@article{Mahoudeau2026,

title = {The interplay between the marine diazotroph                    \textit{Vibrio diazotrophicus}                    and its prophage shapes both biofilm structure and nitrogen release},

author = {Louise Mahoudeau and Pauline Crétin and Aurélie Joublin-Delavat and Sophie Rodrigues and Clara Guillouche and Isabelle Louvet and Nadège Bienvenu and Claire Geslin and Gabriel Dulaquais and Jean-François Maguer and François Delavat},

editor = {Julia C. van Kessel},

doi = {10.1128/aem.01564-25},

issn = {1098-5336},

year  = {2026},

date = {2026-01-27},

urldate = {2026-01-27},

journal = {Appl Environ Microbiol},

volume = {92},

number = {1},

publisher = {American Society for Microbiology},

abstract = {<jats:title>ABSTRACT</jats:title>

                  <jats:sec>

                    <jats:title/>

                    <jats:p>

                      Marine environments are frequently oligotrophic, characterized by low amount of bioassimilable nitrogen sources. At the global scale, the microbial fixation of N₂, or diazotrophy, represents the primary source of fixed nitrogen in pelagic marine ecosystems, playing a key role in supporting primary production and driving the export of organic matter to the deep ocean. However, given the high energetic cost of N₂ fixation, the active release of fixed nitrogen by diazotrophs appears counterintuitive, suggesting the existence of alternative passive release pathways that remain understudied to date. Here, we show that the marine non-cyanobacterial diazotroph

                      <jats:italic toggle="yes">Vibrio diazotrophicus</jats:italic>

                      is endowed with a prophage belonging to the

                      <jats:italic toggle="yes">Myoviridae</jats:italic>

                      family, whose expression is induced under anoxic and biofilm-forming conditions. We demonstrate that this prophage can spontaneously excise from the genome of its host and that it forms intact and infective phage particles. Moreover, phage-mediated host cell lysis leads to increased biofilm production compared with a prophage-free derivative mutant and to increased release of dissolved organic carbon and ammonium. Altogether, the results suggest that viruses may play a previously unrecognized role in oceanic ecosystem dynamics by structuring microhabitats suitable for diazotrophy and by contributing to the recycling of (in)organic matter.

                    </jats:p>

                  </jats:sec>

                  <jats:sec>

                    <jats:title>IMPORTANCE</jats:title>

                    <jats:p>

                      Diazotrophs are key players in ocean functioning by providing fixed nitrogen to ecosystems and fueling primary production. However, from a physiological point of view, the active release of nitrogenous compounds by diazotrophs is paradoxical, since they would invest in an energy-intensive process and supply nutrient to non-sibling cells, with the risk of being outcompeted. Therefore, alternative ways leading to the release of fixed nitrogen must exist. Here, we show that the marine non-cyanobacterial diazotroph

                      <jats:italic toggle="yes">Vibrio diazotrophicus</jats:italic>

                      possesses one prophage, whose activation leads to cell death, increased biofilm production, and the release of dissolved organic compounds and ammonium. Taken together, our results provide evidence that marine phage–diazotroph interplay leads to the creation of microhabitats suitable for diazotrophy, such as biofilm, and to nutrient cycling, and contributes to better understanding of the role of viruses in marine ecosystems.

                    </jats:p>

                  </jats:sec>},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Crétin2025,

title = {High metabolic versatility and phenotypic heterogeneity in a marine non-cyanobacterial diazotroph},

author = {Pauline Crétin and Louise Mahoudeau and Aurélie Joublin-Delavat and Nicolas Paulhan and Elise Labrune and Julien Verdon and Isabelle Louvet and Jean-François Maguer and François Delavat},

doi = {10.1016/j.cub.2025.04.071},

issn = {0960-9822},

year  = {2025},

date = {2025-05-00},

urldate = {2025-05-00},

journal = {Current Biology},

publisher = {Elsevier BV},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1128/spectrum.04091-23,

title = {Development and utilization of new O_{2}-independent bioreporters},

author = {Eva Agranier and Pauline Crétin and Aurélie Joublin-Delavat and Léa Veillard and Katia Touahri and François Delavat},

url = {https://journals.asm.org/doi/abs/10.1128/spectrum.04091-23

hal-04505221v1 },

doi = {10.1128/spectrum.04091-23},

year  = {2024},

date = {2024-03-05},

urldate = {2024-03-05},

journal = {Microbiology Spectrum},

volume = {0},

number = {0},

pages = {e04091-23},

abstract = {Fluorescent proteins are used for decades, and have allowed major discoveries in biology in a wide variety of fields, and are used in environmental as well as clinical contexts. Green fluorescent protein (GFP) and all its derivatives share a common feature: they rely on the presence of dioxygen (O2) for protein maturation and fluorescence. This dependency precludes their use in anoxic environments. Here, we constructed a series of genetic circuits allowing production of KOFP-7, an O2-independant flavin-binding fluorescent protein. We demonstrated that Escherichia coli cells producing KOFP-7 are fluorescent, both at the population and single-cell levels. Importantly, we showed that, unlike cells producing GFP, cells producing KOFP-7 are fluorescent in anoxia. Finally, we demonstrated that Vibrio diazotrophicus NS1, a facultative anaerobe, is fluorescent in the absence of O2 when KOFP-7 is produced. Altogether, the development of new genetic circuits allowing O2-independent fluorescence will open new perspective to study anaerobic processes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid37853951,

