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Appl. Environ. Microbiol., May 1997, 1749-1755, Vol 63, No. 5
MT Moreira, G Feijoo, R Sierra-Alvarez, J Lema and JA Field
The white rot fungus Bjerkandera sp. strain BOS55 extensively delignified
and bleached oxygen-delignified eucalyptus kraft pulp handsheets.
Biologically mediated brightness gains of up to 14 ISO (International
Standards Organization units) were obtained, providing high final
brightness values of up to 80% ISO. In nitrogen-limited cultures (2.2 mM
N), manganese (Mn) greatly improved manganese-dependent peroxidase (MnP)
production. However, the biobleaching was not affected by the Mn nutrient
regimen, ranging from 1,000 (mu)M added Mn to below the detection limit of
0.26 (mu)M Mn in EDTA-extracted pulp medium. The lowest Mn concentration
tested was at least several orders of magnitude lower than the K(infm)
known for MnP. Consequently, it was concluded that Mn is not required for
biobleaching in Bjerkandera sp. strain BOS55. Nonetheless, fast protein
liquid chromatography profiles indicated that MnP was the predominant
oxidative enzyme produced even under culture conditions in the near absence
of manganese. High nitrogen (22 mM N) and exogenous veratryl alcohol (2 mM)
repressed biobleaching in Mn-deficient but not in Mn-sufficient culture
medium. No correlation was observed between the titers of extracellular
peroxidases and the biobleaching. However, the decolorization rate of the
polyaromatic dye Poly R-478 was moderately correlated to the biobleaching
under a wide range of Mn and N nutrient regimens.
Copyright © 1997, American Society for Microbiology
Manganese Is Not Required for Biobleaching of Oxygen-Delignified Kraft Pulp by the White Rot Fungus Bjerkandera sp. Strain BOS55
Division of Wood Science, Department of Forestry, and Division of Industrial Microbiology, Department of Food Science, Wageningen Agricultural University, 6700 AH Wageningen, The Netherlands, and Department of Chemical Engineering, University of Santiago de Compostela, E-15706 Santiago de Compostela, Spain
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