Abstract: Currently it has been detected that the bleaching process in the paper industry generates most of the pollution and environmental issues that we know today, the main goal in the bleaching process is the elimination of the lignin out of the paper, having chromophore groups, responsible of a brown coloration on the unbleached paper pulps; it has been created different process decreasing the polluting factor, but has not been totally eliminated. In this investigation we propose the genetic modification of the yeast Saccharomyces cerevisiae as a lignin degradative organism at contact with the cellulose which we can accomplish with a gene called Lignin Peroxidase, an enzyme that oxidizes substructures not phenolic of the lignin, removing an electron from this and generating cationic radicals which are attacked enzymatically, in this way in order to produce a biological bleaching method that allows reducing contaminants residues from the paper industry.

Our story

In paper industries there are great conflicts regarding pollution in the cellulose bleaching process, this has happened because the cellulose pulp can exhibit a big or small dark brown coloration depending on the percentage of lignin in the paper. Thanks to this, a lot of processes for the bleaching were created, along with the use of a great amount of water, which is necessary, they generate different kinds of waste with different techniques, and despite how modern this process might be, the paper industry continues to be one of the most polluting industries in the world. There are many processes for the bleaching of the pulp; one of the most known is the conventional one, where elemental chlorine is used; this process presents major pollution rates. Another one is Solvopulping, in this process alcohol is used, which is better than chlorine, however, it’s too dangerous and not frequently used because of the workers safety. That is why we propose the modification of a kind of yeast called Saccharomyces cerevisiae, that acts as an organism (system) for the bleaching of lignin when it is in contact with the cellulose, a process we will accomplish with two genes obtained from white fungus putrescence: the lignin peroxidase and laccase. The lignin peroxidase is one of the main responsibles in the bleaching of the lignin inside the cell walls. It differences itself from another peroxidases for its high oxide-reduction(redox) potencial that directly oxidizes non-phenolic aromatic compounds ; and Laccase (Lac), belonging to the blue copper oxidase group, catalyzes the oxidation of organic or inorganic substrates in some fungus and plants they are an important part of lignin bleaching process and toxic phenol elimination derived from this process.