Impact of bubble size on growth and CO2 uptake of Arthrospira (Spirulina) platensis KMMCC CY-007.

Abstract Optimisation of cyanobacterial cell productivity should consider the key factors light cycle and carbon source. We studied the influence of CO 2 bubble size on carbon uptake and fixation, on basis of mRNA expression levels in Arthrospira platensis KMMCC CY-007 at 30 °C (light intensity: 40 μmol m −2  s −1 ; 1% CO 2 ). Growth rate, carbon fixation and lipid accumulation were examined over 7 days under fine bubble (FB) (100 μm O) bulk bubble (BB) (5000 μm O) and non-CO 2 (NB) aeration. The low affinity CO 2 uptake mRNA (NDH-I 4 complex) was stronger expressed than the high affinity NDH-I 3 complex ( bic A and sbt A) under 1% CO 2 and FB conditions, with no expression of bic A1 and sbt A1 after 4 days. The high affinity CO 2 uptake mRNA levels corresponded to biomass, carbon content and lipid accumulation, and increase in NDH-I 3 complex (9.72-fold), bic A (5.69-fold), and sbt A (10.61-fold), compared to NB, or BB conditions.