Optimization of cyclodextrin glucanotransferase production from Bacillus clausii E16 in submerged fermentation using response surface methodology

Cyclodextrin glucanotransferase production from Bacillus clausii E16, a new bacteria isolated from Brazilian soil samples was optimized in shake-flask cultures. A 2 4 full-factorial central composite design was performed to optimize the culture conditions, using a response surface methodology the combined effect among the soluble starch concentration, the peptone concentration, the yeast extract concentration, and the initial pH value of the culture medium was investigated. The optimum concentrations of the components, determined by a 2(4) full-factorial central composite design, were 13.4 g/L soluble starch, 4.9 g/L peptone, 5.9 g/L yeast extract, and initial pH 10.1. Under these optimized conditions, the maximum cyclodextrin glucanotransferase activity was 5.9 U/mL after a 48-h fermentation. This yield was 68% higher than that obtained when the microorganism was cultivated in basal culture medium.

Investigating the effect of different positioning of lysine residues along the peptide chain of mastoparans for their secondary structures and biological activities

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

Effect of tartrate content on aging and deposition condition of copper-tin electrodeposits from a non-cyanide acid bath

The effect of the presence of tartrate additive on the chemical stability of a Cu-Sn acid bath was evaluated. It was observed that this additive hinders decomposition of the Cu/Sn deposition bath with storage time, since the decrease in electrochemical efficiency was attenuated. In addition, it was observed that optimal galvanostatic deposition with or without tartrate occurs at approximately 11 mA cm(-2). However, in the presence of tartrate the deposition charge was lower, leading to lower energy consumption. SEM analysis showed that the tartrate added to the plating bath caused a marked change in the morphology of the Cu/Sn films obtained gal vanostatic ally. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Effect of C/N Ratio and Physicochemical Conditions on the production of Rhamnolipids by Pseudomonas Aeruginosa LBI

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The Use of Response Surface Methodology in Optimization of Lactic Acid Production: Focus on Medium Supplementation, Temperature and pH Control

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

Effect of fertilization in water quality and in zooplankton community in open plankton-culture ponds

The effect of swine manure fertilization on the water quality of zooplankton artificial culture in two ponds was measured in diel cycles on different months (October 1999, January and March 2000). Fertilization affected directly water quality; values for total phosphorus were above 1.4 mgL(-1) and maximum rates for ammonia reached 108 mu gL(-1). Zooplankton community comprised four species, namely, Brachionus calyciflorus, B. falcatus, Moina sp. and Thermocyclops sp. B. falcatus (Rotifera) and Moina sp (Cladocera) were dominant respectively in January and in March. There was no difference in abundance of zooplankton between the two ponds (p>0.05), although adult cyclopoid Thermocyclops sp was different between diel cycles (p<0.05). There were significant differences (p<0.05) in dissolved oxygen, ammonia, total phosphorus, orthophosphate, nitrite and nitrate between ponds. In fact, only dissolved oxygen and pH were significantly different (p<0.05) between the ponds' surface and bottom. Organic fertilization also provided greater amount of nutrients and higher pH and conductivity, coupled to greater oscillations in the concentration of dissolved oxygen, directly affecting the zooplanktonic composition.

Effect of pectinolitic enzymes on the physical properties of caja-manga (Spondias cytherea Sonn.) pulp

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

Effect of acid-ethanol treatment followed by ball milling on structural and physicochemical characteristics of cassava starch

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

Effect of annealing on the semicrystalline structure of normal and waxy corn starches

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

Effect of enzymatic hydrolysis on some physicochemical properties of root and tuber granular starches

A hidrólise enzimática do amido pode fornecer informações importantes sobre sua estrutura granular. Amidos de mandioca, batata-doce, mandioquinha-salsa e batata foram hidrolisados por α-amilase bacteriana a 37 °C durante 48 horas, e algumas propriedades físico-químicas dos resíduos da hidrólise foram determinadas. O amido de mandioca foi o mais suscetível à enzima com 20,9% de hidrólise, enquanto o amido de batata foi o mais resistente com 5,9%. O tamanho médio dos grânulos variou de 10,8 a 23,4 μm para os amidos de mandioquinha-salsa e batata, respectivamente. Amidos de mandioca e batata-doce apresentaram um padrão de difração de raio-X tipo A, enquanto os amidos de mandioquinha-salsa e batata mostraram padrão tipo B. Todos os amidos nativos mostraram superfície granular lisa e, após hidrólise, os amidos de mandioca, batata-doce e mandioquinha-salsa mostraram alguns grânulos bastante degradados, enquanto o amido de batata apresentou sutil sinal de degradação. O teor de amilose dos amidos diminuiu com a hidrólise para os amidos de mandioca, batata-doce e mandioquinha-salsa, permanecendo inalterado para o amido de batata. Como esperado, a viscosidade intrínseca e as propriedades de pasta diminuíram para todos os amidos hidrolisados. Não houve diferença significativa entre as propriedades térmicas dos amidos nativos e hidrolisados. Estes resultados sugeriram que a hidrólise ocorreu nas áreas cristalinas e amorfas dos grânulos. O padrão de difração do tipo B e o grande tamanho dos grânulos do amido de batata podem ter contribuído para a maior resistência deste amido à hidrólise.

