Extraction of phenolic compounds using citric residues and bagasse as substrate.

ORTELLADO, LAURA E; PD ZAPATA.; FONSECA, MI.

Congreso; XVIII Congreso de la Sociedad Argentina de Microbiologia General SAMIGE; 2023

Bioactive compounds are defined as secondary metabolites that are naturally derived from living organisms and have beneficial effects on human health. Among these, phenolic compounds constitute one of the most prominent bioactive compounds, characterized by their diverse biological activities and low toxicity. These products are usually obtained by aggressive methods such as thermal, chemical, or physical processes, which may lead to degradation or alteration of the chemical structures of the compounds of interest. A more efficient and less impactful technological alternative is extraction mediated by organisms or their components, such as enzymes, or a combination of conventional and biological approaches, thus enhancing their ecological character. In this context, exploring new eco-friendly strategies to obtain bioactive compounds is extremely attractive from a research perspective. Based on the above, we evaluated citrus by-products (grapefruit peels) and lignocellulosic residues (cane bagasse) as substrates for the cultivation of the fungus Aspergillus niger LBM 134 to obtain bioactive compounds. For this purpose, A. niger LBM 134, previously deposited at the Misiones Institute of Biotechnology (InBioMis), was grown in plates containing sugar potato agar medium 39 gL-1 (PDA) and incubated at 28°C until the desired mycelial development was achieved. Subsequently, tests were carried out in which different proportions of citrus by-products and lignocellulosic residues (1:1, 1:2, 1:3, 1:4) were evaluated as substrates for growth, with the aim of establishing the optimal proportion of each type of residue. Colonization of the substrate was qualitatively evaluated as a criterion to determine this optimal ratio. After the colonization of each substrate mix with A. niger LBM 134 and 12 days of culture, extractions were made with ethanol. Subsequently, the content of total phenols (CFT) was quantified using Folin-Ciocalteu 1N. CFT was expressed in milligrams of gallic acid equivalents per milliliter (mg GAE mL-1). The results of the trials revealed that the best mycelial expansion was achieved with a ratio of 1:2 (grapefruit peels: cane bagasse). Regarding the quantification of CFT, the values obtained for the different proportions evaluated were 25, 59, 55, and 35 mg GAE mL-1 for mixes containing 1:1, 1:2, 1:3, and 1:4 grapefruit peels: cane bagasse respectively. The values for the controls of the substrate without mycelium and mycelium without substrate were 19 and 10 mg GAE mL-1.Based on these results, it was established that agroindustrial residues can be effectively used as substrates in the cultivation of A. niger for the generation of bioactive by-products. This finding highlights the importance of this approach as a promising way to obtain beneficial compounds from an environmentally conscious perspective.