Document Type : Research Articles
Author
Department of Industrial Microbial Biotechnology, Research Institute for Industrial Biotechnology, Academic Center for Education, Culture, and Research (ACECR), Mashhad, Khorasan Razavi Province, Iran
10.22067/jcmr.2026.98386.1133
Abstract
Light quality is a critical environmental factor regulating photosynthetic pigment synthesis and biomass accumulation in cyanobacteria. Understanding how different light wavelengths influence pigment production and growth is essential for optimizing cyanobacterial cultivation for biotechnological applications. This study investigated the effects of red, white, and green light on biomass production, lipophilic pigments (chlorophylls and carotenoids), and phycobiliproteins including phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE) in two cyanobacterial strains, Calothrix and Microchaete. Cyanobacteria were subjected to a constant light intensity of 500 lux with a 16/8 h photoperiod, continuous aeration, and a temperature of 25°C throughout the two-week experimental period. In Microchaete, red light maximized biomass, chlorophyll, carotenoid, PC, and APC production, while white light enhanced PE levels. The total phycobiliprotein pool peaked under white and red light, indicating that these two wavelengths are most effective for overall PBP accumulation in this strain. In contrast, Calothrix exhibited distinctly different responses. Green light stimulated chlorophyll and carotenoid accumulation up to 3 fold, white light enhanced biomass and total PBPs, and red light selectively increased PC production. Notably, green light boosted chlorophyll production by 2.5 fold and carotenoid production by 3 fold in Calothrix, demonstrating a unique green-light-driven enhancement of lipophilic pigments. Phycobiliprotein levels in Calothrix reached up to 15- fold higher than Microchaete under green light, highlighting a striking species-specific difference in PBP accumulation. These findings demonstrate species-specific chromatic acclimation strategies and highlight the potential of light engineering for targeted overproduction of high-value pigments in cyanobacteria, providing a basis for light-driven bioprocess optimization.
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