title: Link between domoic acid production and cell physiology after exchange of bacterial communities between toxic Pseudo-nitzschia multiseries and non-toxic Pseudo-nitzschia delicatissima.
abstract: Bacteria are known to influence domoic acid (DA) production by Pseudo-nitzschia spp., but the link between DA production and physiology of diatoms requires more investigation. We compared a toxic P. multiseries to a non-toxic P. delicatissima, investigating links between DA production, physiological parameters, and co-occurring bacteria. Bacterial communities in cultures of both species were reduced by antibiotic treatment, and each of the diatoms was inoculated with the bacterial community of the other species. The physiology of P. delicatissima was minimally affected by the absence of bacteria or the presence of alien bacteria, and no DA was detected. P. multiseries grew faster without bacteria, did not produce a significant amount of DA, and exhibited physiological characteristics of healthy cells. When grown with alien bacteria, P. multiseries did not grow and produced more DA; the physiology of these cells was affected, with decreases in chlorophyll content and photosynthetic efficiency, an increase in esterase activity, and almost 50% mortality of the cells. The alien bacterial community had morphological and cellular characteristics very different from the original bacteria, and the number of free-living bacteria per algal cell was much higher, suggesting the involvement of bacteria in DA production.
authors.affiliation: Marine Environmental Sciences Laboratory (Laboratoire des sciences de l'environnement marin, LEMAR), UMR6539, European Institute for Marine Studies (Institut Universitaire Européen de la Mer, IUEM), Rue Dumont d'Urville, Plouzané 29280, France. aurelai86@hotmail.com.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Lelong
authors.affiliation: Marine Environmental Sciences Laboratory (Laboratoire des sciences de l'environnement marin, LEMAR), UMR6539, European Institute for Marine Studies (Institut Universitaire Européen de la Mer, IUEM), Rue Dumont d'Urville, Plouzané 29280, France. helene.hegaret@univ-brest.fr.
authors.forename: Hélène
authors.initials: H
authors.lastname: Hégaret
authors.affiliation: Marine Environmental Sciences Laboratory (Laboratoire des sciences de l'environnement marin, LEMAR), UMR6539, European Institute for Marine Studies (Institut Universitaire Européen de la Mer, IUEM), Rue Dumont d'Urville, Plouzané 29280, France. philippe.soudant@univ-brest.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Soudant
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000378:metabolism*; D002468:Cell Physiological Phenomena / Q000502:physiology; D002734:Chlorophyll / Q000378:metabolism; D017377:Diatoms / Q000378:metabolism* / Q000382:microbiology / Q000502:physiology; D007608:Kainic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D008387:Marine Toxins / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology; D013045:Species Specificity
chemical_list: D000900:Anti-Bacterial Agents; D008387:Marine Toxins; D002734:Chlorophyll; C012301:domoic acid; D007608:Kainic Acid