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1. Marine gas-phase sulfur emissions during an induced phytoplankton bloom

   https://doi.org/10.5194/acp-22-1601-2022  

   Kilgour, Delaney B.; Novak, Gordon A.; Sauer, Jon S.; Moore, Alexia N.; Dinasquet, Julie; Amiri, Sarah; Franklin, Emily B.; Mayer, Kathryn; Winter, Margaux; Morris, Clare K.; et al (January 2022, Atmospheric Chemistry and Physics)

   Abstract. The oxidation of dimethyl sulfide (DMS;CH3SCH3), emitted from the surface ocean, contributes to theformation of Aitken mode particles and their growth to cloud condensationnuclei (CCN) sizes in remote marine environments. It is not clear whetherother less commonly measured marine-derived, sulfur-containing gases sharesimilar dynamics to DMS and contribute to secondary marine aerosolformation. Here, we present measurements of gas-phase volatile organosulfurmolecules taken with a Vocus proton-transfer-reaction high-resolutiontime-of-flight mass spectrometer during a mesocosm phytoplankton bloomexperiment using coastal seawater. We show that DMS, methanethiol (MeSH;CH3SH), and benzothiazole (C7H5NS) account for on averageover 90 % of total gas-phase sulfur emissions, with non-DMS sulfur sourcesrepresenting 36.8 ± 7.7 % of sulfur emissions during the first 9 d of the experiment in the pre-bloom phase prior to major biologicalgrowth, before declining to 14.5 ± 6.0 % in the latter half of theexperiment when DMS dominates during the bloom and decay phases. The molarratio of DMS to MeSH during the pre-bloom phase (DMS : MeSH = 4.60 ± 0.93) was consistent with the range of previously calculated ambient DMS-to-MeSH sea-to-air flux ratios. As the experiment progressed, the DMS to MeSHemission ratio increased significantly, reaching 31.8 ± 18.7 duringthe bloom and decay. Measurements of dimethylsulfoniopropionate (DMSP),heterotrophic bacteria, and enzyme activity in the seawater suggest theDMS : MeSH ratio is a sensitive indicator of the bacterial sulfur demand andthe composition and magnitude of available sulfur sources in seawater. Theevolving DMS : MeSH ratio and the emission of a new aerosol precursor gas,benzothiazole, have important implications for secondary sulfate formationpathways in coastal marine environments. 

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2. Bacterial virulence against an oceanic bloom-forming phytoplankter is mediated by algal DMSP

   https://doi.org/10.1126/sciadv.aau5716  

   Barak-Gavish, Noa; Frada, Miguel José; Ku, Chuan; Lee, Peter A.; DiTullio, Giacomo R.; Malitsky, Sergey; Aharoni, Asaph; Green, Stefan J.; Rotkopf, Ron; Kartvelishvily, Elena; et al (October 2018, Science Advances)

   Emiliania huxleyi is a bloom-forming microalga that affects the global sulfur cycle by producing large amounts of dimethylsulfoniopropionate (DMSP) and its volatile metabolic product dimethyl sulfide. Top-down regulation of E. huxleyi blooms has been attributed to viruses and grazers; however, the possible involvement of algicidal bacteria in bloom demise has remained elusive. We demonstrate that a Roseobacter strain, Sulfitobacter D7, that we isolated from a North Atlantic E. huxleyi bloom, exhibited algicidal effects against E. huxleyi upon coculturing. Both the alga and the bacterium were found to co-occur during a natural E. huxleyi bloom, therefore establishing this host-pathogen system as an attractive, ecologically relevant model for studying algal-bacterial interactions in the oceans. During interaction, Sulfitobacter D7 consumed and metabolized algal DMSP to produce high amounts of methanethiol, an alternative product of DMSP catabolism. We revealed a unique strain-specific response, in which E. huxleyi strains that exuded higher amounts of DMSP were more susceptible to Sulfitobacter D7 infection. Intriguingly, exogenous application of DMSP enhanced bacterial virulence and induced susceptibility in an algal strain typically resistant to the bacterial pathogen. This enhanced virulence was highly specific to DMSP compared to addition of propionate and glycerol which had no effect on bacterial virulence. We propose a novel function for DMSP, in addition to its central role in mutualistic interactions among marine organisms, as a mediator of bacterial virulence that may regulate E. huxleyi blooms. 

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3. Indole-3-acetic acid promotes growth in bloom-forming Microcystis via an antioxidant response

   https://doi.org/10.1016/j.hal.2024.102575  

   Baylous, Hunter R; Gladfelter, Matthew F; Gardner, Malia I; Foley, Madalynn; Wilson, Alan E; Steffen, Morgan M (March 2024, Harmful Algae)
4. Molecular forecasting of toxic bloom events

   https://doi.org/10.1073/pnas.2417139121  

   Alexander, Harriet (October 2024, Proceedings of the National Academy of Sciences)
5. Regular multi-types and the Bloom conjecture

   https://doi.org/10.1016/j.matpur.2020.05.007  

   Huang, Xiaojun; Yin, Wanke (February 2021, Journal de Mathématiques Pures et Appliquées)

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