Efficient immobilization of epoxide hydrolase onto silica gel and use in the enantioselective hydrolysis of racemic para-nitrostyrene oxide

Epoxide hydrolase from Aspergillus niger (E.C. 3.3.2.3) was immobilized by covalent linking to epoxide-activated silica gel under mild conditions. A very easy procedure allowed to prepare an immobilized biocatalyst with more than 90% retention of the initial enzymatic activity. Immobilized and free enzyme showed very similar behaviour with respect to the effect of pH on activity and stability. One benefit of immobilizing epoxide hydrolase from A. niger on silica gel was the enhanced enzyme stability in the presence of 20% DMSO. The kinetic resolution of racemic para-nitrostyrene oxide was investigated by using this new immobilized biocatalyst. The enantioselectivity of the enzyme was not altered by the immobilization reaction: both unreacted epoxide and formed diol were obtained with very high ee (99 and 92%, respectively). In addition, the biocatalyst could be easily separated from the reaction mixture and re-used for over nine cycles without any noticeable loss of enzymatic activity or change in the enantioselectivity extent. The activity of immobilized AnEH was retained for several months.     

Correction to: Physical-Mechanical and Antifungal Properties of Pectin Nanocomposites / Neem Oil Nanoemulsion for Seed Coating

Food Biophysics - The original version of this article unfortunately contained errors. The author name “Michele Valquíria dos Reis” and affiliation were incorrect.     

A new approach to obtain cellulose nanocrystals and ethanol from eucalyptus cellulose pulp via the biochemical pathway

The feasibility of integration of cellulosic ethanol production with the manufacture of cellulose nanofibers (CNF) and cellulose nanocrystals (CNC) was evaluated using eucalyptus cellulose pulp as feedstock and employing the biochemical route alone. For the enzymatic hydrolysis step, experimental central composite design (CCD) methodology was used as a tool to evaluate the effects of solids loading (SL) and enzymatic loading (EL) on glucose release and cellulose conversion. Glucose concentrations from 45 to 125 g/L were obtained after 24 h, with cellulose conversions from 35 to 96%. Validation of the statistical model was performed at SL of 20% and EL of 10 mg protein/g, which was defined by the desirability function as the optimum condition. The sugars released were used for the production of ethanol by Saccharomyces cerevisiae, resulting in 62.1 g/L ethanol after 8 h (yield of 95.5%). For all the CCD experimental conditions, the residual solids presented CNF characteristics. Moreover, the use of a new strategy with temperature reduction from 50 to 35°C after 24 h of enzymatic hydrolysis enabled CNC to be obtained after 144 h. The CNC showed a crystallinity index of 83%, length of 260 nm, diameter of 15 nm, and aspect ratio (L/D) of 15. These characteristics are suitable for many applications, such as reinforcement in polymeric materials and other lower volume higher value bio‐based products. The findings indicate the viability of obtaining ethanol and CNC using the biochemical route exclusively, potentially contributing to the future implementation of forest biorefineries. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1085–1095, 2017     

Prevalence, ultrastructure of the cyst wall and infectivity for the dog and cat of Sarcocystis sp. from fallow deer (Cervus dama)

The prevalence of Sarcocystis sp. (Protozoa: Sarcocystidae) in fallow deer (Cervus dama) in Tuscany, Italy was determined by digestion technique and histological examination. Forty-four of 45 fallow deer were infected. Infections occurred in adult deer and in fawns. Samples from the heart were more intensively parasitized than samples from tongue, oesophagus and diaphragm muscle. With transmission electron microscopy, the primary cyst wall was folded and formed narrow, overlapping, sinuous projections which were often parallel to the cyst surface. Dogs fed heart samples from infected fallow deer shed sporocysts after 10-11 days. Cats fed the same samples did not shed any sporocysts.     

