Study on lignin decomposition and elimination methods using microorganisms for environmental conservation

An investigation was made on the structure and the decomposition mechanism of lignin, which is distantly related to environmental pollution and the composition of bacteria with a highly decomposing activity for lignin was attempted by gene manipulation and γ-ray irradiation. The biosynthetic pathway of lignin was investigated using Populus euromericana after 1 month culture. And the presence of a regulating system for mutual conversion between G and S nucleus in its biosynthesis was found at crude enzyme level. However, the structures of the related enzymes including their co-enzymes could not be identified. Then, PCR amplification of glyceraldehydephosphate dehydrogenase (GAPDH) was made using two pimers for 5' and 3' end regions of the gene, PGPDF1 and PGPDF2 and a gene fragment of ca. 800 bp was produced. The screening of lignin decomposing bacteria is underway using the fragment. In addition, it was suggested that mutagenic treatment by γ-ray irradiation might increase the decomposing capacity for lignin by microorganisms. (M.N.)