An integrated approach for pulp biobleaching: application of cocktail of enzymes.

One of the paper industry's major focuses is shifting toward eco-friendly paper production. Chemical-based bleaching of pulp, which is widely used in the paper industry, is a highly polluting step. Replacing it with enzymatic biobleaching is the most viable alternative to make the process of papermaking greener. Enzymes such as xylanase, mannanase, and laccase are suitable for the biobleaching of pulp, which involves the removal of hemicelluloses, lignins, and other undesirable components. However, as no single enzyme can achieve this, their application in industry is limited. To overcome these limitations, a cocktail of enzymes is required. A number of strategies have been explored for the production and application of a cocktail of enzymes for pulp biobleaching, but no comprehensive information is available in the literature. The present short communication has summarized, compared, and discussed the various studies in this regard, which will be highly useful to pursue further research in this regard and make the process of papermaking greener.

Lignolytic and hemicellulolytic enzyme cocktail production from Bacillus tequilensis LXM 55 and its application in pulp biobleaching.

Bioprocessing of pulp requires lignolytic as well as hemicellulolytic enzymes. The present study is the first report of a cocktail of laccase (L), xylanase (X), and mannanase (M), from a single bacterium for pulp biobleaching. A novel strain Bacillus tequilensis LXM 55 produced thermo-alkali stable L + X + M. On optimization higher enzyme yield (IUml-1/fold increase) of laccase (396.35/24.16), xylanase (212.95/81.90) and mannanase (153.33/102.90) were achieved in the cocktail. Treatment of pulp with cocktail of enzymes led to 49.35% reduction in kappa number and considerable enhancement in the brightness (11.59%), whiteness (4.11%), and other pulp properties. Most importantly, no mediator system was required for the application of laccase. 40% less chlorine consumption was required to obtain the paper of the same quality as that of pulp treated without enzyme but with 100% chlorine. Therefore, this cocktail of enzymes is highly suitable for pulp biobleaching in the paper mill.

Combinatorial Biobleaching of Mixedwood Pulp with Lignolytic and Hemicellulolytic Enzymes for Paper Making.

Microbial enzymes are the safe alternatives to chemical based bleaching of pulp in paper mills. For effective biobleaching, both hemicellulolytic and lignolytic enzymes are required. This study reports laccase (L) + xylanase (X) and laccase (L) + mannanase (M) enzyme concoctions for pulp biobleaching derived from Bacillus sp. LX and Bacillus sp. LM isolated from the decaying organic matter. All enzymes were thermo-alkali-stable, hence were suitable for their application in pulp biobleaching. When a mixture of L + X/L + M was used for mixedwood pulp biobleaching, 46.32/40.25% reduction in kappa number; 13.21/10.01% and 3.36/2.76% improvement in brightness and whiteness was achieved respectively. Moreover, no laccase mediator system was required in the current process. Significant changes in the structure of enzymatically treated pulp were also observed. All these properties make these concoctions of enzymes suitable for their application in pulp and paper mill.