Modeling shear-sensitive dinoflagellate microalgae growth in bubble column photobioreactors

Area of Science:

• * Biotechnology and Algal Cultivation
• * Microbial Physiology and Biomechanics

Background:

• * Karlodinium veneficum, a shear-sensitive dinoflagellate, is relevant for biofuel and bioproducts.
• * Bubble column photobioreactors are common for microalgal cultivation but induce shear stress.
• * Understanding shear stress effects is crucial for optimizing microalgal growth.

Purpose of the Study:

• * To investigate the impact of mass transfer and shear stress on K. veneficum growth and physiology.
• * To develop a predictive model for K. veneficum growth in a bubble column photobioreactor.
• * To differentiate the effects of bubble formation versus bubble rupture on cell viability.

Main Methods:

• * Cultivation of K. veneficum in a sparged bubble column photobioreactor.
• * Measurement of cell growth, reactive oxygen species, membrane fluidity, and photosynthetic efficiency.
• * Development and validation of a mathematical model correlating growth with mass transfer and culture parameters.

Main Results:

• * Mass transfer limits growth at low airflow rates (vvm).
• * Shear stress from bubbles becomes detrimental above 0.1 vvm, impacting cell physiology.
• * The developed model accurately predicts K. veneficum growth under varying conditions.
• * Bubble rupture was identified as significantly more harmful than bubble formation.

Conclusions:

• * Optimizing airflow is critical to balance mass transfer benefits and shear stress damage.
• * Bubble rupture mitigation strategies are essential for improving K. veneficum cultivation.
• * The study provides a model for predicting and controlling microalgal growth in photobioreactors.