Microcystis Chemotype Diversity in the Alimentary Tract of Bigheaded Carp

Abstract

Most cyanobacterial organisms included in the genus Microcystis can produce a wide repertoire of secondary metabolites. In the mid-2010s, summer cyanobacterial blooms of Microcystis sp. occurred regularly in Lake Balaton. During this period, we investigated how the alimentary tract of filter-feeding bigheaded carps could deliver different chemotypes of viable cyanobacteria with specific peptide patterns. Twenty-five Microcystis strains were isolated from pelagic plankton samples (14 samples) and the hindguts of bigheaded carp (11 samples), and three bloom samples were collected from the scums of cyanobacterial blooms. An LC-MS/MS-based untargeted approach was used to analyze peptide patterns, which identified 36 anabaenopeptin, 17 microginin, and 13 microcystin variants. Heat map clustering visualization was used to compare the identified chemotypes. A lack of separation was observed in peptide patterns of Microcystis that originated from hindguts, water samples, and bloom-samples. Except for 13 peptides, all other congeners were detected from the viable and cultivated chemotypes of bigheaded carp. This finding suggests that the alimentary tract of bigheaded carps is not simply an extreme habitat, but may also supply the cyanobacterial strains that represent the pelagic chemotypes.

Anabaenopeptins: What We Know So Far

“…A total of 45, 29, and 12 cyanobacteria strains from freshwater, marine and terrestrial environment have been analyzed for AP production, respectively. As seen in Table 2 and according to the literature [ 34 , 40 , 41 , 53 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 ], marine strains produced a total of 50 different variants of APs, in comparison to 43 and 34 variants from freshwater, and terrestrial strains, respectively ( Figure 7 ). Thus, marine cyanobacteria demonstrate to produce a higher number of distinct APs variants in comparison to the remaining strains from different sources.…”

Anabaenopeptins from Cyanobacteria in Freshwater Bodies of Greece

“…The detection of APs was based on the diagnostic fragment ion of lysine (Lys) m/z 84 [3], which was present in the fragmentation spectra of all APs (Figures 2-4 and S2-S11). Structural elucidation of APs was based on fragmentation patterns described in previous studies [3,9,10,23,25,44,48] and on immonium ions of the common amino acids. In Table 1, both leucine (Leu) and isoleucine (Ile) are provided in the proposed AP sequences as these amino acids are isobaric compounds with the same chemical formula (C 6 H 13 NO 2 ) and they could not be distinguished.…”

“…The presence of APs has been reported in freshwater [2][3][4][5][6] and marine cyanobacterial blooms [7][8][9], as well as in terrestrial environments, including the leaves of plants in a coastal forest [10] and the terrestrial mat in a bamboo forest [11]. APs are produced by freshwater, marine and terrestrial cyanobacteria [12] mainly belonging to the genera Planktothrix [13,14], Anabaena [15][16][17][18], Microcystis [19][20][21][22][23] and Nostoc [24,25]. They especially belong to the species Planktothrix (Oscillatoria) agardhii [3,[26][27][28][29][30][31][32], Planktothrix rubescens [30,31,33,34], Anabaena (Dolichospermum) flos-aquae [35], Anabaena lemmermannii [36], Microcystis aeruginosa [3,[37][38][39], Microcystis flos-aquae [36], Microcystis ichthyoblabe, Microcystis wesenbergii [19] and Nostoc punctiforme [40], as we...…”

“…Furthermore, APs could possibly control cyanobacterial population density as the presence of APs (i.e., Anabaenopeptin B and Anabaenopeptin F) has been correlated with the triggering of cell lysis that ends up in the collapse of cyanobacterial blooms [72]. The occurrence of APs in cyanobacterial blooms and cultured strains from freshwater bodies has been reported more frequently during recent years in several countries worldwide, including Japan [2,[26][27][28], Germany [3,13,19,20], Finland [16,18], Norway [73,74], Poland [47,75,76], Slovenia [33], Czech Republic [22,77], Austria [34], Hungary [23], Switzerland [78], Spain [4,6,79], Portugal [37,38], Italy [80][81][82][83][84], France [85,86], United Kingdom [85,87], Turkey [44], Israel [21,39,88], Brazil [89], Canada [59,86,90], USA [64,…”

“…Nuclear magnetic resonance (NMR), after the isolation of the compound, usually from a cyanobacterial strain culture, has been used for the structural elucidation of APs e.g., [2,26,27,35]. Mass spectrometric (MS) techniques such as Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) [3,22,95] or MS coupled with liquid chromatography such as liquid chromatography-hybrid triple quadrupole/linear ion trap mass spectrometry (LC-qTRAP) [8,23,25,40,45,48] or liquid chromatography-hybrid triple quadrupole/Time-of-Flight (LC-qTOF) [24,44] are nowadays widely used as they can be applied directly to extracts of field samples or strain cultures. A significant indicator of APs fragmentation spectrum is the characteristic fragment ion of lysine (Lys) at m/z 84 [3].…”