Xylan-hydrolyzing enzyme system from Bacillus pumilus CBMAI 0008 and its effects on Eucalyptus grandis kraft pulp for pulp bleaching improvement.
The extracellular productions of beta-xylanase, beta-xylosidase, beta-glucosidase, beta-mannanase, arabinosidase, alpha-glucuronidase, alpha-galactosidase and Fpase from Bacillus pumilus CBMAI 0008 were investigated with three different xylan sources as substrate. The enzymatic profiles on birchwood, Eucalyptus grandis and oat were studied at alkaline and acidic pH conditions. B. pumilus CBMAI 0008 grown on the three carbon sources produced mainly beta-xylanase. At pH 10, the levels of xylanase were 328, 160 and 136 U/ml, for birch, oat and E. grandis, respectively. beta-Mannanase production was induced on E. grandis (5 U/ml) and arabinofuranosidase on oat (5 U/ml). Although small quantities of alpha-glucuronidase had been produced at pH 10, activity at pH 4.8 was 1.5 U/ml, higher than observed for Aspergillus sp. in literature reports. Preliminary assays carried out on E. grandis kraft pulp from an industrial paper mill (RIPASA S.A. Celulose e Papel, Limeira, SP, Brazil) showed a reduction of 0.3% of chlorine use in the pulp treated with the enzymes, resulting in increased brightness, compared to conventional bleaching. The enzymes were more efficient if applied before the initial bleaching sequence, in a non-pre-oxygenated pulp.
Duarte
Marta C Teixeira
MC
Center for Chemical, Biological and Agricultural Research, CPQBA/UNICAMP, P.O. Box 6171, CEP, SP 13083-970, Campinas, Brazil. mduarte@cpqba.uniamp.br
da Silva
Elizete Cristina
EC
de Bulhões Gomes
Isabel Menezes
IM
Ponezi
Alexandre Nunes
AN
Portugal
Edilberto Princi
EP
Vicente
João Roberto
JR
Davanzo
Ednilson
E
D018554:Avena; D001407:Bacillus / Q000201:enzymology*; D005052:Eucalyptus; D006026:Glycoside Hydrolases / Q000032:analysis / Q000302:isolation & purification / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007221:Industry; D013696:Temperature; D014934:Wood; D043325:Xylan Endo-1,3-beta-Xylosidase; D014995:Xylosidases / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology*
D006026:Glycoside Hydrolases; D014995:Xylosidases; D043325:Xylan Endo-1,3-beta-Xylosidase