title = {Normal B cells express ZAP70 in chronic lymphocytic leukemia: A link between autoimmunity and lymphoproliferation?},

author = {Dana Ghergus and Mickaël Martin and Anne-Marie Knapp and Fabien Delmotte and Aurélie Joublin-Delavat and Sophie Jung and Jean-Nicolas Schickel and Isabelle Mendel and Arnaud Dupuis and Bernard Drénou and Hervé Ghesquières and Gilles Salles and Lucile Baseggio and Raoul Herbrecht and Anne-Sophie Korganow and Laurent Vallat and Pauline Soulas-Sprauel and Eric Meffre and Thierry Martin},

url = {https://hal.science/hal-04343628v1},

doi = {10.1002/ajh.27137},

issn = {1096-8652},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

journal = {Am J Hematol},

volume = {99},

number = {1},

pages = {48--56},

abstract = {ZAP70 has a prognostic value in chronic lymphocytic leukemia (CLL), through altered B-cell receptor signaling, which is important in CLL pathogenesis. A good correlation between ZAP70 expression in CLL cells and the occurrence of autoimmune phenomena has been reported. Yet, the great majority of CLL-associated autoimmune cytopenia is due to polyclonal immunoglobulin (Ig) G synthesized by nonmalignant B cells, and this phenomenon is poorly understood. Here, we show, using flow cytometry, that a substantial percentage of CD5- nonmalignant B cells from CLL patients expresses ZAP70 compared with CD5- B cells from healthy subjects. This ZAP70 expression in normal B cells from CLL patients was also evidenced by the detection of ZAP70 mRNA at single-cell level with polyclonal Ig heavy- and light-chain gene transcripts. ZAP70+ normal B cells belong to various B-cell subsets and their presence in the naïve B-cell subset suggests that ZAP70 expression may occur during early B-cell development in CLL patients and potentially before malignant transformation. The presence of ZAP70+ normal B cells is associated with autoimmune cytopenia in CLL patients in our cohort of patients, and recombinant antibodies produced from these ZAP70+ nonmalignant B cells were frequently autoreactive including anti-platelet reactivity. These results provide a better understanding of the implication of ZAP70 in CLL leukemogenesis and the mechanisms of autoimmune complications of CLL.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{joublindelavat_genetic_2022,

title = {Genetic and physiological insights into the diazotrophic activity of a non-cyanobacterial marine diazotroph},

author = {Aurélie Joublin-Delavat and Katia Touahri and Pauline Crétin and Amandine Morot and Sophie Rodrigues and Bruno Jesus and Florian Trigodet and François Delavat},

url = {https://onlinelibrary.wiley.com/doi/10.1111/1462-2920.16261

hal-03993957v1 },

doi = {10.1111/1462-2920.16261},

issn = {1462-2912, 1462-2920},

year  = {2022},

date = {2022-12-01},

urldate = {2022-12-01},

journal = {Environmental Microbiology},

volume = {24},

number = {12},

pages = {6510--6523},

abstract = {Nitrogen (N2) fixation, or diazotrophy, supports a large part of primary production in oceans. Culture-independent approaches highlighted the presence in abundance of marine non-cyanobacterial diazotrophs (NCD), but their ecophysiology remains elusive, mostly because of the low number of isolated NCD and because of the lack of available genetic tools for these isolates. Here, a dual genetic and functional approach allowed unveiling the ecophysiology of a marine NCD affiliated to the species Vibrio diazotrophicus. Physiological characterization of the first marine NCD mutant obtained so far was performed using a soft-gellan assay, demonstrating that a ΔnifH mutant is not able to grow in nitrogen-free media. Furthermore, we demonstrated that V. diazotrophicus produces a thick biofilm under diazotrophic conditions, suggesting biofilm production as an adaptive response of this NCD to cope with the inhibition of nitrogen fixation by molecular oxygen. Finally, the genomic signature of V. diazotrophicus is essentially absent from metagenomic data of Tara Ocean expeditions, despite having been isolated from various marine environments. We think that the genetically tractable V. diazotrophicus strain used in this study may serve as an ideal model to study the ecophysiology of these overlooked procaryotic group.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}