Biological activity of microalgae can be enhanced by manipulating the cultivation temperature and irradiance

The escalating levels of antibiotic resistance among pathogenic bacteria and the side effects of chemotherapeutic drugs in use forced the efforts of scientists to search for natural antimicrobial and anticancer substances with novel structures and unique mechanism of action. Focusing on bioproducts, recent trends in drug research have shown that microalgae (including the cyanobacteria) are promising organisms to furnish novel and safer biologically active compounds. Many microalgal metabolites have been found to possess potent antibacterial, antifungal, antiviral, anticancer and antiinflammatory activities, as well as antioxidant, enzyme inhibiting and immunostimulating properties. In this paper, the studies on the biological activity of microalgae associated with potential medical and pharmaceutical applications are briefly presented. Attention is focused on the impact of cultivation temperature, irradiance and growth stage on the biomass accumulation, activity and pathways of cell metabolism and the possibilities of using these variable factors to increase the diversity and quantity of biologically active substances synthesized by microalgae.