Diversity and distribution of Microcystis (Cyanobacteria) oligopeptide chemotypes from natural communities studied by single-colony mass spectrometry

Abstract

Microcystis sp. has been recognized in recent years as a producer of a high number of secondary metabolites. Among these, peptides that are produced by the non-ribosomal peptide synthetase pathway often show bioactivity or are toxic to humans. The production of particular peptides is specific for individual Microcystis clones, allowing their characterization as chemotypes by analysing the peptidome. The authors studied the in situ diversity of peptides and chemotypes in Microcystis communities from lakes in and around Berlin, Germany, by direct analysis of individual colonies by MALDI-TOF mass spectrometry. From 165 colonies analysed a total of 46 individual peptides could be identified, 21 of which have not been described previously. For six of the new peptides the structures could be elucidated from fragment patterns, while for others only a preliminary classification could be achieved. In most colonies, two to ten individual peptides were detected. In 19 colonies, 16 of which were identified as M. wesenbergii, no peptide metabolites could be detected. The peptide data of 146 colonies were subjected to an ordination (principal components analysis). The principal components were clearly formed by the microcystin variants Mcyst-LR, -RR and -YR, anabaenopeptins B and E/F, a putative microviridin, and a new cyanopeptolin. In the resulting ordination plots most colonies were grouped into five distinct groups, while 40 colonies scattered widely outside these groups. In some cases colonies from different lakes clustered closely, indicating the presence of similar chemotypes in the respective samples. With respect to colony morphology no clear correlation between a chemotype and a morphospecies could be established, but M. aeruginosa, for example, was found to produce predominantly microcystins. In contrast, M. ichthyoblabe colonies were mostly negative for microcystins and instead produced anabaenopeptins. The number of peptides detected in a limited number of samples and the various combinations of peptides in individual Microcystis colonies highlights the immense metabolic potential and diversity of this genus.

Belowground responses of Picea asperata seedlings to warming and nitrogen fertilization in the eastern Tibetan Plateau

“…Many studies have reported warming effects on ecosystem C exchange (Welker et al 2004;Niu et al 2008). Warming induced more litter and root production, which could possibly explain the higher soil organic carbon storage in UW plots.…”

Intact-cell MALDI-TOF mass spectrometry analysis of peptaibol formation by the genus Trichoderma/Hypocrea: can molecular phylogeny of species predict peptaibol structures?

“…ICMS spectra in the range below 2 kDa identify characteristic metabolites, e.g. of bacilli (Williams et al, 2002;Pabel et al, 2003) and cyanobacteria (Erhard et al,1997;Welker et al, 2002Welker et al, , 2004a, and we show here that highly characteristic peptaibol spectra can readily be obtained from microgram amounts of mycelia, thus providing characteristic metabolite fingerprints. A comparison of these fingerprints with molecular phylogenies of the species documents some correlation between types of peptaibol formed and phylogeny.…”

“…Both types of spectra are useful for the identification of specific strains (Neuhof et al, 2007a, b (Fastner et al, 2001;Welker et al, 2004aWelker et al, , b, 2006.…”

“…Both cases have been well documented in cyanobacteria, where numerous isolates from single biotopes showed a large variety of chemotypes. As in the case of Trichoderma/Hypocrea, the compounds derived from NRPS genes in cyanobacteria have been used for chemotype definition (Welker et al, 2004a(Welker et al, , b, 2006.…”

“…In the case of peptaibols, we also see a patchwork-like distribution of products, and even strains of the same (confirmed) species may display variable product patterns. Such distributions have been analysed by employing MALDI-TOF MS typing of single filaments or microcolonies of cyanobacteria characterizing single clones within defined biotopes (Fastner et al, 2001;Welker et al, 2002Welker et al, , 2004aWelker et al, , b, 2006Welker & von Döhren, 2006). In one example, 18 clones isolated from single filaments of Planktothrix from a single lake represented 15 chemotypes with respect to at least 11 different non-ribosomal peptides, including 25 analogues.…”