Ranulfo Monte Alegre

Partitioning of pectinolytic enzymes in polyethylene glycol/potassium phosphate aqueous two-phase systems

Abstract Four different pectinolytic enzymes have been partitioned in polyethylene glycol (PEG)-potassium phosphate aqueous two-phase systems (20–15%). The influence of PEG molecular weight and the addition of sodium chloride were investigated. The best results concerning to the partition coefficients (Kp and Ke) and the yield recovery (R) were: PEG-400/phosphate with NaCl for exo-polygalacturonase (Ke=5.35 and R=89.5%), PEG-600/phosphate for pectin lyase (PL) (Ke=43.18 and R=98.5%) and pectinesterase (PE) (Ke=1.51 and R=69.6%), and PEG-10,000/phosphate for endo-polygalacturonase (Ke=1.35 and R=53.5%). The best purification factors were observed in the upper phase for the systems containing high molecular weight PEG without NaCl: PEG-6000 for exo-polygalacturonase (5.49 fold) and PEG-10,000 for endo-polygalacturonase (16.28 fold), PE (16.64 fold) and PL (14.27 fold).

Ethanol fermentation of a diluted molasses medium by Saccharomyces cerevisiae immobilized on chrysotile

In this work, the catalytic role of chrysotile support on the acceleration of alcoholic fermentation under non-aseptic conditions by Saccharomyces cerevisiae was investigated. The fermentation medium employed consisted only of diluted sugar-cane molasses. In the batch fermentations process with immobilized yeasts, the initial rate of CO2 production increased roughly 27 % during the first 30 minutes, compared to systems containing no chrysotile. A study of continuous alcoholic fermentation with chrysotile in the reactor bed showed a higher ethanol production rate at the different dilution rates investigated compared to similar fermentations without chrysotile.

Growth of Escherichia coli under extremely low-frequency electromagnetic fields.

The inflence of extremely low-frequency (ELF) electromagnetic fields on Escherichia coli cultures in submerse fermentation was studied. The fermentation processes were carried out recycling the culture medium externally through a stainless steel tube inserted in a magnetic field generator (solenoid). The exposure time and electromagnetic induction were varied in a range of 1 to 12 h and 0.010 to 0.10 T, respectively, according to a Box-Wilson Central Composite Designs of face centered with five central points. Growth of E. coli could be altered (stimulated or inhibited) under magnetic fieldinduced effects. E. coli culturesexposed at 0.1 T during 6.5 h exhibited changes in its viability compared to unexposed cells, which was 100 times higher than the control. The magnetic field generator associated with the cellular suspension recycle is a new way of magnetic treatment in fermentation processes and could be appropriate to industrial scale up.The influence of extremely low-frequency (ELF) electromagnetic fields on Escherichia coli cultures in submerse fermentation was studied. The fermentation processes were carried out recycling the culture medium externally through a stainless steel tube inserted in a magnetic field generator (solenoid). The exposure time and electromagnetic induction were varied in a range of 1 to 12 h and 0.010 to 0.10 T, respectively, according to a Box-Wilson Central Composite Designs of face centered with five central points. Growth of E. coli could be altered (stimulated or inhibited) under magnetic fieldinduced effects. E. coli cultures exposed at 0.1 T during 6.5 h exhibited changes in its viability compared to unexposed cells, which was 100 times higher than the control. The magnetic field generator associated with the cellular suspension recycle is a new way of magnetic treatment in fermentation processes and could be appropriate to industrial scale up.

