Note on the effect of high nitrate concentration and light intensity on the growth and uptake rates of Phaeodactylum tricornutum (Bohlin) culture

Schmidt, G

doi:10.1590/s0373-55241983000100010

Cited by 2 publications

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“…La concentration de NO3 -+ NO2 -du milieu de culture (Cnc) diminue rapidement durant la croissance cellulaire exponentielle (de 17,8 a 3,6 p m o 1 -L ' ) et elle tend vers des valeurs constantes (dCnc/dt = 0) s'approchant de 0 (< 1-2 pmol L -I). Ces concentrations ne permettent plus la croissance exponentielle puisqu'elles se situent en d e~a de la valeur du K, (7,O-10,l pM) spkcifique a l'activite d'absorption du substrat (Syrett 1988;Schmidt 1983). La culture entreprend donc une croissance ralentie (postexponentielle) durant laquelle sera formke la plus grande partie de sa biomasse en azote (XN) situation qui ne peut kvidemment Etre observke en culture ND ( fig.…”

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Croissance de la biomasse azotée du Phaeodactylum tricornutum (Bacillariophyceae) en cultures discontinues dialysante et non dialysante

Marsot¹,

Cembella²,

Mouhri³

1992

Can. J. Microbiol.

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~ouvelle-~cosse), Canada B3H 321 KHADIJA MOUHRI Laboratoire de biologie vkge'tale, Facult6 des sciences, Universite' Cadi Ayyad, Marrakech, Maroc Requ le 13 novembre 1991 Revision reque le 1 1 mars 1992 Accepte le 23 mars 1992 MARSOT, P., CEMBELLA, A. D., et MOUHRI, K. 1992. Croissance de la biomasse azotee du Phaeodactylum tricornutum (Bacillariophyceae) en cultures discontinues dialysante et non dialysante. Can. J. Microbiol. 38 : 945-952. Les operations et les conditions particulikres de la technique de culture discontinue a dialyse determinent, chez la diatomee Phaeodactylum tricornutum, des comportements nutritionnels differents de ceux observes en culture non dialysante. Les mesures simultanees des concentrations de biomasse azotee et des nutriments azotes (NO, -+ NO, -), du milieu de culture et du milieu nourricier, revklent que la plus grande partie de la biomasse en azote (>90%) d'une culture a dialyse est produite durant la croissance postexponentielle, quand les substrats nutritifs (NO,-+ NO,-)sont en concentrations limitantes, inferieures a la constante de Michaelis-Menten. Prks de la moitie de cette biomasse est produite a la limite de diffusion de l'appareil, c'est-a-dire lorsque le transfert de masse des substrats, determinant l'activite d'absorption de la culture, atteint son maximum. Les cultures discontinues non dialysantes, dont la periode de croissance postexponentielle est courte, rkalisent leur biosynthkse en azote surtout durant la croissance active. Certains indices physiologiques touchant les activites metaboliques d'absorption et d'assimilation des nutriments azotes nous permettent de discerner des comportements nutritionnels distincts du P. tricornutum dans les deux types de culture et d'expliquer le niveau eleve de biomasse obtenu en culture a dialyse.Mots clds : culture dialysante, diatomee, metabolisme de l'azote.MARSOT, P., CEMBELLA, A. D., and MOUHRI, K. 1992. Croissance de la biomasse azotee du Phaeodactylum tricornutum (Bacillariophyceae) en cultures discontinues dialysante et non dialysante. Can. J. Microbiol. 38: 945-952. The unique conditions associated with discontinuous (batch) dialysis culture of the diatom Phaeodactylum tricornutum elicit different nutritional responses from those observed in nondialysis culture. Simultaneous determinations of the nitrogen biomass concentration and of the nitrogen nutrients (NO, -+ NO, -) in the culture chamber, as well as in the seawater nutrient medium at the entrance and exit of the dialyzer, revealed that nitrogen-biomass production in dialysis cultures is achieved mainly (>90%) during postexponential growth, when the concentration of nutrients is limiting (smaller than Michaelis-Menten constant). Almost half of this biomass is produced at the diffusion limit of the apparatus, i.e., when the mass transfer of nutrient substrates, which determines the total uptake activity of the culture, reaches a maximum. In contrast, in nondialysis discontinuous cultures, in which the postexponential growth phase is short, most of the total cellular n...

