Aprovechamiento de biomasa lignocelulósica de semilla de aguacate (Persea Americana Mill): evaluación de la capacidad fungistática y adsorción de metales pesados en solución acuosa

Abstract

Currently, one of the environmental challenges of researchers at national and international level is the use of renewable materials and the use of their biological, chemical and physical properties. These materials include residues from natural sources generally known as residual biomass. The seed of the Persea americana Mill (common name: avocado or avocado) is considered as "residue" of the food industry. To provide an additional alternative to those existing for the exploitation of avocado seed, it is proposed in this research to evaluate the chemical, biological and physical properties. In this way, the comparative study of the extraction of the seed of Persea americana Mill was carried out by various techniques (percolation, Soxleth, MWHD), being the Soxleth-type ethanolic extraction in which a higher percentage of extraction was obtained (7.7 %). The ethanolic extract obtained was characterized by UV-Vis, IR, NMR and GC-MS, techniques that allowed identifying that the major compounds are avocatins. The evaluation of the biological properties of the Botrytis cinerea strain DSM5144 with the ethanolic extract of the avocado seed which demonstrated its fungistatic power with a percentage of inhibition of 82 % of the radial growth of the plant pathogen at a concentration of 6.0 mg/mL under the plate dilution technique. During the in vivo trial on fragaria fruits, a 40 % inhibition of phytopathogenic growth was obtained in 96 h. Likewise, the physical capacities of the seed residue as raw material to produce filtration systems for filter media used in the decontamination of water bodies contaminated with heavy metals (Pb, Cr, Cu, Cd and Hg) were evaluated. In this research, filter media were developed from the residual biomass of avocado modified with acid and the coupling of nanoparticles on the same calcined biomass (biochar). The filtering media were characterized by IR, SEM and TEM techniques that allowed identifying acid treatment as the most effective for the formation of pores in biomass and to corroborate those magnetic nanoparticles were coupled during synthesis on the biochar. Finally, the filter media were evaluated for bioadsorption, where the most relevant result was obtained when the residual avocado biomass was used for the removal of mercury in solution (100 ppm) with 91% removal. These results allowed to postulate the residual biomass of the utilization of the avocado as source of an extract with biological properties as fungistatic control agent on the phytopathogenic fungus Botrytis cinerea and from this material to obtain means filters that serve as a viable alternative for removal of metals in water, allowing to give an added value to a waste favoring the decrease of the environmental impact.