@article{fdi:010072997,
  title = {{A}ssessment of the dinitrogen released as ammonium and dissolved organic nitrogen by unicellular and filamentous marine diazotrophic cyanobacteria grown in culture},
  author = {{B}erthelot, {H}. and {B}onnet, {S}ophie and {C}amps, {M}. and {G}rosso, {O}. and {M}outin, {T}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he dinitrogen ({N} 2) fixed by diazotrophs and released as dissolved nitrogen ({DN}) has been compared in batch cultures of four marine diazotrophic cyanobacteria: the colony forming {T}richodesmium {IMS}101 and the unicellular strains {C}yanothece {ATCC}51142, {C}rocosphaera watsonii {WH}8501 and {WH}0003. {T}wo approaches were conducted for this purpose. {T}he first approach consisted in the comparison of the total accumulation of fixed {N} 2 in the culture medium (both in the dissolved and particulate pools) with the net {N} 2 fixation rates (i.e., the fixed {N} 2 incorporated only in the particulate fraction after 15 {N} 2 incubation). {T}he difference between the two measures accounted for the fixed {N} 2 released as {DN}. {T}he second approach consisted in the direct measure of the 15 {N}-enrichment of ammonium ({NH} +) and dissolved organic {N} ({DON}) following 15 {N} 4 2 incubations. {T}he fixed {N} 2 released as {DN} accounted for ∼0–20% and ∼1% of the fixed {N} 2 after 24 h in the first and second approach, respectively. {W}e show that the recent methodological improvements in the net {N} 2 fixation determination applied in this study tend to reconcile the two approaches that formerly led to contrasted values. {H}owever, the large analytical uncertainties of the first approach limit its reliability. {T}hus, the direct determination of the 15 {N}-enrichment of the dissolved pool remains the best tool to assess the fixed {N} 2 released in the {DN} pool, in particular as it allows shorter incubation times. {T}here were no clear patterns detected between the filamentous {T}richodesmium and unicellular strains, neither in terms of the amount of fixed {N} 2 released as {DN} nor in terms of the proportion of {NH} + relative to {DON}. {T}his suggests that the release of fixed {N} 4 2 is a process shared among the filamentous and free living diazotrophs.},
  keywords = {},
  booktitle = {},
  journal = {{F}rontiers in {M}arine {S}cience},
  volume = {2},
  numero = {},
  pages = {art. no 80 [14 ]},
  ISSN = {2296-7745},
  year = {2015},
  DOI = {10.3389/fmars.2015.00080},
  URL = {https://www.documentation.ird.fr/hor/fdi:010072997},
}