Extraction of lipase from Burkholderia cepacia by PEG/Phosphate ATPS and its biochemical characterization

ABSTRACT This work aimed to study the partitioning of a lipase produced by Burkholderia cepacia in PEG/Phosphate aqueous two phase system (ATPS) and its characterization. Lipase was produced by B. cepacia strains in a fermenter. Enzyme partitioning occurred at pH 6.0 and 8.0, using PEG 1500 and 6000 on two tie lines. Metal ions, pH and temperature effects on enzyme activity were evaluated. Five milliliter of 7.5% olive oil emulsion with 2.5% gum-arabic in 0.1M sodium phosphate buffer at pH 8.0 and 37oC were used for the activity determinations. Results showed that crude stratum from B. cepacia was partitioned by PEG1500/phosphate ATPS at pH 6.0 or 8.0 for, which the partitioning coefficients were 108- and 209-folds. Lipase presented optimal activity conditions at 37 o C and pH 8.0; it showed pH-stability for 4 h of incubation at different pH values at 37 o C. Metal ions such as Mn 2+ , Co 2+ , I - and Ca 2+ sustained enzymatic activities; however, it was inhibited by the presence of Fe

Nisin production from Lactococcus lactis A.T.C.C. 7962 using supplemented whey permeate.

The influence of pH control and aeration (20% dissolved oxygen) on nisin production in a supplemented cheese whey permeate was examined during batch fermentation with Lactococcus lactis subsp. lactis A.T.C.C. 7962. A maximum nisin activity of 5280 i.u./ml of medium was observed in the raw extract of nisin after 9 h of fermentation with a constant pH at 4.9. However, the fermentation was continued until 24 h, when a decrease in the nisin activity was observed. The pH control did not influence the nisin production and aeration of the culture medium increased cell growth (biomass) but not nisin activity. The yeast Kluyveromyces marxianus, used as an alternative method to control pH, has not been efficient.

Bioreactor coupled with electromagnetic field generator : Effects of extremely low frequency electromagnetic fields on ethanol production by Saccharomyces cerevisiae

The effect of extremely low frequency (ELF) magnetic fields on ethanol production by Saccharomyces cerevisiae using sugar cane molasses was studied during batch fermentation. The cellular suspension from the fermentor was externally recycled through a stainless steel tube inserted in two magnetic field generators, and consequently, the ethanol production was intensified. Two magnetic field generators were coupled to the bioreactor, which were operated conveniently in simple or combined ways. Therefore, the recycle velocity and intensity of the magnetic field varied in a range of 0.6–1.4 m s−1 and 5–20 mT, respectively. However, under the best conditions with the magnetic field treatment (0.9–1.2 m s−1 and 20 mT plus solenoid), the overall volumetric ethanol productivity was approximately 17% higher than in the control experiment. These results made it possible to verify the effectiveness of the dynamic magnetic treatment since the fermentations with magnetic treatment reached their final stage in less time, i.e., approximately 2 h earlier, when compared with the control experiment.

Expanded bed adsorption of an alkaline lipase from Pseudomona cepacia.

An extracellular lipase was isolated from Pseudomona cepacia by expanded bed adsorption on an Amberlite 410 ion-exchange resin. Enzyme characterization and hydrodynamic study of a chromatography column were done. Enzyme purification was done at three condition of expanded bed height (H): at one and half (6cm), at two (8cm) and at three (12cm) times the fixed bed height (H(0)=4cm). The results showed that the experimental data was fitted to the Richardson and Zaki equation, and the comparison between the experimental and calculated terminal velocities showed low relative error. In enzyme purification for better condition, a purification factor of about 80 times was found at 6cm of expanded bed height, or 1.5 times of expansion degree. Purified lipase had an optimal pH and a temperature of 8 and 37 degrees C, respectively.

INFLUÊNCIA DO TEOR DE NITROGÊNIO NO CULTIVO DE Spirulina maxima EM DOIS NÍVEIS DE TEMPERATURA: Parte II: PRODUÇÃO DE LIPÍDIOS

