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This work aimed to produce porous poly‐hydroxybutyrate (PHB) pellets in order to evaluate the pellets as a support for immobilization of the metagenomic lipase, LipG9. Four types of pelletized PHB particles with different morphological characteristics were obtained using the double emulsion and solvent evaporation technique (DESE). The micropores of these PHB pellets had similar average diameters (about 3 nm), but the pellets had different specific surface areas: 11.7 m2 g−1 for the PHB powder, 8.4 m2 g−1 for the control pellets (Ø < 0.5 mm, produced without the pore forming agent), 10.0 m2 g−1 for the small pellets (Ø < 0.5 mm), 9.5 m2 g−1 for the medium pellets (0.5 < Ø < 0.8 mm) and 8.4 m2 g−1 for the large pellets (Ø > 1.4 mm). Purified LipG9 was immobilized by adsorption on these pellets, and the results were compared with those obtained with PHB powder. The highest immobilization yield (83%) was obtained for the medium PHB pellets, followed by large (76%) and small (55%) PHB pellets. The activity of LipG9 immobilized on the pellets, for the synthesis of ethyl oleate in n‐hexane, was highest for the medium pellets (22 U g−1). The immobilization yield was high for PHB powder (99%) but the esterification activity was slightly lower (20 U g−1). These results show that pelletized PHB beads can be used for the immobilization of lipases, with the advantage that pelletized PHB will perform better than PHB powder in large‐scale enzyme bioreactors. [ABSTRACT FROM AUTHOR]

In this work, ultrasound was used to assist the ethanolysis of castor oil in a solvent‐free system, catalyzed by a dry fermented solid containing the lipase from Burkholderia contaminans (BCFS). Reactions were done at 45°C. The maximum conversion in Erlenmeyer flasks was 71% in 96 h, using a loading of 9% (mass of BCFS in relation to the mass of triacylglycerols in the castor oil) and a molar ratio of ethanol:oil of 6:1, with addition of ethanol in 12 steps. In a packed‐bed reactor containing 12 g of BCFS, the conversions were 78% in 48 h, and 83% in 72 h with an ethanol to oil molar ratio of 3:1 and treatment with an ultrasound probe, with maximum power of 500 W, frequency of 20 kHz, and 75% of the maximum power. These results are promising given that, with an ultrasound assisted bioreactor, a higher conversion in a shorter time was achieved, with a lower ethanol to oil molar ratio than was the case in the Erlenmeyer flasks without ultrasound. [ABSTRACT FROM AUTHOR]

The production and direct employment in organic medium in the ethyl‐oleate synthesis of a fermented solid (FS) containing lipases by Penicillium roqueforti ATCC 10110 (PR10110) was investigated. For the production of this FS, the solid‐state fermentation of different agroindustrial waste was used, such as: cocoa shell, sugarcane bagasse, sugarcane bagasse with cocoa shell, and cocoa shell with soybean oil and nutrient solution. The response surface methodology was used to study the effect of independent variables of initial moisture content and inductor concentration, as carbon source and inducer on lipase production. The characterization of the fermented solid in organic medium was also carried out. The highest lipase activity (53 ± 5 U g−1) was 16% higher than that obtained with the nonoptimized conditions. The characterization studies observed high stability of the FS in organic solvents for 5 h at 30°C, as well as at different temperatures, and the residual activity was measured against triolein. The FS was also able to catalyze ethyl‐oleate synthesis maintaining high relative conversion over five reaction cycles of 96 h at 40°C in n‐heptane. These results are promising and highlight the use of the FS containing PR10110 lipases for the first time in biocatalytic processes. [ABSTRACT FROM AUTHOR]

A biocatalytic process to synthesize regioselective monohydroxy glycosyl building blocks has been optimized. Lipases immobilized on commercial supports were treated with water-soluble carbodiimide (EDC) at different concentrations. In the presence of cosolvents, the stability of lipases adsorbed on octyl-Sepharose improved after the EDC modification. The new Candida rugosa lipase (CRL) modified heterogeneous biocatalysts were tested in the production of 6-OH hydroxyl-tetraacetyl glucose by a regioselective mono-deacetylation in aqueous media. Improvements in activity and excellent regioselectivity were obtained for octyl-CRL-EDC10mM preparation, with 95 % isolated yield of product on a multimilligram scale. We also observed excellent recyclability. The C-6 alcohol was transformed to a C-3 alcohol by chemical migration, and both compounds were transformed successfully in the corresponding new trichloroacetimidyl glucoderivatives. Modified CRL biocatalysts were also tested in the selective deprotection of peracetylated thymidine, and octyl-CRL-EDC10mM showed excellent specificity and improved regioselectivity to produce 3-hydroxy-5-acetyl-thymidine, a precursor of azidethymidine (AZT), in 95 % yield. The new Rhizomucor miehei lipase (RML)-modified heterogeneous biocatalysts showed excellent regioselectivity and recyclability in the 3-OH mono-deprotection of peracetylated lactal. [ABSTRACT FROM AUTHOR]