Nitrogen nutritional condition affects the response of energy metabolism in diatoms to elevated carbon dioxide

Marine phytoplankton are expected to benefit from enhanced carbon dioxide (CO2), attributable largely to down-regulation of the CO2 concentrating mechanism (CCM) which saves energy resources for other cellular processes. However, the nitrogen (N) nutritional condition (N-replete vs. N-limiting) of phytoplankton may affect the responses of their intracellular metabolic processes to elevated CO2. We cultured the model diatoms Thalassiosira pseudonana, Phaeodactylum tricornutum, and Thalassiosira weissflogii at ambient and elevated CO2 levels under N-replete and N-limiting conditions. Key metabolic processes, including light harvesting, C fixation, photorespiration, respiration, and N assimilation, were assessed systematically and then incorporated into an energy budget to compare the effects of CO2 on the metabolic pathways and the consequent changes in photosynthesis and C fixation as a result of energy reallocation under the different N nutritional conditions. Under the N-replete condition, down-regulation of the CCM at high CO2 was the primary contributor to increased photosynthesis rates of the diatoms. Under N-limiting conditions, elevated CO2 significantly affected the photosynthetic photon flux and respiration, in addition to CCM down-regulation and declines in photorespiration, resulting in an increase of the C:N ratio in all 3 diatom species. In T. pseudonana and T. weissflogii, the elevated C:N ratio was driven largely by an increased cellular C quota, whereas in P. tricornutum it resulted primarily from a decreased cellular N quota. The N-limited diatoms therefore could fix more C per unit of N in response to elevated CO2, which could potentially provide a negative feedback to the ongoing increase in atmospheric CO2.

Hong H., Li D.,Lin W., Li W. & Shi D., 2017. Nitrogen nutritional condition affects the response of energy metabolism in diatoms to elevated carbon dioxide. Marine Ecology Progress Series 567:41-56. Article (subscription required).

0 Responses to “Nitrogen nutritional condition affects the response of energy metabolism in diatoms to elevated carbon dioxide”



  1. Leave a Comment

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s




Subscribe to the RSS feed

Powered by FeedBurner

Follow AnneMarin on Twitter

Blog Stats

  • 984,072 hits

OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book