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Poster Presentation 3-24
Production and Application of Thermostable Xylanase from Bacillus circulans D1 in the Biobleaching of Eucalyptus Kraft Pulp
Daniela A.Bocchini, Valquíria B. Damiano, Eleni Gomes, and Roberto Da-Silva.
Laboratory of Process Biochemistry and Applied Microbiology Department of Chemistry, UNESP - Universidade Estadual Paulista Rua Cristovao Colombo 2265, Sao Jose do Rio Preto, Sao Paulo 15054-000 Brazil
Telephone: (019)2212354; Fax: (019)2212356; E-mail: dasilva@qeg.ibilce.unesp.br
An alkalophilic Bacillus circulans D1 producing high levels of extracellular cellulase-free xylanase was isolated. The enzyme showed important characteristics that allow its application in the biobleaching process, such as long thermal stability at 55ºC, optimum temperature of hydrolysis at 70ºC, and a wide range of pH stability. The enzyme retained 80% of its activity at pH 9.0. Enzymatic treatment of Kraft pulp carried out using 13.5 U of enzyme per gram of dried pulp resulted in a 23% decrease in ClO2 rate used in the pulp delignification. The application of the enzyme on Sephadex G-50 led to the separation of three groups of fractions with xylanolytic activity representing enzymes of distinct molecular weights.
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