidium , Microcystis , Nostoc , Anabaenopsis , Geitlerinema , Leptolyngbya ) have been identified through molecular analysis of dry spirulina samples [ 33 ].…”

Microalgae: A Promising Future

“…Among microalgae, cyanobacteria are one of the most investigated microorganisms for biotechnological purposes, as three reports of the Special Issue demonstrate [ 17 , 18 , 19 ].…”

“…Although new bioactive molecules from the microbial world continue to be discovered, this however remains a field that is still little explored. With the investigations on two cyanobacterial strains, Pagliara and co-authors [ 19 ] intended to contribute to increasing the amount of information on the properties of these microorganisms, expanding the cyanobacteria range from which new compounds with significant bioactivity could be identified. The two strains, belonging to Cyanobium and Synechococcus genera, have been previously identified after their isolation from a Mediterranean marine sponge [ 23 , 24 ].…”