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:Cyanobacteria are photosynthetic prokaryotes vital to global biogeochemical cycles. However, some form harmful algal blooms (cyanoHABs) that disrupt ecosystems and produce toxins. The mechanisms by which these blooms form have yet to be fully understood, particularly the role of extracellular components. Here, we present a 2.4 Å cryo-EM structure of a pilus, termed the cyanobacterial tubular (CT) pilus, found in the cyanoHAB-forming species Microcystis aeruginosa. The pilin exhibits a novel protein fold, forming a tubular pilus structure with tight, double-layer anti-parallel β-sheet interactions. We show that CT pili are essential for buoyancy by facilitating the formation of micro-colonies, which increases drag force and prevents sinking. Furthermore, the CT pilus surface is heavily glycosylated with ten monosaccharide modifications per pilin. We also found that CT pili can enrich microcystin, potentially enhancing cellular resilience, and co-localize with iron-enriched extracellular matrix components. Thus, we propose that this pilus plays an important role in the proliferation of cyanoHABs. This newly discovered pilus family appears to be widely distributed across several cyanobacterial orders, including Chroococcales, Nostocales, and Synechococcales. Our structural and functional characterization of CT pili provide insights into cyanobacterial cell morphology, physiology, and toxin interactions, and identify potential targets for disrupting bloom formation.
Project description:Freshwater lake microbial communities from Lake Erie, under a cyanobacterial bloom - NOAA_Erie_Diel7S_1600h metaT metatranscriptome
Project description:Freshwater lake microbial communities from Lake Erie, under a cyanobacterial bloom - NOAA_Erie_Diel2S_0400h metaT metatranscriptome