Cyanobacterial Polyhydroxyalkanoates: A Sustainable Alternative in Circular Economy

Abstract

Conventional petrochemical plastics have become a serious environmental problem. Its unbridled use, especially in non-durable goods, has generated an accumulation of waste that is difficult to measure, threatening aquatic and terrestrial ecosystems. The replacement of these plastics with cleaner alternatives, such as polyhydroxyalkanoates (PHA), can only be achieved by cost reductions in the production of microbial bioplastics, in order to compete with the very low costs of fossil fuel plastics. The biggest costs are carbon sources and nutrients, which can be appeased with the use of photosynthetic organisms, such as cyanobacteria, that have a minimum requirement for nutrients, and also using agro-industrial waste, such as the livestock industry, which in turn benefits from the by-products of PHA biotechnological production, for example pigments and nutrients. Circular economy can help solve the current problems in the search for a sustainable production of bioplastic: reducing production costs, reusing waste, mitigating CO2, promoting bioremediation and making better use of cyanobacteria metabolites in different industries.

Plant Biostimulants from Cyanobacteria: An Emerging Strategy to Improve Yields and Sustainability in Agriculture

“…Among the available possibilities, the residual pellet after extraction could be used as a biofertilizer [82]. If aqueous cellular extracts are the main biostimulants components, the remaining lipid fraction could be used for the production of biofuels [176] or to obtain polyunsaturated fatty acids (PUFAs) which have several cosmetics, medical, and nutraceutical applications [164], or polyhydroxyalkanoates (PHA) which could be used for the production of bioplastics [177]. Moreover, when polysaccharides are used to obtain the biostimulant, the residual proteins can find application as food or feed [164].…”

Anabaenopeptins: What We Know So Far

“…They can inhabit several types of ecosystems, including aquatic and terrestrial. These microorganisms produce a great variety of bioactive compounds, which have been investigated mainly due to their biotechnological potential and environmental relevance [ 1 , 2 , 3 ]. Cyanotoxins are among the most studied compounds originated from cyanobacteria since they are capable of negatively affecting human and animal health [ 4 , 5 ].…”

Glucosidase Inhibitors Screening in Microalgae and Cyanobacteria Isolated from the Amazon and Proteomic Analysis of Inhibitor Producing Synechococcus sp. GFB01

“…With occurrence in animals, plants and microorganisms [ 24 , 25 , 26 , 27 ], the bioprospection of glucosidase inhibitors in sustainable natural sources was once concentrated on macroalgae [ 28 , 29 , 30 ] but it is interesting to look for alternatives with cheaper cultivation and that require less area, such as microalgae, including cyanobacteria [ 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. The possibility of associating the production of these inhibitors with other metabolites of biotechnological interest produced by cyanobacteria, such as antioxidants [ 38 ]; pigments [ 39 ], acids and polysaccharides of cosmetic and pharmacological interest [ 40 , 41 ] in addition to joint production with polyhydroxybutyrate (PHB) [ 42 , 43 ] and biofuels [ 44 , 45 , 46 ], while mitigating CO 2 [ 43 , 44 ], is yet another advantage of this bacterial phylum.…”

“…The exact biological function of these inhibitors in cyanobacteria is still unknown, with defense against predators being the most discussed action [ 33 , 34 , 35 ]. The search for cyanobacteria that produce glucosidase inhibitors in environments with different physical and chemical conditions, and therefore, with different ecological relationships, is a good strategy to find biological compounds that are often still unexplored, such as the search for inhibitors in marine cyanobacteria the Baltic Sea [ 51 ], tropical environments [ 37 ] and flooded regions in the Nile delta [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ].…”