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Croissance de la biomasse azotée du Phaeodactylum tricornutum (Bacillariophyceae) en cultures discontinues dialysante et non dialysante

Marsot¹,

Cembella²,

Mouhri³

1992

Can. J. Microbiol.

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INTRACELLULAR AND EXTRACELLULAR AMINO ACID POOLS OF THE MARINE DIATOM PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE) GROWN ON UNENRICHED SEAWATER IN HIGH‐CELL‐DENSITY DIALYSIS CULTURE¹

Marsot

Cembella

Colombo

1991

Journal of Phycology

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The consumption of inorganic macronutrients (NO3−+ NO2−, NH4+, and PO4−3) and the composition of intra‐ and extracellular dissolved free amino acid pools (IDFAA and EDFAA, respectively) were determined in continuous‐reservoir batch dialysis cultures of the marine diatom Phaeodactylum tricornutum Bohlin maintained on unenriched natural seawater as a growth medium. Nutrient diffusion (Nd), which equals the nutrient uptake of the culture, increased with the cell density and the age of the culture. A concentration of 6.77 × 107 cells · mL−1 was obtained in stationary phase, which coincided with the NO3−+ NO2− diffusion limit (Ndmax) of the dialysis apparatus. The Ndmax for NH4+ occurred much earlier, at the end of exponential growth, whereas Ndmax for PO4−3 was not attained during the growth cycle of the culture, even in early stationary phase. A significant depletion (77%) of the IDFAA pool during exponential phase was followed by a reestablishment–to approximately 60% of the initial level–of internal pools during linear and stationary growth phases. This recovery occurred during the illuminated portion of the photoperiod (12:12 h LD) and involved principally the amino acids GLN, GLU, β‐GLU, and ASN. The recovery of GLN and ASN levels was particularly significant, because the intracellular concentrations of these amino acids were higher at the end of the growth cycle than before. The EDFAA pool was generally dominated by the amino acids SER and GLY+THR; however, during active growth, ORN and LYS often constituted an important fraction. The EDFAA concentration increased until linear growth phase was reached, during which a higher concentration of total free amino acids was attained in darkness than under illumination. The EDFAA component diminished afterward, and in stationary phase this fraction returned to concentrations equivalent to those observed at the beginning of the growth cycle. The variations in EDFAA concentrations were expressed by a pronounced decrease in the cellular excretion of amino acids with increasing cell density. These cellular responses of Phaeodactylum tricornutum in dense culture, specifically the regulation of amino acid excretion and intracellular pool size, may affect the N‐conversion coefficient (YN). Consequently, by prolonging the linear phase of growth and reducing the concentration of autoinhibitory metabolites by diffusion, a markedly enhanced final cell density can be achieved in cultures grown on natural unenriched seawater.

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Note on the effect of high nitrate concentration and light intensity on the growth and uptake rates of Phaeodactylum tricornutum (Bohlin) culture

Cited by 2 publications

References 15 publications

Croissance de la biomasse azotée du Phaeodactylum tricornutum (Bacillariophyceae) en cultures discontinues dialysante et non dialysante

Croissance de la biomasse azotée du Phaeodactylum tricornutum (Bacillariophyceae) en cultures discontinues dialysante et non dialysante

INTRACELLULAR AND EXTRACELLULAR AMINO ACID POOLS OF THE MARINE DIATOM PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE) GROWN ON UNENRICHED SEAWATER IN HIGH‐CELL‐DENSITY DIALYSIS CULTURE¹

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Note on the effect of high nitrate concentration and light intensity on the growth and uptake rates of Phaeodactylum tricornutum (Bohlin) culture

Cited by 2 publications

References 15 publications

Croissance de la biomasse azotée du Phaeodactylum tricornutum (Bacillariophyceae) en cultures discontinues dialysante et non dialysante

Croissance de la biomasse azotée du Phaeodactylum tricornutum (Bacillariophyceae) en cultures discontinues dialysante et non dialysante

INTRACELLULAR AND EXTRACELLULAR AMINO ACID POOLS OF THE MARINE DIATOM PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE) GROWN ON UNENRICHED SEAWATER IN HIGH‐CELL‐DENSITY DIALYSIS CULTURE1

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INTRACELLULAR AND EXTRACELLULAR AMINO ACID POOLS OF THE MARINE DIATOM PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE) GROWN ON UNENRICHED SEAWATER IN HIGH‐CELL‐DENSITY DIALYSIS CULTURE¹