Production and properties of xylanases from Aspergillus terricola Marchal and Aspergillus ochraceus and their use in cellulose pulp bleaching

M. Michelin • S. C. Peixoto-Nogueira • J. H. A. Betini • T. M. da Silva • J. A. Jorge • H. F. Terenzi • M. L. T. M. Polizeli

Bioprocess Biosyst Eng (2010) 33:813–821

Aspergillus terricola and Aspergillus ochraceus, isolated from Brazilian soil, were cultivated in Vogel and Adams media supplemented with 20 different carbon sources, at 30ºC, under static conditions, for 120 and 144 h, respectively. High levels of cellulase-free xylanase were produced in birchwood or oat spelt xylan-media. Wheat bran was the most favorable agricultural residue for xylanase production. Maximum activity  was obtained at 60ºC and pH 6.5 for A. terricola, and 65ºC and pH 5.0 for A. ochraceus. A. terricola

Cadeia respiratória e síntese de ATP

Assuntinho difícil que pode ser divertido! Click no link abaixo:

http://www.youtube.com/watch?v=ywH_lgRZtZQ

Autoria de terceiros

Purification and characterization of a thermostable a-amylase produced by the fungus Paecilomyces variotii

Michele Michelin, Tony M. Silva, Vivian M. Benassi, Simone C. Peixoto-Nogueira, Luiz Alberto B. Moraes, Juliana M. Leão, João A. Jorge, Héctor F. Terenzi, Maria de Lourdes T. M. Polizeli

Carbohydrate Research 345 (2010) 2348–2353

An a-amylase produced by Paecilomyces variotii was purified by DEAE-cellulose ion exchange chromatography, followed by Sephadex G-100 gel filtration and electroelution. The a-amylase showed a molecular mass of 75 kDa (SDS–PAGE) and pI value of 4.5. Temperature and pH optima were 60ºC and 4.0, respectively. The enzyme was stable for 1 h at 55ºC, showing a t50 of 53 min at 60 ºC. Starch protected the enzyme against thermal inactivation. The a-amylase was more stable in alkaline pH. It was activated mainly

Hemiceluloses e o sistema xilanolítico

As hemiceluloses são classificadas de acordo com o açúcar presente em sua molécula. Assim, a xilana é um homopolímero linear que contém monômeros de b-D-xilopiranosil unidos por ligações glicosídicas b-1,4 que, na natureza, geralmente está associada a outros açúcares, formando glucuronoxilanas, glucuronoarabinoxilanas, glucomananas, arabinogalactanas e galactoglucomananas. Devido a sua heterogeneidade estrutural, a degradação da xilana requer a ação de várias enzimas, ou seja, de um sistema enzimático que se encontra presente em fungos e bactérias. As enzimas pertencentes ao sistema xilanolítico

Enzimas: A Base Molecular da Vida

Clik no link abaixo e veja o vídeo extremamente interessante! Mostra uma aula sobre enzimas discutindo os principais conceitos deste assunto: o que é uma enzima, quais são seus co-fatores, inibidores, etc.


http://www.youtube.com/watch?v=DJf1YXCvD3s

Autoria de terceiros

Xylanases from Aspergillus niger, Aspergillus niveus and Aspergillus ochraceus produced under solid-state fermentation and their application in cellulose pulp bleaching

Bioprocess Biosyst Eng (2009) 32:819–824

J. H. A. Betini, M. Michelin, S. C. Peixoto-Nogueira, J. A. Jorge, H. F. Terenzi, M. L. T. M. Polizeli

This study describes the production of xylanases from Aspergillus niveus, A. niger, and A. ochraceus under solid-state fermentation using agro-industrial residues as substrates. Enzyme production was improved using a mixture of wheat bran and yeast extract or peptone. When a mixture of corncob and wheat bran was used, xylanase production from A. niger and A. ochraceus increased by 18%. All cultures were incubated at 30ºC at 70–80% relative humidity for 96 h. For biobleaching assays, 10 or 35 U of xylanase/g dry cellulose pulp were incubated at pH 5.5 for 1 or 2 h, at 55ºC. The delignification efficiency was 20%, the brightness (percentage of ISO) increased two to three points and the viscosity was maintained confirming the absence of cellulolytic activity. These results indicated that the use of xylanases could help to reduce the amount of chlorine compounds used in cellulose pulp treatment.

Evidence of thermostable amylolytic activity from Rhizopus microsporus var. rhizopodiformis using wheat bran and corncob as alternative carbon source

Bioprocess Biosyst Eng (2008) 31:329–334

S. C. Peixoto-Nogueira, V. C. Sandrim, L. H. S. Guimarães, J. A. Jorge, H. F. Terenzi, M. L. T. M. Polizeli

DOI 10.1007/s00449-007-0166-4

Rhizopus microsporus var. rhizopodiformis produced high levels of a-amylase and glucoamylase under solid state fermentation, with several agricultural residues, such as wheat bran, cassava flour, sugar cane bagasse, rice straw, corncob and crushed corncob as carbon sources. These materials were humidified with distilled water, tap water, or saline solutions—Segato Rizzatti (SR), Khanna or Vogel. The best substrate for amylase production was wheat bran with SR saline solution (1:2 v/v). Amylolytic activity was still improved (14.3%) with a mixture of wheat bran, corncob, starch and SR saline solution (1:1:0.3:4.6 w/w/w/v). The optimized