Diazotrophic Cyanobacteria for Protein Production: Photorespirometry to Assess the Effect of Light and Temperature

Abstract

Protein production, thriving on the chemical fixation of nitrogen in fertilizers and intensive use of agricultural and livestock practices, significantly compromises environmental sustainability. The need for alternative food resources to meet the raised demand due to the fast-growing global population has turned pressing. Diazotrophic cyanobacteria, capable of converting atmospheric nitrogen into bioavailable forms, offer promise in sustainable protein production, bypassing traditional inefficiencies. Such microorganisms’ potential might be fully exploited if the production process is well-characterized and controlled. The primary objective of this study is to investigate the specific effects of light and temperature on the growth dynamics of Nostoc PCC 7120 by using photorespirometry. The study aims to retrieve kinetic parameters essential for predictive modeling in industrial applications. The optimal light intensity (376 µmol m-2 s-1) was estimated, as well as the optimal temperature. The latter showed to be dependent on culture conditions: under nitrogen-fixing conditions, it drops from 30 to 27 °C, highlighting temperature-driven effects based on the nitrogen source.