Eco-sustainable production of bioplastics and high added value products from micro and macroalgae (acronym MAREA - MAterial REcovery from Algae)

Many of the bioplastics (BP) on the market derive from plant materials such as starch and dextrose from corn and potato. In Italy, the land dedicated to BP production, mainly based on corn/potato starch, is about 2300 ha, but on the basis of the growth forecast in 2020 of the main BP manufacturer, the increase in terms of land required would be over 9600 ha to guarantee a production of about 200000 tons. Clearly the use of such biomass for the BP production can increasingly come into conflict with their food use in view of the growing trend of their market. This conflict can be overcome by promoting the use of other natural resources not yet widely exploited in Italy and Europe, such as algae. Algae can represent a potential renewable source for the production of BP due to their biochemical composition and the many advantages they present: their cultivation does not compete with the agricultural production destined for food, productivity per unit of surface (kg/ha) and growth rates higher than those of agricultural crops with less or no fertilizer requirements and high adaptability to a wide range of environments. The MAREA Project will move in this direction, aiming at: - developing an integrated eco-sustainable production process of bioplastics based on polyhydroxyalkanoates (PHAs), produced using microalgae, and marine algal polysaccharides (MAPs) extracted from green macroalgae, specially cultivated in aquaculture systems. - producing thermoplastic biodegradable/compostable "green" composites based on PHA/MAPs and low-cost natural fibers for applications in terrestrial and marine environments. Specific cyanobacteria will be used as PHA producers in new generation photobioreactors fed with different low-cost agro-industrial wastewaters, coming from dairy and olive oil industry, as carbon sources. The process will be scaled-up from lab to semi-pilot scale with an outdoor tubular bioreactor (volume of 70 L). Selected green macroalgae (Chlorophyta), known to synthesize large quantities of sulfated polysaccharides (up to 54 wt.% on dry weight) will be cultivated in pilot-scale in situ and ex situ aquaculture systems. Culture conditions will be optimized to increase their productivity and to offer a continuous supply of algal biomass. The extraction of PHAs from the bacterial biomass and MAPs from the green macroalgae will be carried out by using selected "green" solvents as ionic liquids. The obtained extraction efficiencies and the quality of the extracted products will be compared with those obtained with conventional methods. PHA and extracted MAPs will be processed by melt extrusion with addition of low-cost natural lignocellulose fibers to obtain thermoplastic composites that will be optimized in terms of processability and mechanical performance. The optimized formulations will be processed by injection molding to produce pots/supports for terrestrial plant nursery and marine restoration interventions. Waste lignocellulose fibers, coming from wood industry, agricultural and industrial crops, and fibers of Posidonia oceanica (PO), a dominant sea grass in the Mediterranean Sea, will be used to produce the PHA/MAPS based biocomposites for the terrestrial and marine/dune applications, respectively. In view of their potential applications, the biodegradability of the developed MAREA composites will be evaluated in different environments: under controlled composting conditions and in soil, for the "terrestrial" composites and items, because their expected fate is to be treated in composting plants or used in agriculture; in sea water on natural marine sediments in mesocosms and dune habitat for the PO-based composites, because their potential applications are natural engineering interventions, such as marine habitat restoration (i.e. marine forests, Coralligenous, seagrasses). The degradation degree of composite specimens will be evaluated in different natural environments monitoring their weight losses and changes of mechanical performance over time. A detailed analysis on the microbial populations (bacteria, actinomycetes and fungi) capable of degrading or ingesting the MAREA composites in soil, compost and marine environments will be carried out, identifying the polymer-degrading strains by high throughput sequencing of bacterial DNA and RNA and characterizing them in terms of degradation capacity. Cytogenotoxicity assays will be carried out using bacteria or cell tests to identify potential hazardous polymer components or degradation products that might cause mutations and degradation of DNA of indigenous microbial populations. In this way, MAREA will allow to expand scientific knowledge not only of the effects of the environmental conditions and microorganisms in nature on the performance of the developed bioplastics but also on the biological effects of their degradation products on bacterial communities and on coastal ecosystems that will represent their "hot" deposit spots.