Effects of organic carbon sources on growth, photosynthesis, and respiration of Phaeodactylum tricornutum

Abstract

The growth, photosynthesis, and respiration of the marine diatom Phaeodactylum tricornutum were examined under photoautotrophic and mixotrophic conditions. 100 mM glycerol, acetate, and glucose significantly increased specific growth rate, and mixotrophic growth achieved higher biomass concentrations. Under mixotrophic conditions, respiration rate (R d ) and light compensation irradiance (I c ) were significantly higher, but net maximum photosynthetic O 2 evolution rate (P m ) and saturation irradiance (I k ) were depressed. Organic carbon sources decreased the cell photosynthetic pigment content and chlorophyll a to c ratio, but with a higher carotenoid to chlorophyll a ratio. Ratios of variable to maximum chlorophyll fluorescence (F v /F m ) and 77 K fluorescence spectra of mixotrophic cells indicated a reduced photochemical efficiency of photosystem II. The results were accompanied by lower electron transport rate. Therefore, organic carbon sources reduced the photosynthesis efficiency, and the enhancement of biomass of P. tricornutum implied that organic carbon sources had more pronounced effects on respiration than on photosynthesis.

Modeling growth and photosynthetic response in Arthrospira platensis as function of light intensity and glucose concentration using factorial design

“…Therefore, organic carbon sources reduced the photosynthetic efficiency in this phase, and the enhancement of biomass of A. platensis implied that organic sources had more pronounced effects on respiration than on photosynthesis. These conclusions are in agreement with results obtained with Phaeodactylum tricornutum under mixotrophic culture (Liu et al 2009). …”

Impact of temperature and light intensity on triacylglycerol accumulation in marine microalgae

“…Again, the other two microalgae showed no significant differences between their growth rates (around 0.85 d À1 ; p > 0.05), and biomass yields with maximum values (around 1.100 mg mL À1 ; p > 0.05) in late stationary phase (Table 1). Increase in growth parameters has been reported for cultures of P. tricornutum associated with mixotrophic growth and/or photobioreactors [20,21], as well as for N. oceanica cultured at different temperatures [22]. In contrast, growth rates and biomass yields for cultures of I. galbana reported in the literature are typically lower than those observed in the present work [23,24].…”

Photosynthetic Behavior of Microalgae in Response to Environmental Factors

“…Therefore, organic carbon sources reduced the photosynthetic efficiency in this phase, and the enhancement of biomass of Arthrospira platensis implied that organic sources had more pronounced effects on respiration than on photosynthesis. These conclusions are in agreement with results obtained with Phaeodactylum tricornutum under mixotrophic culture (Liu et al, 2009). All the above results confirmed that, in the second phase, Arthrospira platensis might use and metabolize glucose and then shift to the heterotrophic nutrition mode.…”