PHOTOSYNTHETICA

Photosynthetica X:X | DOI: 10.32615/ps.2026.015

Salt stress in cyanobacteria and its relevance to energy management

I. ALAMIN^{1, 2}, J. SEBESTA³, V.A. DENNIS², J. YU³, H.J.M. HOU^{1, 2}

¹ RENEW Cyanobacteria Collection Center, Department of Physical and Forensic Sciences, Alabama State University, Montgomery, AL 36104, USA

² Center for NanoBiotechnology Research, Ph.D. Program in Microbiology, Department of Biological Sciences, Alabama State University, Montgomery, AL 36104, USA

³ Biosciences Center, National Laboratory of the Rockies, Golden, Colorado 80401, USA

Energy management in photosynthetic organisms occurs at multiple levels, including the electron transfer and metabolic reactions. Salt stress imposes osmotic, ionic, energetic, and oxidative constraints on cyanobacteria, profoundly reshaping carbon allocation and photosynthetic performance. To maintain osmotic balance, cyanobacteria employ a salt-out strategy, accumulating compatible solutes such as glucosylglycerol and sucrose while maintaining low intracellular Na⁺ concentrations. This review provides a comprehensive perspective by synthesizing current knowledge on cyanobacterial overflow under salt stress, emphasizing its physiological context rather than focusing on a single dedicated pathway. We compare metabolite overflow responses under nitrogen limitation, high light, mixotrophy, and combined stresses, and discuss methodological approaches integrating targeted analytics, untargeted exometabolomics, energy charge measurements, and flux analysis. Collectively, energy management via metabolite overflow under salt stress is proposed as an emergent, condition-dependent outcome of integrated carbon, energy, and redox regulation.

Additional key words: carbon imbalance; cyanobacteria; energy management; metabolism; metabolite overflow; salinity.

Received: March 30, 2026; Revised: May 23, 2026; Accepted: June 11, 2026; Prepublished online: July 30, 2026