Comparison of lipase production by Geotrichum candidum in stirring and airlift fermenters

The production of lipase by Geotrichum candidum in both, stirred tank and airlift bioreactors were compared. G candidum an imperfect filamentous fungus, grows well in liquid medium, and produces a lipase with specific affinity for long‐chain fatty acids with cis‐9 double bonds but, lipase production is generally not efficient because the optimum medium composition and fermentation conditions are not known. Response surface methodology was used to optimize the agitation speed (100–500 rpm) and aeration (0.2–1.8 vvm) for production of lipase by G candidum in a bench‐scale stirred fermenter. A Central Composite Rotatable Design (CCRD) was used to optimize lipase activity and productivity. Lipase production in an airlift fermenter was also studied with aeration ranging from 1 to 3 vvm. A previously optimized culture medium containing 3.58% of peptone, 0.64% of soy oil and an initial pH of 7.0, was used in the experiments, incubating at 30°C. In the stirred reactor the optimum conditions of agitation and aeration for lipase production and productivity were 300 rpm and 1 vvm, leading to an activity of 20 U cm^?3 in 54 h of fermentation and 0.3900 (U cm^?3 h^?1) of productivity. The best aeration condition in the airlift fermenter was 2.5 vvm, which yielded similar lipase activity after 30 h of fermentation, resulting in a productivity of 0.6423 (U cm^?3 h^?1). In the absence of mechanical agitation similar lipase yields were achieved but in less time, resulting in productivity, about 60% greater than in a stirred fermenter; the lower energy demand for the same lipase yield offers economic advantages. Copyright © 2004 Society of Chemical Industry     

Description of volatile compounds generated by the degradation of carotenoids in paprika,tomato and marigold oleoresins

Here we describe the profiles of volatile compounds from the thermal degradation of carotenoids present in oleoresins of marigold, tomato and paprika. The profiles obtained by SPME-GC were complex, with identical compounds, such as toluene and m-xylene, being detected in all three oleoresins. Intramolecular cyclisation is proposed as the main reaction mechanism in the formation of the volatile compounds detected; this process is activated by the thermal impact generated during the processing and is followed by a reaction of elimination in the chain or a heterolytic fragmentation reaction. The presence of other compounds, such as various methyl benzaldehydes or isophorone (1,1,3-trimethyl-3-cyclohexene-5-one), also indicates the concurrence of carotenoid oxidation reactions that affect either the central polyenoic chain or the end-groups (β or ε rings). Ethanone,1-(methylphenyl), (4prime-methylacetophenone) not previously reported as a compound resulting from the thermal degradation of carotenoids, was also characterised and the same mechanism is proposed for its formation.     

Biodesulfurization of two Colombian coals with native microorganisms

A biodesulfurization process was carried out for two coals from the southwest of Colombia using a consortium of native microorganisms Acidithiobacillus ferrooxidans-like and Acidithiobacillus thiooxidans-like. Characterization techniques as X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM/EDX) and chemical analysis were used in order to establish the mineralogy of the process. The sulfur content in coals varies from 2.6% to 5.7%, and pyrite is the main sulphide present in the inorganic phase. Other minerals in the substrates include kaolinite, calcite, dolomite and quartz. An 85–95% reduction of pyritic sulfur and 31–51% of total sulfur in a period of 30 days were achieved, for a particle size of − 74 µm, 10% w/v pulp density and 30 °C.     

Astra blue and basic fuchsin double staining of plant materials

Methods for double staining plant materials using astra blue and basic fuchsin are described here. These methods can be applied to free hand and microtome sections embedded in paraffin, paraplast or historesin. Also, they can be used to study isolated epidermal peels and pollen preparations. Temporary, semipermanent and permanent preparations were studied. Astra blue stained polysaccharides of the cell wall such as cellulose and pectins. Basic fuchsin showed an affinity for lignified, suberized or cutinized walls. The easy preparation of the reagents, excellent color contrast of the histological preparations, and brief staining times of some methods makes them useful for both routine research and didactic purposes. Also, excellent color or black and white photomicrography can be obtained after the double staining described here.     

Natural origin biodegradable systems in tissue engineering and regenerative medicine: present status and some moving trends.