The micraolgae Spirulina maxima was cultivated in medium with 2,5g/L KNO3 (2,5N), proposed by Paoletti et al [10] and considered standard medium, in media with 0,2g/L KNO3 (0,2N) and in absence of nitrogen (0,0N) in temperatures of 25°C and 35°C. The composition of the dry cellular biomass presented to 35°C a medium increase of the total lipids, of 2,8 times of the middle with absence of nitrogen (0,0N) and 2,9 times of the half 0,2N in relation to the standard medium. To 25°C it presented a medium increase of 3,1 times of the medium with absence of nitrogen (0,0N) and 3,2 times of the half 0,2N in relation to the standard medium. The biomass in form of gel of each treatment was picked up and made the extraction of the total lipids, which were heavy in base evaporate. The statistical analyses of the results, in estimate non lineal with answer surface and multiple regression with analysis of residues, showed for the increase of the total lipids a lineal function with the temperature (T) and not lineal with the nitrogen (N), being adjusted to a model where the regression coefficient R=0,99459 and the equation LIPT = A+B2T+CN2.

Evaluation of emulsifier stability of biosurfactant produced by Saccharomyces lipolytica CCT-0913

Surface-active compounds of biological origin are widely used for many industries (cosmetic, food, petrochemical). The Saccharomyces lipolytica CCT-0913 was able to grow and produce a biosurfactant on 5% (v/v) diesel-oil at pH 5.0 and 32oC. The cell-free broth emulsified and stabilized the oil-in-water emulsion through a first order kinetics. The results showed that the initial pH value and temperature influenced the emulsifier stability (ES), which was the time when oil was separated. The biosurfactant presented different stabilization properties for vegetable and mineral oil in water solution, despite the highest values of the ES occurring with vegetable oil. The biosurfactant presented smallest ES when compared to commercial surfactants; however, this biosurfactant was not purified.

Glutathione production using magnetic fields generated by magnets

ABSTRACT The objective of this work was to study the production of GSH by Saccharomyces cerevisiae ATCC 7754 in a fermentor (5 L) using a cell recycle system with magnets. The fermentation conditions were 20°C, 500 rpm, 5% (v/v) of inoculum, pH initial 5, 1.1 vvm aeration and total fermentation time of 72 h. The time of application of MF ranged from 24, 48 or 72 h. In comparison to the control experiment, the best results were obtained with 72 h of application of MF. The cell concentration reached 19.5 g/L and GSH concentration was 271.9 mg/L that corresponded to an increase of 2.63 and 32.1% compared to the control experiment, respectively. Key words: glutathione, magnetic field, Saccharomyces cerevisiae, batch fermentation *Author for correspondence: santoslucielen@gmail.com INTRODUCTION Glutathione, (GSH) is a biologically active tripeptide consisting of L-glutamate, L-cysteine and glycine (Zhang et al. 2007). The biosynthesis of GSH in humans occurs in virtually all cell types, with the liver being the major producer and exporter (Wu et al . 2004). One of its most important functions is as an antioxidant against the toxic effects of oxygen and other oxidative compounds (Fan et al . 2004). Glutathione deficiency contributes to oxidative stress, which plays a key role in aging and the pathogenesis of many diseases (including kwashiorkor, seizure, Alzheimer’s disease, Parkinson’s disease, liver disease, cystic fibrosis, sickle cell anemia, HIV, AIDS, cancer, heart attack, stroke and diabetes) (Wu et al. 2004). Zhang et al. (2007) reported that GSH was widely used as a pharmaceutical compound and has the potential to be used in food additives and in the cosmetic industries. Some yeast strains have the ability to accumulate glutathione in the cells. Yeast fermentation is an efficient approach to commercially produce glutathione (Wen et al . 2005). Glutathione can be produced by direct fermentative methods using sugar as a starting material. Saccharomyces cerevisiae and Candida utilis are currently used to produce glutathione on an industrial scale (Li et al . 2004). S. cerevisiae is widely used in ethanol production. Many studies have been conducted to assess the culture media, types of fermenters and immobilization of yeasts (Alegre et al . 2003). Being an intracellular product in yeast, GSH production can be enhanced in two ways: increasing the cell biomass largely, or improving GSH content in yeast greatly. It is comparatively easier to increase the cell mass by fermentation