Chemical and Genetic Diversity of Nodularia spumigena from the Baltic Sea

Abstract

Nodularia spumigena is a toxic, filamentous cyanobacterium occurring in brackish waters worldwide, yet forms extensive recurrent blooms in the Baltic Sea. N. spumigena produces several classes of non-ribosomal peptides (NRPs) that are active against several key metabolic enzymes. Previously, strains from geographically distant regions showed distinct NRP metabolic profiles. In this work, conspecific diversity in N. spumigena was studied using chemical and genetic approaches. NRP profiles were determined in 25 N. spumigena strains isolated in different years and from different locations in the Baltic Sea using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Genetic diversity was assessed by targeting the phycocyanin intergenic spacer and flanking regions (cpcBA-IGS). Overall, 14 spumigins, 5 aeruginosins, 2 pseudaeruginosins, 2 nodularins, 36 anabaenopeptins, and one new cyanopeptolin-like peptide were identified among the strains. Seven anabaenopeptins were new structures; one cyanopeptolin-like peptide was discovered in N. spumigena for the first time. Based on NRP profiles and cpcBA-IGS sequences, the strains were grouped into two main clusters without apparent influence of year and location, indicating persistent presence of these two subpopulations in the Baltic Sea. This study is a major step in using chemical profiling to explore conspecific diversity with a higher resolution than with a sole genetic approach.

High Diversity of Microcystin Chemotypes within a Summer Bloom of the Cyanobacterium Microcystis botrys

“…The factor scores were saved as variables using a regression method and plotted with R [78]. MC profiles of toxigenic strains were visualized by hierarchical clustering using a Jaccard dissimilarity matrix (presence/absence, see Table 2) [79]. A permutation test was performed to test for equality of means of the number of MC variants produced among the sampling occasions.…”

Thiamin (vitamin B1) content in phytoplankton and zooplankton in the presence of filamentous cyanobacteria

“…This enzyme is inhibited under oxidative stress, which limits the production of NADH that ultimately leads to less energy available for other crucial cellular processes (Tretter and Adam‐Vizi ). Filamentous cyanobacteria produce nonribosomal peptides, e.g., microcystin and nodularin (Mazur‐Marzec et al ), which can cause oxidative stress in exposed cells (Bouaïcha and Maatouk ) as well as in several aquatic organisms (Jos et al ; Persson et al ; Esterhuizen‐Londt et al ). This could explain the reduced copepod TDP content in cyanobacteria treatments but the cellular mechanisms are beyond the scope of this study.…”

Genomic and Metabolomic Analyses of Natural Products in Nodularia spumigena Isolated from a Shrimp Culture Pond

“…A search for gene clusters responsible for the synthesis of natural products in N. spumigena CENA596 revealed a similar genomic construction to that found in the genomes of the Baltic N. spumigena CCY9414 and UHCC 0039 strains. However, LC-HR-QTOF mass spectrometry analyses showed lower variant production of the nonribosomal peptides NOD, SPU, APT, and AER by the Brazilian strain than the Baltic strains [42,44,46,50]. The co-production of toxin (NOD) and odorous (geosmin) metabolites by N. spumigena CENA596 during bloom episodes in shrimp ponds raises concern for human and animal health issues along with economic losses.…”

“…CENA596 produced two variants of NOD (NOD and [D-Asp 1 ]NOD), SPU (D and F), and AER (NAL2 and NOL3) (File S1); compounds which were previously identified in CCY9414 and UHCC 0039 [42,44,50] (Table 1). However, the Baltic strains produced several other variants of SPU and AER that were not identified in CENA596.…”

“…Table 1. Natural products identified in the Nodularia spumigena CENA596 and comparison to those previously identified in strains CCY9414 and UHCC 0039 (AV1) [42,44,50]. MW represents the molecular weight of the compounds.…”