The effect of ionic strength on the structural organization of dioctadecyldimethylammonium bromide in aqueous solution

High-curvature and stabilized vesicles of dioctadecyldimethylammonium bromide (DODABr) can be formed spontaneously in aqueous electrolytic solution. It is shown by cryo-transmission electron microscopy that 5.0 mM DODABr molecules associate in water at a temperature above its gel-to-liquid-crystalline phase transition temperature (T(m)approximate to45 degreesC) in a variety of complex bilayer structures. However, in the presence of NaCl the preferred structures formed are unilamellar and bilamellar vesicles with high curvature and the dispersion is polydisperse in size and geometry, but the main vesicle population contains spherical, flattened and smoothed structures. It is, however, less polydisperse than the corresponding salt-free dispersion, and the size polydispersity and the vesicle curvature radius tend to decrease with NaCl concentration. Long cylindrical bilamellar vesicles, with a very thin water layer separating the bilayers are also formed in the presence of 10 mM NaCl. The effect of the ionic strength on T-m, obtained by differential scanning calorimetry, is shown to depend on the nature of the counterion: Br- decreases, whereas Cl- increases Tm of DODABr, indicating different affinity of these counterions for the vesicle surfaces.

The Water Effect on the Kinetics of the Bovine Liver Catalase

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Optimization of xylanase production by Bacillus circulans D1 in submerged fermentation using response surface methodology

In this work, a 3(3) factorial design was performed with the aim of optimizing the culture conditions for xylanase production by an alkalophilic thermophilic strain of Bacillus circulans, using response surface methodology. The variables involved in this study were xylan concentration (X-1), pH (X-2) and cultivation time (X-3). The optimal response region was approached without using paths of steepest ascent. Statistical analysis of results showed that, in the range studied, only pH did not have a significant effect on xylanase production. A second-order model was proposed to represent the enzymic activity as a function of xylan concentration (X-1) and cultivation time (X-3). The optimum xylan concentration and cultivation time were 5 g/l and 48 h, respectively. Under these conditions, the model predicted a xylanase activity of 19.1 U/ml. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Effect of Airborne-Particle Abrasion and Mechanico-Thermal Cycling on the Flexural Strength of Glass Ceramic Fused to Gold or Cobalt-Chromium Alloy

Purpose: To evaluate the effect of airborne-particle abrasion and mechanico-thermal cycling on the flexural strength of a ceramic fused to cobalt-chromium alloy or gold alloy.Materials and Methods: Metallic bars (n = 120) were made (25 mm x 3 mm x 0.5 mm): 60 with gold alloy and 60 with Co-Cr. At the central area of the bars (8 mm x 3 mm), a layer of opaque ceramic and then two layers of glass ceramic (Vita VM13, Vita Zahnfabrick) were fired onto it (thickness: 1 mm). Ten specimens from each alloy group were randomly allocated to a surface treatment [(tungsten bur or air-particle abrasion (APA) with Al(2)O(3) at 10 mm or 20 mm away)] and mechanico-thermal cycling (no cycling or mechanically loaded 20,000 cycles; 10 N distilled water at 37 degrees C and then thermocycled 3000 cycles; 5 degrees C to 55 degrees C, dwell time 30 seconds) combination. Those specimens that did not undergo mechanico-thermal cyclingwere stored inwater (37 degrees C) for 24 hours. Bond strength was measured using a three-point bend test, according to ISO 9693. After the flexural strength test, failure types were noted. The data were analyzed using three factor-ANOVA and Tukey's test (alpha = 0.05).Results: There were no significant differences between the flexural bond strength of gold and Co-Cr groups (42.64 +/- 8.25 and 43.39 +/- 10.89 MPa, respectively). APA 10 and 20 mm away surface treatment (45.86 +/- 9.31 and 46.38 +/- 8.89 MPa, respectively) had similar mean flexural strength values, and both had significantly higher bond strength than tungsten bur treatment (36.81 +/- 7.60 MPa). Mechanico-thermal cycling decreased the mean flexural strength values significantly for all six alloy-surface treatment combinations tested when compared to the control groups. The failure type was adhesive in the metal/ceramic interface for specimens surface treated only with the tungsten bur, and mixed for specimens surface treated with APA 10 and 20 mm.Conclusions: Considering the levels adopted in this study, the alloy did not affect the bond strength; APA with Al(2)O(3) at 10 and 20 mm improved the flexural bond strength between ceramics and alloys used, and the mechanico-thermal cycling of metal-ceramic specimens resulted in a decrease of bond strength.

Effect of axial loads on implanted-supported partial fixed prostheses by strain gauge analysis

Objectives: The present study used strain gauge analysis to perform an in vitro evaluation of the effect of axial loading on 3 elements of implant-supported partial fixed prostheses, varying the type of prosthetic cylinder and the loading points. Material and methods: Three internal hexagon implants were linearly embedded in a polyurethane block. Microunit abutments were connected to the implants applying a torque of 20 Ncm, and prefabricated Co-Cr cylinders and plastic prosthetic cylinders were screwed onto the abutments, which received standard patterns cast in Co-Cr alloy (n=5). Four strain gauges (SG) were bonded onto the surface of the block tangentially to the implants, SG 01 mesially to implant 1, SG 02 and SG 03 mesially and distally to implant 2, respectively, and SG 04 distally to implant 3. Each metallic structure was screwed onto the abutments with a 10 Ncm torque and an axial load of 30 kg was applied at five predetermined points (A, B, C, D, E). The data obtained from the strain gauge analyses were analyzed statistically by RM ANOVA and Tukey's test, with a level of significance of p<0.05. Results: There was a significant difference for the loading point (p=0.0001), with point B generating the smallest microdeformation (239.49 mu epsilon) and point D the highest (442.77 mu epsilon). No significant difference was found for the cylinder type (p=0.748). Conclusions: It was concluded that the type of cylinder did not affect in the magnitude of microdeformation, but the axial loading location influenced this magnitude.