On-line stable isotope gas exchange reveals an inducible but leaky carbon concentrating mechanism in Nannochloropsis salina

Autor: Aaron M. Collins, Howland D. T. Jones, Samuel Lopez-Nieves, Jerilyn A. Timlin, David T. Hanson, John Roesgen
Rok vydání: 2014
Předmět:
Zdroj: Photosynth Res
ISSN: 1573-5079
0166-8595
Popis: Carbon concentrating mechanisms (CCMs) are common among microalgae, but their regulation and even existence in some of the most promising biofuel production strains is poorly understood. This is partly because screening for new strains does not commonly include assessment of CCM function or regulation despite its fundamental role in primary carbon metabolism. In addition, the inducible nature of many microalgal CCMs means that environmental conditions should be considered when assessing CCM function and its potential impact on biofuels. In this study, we address the effect of environmental conditions by combining novel, high frequency, on-line (13)CO(2) gas exchange screen with microscope-based lipid characterization to assess CCM function in Nannochloropsis salina and its interaction with lipid production. Regulation of CCM function was explored by changing the concentration of CO(2) provided to continuous cultures in airlift bioreactors where cell density was kept constant across conditions by controlling the rate of media supply. Our isotopic gas exchange results were consistent with N. salina having an inducible “pump-leak” style CCM similar to that of Nannochloropsis gaditana. Though cells grew faster at high CO(2) and had higher rates of net CO(2) uptake, we did not observe significant differences in lipid content between conditions. Since the rate of CO(2) supply was much higher for the high CO(2) conditions, we calculated that growing cells bubbled with low CO(2) is about 40 % more efficient for carbon capture than bubbling with high CO(2). We attribute this higher efficiency to the activity of a CCM under low CO(2) conditions.
Databáze: OpenAIRE
Externí odkaz: