The effect of lanthanum (III) on the activity of xylanase by and its influence on brightness in the paper pulp bleaching.

Xylanase is widely used in pulp and paper bleaching. In this study, the effects of rare earth ions (La, Ce, Er and Gd) on the activity of xylanase produced by are investigated and the application of a xylanase solution containing La in paper bleaching is presented. Our results indicate that the bleaching effect of the enzyme solution containing La was markedly better when the concentration of La was 10 g/L after 4 days of incubation. The mechanism of lanthanum on the improvement of xylanase activity was revealed through electrical conductivity, atomic absorption spectrometer, infrared spectroscopy and fluorescence microscopy analyses. The PCR result clearly demonstrates that a low concentration of La led to the transversions of three base pair of gene sequences. Our experiment also reveals that the La may have been involved in the cellular metabolic processes of and intervened in the base pairing and DNA replication. This research may provide new insights into the improvement of enzymatic activity by lanthanum (III) and its application in paper pulp bleaching.