Xylanase production by Aspergillus versicolor

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.

Effects of culture conditions on the production of inulinase by Kluyveromyces marxianus

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Effect of Conditioning on the Production of Inulinase by Kluyveromyces marxianus var. bulgaricus through Fed-Batch Fermentation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of nitrogen source and sucrose concentration on inulinase production by Kluyveromyces marxianus in fed-batch fermentation

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.

Phenology, sex ratio, and spatial distribution among dioecious species of Trichilia (Meliaceae)

The flowering, sex ratio, and spatial distribution of four dioecious species of Trichilia (Meliaceae) were studied in a semi-deciduous forest in southeastern Brazil. All reproductive trees (T. clausseni, T. pallida and T. catigua) with dbh greater than or equal to5 cm within a 1-ha plot were collected, sexed, mapped and, for individuals of each species, the distances to the nearest neighbour of the same and opposite sex were measured. For the shrub species T elegans (dbh <5 cm), all reproductive individuals were sampled randomly in 10 samples of 10 x 10 m. The reproductive phenology was observed at weekly to monthly intervals from May 1988 to January 1990. The species are strictly dioecious, did not present any sex-mixed trees or sex switching during the study, and sex ratio did not differ significantly from 1:1. The size distributions and the relative size variation were not significantly different. between sexes. There was no significant segregation or clumping between individuals of either sex and no fruit production without pollination. Onset of flowering and flowering peak were synchronous between male and female plants for all species studied. Flower synchrony was related to outcrossing and pollinator attraction rather than climatic factors.

Screening of culture condition for xylanase production by filamentous fungi

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.

Production of cyclodextrins by CGTase from Bacillus clausii using different starches as substrates

Cyclodextrins ( CDs) are cyclic oligasaccharides composed by D- glucose monomers joined by alpha- 1,4-D glicosidic linkages. The main types of CDs are alpha-,beta-and gamma-CDs consisting of cycles of six, seven, and eight glucose monomers, respectively. Their ability to form inclusion complexes is the most important characteristic, allowing their wide industrial application. The physical property of the CD-complexed compound can be altered to improve stability, volatility, solubility, or bio-availability. The cyclomaltodextrin glucanotransferase ( CGTase, EC 2.4.1.19) is an enzyme capable of converting starch into CD molecules. In this work, the CGTase produced by Bacillus clausii strain E16 was used to produce CD from maltodextrin and different starches ( commercial soluble starch, corn, cassava, sweet potato, and waxy corn starches) as substrates. It was observed that the substrate sources influence the kind of CD obtained and that this CGTase displays a beta- CGTase action, presenting a better conversion of soluble starch at 1.0%, of which 80% was converted in CDs. The ratio of total CD produced was 0: 0.89: 0.11 for alpha/beta/gamma. It was also observed that root and tuber starches were more accessible to CGTase action than seed starch under the studied conditions.

Ribonuclease production by Aspergillus species

Ribonuclease production by Aspergillus flavipes. A sulphureus and A. fischeri in semisynthetic medium, after 24-144 hours at 30 degrees C under shaking, was studied. After cultivation, the medium was separated from micelia by filtration and the resultant solution was used as enzymatic extract. The highest amount of biomass and RNase was obtained after 96 hours of cultivation. The enzymes produced by three species presented similar characteristics, with optimum temperature at 55 degrees C and two peaks of activity at pH 4.5 and 7.0. A. flavipes RNases were more sensitive to temperature: 50% of the initial activity was lost after 1 hour at 70 degrees C. After this heat treatment, RNase of A. sulphureus lost 30% of this activity and that of A. fischeri only 16%. The nucleotides released by enzimatic hydrolysis of RNA were separated by ion exchange chromatography in a AG-1X8-formiate column and identified by paper chromatography. This procedure indicated that the raw enzymatic extract of Aspergillus flavipes is able to hydrolyze RNA, releasing 3'-nucleotides monophosphate at pH 4.5 and 3' and 5'-nucleotides monophosphate at pH 7.0 and 8.5. This result suggests that this strain produces two different types of RNase, one acidic and other alcaline, with different specificities.

Measurement of the ratio of inclusive cross sections sigma(p(p)over-bar -> Z plus b jet)/sigma(p(p)over-bar -> Z plus jet) at root s=1.96 TeV

Using the data collected with the D0 detector at root s=1.96 TeV, for integrated luminosities of about 180 pb(-1), we have measured the ratio of inclusive cross sections for p(p) over bar -> Z+b jet to p(p) over bar -> Z+jet production. The inclusive Z+b-jet reaction is an important background to searches for the Higgs boson in associated ZH production at the Fermilab Tevatron collider. Our measurement is the first of its kind, and relies on the Z -> e(+)e(-) and Z ->mu(+)mu(-) modes. The combined measurement of the ratio yields 0.021 +/- 0.005 for hadronic jets with transverse momenta p(T)> 20 GeV/c and pseudorapidities vertical bar eta vertical bar < 2.5, consistent with next-to-leading-order predictions of the standard model.

Search for W ' boson production in the W ' -> t(b)over-bar decay channel

We present a search for the production of a new heavy gauge boson W' that decays to a top quark and a bottom quark. We have analyzed 230 pb(-1) of data collected with the DO detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events above the standard model expectation is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W' bosons times branching ratio to top quarks at the 95% confidence level for several different W, boson masses. We exclude masses between 200 and 610 GeV for a W' boson with standard-model-like couplings, between 200 and 630 GeV for a W, boson with right-handed couplings that is allowed to decay to both leptons and quarks, and between 200 and 670 GeV for a W' boson with right-handed couplings that is only allowed to decay to quarks. (c) 2006 Elsevier B.V. All rights reserved.

Search for W H associated production in 5.3 fb(-1) of p(p)over-bar collisions at the Fermilab Tevatron

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Measurement of the ratio of the 3-jet to 2-jet cross sections in pp collisions at root s=7 TeV

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Measurement of the Lambda(b) cross section and the (Lambda)over-bar(b) to Lambda(b) ratio with J/psi Lambda decays in pp collisions at root s=7 TeV CMS Collaboration

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Measurement of isolated photon production in pp and PbPb collisions at root s(NN)=2.76 TeV

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Search for pair production of first-generation leptoquarks in p(p)over-bar collisions at root s=1.96 TeV

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