Produção de lipídeos poli-insaturados e quitosana por Lichtheimia hyalospora e Mucor subtilissimus com potencial de aplicação como nutracêuticos

Abstract

Fungi belonging Mucorales order are known to be oleaginous microorganisms and naturally produce chitosan in their cell wall, being considered as promising sources for demand in the food and nutrition industry. The aim of this study was to investigate the production of lipids and chitosan by Mucor subtilissimus UCP 1262 and Lichtheimia hyalospora UCP 1266 in a sustainable and economical way. Initially, soil samples were collected from Caatinga, submitted to serial dilutions and subcultured in Sabouraud medium containing chloramphenicol. The colonies of interest were isolated and identified by macroscopic and microscopic observations. Production of fungal biomass was through cultivation in alternative media enriched with corn steep liquor (CSL), as a nitrogen source, and supplemented with cassava wastewater (CWW) or crude glycerol (CG) as carbon sources. Lipids and chitosan extraction were performed concurrently with the use of organic solvents and alkali acid treatment, respectively. The degree of chitosan deacetylation was analyzed by infrared spectroscopy and the lipid fatty acid profile was analyzed by gas chromatography. L. hyalospora UCP 1266 obtained the highest biomass yield (15.5 g/L) with the highest concentrations of agro-industrial residues (8% CSL and 8% CG), as well as the highest lipid accumulation (82%). Regarding the profile of fatty acids produced by L. hyalospora UCP 1266, α-linolenic acid (omega 3) was the most representative polyunsaturated fatty acid (17.9%). In the cultivation using CWW (4%) and CSL (6%), the highest biomass yields by M. subtilissimus UCP 1262 and L. hyalospora UCP 1266 were 4.832 g/L and 6.540 g/L, respectively, as well as the highest chitosan yield (32.471 mg/g) by M. subtilissimus UCP 1262. However, the highest chitosan yield (45.03 mg/g) obtained by L. hyalospora UCP 1266 was obtained at the central point of the factorial design (4% CSL and 6% CWW). Chitosans produced by M. subtilissimus UCP 1262 and L. hyalospora UCP 1266 cultivated in CWW presented 80.28 and 83.61% of deacetylation degree and viscosity of 2.78 and 3.06 cP, respectively. Therefore, L. hyalospora UCP 1266 was selected for a 22 Central Composite Rotational Design (CCRD), as it exhibited the highest chitosan production in media containing CWW and CSL. The highest chitosan production (63.18 mg/g) was obtained when L. hyalospora UCP 1266 was cultivated in medium containing 8.82% of CSL and 7% of CWW. The medium with CG (5%) and CSL (5%) favored the production of biomass (13.25 g/L), chitosan (44.89 mg/g) and lipids (44.27%) by M. subtilissimus UCP 1262. Chitosan obtained under this condition had deacetylation degree of 80.25% and viscosity of 2.2 cP. The results show that microorganisms are able to metabolize alternative substrates and produce bioactive biomolecules that may complement the need for innovative products as nutraceuticals because they are natural resources with low toxicity.