The influence of carbon limitation on growth of Heterosigma akashiwo: A case study in fatty acids composition.
Heterosigma akashiwo is an algal blooms species, and thus selected as the target microalgae in this work. This study attempted to investigate the influence of carbon limitation on the growth of H. akashiwo. Experiments were carried out in CO2-unlimited and CO2-limited systems (both include three nutritional groups). The stable isotope signatures and compound-specific stable three nutritional groups carbon isotopic composition of fatty acids were measured. Here we hypothesized that the carbon limitation could lead to the enriched of stable isotope ratios in the H. akashiwo. The results showed that carbon limitation made δ13C and δ13CFAs values more and more enriched in H. akashiwo. δ13C values were enriched in normal group of H. akashiwo within CO2-limited. δ15N values were enriched in nitrogen deficiency of H. akashiwo within both CO2-unlimited and CO2-limited. Furthermore, compared with the exponential phase, the enriched in δ13C was detected during the stationary phase in H. akashiwo within CO2-limited. A total of 8 major FAs were detected in H. akashiwo. Within CO2-unlimited, nitrogen deficiency promoted the synthesis of 4 FAs (14:1n-5c, 16:0, 18:0 and 18:3n-6c) in exponential phase. Within CO2-limited, nitrogen deficiency promoted the synthesis of FAs 14:0, 16:0 and 18:3n-3c, while phosphorus deficiency promoted the synthesis of all 6 FAs in exponential phase. δ13CFAs of H. akashiwo within CO2-limited showed the valley values and were significantly greater than those within CO2-unlimited. Furthermore, δ13CFAs of stationary phase were greater than those of exponential phase. δ13C14:1n-5c in nitrogen deficiency were the highest of the three nutrient groups within CO2-unlimited. This may point out that δ13CFAs could become an indicator of marine phytoplankton blooms. Overall, the present study may provide a novel approach to investigate the physiology and lipid metabolism of H. akashiwo blooms by using stable isotope ratios coupled with FAs profiles.
PubMed Abstracts
PubMed Abstracts