Production of xylanolytic enzymes by Penicillium janczewskii

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cassava wastewater as a substrate for the simultaneous production of rhamnolipids and polyhydroxyalkanoates by Pseudomonas aeruginosa

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of Fungal Contamination on Substrate Carrying by the Leafcutter Ant Atta sexdens rubropilosa (Hymenoptera: Formicidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Seasonal metabolic depression, substrate utilisation and changes in scaling patterns during the first year cycle of tegu lizards (Tupinambis merianae)

The tegus increase in body mass after hatching until early autumn, when the energy intake becomes gradually reduced. Resting rates of oxygen consumption in winter drop to 20% of the values in the active season (Vo(2)=0.0636 ml g(-1) h(-1)) and are nearly temperature insensitive over the range of 17-25degreesC (Q(10)=1.55). During dormancy, plasma glucose levels are 60% lower than those in active animals, while total protein, total lipids and beta-hydroxybutyrate are elevated by 24%, 43% and 113%, respectively. In addition, a significant depletion of liver carbohydrate (50%) and of fat deposited in the visceral fat bodies (24%) and in the tail (25%) and a slight loss of skeletal muscle protein (14%) were measured halfway through the inactive period. Otherwise, glycogen content is increased 4-fold in the brain and 2.3-fold in the heart of dormant lizards, declining by the onset of arousal. During early arousal, the young tegus are still anorexic, although Vo(2) is significantly greater than winter rates. The fat deposits analysed are further reduced (62% and 45%, respectively) and there is a large decrease in tail muscle protein (50%) together with a significant increase in glycogen (2-3-fold) and an increase in plasma glucose (40%), which suggests a role for gluconeogenesis as a supplementary energy source in arousing animals. No change is detectable in citrate synthase activity, but beta-hydroxyacyl CoA dehydrogenase activities are strongly affected by season, reaching a Mold and 5-fold increase in the liver tissue of winter and arousing animals, respectively, and becoming reduced by half in skeletal muscle and heart of winter animals compared with late fall or spring active individuals. From hatching to late autumn, the increase of the fat body mass relatively to body mass is disproportionate (b=1.44), and the mass exponent changes significantly to close to 1.0 during the fasting period. The concomitant shift in the Vo(2) mass exponent in early autumn (b=0.75) to values significantly greater than 1.0 in late autumn and during winter dormancy indicates an allometric effect on the degree of metabolic depression related to the size of the fat stores and suggests greater energy conservation in the smaller young.

Three-dimensional structure of ribonuclease T-1 complexed with an isosteric phosphonate substrate analogue of GpU: Alternate substrate binding modes and catalysis

The X-ray crystal structure of a complex between ribonuclease T-1 and guanylyl(3'-6')-6'-deoxyhomouridine (GpcU) has been determined at 2.0 Angstrom resolution. This Ligand is an isosteric analogue of the minimal RNA substrate, guanylyl(3'-5')uridine (GpU), where a methylene is substituted for the uridine 5'-oxygen atom. Two protein molecules are part of the asymmetric unit and both have a GpcU bound at the active site in the same manner. The protein-protein interface reveals an extended aromatic stack involving both guanines and three enzyme phenolic groups. A third GpcU has its guanine moiety stacked on His92 at the active site on enzyme molecule A and interacts with GpcU on molecule B in a neighboring unit via hydrogen bonding between uridine ribose 2'- and 3'-OH groups. None of the uridine moieties of the three GpcU molecules in the asymmetric unit interacts directly with the protein. GpcU-active-site interactions involve extensive hydrogen bonding of the guanine moiety at the primary recognition site and of the guanosine 2'-hydroxyl group with His40 and Glu58. on the other hand, the phosphonate group is weakly bound only by a single hydrogen bond with Tyr38, unlike ligand phosphate groups of other substrate analogues and 3'-GMP, which hydrogen-bonded with three additional active-site residues. Hydrogen bonding of the guanylyl 2'-OH group and the phosphonate moiety is essentially the same as that recently observed for a novel structure of a RNase T-1-3'-GMP complex obtained immediately after in situ hydrolysis of exo-(S-p)-guanosine 2',3'-cyclophosphorothioate [Zegers et al. (1998) Nature Struct. Biol. 5, 280-283]. It is likely that GpcU at the active site represents a nonproductive binding mode for GpU [:Steyaert, J., and Engleborghs (1995) fur. J. Biochem. 233, 140-144]. The results suggest that the active site of ribonuclease T-1 is adapted for optimal tight binding of both the guanylyl 2'-OH and phosphate groups (of GpU) only in the transition state for catalytic transesterification, which is stabilized by adjacent binding of the leaving nucleoside (U) group.

