Back to Search
Start Over
Physiological and Ecological Aspects of Chlorella sorokiniana (Trebouxiophyceae) Under Photoautotrophic and Mixotrophic Conditions.
- Source :
-
Microbial ecology [Microb Ecol] 2018 Oct; Vol. 76 (3), pp. 791-800. Date of Electronic Publication: 2018 Mar 08. - Publication Year :
- 2018
-
Abstract
- Mixotrophy is a metabolic strategy in which an organism is autotrophic and heterotrophic simultaneously. Considering that the aquatic environment provides several organic sources of carbon, it is probably common for microalgae to perform mixotrophy and not only photoautotrophy, but little is known about microalgae mixotrophy. The present work aimed at investigating the growth, photosynthetic activity, morphology, and biochemical composition of the microalga Chlorella sorokiniana in mixotrophic and photo-mixotrophic conditions, comparing it with photoautotrophy. The results showed pH changes after glucose addition, reaching pH 11.62 in mixotrophic and 10.47 in sequential photo-mixotrophic cultures, which limited the microalgal growth. Highest biomass was obtained in the mixotrophic culture in comparison with the sequential photo-mixotrophic one. Rapid light saturation curves showed that α (photosynthetic efficiency, 1.69) and relative electron transport rate (rETR; 565.61) were higher in the mixotrophic cultures, whereas the highest I <subscript>k</subscript> (irradiance saturation, 386.68) was obtained in the photoautotrophic ones. In the sequential photo-mixotrophic cultures, photosynthetic activity varied during glucose consumption, decreasing the maximum quantum yield F <subscript>v</subscript> /F <subscript>m</subscript> after glucose addition, indicating change in metabolism, from photoautotrophy to mixotrophy by the microalga. The results showed that the mixotrophic cultures had higher production of chlorophyll a (6.26 mg mL <superscript>-1</superscript> ), cell density (6.62 × 10 <superscript>7</superscript> cell mL <superscript>-1</superscript> ), and lipids (0.06 pg μm <superscript>-3</superscript> ). Sequential photo-mixotrophic cultures showed the highest biovolume (360.5 μm <superscript>3</superscript>  cell <superscript>-1</superscript> ) and total carbohydrates (0.026 pg μm <superscript>-3</superscript> ). The protein concentration was 3.2 and 2.4 times higher in photoautotrophy and photo-mixotrophic growth, respectively, than in mixotrophy, but lipids were three times higher under mixotrophy. The biochemical changes we observed indicate that the microalga's plasticity in face of new environmental characteristics, such as the presence of organic carbon, can change the flow of energy through natural ecosystems.
- Subjects :
- Autotrophic Processes radiation effects
Biomass
Chlorella growth & development
Chlorophyll metabolism
Chlorophyll A
Glucose metabolism
Heterotrophic Processes radiation effects
Light
Microalgae growth & development
Microalgae metabolism
Microalgae radiation effects
Nitrogen metabolism
Photosynthesis radiation effects
Chlorella metabolism
Chlorella radiation effects
Subjects
Details
- Language :
- English
- ISSN :
- 1432-184X
- Volume :
- 76
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Microbial ecology
- Publication Type :
- Academic Journal
- Accession number :
- 29520451
- Full Text :
- https://doi.org/10.1007/s00248-018-1170-8