Physical-Mechanical and Antifungal Properties of Pectin Nanocomposites / Neem Oil Nanoemulsion for Seed Coating

Biodegradable polymers, when reinforced with nanostructures, are considered good sustainable coatings and viable alternatives to replace conventional coatings. In addition, biopesticides are also considered safe, biodegradable and environmentally friendly; therefore there is a growing interest in nanoemulsions based on phytochemical mixtures. In this context, the aim of this study is to aggregate Neem oil nanoemulsions and pectin matrices to produce nanocomposite films, as well as evaluate the nanoemulsions effect on the film properties for coating soybean seeds. Nanoemulsions were characterized assessing their average diameter and stability, while the nanocomposite antifungal, morphology, mechanical and barrier properties were analyzed. In general, the nanoemulsions had an average diameter close to 59 ± 0.61 nm, showed good stability and its addition improved film mechanical properties: reduced stiffness, resistance, and water vapor permeability, and increased extensibility. In addition, Neem oil provided antifungal properties against Aspergillus Flavus and Penicillium Citrinum. The seed coatings promoted a positive effect on the germination process of soybean seeds. Thus, antifungal nanocomposite films from renewable sources were successfully produced. The fungicidal inhibition of Neem oil as a nanoemulsion makes these new materials promising for the production of seed coatings.

     

Feasibility of Manufacturing Cellulose Nanocrystals from the Solid Residues of Second-Generation Ethanol Production from Sugarcane Bagasse

The reuse of the solid residues generated in the production of second-generation (2G) ethanol to obtain high-value products is a potential strategy for improving the economic and environmental viability of the overall process. This study evaluated the feasibility of using the residual solids remaining after the enzymatic hydrolysis of sugarcane bagasse for the production of cellulose nanocrystals (CNC), a valuable bionanomaterial. To this end, sugarcane bagasse subjected to steam explosion (SEB) or liquid hot water (LHWB) pretreatment was hydrolysed using different loadings of a commercial cellulase cocktail. Samples of SEB and LHWB were hydrolysed enzymatically, resulting in glucose releases close to 40 g/L, which would be suitable for producing 2G ethanol by microbial fermentation. The solid residues after the enzymatic hydrolysis step presented cellulose contents of up to 54 %, indicating that a significant amount of recalcitrant crystalline cellulose remained available for subsequent use. These solid residues were purified and submitted to acid hydrolysis, resulting in the successful formation of CNC with crystallinity close to 80 %, lengths of 193–246 nm and diameters of 14–18 nm. The CNC produced presented morphology, dimensions, physical-chemical characteristics, thermal stability and crystallinity within the ranges reported for this type of material. Moreover, the enzyme loading or the type of hydrothermal pretreatment process employed here showed no significant effects on the CNC obtained, indicating that these variables could be flexibly adjusted according to specific interests.     

Orbital cobalt radiotherapy and systemic or retrobulbar corticosteroids for Graves' ophthalmopathy

Orbital radiotherapy and corticosteroids are two well-established medical treatments for severe Graves' ophthalmopathy. In this report we analyze the results obtained by the combination of orbital radiotherapy and systemic or retrobulbar corticosteroids in patients with severe Graves' ophthalmopathy. Orbital cobalt radiotherapy was carried out by a cobalt unit, delivering a total of 2,000 rads to each eye in 10 daily doses. Systemic corticosteroid treatment was started with 70-80 mg methylprednisolone/day for 2-3 weeks with subsequent progressive reduction of the dose until discontinuation of the drug after 5-6 months. Retrobulbar corticosteroid therapy was performed by 14 bilateral injections of 40 mg methylprednisolone acetate at 20- to 30-day intervals. Results were evaluated both on clinical grounds and by numerical scoring (ophthalmopathy index, OI). Excellent or good responses were obtained in the majority of 72 patients by combined treatment with orbital cobalt radiotherapy and systemic corticosteroids. Soft tissue changes, newly developed eye muscle dysfunction and optic neuropathy showed the most beneficial effects from treatment, whereas proptosis, corneal lesions and long-standing eye muscle abnormalities responded to a lesser extent. The results of a controlled clinical trial showed that the combined treatment was more effective than the administration of systemic methylprednisolone alone. Because relevant side effects of systemic corticosteroid therapy were observed in 4 cases, the clinical validity of retrobulbar corticosteroids in substitution for systemic corticosteroids was evaluated in 44 patients. Excellent or good responses were observed in 25% of these patients, slight responses being obtained in 55% and no change in 20%.(ABSTRACT TRUNCATED AT 250 WORDS)