Production of biomass and biomolecules in Limnospira indica PCC 8005 cultivation under magnetic fields and polymeric nanofibers

Abstract

Researchers often apply physical, chemical, or biological stresses to cyanobacteria cultivation to enhance biomass production by triggering cellular adaptation mechanisms, increasing growth or boosting target compound synthesis. Static magnetic fields (SMF) offer a non-toxic, cost-effective way to modulate microalgal growth, alter biomass composition, and promote metabolite production. Polymeric nanofibers (Nano) function as a physical barrier in cultivation, while monoethanolamine (MEA) acts as a chemical absorbent, reducing CO₂ loss and enhancing biofixation. This study investigated the effects of SMF and nanofibers on the biomass yield and molecular composition of Limnospira indica PCC 8005. The combined SMF and Nano treatment achieved the highest biomass yield (5.87 ± 0.06 g L⁻¹), a 28 % increase compared to the control. SMF application increased protein content by 16 % but reduced carbohydrate levels by 73 % relative to the nanofiber-only treatment (39.58 ± 0.98 % ww⁻¹). Exopolysaccharide (EPS) produced under the SMF+NanoMEA treatment contained 39.9 % uronic acid, while the Nano-only treatment had the highest sulphate content (8.4 %) but the lowest uronic acid concentration (25.4 %). The EPS were identified as acidic, sulphated polysaccharides. SMF and nanofibers significantly enhances biomass production, alters the carbohydrate and protein proportions in biomass, and influences the composition of sugars, acids, and sulphate in exopolysaccharides.