PEPCY-Toxic and Bioactive PEPtides in CYanobacteria

Background

Cyanobacterial peptides (cyanopeptides) are among the most ubiquitously found potentially hazardous substances in surface waters used by humans. Though these substances are natural in origin, eutrophication (i.e. excessive loading with fertilising nutrients) has caused massive cyanobacterial proliferation throughout Europe. Thus, cyanopeptides now occur with unnatural frequency and concentration.

A large group among the diverse cyanopeptides are the oligopeptides (peptides with a molecular weight of <1KD). But while specific cyanopeptides - e.g. microcystins and nodularins - are well studied and recognised as being causative for many animal poisonings and human illness, a substantial and increasing body of evidence points toward a decisive role of other potentially toxic cyanopeptides in the causation of both acute and chronic human illnesses:

Recently, substantial progress in elucidation of the structures and the biosynthesis of some of these other cyanopeptides has been made (by partners of this consortium), and preliminary information on toxicity of microviridins, aeruginosins, cyanopeptolins, microginins and other cyanopeptides is emerging. This information shows that one species or "morphotype" (i.e. individuals with the same morphological characteristics) may comprise a range of genotypes that encode for different "chemotypes" (i.e. morphologically indistinguishable individuals containing different cyanopeptides). Prediction of the occurrence of toxic cyanobacterial blooms is thus at best difficult if not impossible.

Therefore, it is of utmost importance to identify and to structurally, physiologically and toxicologically characterize these cyanopeptides (and associated taxa) and, in conjunction with a thorough understanding of the genetic and environmental factors leading to toxin occurrence, to provide a basis for exposure pathway specific and mechanism based human health risk assessment. However, the evidence on toxic cyanopeptides beyond the well-studied microcystins and nodularins is highly fragmented. Therefore, a concerted effort for a comprehensive assessment of human health hazards caused by the spectrum of cyanopeptides is crucial for proper risk assessment and risk management.