DIRECTED EVOLUTION OF LACCASE FOR APPLICATION IN POLYCARBONATE PLASTIC DEGRADATION

Abstract

Polycarbonate plastic is a ubiquitous material present in various forms. It is built from monomers of bisphenol A (BPA) which is known to be an estrogen stimulating compound and believed to play a key role in the development of life-threating diseases such as various forms of cancer and diabetes. Non-life threatening health issues associated with BPA are early puberty and obesity. BPA has been found in 92.6% of 2,517 people sampled in the U.S. between 2003-2004 (Calafat et at. 2007). Artham and Doble (Doble and Artham 2009) , discovered that UV-treated polycarbonate plastics were degraded by laccase excreted by fungal species Engyodontium album MTP091, Phanerochaete chrysosporium NCIM 1170 and Pencillium spp. MTP09. The polycarbonate plastic was degraded at a rate of 5.4% weight reduction per year without the release of Bisphenol A monomers. The goal of the project is to use directed evolution to alter the GLlacl gene, which codes for laccase in the fungus Ganoderma lucidum and then exposing the laccase enzyme to UV- treated polycarbonate plastic, it is possible to select an altered laccase gene that degrades the polycarbonate plastic at a faster rate than the rate observed by Doble and Artham.