# Sustainable Microalgae and Cyanobacteria Biotechnology
###### Abstract  
Marine organisms are a valuable source of new compounds, many of which have remarkable biotechnological properties, such as microalgae and cyanobacteria, which have attracted special attention to develop new industrial production routes. These organisms are a source of many biologically active molecules in nature, including antioxidants, immunosuppression, antivirals, antibiotics, hemagglutinates, polyunsaturated fatty acids, peptides, proteins, biofuels, and pigments. The use of several technologies to improve biomass production, in the first step, industrial processes schemes have been addressed with different accomplishments. It is critical to consider all steps involved in producing a bioactive valuable compound, such as species and strain selection, nutrient supply required to support productivity, type of photobioreactor, downstream processes, namely extraction, recovery, and purification. In general, two product production schemes can be mentioned; one for large amounts of product, such as biodiesel or any other biofuel and the biomass for feeding purposes; the other for when the product will be used in the human health domain, such as antivirals, antibiotics, antioxidants, etc. Several applications for microalgae have been documented. In general, the usefulness of an application for each species of microalgae is determined by growth and product production. Furthermore, the use of OMICS technologies enabled the development of a new design for human therapeutic recombinant proteins, including strain selection based on previous proteomic profiles, gene cloning, and the development of expression networks. Microalgal expression systems have an advantage over traditional microbial, plant, and mammalian expression systems for new and sustainable microalga applications, for responsible production and consumption. s 2022  
important for life on the earth, producing close to half of the atmospheric oxygen by using carbon dioxide and sunlight. Microalgae, cyanobacteria, and bacteria are the base of the food web, providing energy for all the trophic levels above them. Cyanobacteria are microscopic organisms that perform photosynthesis as well, but they are prokaryotic organisms. The production of microalgae or cyanobacteria, on the other hand, is entirely dependent on the species, nutrients for mutation, cultivation conditions, particularly light intensity and quality, as well as the mode of process operation and configurations. Finally, all important factors affecting growth performance and productivity should adhere to the best strategy for improved compound productivity. Some microalgal metabolites have also been reported to act as antimicrobial agents, particularly in inhibiting the growth of various bacteria and fungi. Marine algae antibacterial substances have been found to be effective against some enterobacterial strains such as _Escherichia coli_, _Salmonella typhoid_, _Staphylococcus aureus_, and _Enterococcus faecalis_[3]. Because of the enormous diversity of marine organisms and the incalculable potential for discovering new antimicrobials, they are very promising candidates for antibiotic isolation. Furthermore, extracts from marine algae have been used to treat wounds, fever, and stomach aches, as well as harmful agents such as leishmaniasis, chagas, and trypanosomiasis. Another novel natural biochemical derived from algae has been used for cancer therapy (breast, cervical, and stomach cancer) with a satisfactory reduction in side effects. Antiviral agents produced by microalgae have also been discovered, which may represent other important biochemicals; these have different chemical compositions and apoptosis-focused action mechanisms [4; 5]. Microalgae has also demonstrated a high potential as an alternative feedstock for third-generation biofuel production. Among the potential biofuels that can be produced from microalgal biomass are biodiesel, bioethanol, biobutanol, biogas, and biohydrogen [6].