968 resultados para Sound production by animals.


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Temperature (23 to 31 degrees C) and sucrose concentration ( 3 and 4%) effects on dextransucrase production by Leuconostoc mesenteroides NRRL B 512 ( F) and Leuconostoc mesenteroides FT 045 B were studied. The conditions in all fermentations were: total reaction volume 2 L, 132 rev. min-1, 0.5 vvm and pH 6.0. The optimum temperature for enzyme yield for strain NRRL B 512 ( F) was 23 degrees C, where at 8-h fermentation was possible to achieve 49.3 DSU/mL. When FT 045 B strain was utilized, 3.2 DSU/mL was obtained at temperature 23 to 25 degrees C.

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The xylanolytic system of Aspergillus versicolor is controlled by induction and carbon catabolite repression. Carboxymethylcellulose and wheat bran were the best inducers of xylanolytic activity. When the fungus was grown for 5 days on VOGEL's liquid medium with wheat bran, the optimal pH and temperature for xylanase production were 6.5 and 30 degrees C, respectively. Optimal conditions for the xylanolytic activity assay were at pH 6.0 and 55 degrees C. The half-life at 60 degrees C of the crude enzyme was 6.5 and 21 minutes, in the absence or presence of substrate, respectively.Xylan is the main hemicellulosic component of plant biomass being present in appreciable quantities in agricultural and several agroindustrial wastes. From the products of xylan enzymatic hydrolysis it is possible to obtain cell protein, fuels and other chemicals. Xylanases combined with cellulase could have applications in food processing. Cellulase-free xylanases can be also utilized for preparation of cellulose pulps and liberation of textile fibres (WOODWARD 1984; BIELY 1985, WONG et al. 1988). In view of the potential applications of xylanases, a study of these enzymes from various sources and their multiplicity is desirable.Among xylanolytic microorganisms, filamentous fungi have been more extensively studied and the genus Aspergillus has been shown to be an efficient producer of xylanases. Preliminary observations from our laboratory have demonstrated that a strain of Aspergillus versicolor, isolated from Brazilian soil, produced high xylanase and low cellulase levels, which is an interesting characteristic for some industrial applications. In this report we describe the production and some properties of xylanase obtained from this fungus.

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

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

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This paper presents the results from study investigating the capacity of Pseudomonas aeruginosa LBI growing on several carbon (Hydrophilic substrate) and nitrogen sources. The carbon source (2016) studied were: glycerol, manitol, fructose, glucose, lactose and the nitrogen sources (2; 3; 4 and 5016) were: NaNO3, NH4NO3, (NH4)(2)SO4 and (NH2)(2)CO. At the 96 h of fermentation, the medium with glycerol as a carbon source reached 7.9 g/L of rhamnolipids and 1. 2 g/L cellular protein. The surface tension reduction was 38.46 % for glycerol as a carbon source. The NaNO3 at 3% was the best concentration for rhamnolipids production (7.35 g/L) and cellular protein (1.12 g/L). The influences of metal ions [FeSO4.7H(2)O (0.001g/L, 0.005 g/L and 0.1 g/L) and MgSO4.7H(2)O (0.001 g/L, 0.005 g/L and 0.1 g/L)] on ramnolipids production were studied. Fe2+ had a negative influence on the studied concentrations while Mg2+ had a positive influence when its concentration was increased.

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This work studied the influence of nitrogen source and sucrose concentration in the feeding medium for biomass and inulinase production by Kluyveromyces marxianus var. bulgaricus. The results show that the best nitrogen source was a combination of 5 g/L of yeast extract and 10 g/L of peptone. Both cellular growth and enzymatic activity increased with sucrose concentration in the feeding medium (from 200 to 500 g/L). When the sucrose concentration reached 600 g/L, both cellular growth and enzymatic activity decreased.

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The objective of this research was to investigate xylanase production by filamentous fungi (Trichoderma viride) to determine the best cultivation conditions in the process, aiming toward optimization of enzyme production. The best temperature, as well as the best carbon source, for biomass production was determined through an automated turbidimetric method (Bioscreen-C). The enzyme activity of this fungus was separately evaluated in two solid substrates (wheat and soybean bran) and in Vogel medium, pure and by adding other carbon sources. Temperature effects, cultivation time, and spore concentrations were also tested. The best temperature and carbon source for enzyme and biomass production was 25 C and sorbitol, respectively. Maximum xylanase activity was achieved when the fungus was cultivated in wheat bran along with sorbitol (1%, w/v), using a spore concentration of 2 x 10(6) spores. mL(-1), pH 5.0, for 144 h cultivation. The study demonstrated not only the importance of the nature of the substrate in obtaining a system resistant to catabolic repression, but also the importance of the culture conditions for biosynthesis of this enzyme. T. viride showed a high potential for xylanase production under the conditions presented in these assays.

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The use of sugarcane bagasse and grass as low cost raw material for xylanase production by Bacillus circulans D1 in submerged fermentation was investigated. The microorganism was cultivated in a mineral medium containing hydrolysate of bagasse or grass as carbon source. High production of enzyme was obtained during growth in media with bagasse hydrolysates (8.4 U/mL) and in media with grass hydrolysates (7.5 U/mL). Xylanase production in media with hydrolysates was very close to that obtained in xylan containing media (7.0 U/ mL) and this fact confirm the feasibility of using this agro-industrial byproducts by B. circulans D1 as an alternative to save costs on the enzyme production process. (c) 2005 Elsevier Ltd. All rights reserved.

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