RESUMO
This study evaluates the activity of a recombinant chitinase from the leaf-cutting ant Atta sexdens (AsChtII-C4B1) against colloidal and solid α- and ß-chitin substrates. 1H NMR analyses of the reaction media showed the formation of N-acetylglucosamine (GlcNAc) as the hydrolysis product. Viscometry analyses revealed a reduction in the viscosity of chitin solutions, indicating that the enzyme decreases their molecular masses. Both solid state 13C NMR and XRD analyses showed minor differences in chitin crystallinity pre- and post-reaction, indicative of partial hydrolysis under the studied conditions, resulting in the formation of GlcNAc and a reduction in molecular mass. However, the enzyme was unable to completely degrade the chitin samples, as they retained most of their solid-state structure. It was also observed that the enzyme acts progressively and with a greater activity on α-chitin than on ß-chitin. AsChtII-C4B1 significantly changed the hyphae of the phytopathogenic fungus Lasiodiplodia theobromae, hindering its growth in both solid and liquid media and reducing its dry biomass by approximately 61%. The results demonstrate that AsChtII-C4B1 could be applied as an agent for the bioproduction of chitin derivatives and as a potential antifungal agent.
RESUMO
The uvaia is a native Brazilian Atlantic Forest Myrtaceae fruit with a soft pulp, ranging from yellow to orange, with a sweet acidic flavor and sweet fruity aroma. Uvaias present consumption potential, but their physicochemical characteristics are still understudied. In this context, we describe herein the metabolites of uvaia that have been determined by nuclear magnetic resonance spectroscopy. We screened 41 accessions and selected 10 accessions based on their diversity of physicochemical attributes, i.e., their fresh mass, height, diameter, yield, seed mass, total soluble solids, and titratable acidity. Twenty-six metabolites were identified, including sugars, acids, and amino acids. The results of this study comprise the most complete report on sugars and acids in uvaias. The relevant metabolites in terms of abundance were the reducing sugars glucose and fructose, as well as malic and citric acids. Furthermore, this study represents the first description of the uvaia amino acid profile and an outline of its metabolic pathways. Uvaia quality attributes differ among accessions, demonstrating high variability, diversity, and several possibilities in different economic areas. Our findings may help in future breeding programs in the selection of plant material for industries such as food and pharmaceuticals.
RESUMO
The sediments inside the ballast tanks might compromise the effectiveness of the ballast water exchange procedure. In the present study, the sediment removal from double bottom ballast tanks due to flow-through ballast water exchange is investigated by simplified experimental and numerical models. Two flow rates and two sediment densities were considered to verify their influence on the process. Besides, the effectiveness of two tank configuration modifications to improve the sediments removal was investigated. The first is the introduction of a flow deflector inside the tank and the second is the water inflow from the bottom. A fully Lagrangian particle-based method is adopted to simulate the sediment removal process with complex tank geometry. A new boundary condition is proposed to model the mesh of the bottom inlet in the bottom inflow configuration. Despite the simplifications of the numerical model, the computational results are in good agreement with the experimental ones. The results show that the flow-through ballast water exchange method might not be effective to remove the sediments entrapped between the bottom stiffeners, and the proposed modifications, despite challenging implementation, improve the sediment removal.
