Optimization of β-galactosidase production using Kluyveromyces lactis NRRL Y-8279 by response surface methodology

This paper investigates the production and optimization of β-galactosidase enzyme using synthetic medium by Kluyveromyces lactis NRRL Y-8279 in shake flask cultures. Among the different cell disintegration methods used, the highest specific activity was obtained when the cells were permeabilized using isoamyl alcohol. Response surface methodology was used to investigate the effects of four fermentation parameters (agitation speed, pH, initial substrate concentration and incubation time) on β-galactosidase enzyme production. Results of the statistical analysis showed that the fit of the model was good in all cases. Maximum specific enzyme activity of 4218.4 U g-1 was obtained at the optimum levels of process variables (pH 7.35, agitation speed 179.2 rpm, initial sugar concentration 24.9 g l-1 and incubation time 50.9 hrs). The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in β-galactosidase enzyme production

Exopolysaccharide production of acetic acid bacteria

Polysaccharides derived from Gram-positive and Gram-negative bacteria are divided into two groups; capsular polysaccharides (CPS) and exopolysaccharides (EPS) (Kumar et al. 2007, Ali et al. 2011). CPS is permanently attached to the outer surface of the cells and EPS is secreted into the growth medium (Ali et al. 2011, Perumpuli et al. 2014). These polysaccharides are either homopolysaccharides containing a single type of monosaccharide or heteropolysaccharides containing several types of monosaccharides (Donot et al. 2012, Ahmad et al. 2015). © 2017 by Taylor & Francis Group, LLC

Adsorption equilibrium and dynamics of lactase/CM-Sephadex system

Partitioning behaviour and adsorption isotherms of lactase/CM-Sephadex system at equilibrium were investigated together with the adsorption kinetics in this study. Maximum adsorption was obtained at the pH values between 5.5-6.0. Adsorption isotherm was a close fit to the Langmuir model. © 1995 Chapman & Hall

Optimization of pullulan production from synthetic medium by Aureobasidium pullulans in a stirred tank reactor by response surface methodology

The production of pullulan from synthetic medium by Aureobasidium pullulans P56 in a stirred tank fermenter was investigated. The kinetics of polysaccharide, pullulan and biomass production was determined. Response surface methodology was used to investigate the effects of three factors (initial sugar concentration, aeration rate and agitation speed) on the concentration of pullulan in batch cultures of A pullulans. In the experiments, the range of values used for the three variables described were; 30-70 g dm-3 initial sugar concentration, 200-600 rpm agitation speed and 1.0-3.0 vvm aeration rate. No previous work has used statistical analysis in determining the interactions among these variables in pullulan production. Results of the statistical analysis showed that the fit of the model was good in all cases. Aeration rate, agitation speed and sugar concentration had a strong linear effect on pullulan concentration. Moreover, pullulan concentration was significantly influenced by the negative quadratic effects of the given variables and by their positive or negative interactions with the exception that the interaction between agitation speed and aeration rate was insignificant (P > 0.05). Maximum pullulan concentration of 17.2 g dm-3 was obtained at the optimum levels of process variables (initial sugar concentration 51.4 g dm-3, aeration rate 2.36 vvm, agitation speed 345.3 rpm). These values were obtained by fitting of the experimental data to the model equation. Scanning electron microscope (SEM) photographs of polysaccharide particles containing different concentrations of pullulan were also taken to observe the morphological differences of the samples. © 2005 Society of Chemical Industry