The fields of tissue engineering and regenerative medicine aim at promoting the regeneration of tissues or replacing failing or malfunctioning organs, by means of combining a scaffold/support material, adequate cells and bioactive molecules. Different materials have been proposed to be used as both three-dimensional porous scaffolds and hydrogel matrices for distinct tissue engineering strategies. Among them, polymers of natural origin are one of the most attractive options, mainly due to their similarities with the extracellular matrix (ECM), chemical versatility as well as typically good biological performance. In this review, the most studied and promising and recently proposed naturally derived polymers that have been suggested for tissue engineering applications are described. Different classes of such type of polymers and their blends with synthetic polymers are analysed, with special focus on polysaccharides and proteins, the systems that are more inspired by the ECM. The adaptation of conventional methods or non-conventional processing techniques for processing scaffolds from natural origin based polymers is reviewed. The use of particles, membranes and injectable systems from such kind of materials is also overviewed, especially what concerns the present status of the research that should lead towards their final application. Finally, the biological performance of tissue engineering constructs based on natural-based polymers is discussed, using several examples for different clinically relevant applications.     

Mineralization of aromatics in water by sunlight-assisted electro-fenton technology in a pilot reactor

The viability of the degradation of aqueous solutions of aniline, nitrobenzene, and 4-chlorophenol by the so-called Photoelectro-Fenton process in a pilot reactor is reported. The Electro-Fenton process stage, based on the flow of oxygen through a gas diffusion cathode to produce H2O2, allows mineralization of about a half of the TOC content in ca. 1 h, because anodic oxidation is coupled with Fenton reaction in the presence of Fe2+ catalyst. An intensity of 20 A was applied in a flow cell comprising a Ti/Pt anode and a carbon-PTFE cathode. After electrolysis, samples of the effluent were exposed to sunlight, and almost complete mineralization was reached after ca. 50 min. Effect of parameters such as electrolysis time, pH, initial concentration, and solar or UVA irradiation on the process efficiencies and the running costs are studied. The Photoelectro-Fenton process using sunlight effectively diminishes these costs. The analogous behavior of the three aromatics suggests similar degradation pathways, regardless of the different groups attached to the ring.     

Silver halide sensitized gelatin process effects in holographic lenses recorded on Slavich PFG-01 plates

In this work we study the feasibility of using silver halide sensitized gelatin based on PFG-01 (Slavich) emulsions to construct uniaxial compound lenses. This processing is able to introduce variations in the thickness and refractive index of the emulsion. We prove that these changes are not sufficient to provide the observed variations in Bragg conditions in the reconstruction and that a shear-type effect must exist to explain the performance of processed emulsions. We study the characteristics of a compound lens, obtaining acceptable image quality, good resolution, and the typical field limitation of volume holographic elements.     

Molecular and microbiological analysis of caecal microbiota in rats fed with diets supplemented either with prebiotics or probiotics

The potential health-improving effects of both a prebiotic and a probiotic infant formula have been evaluated in a rat model. Two groups of 10 rats were fed with either prebiotics containing fructo-oligosaccharides or probiotics containing viable Bifidobacterium lactis and Streptococcus thermophilus. The composition of their caecal microbiota was analyzed both by classical plate count of the main bacterial groups and by PCR amplification of a V3 fragment of 16S rRNA genes and denaturing gradient gel electrophoresis (DGGE). Both diets induced a significant reduction of clostridia and Bacteroides spp. compared to a control diet, whereas prebiotics were also able to reduce the number of coliforms and to increase the presence of bifidobacteria. DGGE analysis showed a significant increase of 16S rRNA gene fragments in rats fed with either probotics or prebiotics. Nineteen bands were sequenced and most of them showed similarity to cultured bacteria. Detection of Bifidobacterium spp. by this technique using genus-specific primers only permitted these bacteria to be detected in prebiotics-fed rats, whereas the use of Lactobacillus group-specific primers gave similar results in rats fed with any diet, in agreement with the plate count results.     

Characterization of Lactobacillus strains and monitoring by RAPD-PCR in controlled fermentations of "Almagro" eggplants

The characterization of 23 Lactobacillus strains was performed. The strains were assayed for biogenic amine-forming capacity, hydrogen peroxide production, pectin esterase, cellulase and polygalacturonase production, growth rate, acidifying capacity and salt tolerance. Three strains were selected which belonged to the species, Lactobacillus brevis, Lactobacillus plantarum and Lactobacillus fermentum. Different starter cultures prepared as combinations of these three strains were assayed in pilot scale fermentations and Randomly Amplified Polymorphic DNA (RAPD) analysis, using a previously selected random primer, was applied for monitoring the inoculated strains. The course of fermentations was similar in all batches but sensorial analysis of eggplants fermented using a mixed culture of the three strains displayed the best results, and no differences were obtained when compared with commercial eggplants.