Cyanobacterial green chemistry: a blue-green approach for a sustainable environment, energy, and chemical production

Increased human activity due to the ever-increasing global population has necessitated the urgent need for a sustainable environment, food, and energy. Cyanobacteria, classically known as blue-green algae, are oxygen-producing photosynthetic organisms that are emerging as an option to achieve sustainable development goals. These Gram-negative prokaryotes can efficiently sequester atmospheric CO₂ due to an efficient carbon concentrating mechanism and divert it to the production of energy-rich compounds, i.e., biofuel, and other valuable chemicals, using their flexible metabolic chassis. Additionally, cyanobacteria also minimize the emission of methane, which is another greenhouse gas, by providing oxygen to methane-oxidizing bacteria. In recent years, several genetically engineered strains of cyanobacteria have been developed that can produce biofuels and several other valuable chemicals. Strains have also been engineered for bioplastic production and bioremediation purposes. These organisms have gained attention as biofertilizers and can increase the quality and fertility of soil. Thus, cyanobacteria are promising CO₂ sinks that can contribute to global efforts in carbon capture and storage initiatives while producing bioenergy, cosmetics, pharmaceuticals, and several other valuable chemicals. Therefore, these blue-green cells can be used for green chemistry while minimizing the atmospheric CO₂ concentration. In this review, we present various applications of cyanobacterial biomass to achieve sustainable development goals. We also discuss challenges associated with the wide application of cyanobacteria and the future direction to make full use of these robust organisms to fulfill our future demands in an environment-friendly manner.