Agriculture faces numerous challenges: infectious diseases through phytopathogens and soil nutrient deficiencies hinder plant growth, reducing crop yields. Biopolymer nanocomposites offer promising solutions to these challenges. In this work, we synthesize and characterize novel bionanocomposites (ι-CG-Mn) of manganese (hydr)oxide nanoparticles (approx. 3 to 11 nm) embedded in the matrix of the natural polysaccharide ι-carrageenan (ι-CG). Using spectroscopic methods we verify the presence of the nanoparticles in the polymer matrix while leaving the polysaccharide structural characteristics unaffected. Elemental analysis determines the mass content of metal ions in the ι-CG-Mn to be approx. 1 wt%. Electron microscopy techniques show the supramolecular organization of the ι-CG-Mn and the homogeneous nanoparticle distribution in the polymer matrix, while thermal analysis reveals that the bionanocomposite maintains high thermal stability. Moreover, the co-incubation of the phytopathogen Clavibacter sepedonicus with ι-CG-Mn inhibits the pathogen growth by 67% compared to the control. Our bionanocomposites demonstrate (1) strong bactericidal activity and (2) potential as microfertilizers that stimulate agricultural plant growth through the dosage of metal ions. These properties arise from the bioactivity of the widely available, naturally sulfated polysaccharide biopolymer matrix, combined with the antimicrobial effects of manganese (hydr)oxide nanoparticles, which together enhance the efficacy of the biocomposite. The non-toxic, biocompatible, and biodegradable nature of this biopolymer satisfies the high environmental demands for future biotechnological and agricultural technologies.

The development of methods for soil remediation for removal of chemical contaminants is a large and challenging problem. A new phytoremediation technology, given in the present work, is based on joint application of natural sorbents, microorganisms and plants. The method aims at prevention of chemical contamination of soils. It has the potential to restore a polluted environment and prevent dissemination of toxic compounds from hotbeds of pollution for a considerable length of time. The presented complex biotechnology is important from the viewpoint of prevention. This technology can be applied to soils contaminated with heavy metals, oil hydrocarbons, explosives, pesticides and other pollutants. The main purpose of the carried out work is the development of a novel approach to the provision of ecological safety. The approach is based on using natural minerals composites which are comprised of natural mineral rocks, microorganism strains with high detoxification abilities and plants-phytoremediators. In this composite material, the function of a sorbent is to uptake and to trap pollutants thus restraining their emission in the environment. The role of the microorganisms is to accomplish the first stage of biodegradation of organic contaminants and then to apply phytoremediation as a unique cleanup strategy. Natural sorbent can be applied during the initial stage of cleaning up of contaminated soil, followed by application of a phytoremediation technology through purposeful planting of selected plants. This results in the total assimilation and complete mineralization of pollutants and/or their intermediates or in their partial transformation by microbes.Following contaminants were used in the present work: explosive – 2,4,6 trinitrotoluene (TNT), oil hydrocarbon (hexadecane) and Wax (long chain hydrocarbons). Special attention was paid to enhancement of soil fertility, which improves microorganism and plant growth conditions and is important for bioremediation processes providing total rehabilitation of soil.