Effects of phosphorus starvation versus limitation on the marine cyanobacterium Prochlorococcusâ
MED4 I: uptake physiology.
Environ Microbiol
; 15(7): 2114-28, 2013 Jul.
Article
em En
| MEDLINE
| ID: mdl-23387819
ABSTRACT
Recent measurements of natural populations of the marine cyanobacterium Prochlorococcus indicate this numerically dominant phototroph assimilates phosphorus (P) at significant rates in P-limited oceanic regions. To better understand uptake capabilities of Prochlorococcus under different P stress conditions, uptake kinetic experiments were performed on Prochlorococcusâ
MED4 grown in P-limited chemostats and batch cultures. Our results indicate that MED4 has a small cell-specific Vmax but a high specific affinity (αP ) for P, making it competitive with other marine cyanobacteria at low P concentrations. Additionally, MED4 regulates its uptake kinetics in response to P stress by significantly increasing Vmax and αP for both inorganic and organic P (PO4 and ATP). The Michaelis-Menten constant, KM , for PO4 remained constant under different P stress conditions, whereas the KM for ATP was higher when cells were stressed for PO4 , pointing to additional processes involved in uptake of ATP. MED4 cleaves the PO4 moieties from ATP, likely with a 5'-nucleotidase-like enzyme rather than alkaline phosphatase. MED4 exhibited distinct physiological differences between cells under steady-state P limitation versus those transitioning from P-replete to P-starved conditions. Thus, MED4 employs a variety of strategies to deal with changing P sources in the oceans and displays complexity in P stress acclimation and regulatory mechanisms.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fósforo
/
Proteínas de Bactérias
/
Regulação Bacteriana da Expressão Gênica
/
Prochlorococcus
Idioma:
En
Revista:
Environ Microbiol
Assunto da revista:
MICROBIOLOGIA
/
SAUDE AMBIENTAL
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Estados Unidos