Nova abordagem para produção de nanocelulose bacteriana a partir de frutas nativas brasileiras

Abstract

The superior properties of bacterial nanocellulose (BCN) compared to plant cellulose, such as its high purity, high degree of crystallinity, porous nanostructure, high water retention capacity, excellent mechanical strength, biodegradability and biocompatibility, have aroused interest in its application in the medical, pharmaceutical, food, cosmetics, environmental, electronics and textile fields, among others. However, the high cost of production has limited their large-scale production, encouraging the development of alternative cultivation media based on varying carbon and nitrogen sources. Fruits from the Myrtaceae family such as pitanga Eugenia uniflora), araçá (Psidium cattleianum) and jabuticaba (Plinia sp.) have interesting chemical properties as culture media, due to their source of carbon and bioactive compounds. Until this study, no methodology for producing NCB from the pulp of native Brazilian fruits had been reported in the literature. In this sense, this study aims to develop a process for producing bacterial nanocellulose (NCB) in a culture medium from Brazilian native fruit pulp to obtain NCB at a lower cost and with added value using the bacterium Komagataeibacter xylinus ATCC [trade mark] 53524™. The bacterium was grown in traditional Hestrin & Schramm (HS) liquid medium in static culture at 30°C for 7 days. Six fermentation conditions (traditional HS medium, HS medium with fruit pulp, pure pulp media - jabuticaba, pitanga or araçá and modifications of HS with fruit pulp) were tested for 15 days to evaluate NCB production. In addition, the pulp media of each fruit was characterized based on total carbon and nitrogen, pH, phenolic compounds and antioxidant capacity using the ABTS (2,2'- azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and FRAP (Ferric Reducing Antioxidant Power) assays. The physicochemical properties of the NCB biomaterials produced in the media with the highest yields were also evaluated by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), water retention capacity, porosity, tensile strength, elasticity and antioxidant capacity. The conditions with the pure jabuticaba or pitanga pulp medium, without the addition of another component in the medium, obtained considerable yields compared to the NCB membranes produced in HS medium. Thus, the membranes from the Jabuticaba medium (NCB-J) showed a yield of 4.09 g/L, pitanga (NCB-P) with a yield of 4.33 g/L and HS (NCB-H) with a yield of 5.96 g/L. In addition, the NCB-J and NCB-P membranes maintained the characteristic properties of NCB membranes, such as high water retention capacity of around 98% and high porosity of 73%, mechanical strength, and the structural chemical composition were also maintained. NCB production was achieved under all six conditions, but the results demonstrated the potential of culture media from pure jabuticaba and pitanga pulp. Thus, this study points to an innovative approach to producing NCB from native Brazilian fruits, without adding other complex components to the media, guaranteeing a high yield and low cost.