Enzyme-assisted extraction of red seaweed Solieria chordalis (C.Agardh) J. Agardh 1842—the starting point for the production of biostimulants of plant growth and biosorbents of metal ions

The underexploited biomass of red seaweed Solieria chordalis (C.Agardh) J.Agardh 1842 represents a potential source for biotechnological development. Extracts obtained from S. chordalis by enzyme-assisted extraction using Protamex® and Neutrase® were evaluated as potential biostimulants of plant growth. Additionally, this alga, as well as post-extraction residues, were examined as biosorbents of metal ions. The biostimulant properties of different concentrations of algal extracts (20, 40, 60, 80, 100%) were tested in vitro on radish seeds. Chlorophyll content, plant weight, and height were measured for each experimental group. For all tested concentrations, the plants demonstrated higher chlorophyll content and were higher and heavier than the control group, showing that enzyme extracts could be used as efficient biostimulants. The biosorption properties of seaweed and post-extraction residues were tested on Cr(III) ions for different experimental conditions—pH, initial metal ion concentration, and biosorbent dosage. The maximum biosorption capacity of S. chordalis was 48.1 mg/g, for the post-extraction residue obtained with Protamex®, 47.6 mg/g, and Neutrase®, 50.5 mg/g. The binding of Cr(III) ions to the surface of biosorbents was confirmed by FT-IR analysis. Good biosorption properties of tested materials can be used in the production of novel components of fertilizers or biosorbents for wastewater treatment. In this paper, it was shown that waste biomass of S. chordalis can be turned into valuable bio-products using environmental-friendly technologies.