Comparison of the Photoautotrophic Growth Regimens of <i>Chlorella sorokiniana </i>in a Photobioreactor for Enhanced Biomass Productivity

• Main Authors: Elvira E. Ziganshina, Svetlana S. Bulynina, Ayrat M. Ziganshin
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Biology
• Subjects: <i>Chlorella sorokiniana</i>; PPFD; growth; nutrient removal; photobioreactor; productivity
• Online Access: https://www.mdpi.com/2079-7737/9/7/169

Microalgae have a wide industrial potential because of their high metabolic diversity and plasticity. Selection of optimal cultivation methods is important to optimize multi-purpose microalgal biotechnologies. In this research, <i>Chlorella sorokiniana</i> AM-02 that was isolated from a freshwater lake was cultured under various high photosynthetic photon flux density (PPFD) conditions and CO₂ gas levels in standard Bold’s basal medium (BBM). Furthermore, a wide range of nitrate levels (180–1440 mg L⁻¹) was tested on the growth of <i>C. sorokiniana</i>. Microalgae growth, pigment concentration, medium pH, exit gas composition, as well as nitrate, phosphate, and sulfate levels were measured during an experimental period. The preferred high PPFD and optimal CO₂ levels were found to be 1000–1400 μmol photons m⁻² s⁻¹ and 0.5–2.0% (<i>v</i>/<i>v</i>), respectively. The addition of nitrate ions (up to 1440 mg L⁻¹) to the standard growth medium increased final optical density (OD₇₅₀), cell count, pigment concentration, and total biomass yield but decreased the initial growth rate at high nitrate levels. Our findings can serve as the basis for a robust photoautotrophic cultivation system to maximize the productivity of large-scale microalgal cultures.