Germination of Styrax camporum Pohl. seeds in response to substrate types, moisture contents and the seed morphology

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Bulk density and relationship air/water of horticultural substrate

Alterações na densidade do substrato durante o cultivo das plantas modificam suas propriedades físicas. O trabalho teve como objetivos caracterizar fisicamente dois substratos hortícolas e avaliar o efeito da densidade na relação ar/água dos mesmos, elaborando funções matemáticas que permitam estimar tal relação a partir da densidade do substrato. Para tanto, determinou-se a distribuição do tamanho das partículas, a densidade e a curva de retenção de água. Procedeu-se o acondicionamento dos substratos em três valores de densidade: 10 (D1), 20 (D2) e 30% (D3) maior que a densidade (D) determinada na fase de caracterização. Partindo das amostras com diferentes densidades, determinou-se a curva de retenção de água dos substratos. A influência do aumento da densidade do substrato na porosidade total (PT), no espaço de aeração (EA), na água disponível (AD), na água facilmente disponível (AFD), na água tamponante (AT) e na água remanescente (AR) foi avaliada pela análise de regressão linear simples e análise polinomial. A composição granulométrica e a curva de retenção de água foram significativamente diferentes para os dois substratos. O aumento da densidade diminuiu a PT e o EA e aumentou a AT e AR. Os maiores valores de AD e AFD foram observados para D1. Foram obtidas equações de regressão que podem auxiliar na escolha da relação ar/água mais adequada para cada condição.

THE USE OF AMPPD AS AN ALTERNATIVE SUBSTRATE FOR AP-MEDIATED DETECTION OF NONRADIOLABELED DNA PROBES IN EUCALYPTUS-SALIGNA

We present a non-radioactive alternative to Southern's (J. Mol. Biol. 98: 503-517, 1975) DNA-DNA hybridization technique. The use of AMPPD - Disodium 3-(4-Methoxyspiro {1,2-dioxetane-3,2'tricyclo[3.3.1.1(3,7)]decan}-4-yl)phyenyl phosphate as an alternative substrate for AP-mediated detection of digoxigenin-11 dUTP-labeled probes made possible the simple and nonhazardous reuse of blots. We used 0.8 % agarose gels containing 30 mug per lane of Eucalyptus saligna DNA, digested with Eco RI, electrophoresed and blotted on to nylon membranes (Hybond-N, Amersham, UK), using the Southern blotting procedure, and UV irradiated for one minute for DNA fixation. The hybridizations were carried out overnight with digoxigenin labeled random inserts of E. saligna DNA by using the Genius Kit (Boehringer Mannheim). Detection of the DNA-DNA hybrids was performed in the presence of 0.5% blocking agent and the substrates NBT/BCIP were replaced by 0.26 mM AMPPD in the final alkaline assay buffer (50 mul/cm2). After membrane incubation for five minutes at room temperature in a sealed plastic bag, the AMPPD solution was retrieved and stored at 4-degrees-C for reuse. A Kodak X-BRAF QA-S film was pressed firmly onto the bag containing the wet membrane, exposed for two to six hours and then developed. After use, the probes were stripped off and the blots reutilized, three times so far, with the same results.

A sensor for monitoring the volume of nutrient in a solid substrate-based growth media by using electrochemical admittance spectroscopy

A sensor was fashioned to monitor the volume of nutrient in a solid substrate-based growth media by using electrochemical admittance spectroscopy. Several experimental parameters were investigated (i.e. The use of two- or three-electrode cells, the superficial area of the electrode, the amount of nutrient solution added to the growth media, and the influence of varying the dc and ac potential) to assess how these variables affect the admittance of the system. A linear correlation was observed between the maximum of the imaginary admittance and the volume of nutrient present. The response factor was 2.8 x 10(-5) S cm(-2) ml(-1) and the limit of detection (LOD) was 0.54 ml. The humidity of the growth media does not change the response of the nutrient toward the monitoring measurements. These results demonstrate that the volume of nutrient in this solid substrate-based growth media can be assessed using a ceramic sensor to measure the imaginary admittance. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Modelling and optimization of the cephalosporin C production bioprocess in a fed-batch bioreactor with invert sugar as substrate

