Project description:Harmful algal blooms present severe environmental threats, impacting water quality, aquatic ecosystems, and human health. The frequency and intensity of these blooms are rising, largely driven by global warming and changing climatic conditions. There is an urgent need for innovative methods to monitor blue-green algae, also known as cyanobacteria, to enable the implementation of preventative measures. Here, we show that native mass spectrometry is an effective tool for detecting cyanobacteria directly from lake samples, both prior and during bloom formation. Our approach allows for the rapid characterization of cyanobacterial populations within lakes, offering valuable insights into the dynamics of cyanobacterial species associated with harmful algae blooms. Overall, we highlight the exceptional capability of native mass spectrometry in directly detecting and monitoring cyanobacterial blooms, which will support the development of more effective strategies to mitigate this growing environmental challenge.
Project description:Nodularia spumigena is a toxic, filamentous cyanobacterium capable to fix atmospheric N2, which is often dominating cyanobacterial bloom events in the Baltic Sea and other brackish water systems worldwide. Phosphate (P) limitation has been considered as one environmental parameter that is somehow promoting the establishment of cyanobacterial mass developments. In the present study, we analyzed the response of the N. spumigena strain CCY9914 towards strong P limitation in an experimental approach. Filaments of N. spumigena were incubated under P-replete and P-deplete conditions for 21 days. Samples for RNA-seq were collected after 7 and 14 days. Growth of the strain was diminished under P-deplete conditions, however, filaments contained more polyphosphate under P-deplete compared to P-replete conditions. High polyphosphate contents were also detected within heterocysts. After 7 days, approximately 100 genes were upregulated in P-deplete filaments, among them was a high proportion of genes encoding proteins related to P-homeostasis such as transport systems for different P species. Many of these genes became also up-regulated after 14 days compared to 7 days in filaments grown under P-replete conditions, which was consistent with the almost complete consumption of dissolved P in these cultures after 14 days. In addition to genes directly related to P starvation, for example genes encoding proteins for bioactive compound synthesis, gas vesicle formation, or sugar catabolism were stimulated under the P-deplete conditions. Collectively, our data permitted to describe an experimentally validated P-stimulon in N. spumigena CCY9914 and provide evidence that severe P limitation could indeed support bloom formation by this filamentous strain.