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Vibrio pectenicia Causes Sea Star Wasting Disease

48:34 recording · AUTO · 3 speakers

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Brief overview

Vibrio pectensidia causes sea star wasting disease, and microcolony-seq reveals inherited phenotypic memory inside bacterial populations.

  1. Koch's postulates finally closed a decade-old marine mysteryTransmission, sequencing, pure culture of strain FHCF-3, re-infection and re-isolation all pointed to Vibrio pectensidia, not the densovirus earlier theories favoured.
  2. A single colony is not one phenotypeMicrocolony-seq found stable subpopulations within 500 micron colonies, differing in virulence genes, motility, salt tolerance and adherence to HeLa cells.
  3. Bacterial memory is real, and stationary phase erases itEpigenetic changes carried from host-like conditions persist over many replication rounds, then reset in stationary phase — the finding Mark said blew his hat off.
Executive Summary AI
  • Michael Schmidt opens with a Nature Ecology and Evolution snippet by 15 authors on the epidemic that started in 2013 and wiped out sea stars from Mexico to Alaska, leaving the sunflower sea star Pycnopodia helanthioides functionally extinct in much of its southern range and critically endangered.2:29
  • Deep sequencing of coelomic fluid showed one bacterium, Vibrio pectensidia, making up between 23 and as much as 99% of all bacterial reads in diseased stars, far above the trace levels in healthy-looking ones.6:47
  • Injecting healthy quarantined sea stars with the pure cultured strain FHCF-3 reproduced arm twisting, autonomy and death in a dose-dependent way, while heat-killed controls stayed normal, and a 0.22 micron filter removed the agent — ruling out both a molecular toxin and a virus.8:35
  • Mark Martin then presents a Cell paper from the Hebrew University in Jerusalem describing microcolony-seq, which uncovers inherited phenotypic diversity directly from infected human samples and reveals long-term genetic and non-genetic memory of the host environment.18:46
  • In EPEC grown three hours in DMEM, small and big colony subpopulations differed in flagellar, chemotaxis and type 3 secretion gene expression, and those differences get reset during stationary phase, with the perA and perB genes implicated.22:35
Key Quote
“Today, we're going to be a witness to a classic case of microbial detective work, fulfilling Koch's postulates and finally pinning down a culprit for this devastating CSAR wasting disease.”
— Michael Schmidt2:00
Key Quote
“but life doesn't care about our rules and the small masters of our microbial world agree.”
— Mark Martin14:43
Key Quote
“And we often, every student thinks that a colony forms from a single cell and that that colony is genetically homogenous. It's not so.”
— Mark Martin19:52