Cephalosporin C production process optimization was studied based on four experiments carried out in an agitated and aerated tank fermenter operated as a fed-batch reactor. The microorganism Cephalosporium acremonium ATCC 48272 (C-10) was cultivated in a synthetic medium containing glucose as major carbon and energy source. The additional medium contained a hydrolyzed sucrose solution as the main carbon and energy source and it was added after the glucose depletion. By manipulating the supplementary feed rate, it was possible to increase antibiotic production. A mathematical model to represent the fed-batch production process was developed. It was observed that the model was applicable under different operation conditions, showing that optimization studies can be made based on this model. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

Production of volatile compounds by Geotrichum fragrans using cassava wastewater as substrate

The cassava processing industry generates wastewater named manipueira with a high organic content. Although considered a pollutant, manipueira can be used as substrate for fermentative processes including the cultivation of Geotrichum fragrans. This aerobic microorganism isolated from cassava wastewater has cyanide resistant respiration. Under cassava wastewater cultivation, G. fragrans produced fruit aroma volatile compounds. This study evaluated volatile compounds produced by G. fragrans in cassava liquid waste. The waste had a sugar composition composed of dextrin (2.6%), maltose (1.4%), sucrose (32.1%), glucose (38.3%), and fructose (25.6%). The average value of total sugars was 58.2 g l(-1), composed of 38.0 g l(-1) reducing and 20.2 g l(-1) non-reducing sugars. The chemical oxygen demand (COD) average value was 60 000 mg l(-1). G. fragrans used sugars (fructose and glucose) for energy generation reducing the COD value of the cassava wastewater by 40%. Biomass production of G. fragrans cultivated for 12 h in natural cassava liquid waste was 12.8 g l(-)1. The volatile compounds identified in the cassava liquid waste after 72 h cultivation were: 1-butanol, 3-methyl 1-butanol (isoamylic alcohol), 2-methyl 1-butanol, 1-3 butanodiol and phenylethanol; ethyl acetate, ethyl propionate, 2-methyl ethyl propionate and 2-methyl propanoic. The effect of substrate supplementation with glucose (50 g l(-1)), fructose (50 g l(-1)) and aqueous yeast extract (200 ml l(-1)) did not affect the qualitative and quantitative profiles of volatile compounds. These results indicate that the carbon (C) source utilized by microorganism was glucose or fructose, while nitrogen (N) supplementation was not necessary because the agent did not exhaust all the nitrogen of the wastewater. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

Micro-Raman analysis of cubic GaN layers grown by MBE on (001) GaAs substrate

Cubic GaN layers are grown by molecular beam epitaxy on (001) GaAs substrates. Optical micrographs of the GaN epilayers intentionally grown at Ga excess reveal the existence of surface irregularities such as bright rectangular structures, dark dots surrounded by rectangles and dark dots without rectangles. Micro-Raman spectroscopy is used to study the structural properties of these inclusions and of the epilayers in greater detail. We conclude that the observed irregularities are the result of a melting process due to the existence of a liquid Ga phase on the growing surface.

Erbium- and ytterbium-doped sol-gel SiO2-HfO2 crack-free thick films onto silica on silicon substrate

Aware of the difficulties in applying sol-gel technology on the preparation of thin films suitable for optical devices, the present paper reports on the preparation of crack-free erbium- and ytterbium-doped silica: hafnia thick films onto silica on silicon. The film was obtained using a dispersion of silica-hafnia nanoparticles into a binder solution, spin-coating, regular thermal process and rapid thermal process. The used methodology has allowed a significant increase of the film thickness. Based on the presented results good optical-quality films with the required thickness for a fiber matching single mode waveguide were obtained using the erbium- and ytterbium-activated sol-gel silica:hafnia system. The prepared film supports two transversal electric modes at 1550 nm and the difference between the transversal electric mode and the transversal magnetic mode is very small, indicating low birefringence. Photoluminescence of the I-4(13/2) -> I-4(15/2) transition of erbium ions shows a broad band centered at 1.53 mu m with full width at a half maximum of 28 nm. Up-conversion emission was carried out under different pump laser powers, and just one transition at red region was observed. (c) 2006 Elsevier B.V. All rights reserved.