Cyanobacteria are prokaryotic microorganisms that are present in all freshwater environments. A certain number of cyanobacterial species have the ability of producing toxic secondary metabolites. The massive growth (or bloom) of toxigenic cyanobacteria can lead to high concentrations of toxins in the water, thus posing a threat to human health. Eutrophication is the main driver of cyanobacterial blooms, but ongoing climate changes can exacerbate the problem. Cyanobacterial toxins (cyanotoxins) are secondary metabolites with a huge chemical diversity due to the high flexibility of their biosynthetic pathways.1 Research conducted in the last fifteen years at Fondazione Edmund Mach has revealed that the biosynthetic pathways are common to all toxigenic cyanobacteria, but that the resultant toxic molecules are very dependent on the species.2 For instance, the cyanobacteria Planktothrix rubescens and Microcystis aeruginosa (among the most frequent responsible of toxic blooms around the world) both have the same gene cluster of the hepatotoxic microcystins (MC), but they synthetize different variants of MC. Moreover, the same set of MC are produced in different ratios by different strains of P. rubescens. These examples show how an integrated biological and chemical approach can be very effective in studying toxigenic cyanobacteria. This approach has demonstrated to be very useful in addressing the toxic potential of populations of cyanobacteria in different natural lakes.3 The presence of cyanotoxins in freshwaters is a matter that is taken into consideration by legislation in most countries and specific monitoring programs are routinely carried out by sanitary/environmental agencies. An emerging issue that is not yet considered by legislation is the presence of toxic cyanobacteria attached to different types of substrates (rocks, stones, vegetation) on the shores of lakes and rivers. Our recent studies revealed that some potent neurotoxins (anatoxins) can be produced in very high quantities by cyanobacteria growing in these environments. Such “biofilms” can constitute a relevant sanitary problem, considered that they can be easily accessed by people and animals walking on the shores.
Cerasino, L.; Salmaso, N. (2024). Toxins of freshwater microorganisms: from bio- to chemodiversity. In: XXVIII Congresso Nazionale della Società Chimica Italiana: chimica, elementi di futuro, Milano, 26-30 agosto 2024. handle: https://hdl.handle.net/10449/86695
Toxins of freshwater microorganisms: from bio- to chemodiversity
Cerasino, L.
Primo
;Salmaso, N.Ultimo
2024-01-01
Abstract
Cyanobacteria are prokaryotic microorganisms that are present in all freshwater environments. A certain number of cyanobacterial species have the ability of producing toxic secondary metabolites. The massive growth (or bloom) of toxigenic cyanobacteria can lead to high concentrations of toxins in the water, thus posing a threat to human health. Eutrophication is the main driver of cyanobacterial blooms, but ongoing climate changes can exacerbate the problem. Cyanobacterial toxins (cyanotoxins) are secondary metabolites with a huge chemical diversity due to the high flexibility of their biosynthetic pathways.1 Research conducted in the last fifteen years at Fondazione Edmund Mach has revealed that the biosynthetic pathways are common to all toxigenic cyanobacteria, but that the resultant toxic molecules are very dependent on the species.2 For instance, the cyanobacteria Planktothrix rubescens and Microcystis aeruginosa (among the most frequent responsible of toxic blooms around the world) both have the same gene cluster of the hepatotoxic microcystins (MC), but they synthetize different variants of MC. Moreover, the same set of MC are produced in different ratios by different strains of P. rubescens. These examples show how an integrated biological and chemical approach can be very effective in studying toxigenic cyanobacteria. This approach has demonstrated to be very useful in addressing the toxic potential of populations of cyanobacteria in different natural lakes.3 The presence of cyanotoxins in freshwaters is a matter that is taken into consideration by legislation in most countries and specific monitoring programs are routinely carried out by sanitary/environmental agencies. An emerging issue that is not yet considered by legislation is the presence of toxic cyanobacteria attached to different types of substrates (rocks, stones, vegetation) on the shores of lakes and rivers. Our recent studies revealed that some potent neurotoxins (anatoxins) can be produced in very high quantities by cyanobacteria growing in these environments. Such “biofilms” can constitute a relevant sanitary problem, considered that they can be easily accessed by people and animals walking on the shores.File | Dimensione | Formato | |
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