20.500.12556/DiRROS-31843 Viral lysis accelerates microbial succession patterns resembling diatom senescence Diatom blooms influence carbon cycling through organic matter production and its deposition or remineralization – processes mediated by the microbial community. Viruses can influence diatom bloom dynamics and even terminate blooms, yet interactions between diatoms, their viruses, and associated bacteria remain poorly resolved. Here, we examined how infection of the toxigenic diatom Pseudo-nitzschia galaxiae by its ssRNA virus PnGalRNAV reshapes host physiology, microbiome structure, and organic-matter processing in non-axenic batch cultures. Using epi-fluorescence microscopy, 16S rRNA amplicon sequencing, and metatranscriptomics, we linked microbial composition, localisation, and functional activity during viral lysis. Infection rapidly collapsed diatom growth and induced a senescence-like host state, with broad repression of photosynthesis, silicon metabolism, and core biosynthetic pathways, alongside induction of heat-shock and other stress-related genes. Concurrently, phycosphere-associated bacteria declined, detritosphere-associated bacteria increased, and community composition shifted from Marinobacter (Gammaproteobacteria) dominated, towards Flavobacteriaceae (Bacteroidetes) dominated, especially by Polaribacter. In non-infected controls Alphaproteobacteria proved to benefit from the stable healthy phycospheres with a distinct DOM pool. Bacterial metatranscriptomes showed significant upregulation of polysaccharide-degradation-associated genes in infected cultures, indicating active utilisation of lysis-derived diatom glycans. Similar compositional and metabolic profiles in infected cultures and later-stage senescent controls suggest infection accelerated senescence-associated microbial processes. Overall, viral lysis converted a productive diatom culture into a detrital, DOM-rich environment that selects for specialised polysaccharide degraders, redirects carbon through the viral shunt and may accelerate nutrient recycling in coastal systems. Extending this approach to natural microbial communities and diverse diatom–virus systems will help determine whether these mechanisms are broadly conserved. diatoms virus bacteria Pseudo-nitzschia shunt senescence microbiome phycosphere mikrobiom diatomeja virus okužba transkriptom true false false Angleški jezik Slovenski jezik Neznano 2026-08-10 16:05:04 2026-08-10 16:05:05 2026-08-11 03:45:13 0000-00-00 00:00:00 2026 0 0 Soavtorji: Gutiérrez-Aguirre Ion, Rupnik Tinkara, Tinta Tinkara; Nasl. z nasl. zaslona; Opis vira z dne 10. 8. 2026; str. 1-28 Vol. 2026 0000-00-00 PreprintVObjavi VTisku NiDoloceno 0000-00-00 0000-00-00 2026-08-05 579 1751-7370 10.1093/ismejo/wrag206 287425283 https://doi.org/10.1093/ismejo/wrag206 1 7e1bf620-94c4-11f1-af5a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=49477 RAZ_Turk_Dermastia_Timotej_2026.pdf RAZ_Turk_Dermastia_Timotej_2026.pdf 1 46C5CE00AF21713912781C6BEA94A0A1 080a333c09c936f8a01a2543666b06ec3f323182ffb1bf8036185f3604526efc 8e5ee57e-94c4-11f1-af5a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=49478 Nacionalni inštitut za biologijo 0 0 0