ИСТИНА

Nowadays plastics become one of the most popular materials. Due to their properties, plastics have found wide application in life and industry. The main advantages of plastics are durability, longevity, low density and chemical stability. However, the same properties lead to increasing of environmental risks. Nevertheless, annual consumption of plastics grows up with subsequent increase in environmental load. In this aspect one of the most prominent solutions is the production of biodegradable plastics and polymers. Since 1980s many different variants of their production had been described. Petroleum resources and natural polymers were used as sources for biodegradable plastics production. Nowadays plastics derived from renewable sources become more attractive due to cost efficiency and biodegradability. One of the most perspective sources for biodegradable plastics production is agricultural wastes, including animal processing co-products. Nearly 75% of them are currently subjected to incineration, landfilling or used for soil fertilization. A new technology of sequential high temperature short-term and enzymatic treatment of keratin containing stock leading to obtaining of protein hydrolysates (PH) has been developed recently. The resultant PH are characterized by wide molecular weight distribution (<3 kD -34.3-36.3%, 3-10 kD 57.6-58.5 kD, >10 kD – 6.1-7.3%). It is the first attempt to use PH, particularly from keratinaceous materials, for bioplastics production. This task is quite challenging due to the complexity of PH composition. 3 different methods were applied for obtaining of biodegradable plastics from PH, including casting and pressing of polymer mass with PH as a loading agent; polymerization of peptides by mince of cross-linking agents (glutaraldehyde, carbodiimide) and biocatalytic polymerization of PH with laccase. In the first method up to 50% of PH was incorporated into the common polymers such as sevylene and polyethylene. However, further optimization of PH and polymer proportions will be useful for obtaining of the composition with desirable development type. Under the second approach addition of glutaraldehyde essentially increased the viscosity of the PH compositions. However, this approach was shown to be hampered by the complexity of PH composition resulting into insufficient control of polymerization and obtaining of polymer with tailored properties. Thirdly, a novel approach for production of biodegradable plastics, based on biocatalytic polymerization of peptides incorporated in PH with laccase, was introduced. Laccases (benzenediol:oxygen oxidoreductases, EC 1.10.3.2) represent the largest subgroup of blue multicopper oxidases, using the distinctive redox ability of copper ions to catalyze the oxidation of a wide range of aromatic substrates concomitantly with the reduction of molecular oxygen to water. Incorporation of laccase into water solution of PH led to consumption of oxygen along with increasing of the weight-average molecular mass of PH constituents. Thus, the evidence that, laccase could be used for polymerization of peptide components of PH, was clearly demonstrated. Our preliminary data indicate feasibility of biodegradable polymers production from keratin containing stock. However, further studies required in order to find the most effective strategy and to explore fully the properties of the polymers obtained. Acknowledgement This work was supported by Ministry of Science and Education RF (State Contract 16.512.11.2272).