Animal bones char solubilization by gel-entrapped yarrowia lipolytica on glycerol-based media

Citric acid was produced with free and k-carrageenan-entrapped cells of the yeast Yarrowia lipolytica in single and repeated batch-shake-flask fermentations on glycerol-based media. Simultaneous solubilization of hydroxyapatite of animal bone origin (HABO) was tested in all experiments. The highest citric acid production by free yeast cells of 20.4 g/L and 18.7 g/L was reached after 96 h of fermentation in the absence and presence of 3 g/L HABO, respectively. The maximum values for the same parameter achieved by gel-entrapped cells in conditions of single batch and repeated-batch fermentation processes were 18.7 g/L and 28.1 g/L registered after 96 h and the 3d batch cycle, respectively. The highest citric acid productivity of 0.58 g L−1 h−1 was obtained with immobilized cells in repeated batch mode of fermentation when the added hydroxyapatite of 3 g/L was solubilized to 399 mg/L whereas the maximum efficiency of 89.0% was obtained with 1 g/L of HABO.This work was supported by Projects CTM2008-03524, CTM2011-027797 (Ministerio de Ciencia e Innovación, España), P09-RNM-5196 (Junta de Andalucía, Proyecto de Excelencia), and EU COST FA0905. N. Vassileva is grateful for the SABF PR2010-0422—Ministerio de Educacion, España

Modification of the activity of an a-amylase from Bacillus licheniformis by several surfactants

The influence of different commercial surfactants on the enzymatic activity of a commercial α-amylase from Bacillus licheniformis (Termamyl 300 L) has been studied. As non-ionic surfactants, alkyl polyglycosides (Glucopon® 215, Glucopon® 600 and Glucopon® 650) were studied, as were fatty alcohol ethoxylates (Findet 1214N/23 and Findet 10/15), and nonyl phenol ethoxylate (Findet 9Q/21.5NF). Also, an anionic surfactant, linear alkyl benzene sulfonate (LAS) was assayed. In general, none of the non-ionic surfactants studied, except Findet 10/15, vary substantially the enzymatic activity. Findet 10/15 has the strongest hydrophobic character and reduces the enzymatic activity more significantly the greater its concentration. Regarding LAS, this surfactant significantly depressed enzymatic activity, presumably due to the electrostatic interactions caused by its anionic character.Fellowship awarded to Juan Francisco Martínez Gallegos by Spanish Ministry of Science and Education, FPU fellowships program

Modification of the activity of an \u3b1-amylase from Bacillus licheniformis by several surfactants

The influence of different commercial surfactants on the enzymatic activity of a commercial \u3b1-amylase from Bacillus licheniformis (Termamyl 300 L) has been studied. As non-ionic surfactants, alkyl polyglycosides (Glucopon\uae 215, Glucopon\uae 600 and Glucopon\uae 650) were studied, as were fatty alcohol ethoxylates (Findet 1214N/23 and Findet 10/15), and nonyl phenol ethoxylate (Findet 9Q/21.5NF). Also, an anionic surfactant, linear alkyl benzene sulfonate (LAS) was assayed. In general, none of the non-ionic surfactants studied, except Findet 10/15, vary substantially the enzymatic activity. Findet 10/15 has the strongest hydrophobic character and reduces the enzymatic activity more significantly the greater its concentration. Regarding LAS, this surfactant significantly depressed enzymatic activity, presumably due to the electrostatic interactions caused by its anionic character

Hidrólisis enzimática de carboximetilcelulosa y celobiosa con celluclast

Se ha estudiado la hidrólisis enzimática de celobiosa y carboximetilcelulosa con celluclast, preparado comercial de celulasas de T.reesei. Se ha comprobado que no existe desactivación apreciable de la enzima entre pH 3.9 y 5.9 y hasta 60 C y que existe un tiempo de parada de reacción significativo. Mediante los métodos diferencial e integral se ha determinado que la hidrólisis de celobiosa responde a una cinética de Michaelis-Menten. El estudio de la hidrólisis de carboximetilcelulosa se ha realizado llevando a cabo experimentos de hidrólisis total para establecer las productividades máximas en glucosa y global y experimentos para estudiar la cinética de la actuación de las endoglucanasas y de las exoglucanasas existentes en el complejo enzimático utilizadoUniversidad de Granada. Departamento de Ingenieria Química. Leída 19-12-9

Surface and thermodynamics properties of commercial fatty-alcohol ethoxylate surfactants

Supplementary data to this article can be found online at https://doi.org/10.1016/j.molliq.2023.121396.The present study provides the surface and thermodynamic properties data of commercial fatty-alcohol ethoxylate surfactants (FAEs) at different temperatures (25–60 C). These compounds are a mixture of fatty-alcohol ethoxylate oligomers with different degree of ethoxylation (2.6–11) and length of the alkyl chain (C10-C18). In this work, we analyzed determinate the water content by the Karl-Fisher method and measured the surface tension using the Wilhelmy plate method. In addition, we studied the effect of their structural parameters (degree of ethoxylation and length of alkyl chain) and the temperature on the changes of the thermodynamic functions (Gibbs free energy, enthalpy, and entropy) for the processes of adsorption and micellization. It was found an exponential decrease of the critical micellar concentration (CMC) in molar scale with the length alkyl chain of the fatty-alcohol ethoxylate surfactants, and the CMC values and thermodynamic parameters agree with those values found in literature for pure compounds. Moreover, the micellization entropy increases with the degree of ethoxylation of the surfactant.Funding for open access charge: Universidad de Granada / CBUAJunta de Andalucía predoctoral grant Programa de Incentivos a los Agentes del Sistema Andaluz del Conocimiento 2008-201

Modification of the activity of an α-amylase from Bacillus licheniformis by several surfactants

The influence of different commercial surfactants on the enzymatic activity of a commercial α-amylase from Bacillus licheniformis (Termamyl 300 L) has been studied. As non-ionic surfactants, alkyl polyglycosides (Glucopon® 215, Glucopon® 600 and Glucopon® 650) were studied, as were fatty alcohol ethoxylates (Findet 1214N/23 and Findet 10/15), and nonyl phenol ethoxylate (Findet 9Q/21.5NF). Also, an anionic surfactant, linear alkyl benzene sulfonate (LAS) was assayed. In general, none of the non-ionic surfactants studied, except Findet 10/15, vary substantially the enzymatic activity. Findet 10/15 has the strongest hydrophobic character and reduces the enzymatic activity more significantly the greater its concentration. Regarding LAS, this surfactant significantly depressed enzymatic activity, presumably due to the electrostatic interactions caused by its anionic character