Melaço de soja como substrato para a produção de (1→6)-β-D-glucana (lasiodiplodana)

Abstract

On a commercial scale, glucans have been obtained by extracting the cell wall from yeast such as Saccharomyces cerevisae and cereals such as oats and barley. However, extraction processes commonly have high operating costs, and an alternative to reducing costs could be the production of extracellular glucans using low cost cultivation media. In this context, the present work proposes the production of exocellular lasiodiplodan by the fungus Lasiodiplodia theobromae MMPI in submerged cultivation using medium based soybean molasses. The influence of different sugar concentrations on bioprocess performance was studied. The biopolymers obtained were characterized by Fourier transform infrared spectroscopy (FI-I R), Thermal Analysis (TG, DSC), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). FT-IR analysis revealed typical bands of β-glycosidic polysaccharides, SEM micrographs revealed samples containing surface area with thin and translucent film aspects, containing smooth surface regions and folds along their length. X-ray diffraction analysis showed that both samples have typically amorphous structure but contain regions with some molecular organization. Thermal analysis showed that lasiodiplodan samples obtained from soybean molasses presented high thermal stability, and three mass loss events were observed. Soybean molasses proved to be a good substrate for mycelial growth and lasiodiplodan production by the fungus studied. Higher substrate concentrations promoted better bioprocess performance, including improve the yields and volumetric productivity in lasiodiplodan and mycelial biomass growth.