Optimizing cultivation conditions for enhanced productivity Limnothrix planctonica through pH variation and light quality

The survival and growth of cyanobacteria in diverse environments are influenced by several critical factors when cultivating them for research or industrial purposes. Ensuring their optimal growth necessitates consideration of these factors that potentially impede pigment and biomass production. Therefore, optimizing light conditions and pH levels enhances biomass and pigment yield productivity in cyanobacterial cultivation. This study investigates the cultivation conditions of Limnothrix planctonica (KU.B3) in a BG-11 liquid medium, focusing on pigment production, growth response to light and pH variations, and photosynthetic efficiency assessment. Results demonstrated efficient growth of L. planctonica (KU.B3) under white, orange, and red light within the pH range of 7.4–9.0. Cultivation at pH 7.4, yielded the highest biomass (3.59 ± 0.35 μg ml^-1) and phycocyanin content (0.016 ± 0.01 mg g^-1 dry weight). Red light-induced significant phycocyanin yield (5.49 ± 1.21 mg g^-1 dry weight), while white light promoted substantial biomass production (10.03 ± 1.28 μg ml^-1). Conversely, exposure to blue light reduced biomass but exhibited the highest photosynthetic efficiency (F_v / F_m = 0.48 ± 0.06). The study underscores the tradeoff between productivity and photosynthetic efficiency, emphasizing the need for further research to optimize conditions for both parameters, especially for industrial-scale applications.