Recent advances in Sphingobium sp． SYK-6 for lignin aromatic compounds degradation-A review

Abstract:

Abstract:Lignin is complex heteropolymer produced from hydroxycinnamyl alcohols through radical coupling．In nature，white-rot fungi are assumed initially to attack native lignin and release lignin-derived-low-molecular-weight compounds，and soil bacteria play an importent role for completely degradation of these compounds．Study on the soil bacteria degrading lignin-derived-low-molecular-weight compounds will give way to understand how aromatic compounds recycle in nature，and to utilize lignin compounds as the renewable materials for valuable materials production． Sphingobium sp．SYK-6 that grows on lignin biphenyl (5，5’-dehydrodivanillate) had been isolated from pulp effluent in 1987．We have researched this bacterium more than 25 years，a serious aromatic metabolic pathway has been determined，and related genes have been isolated．As the complete genome sequence of SYK-6 has been opened to the public in 2012，the entire aromatic compounds degradation mechanisms become more clear．Main contents in our review cover: (1) genome information; (2) aryl metabolism; (3) biphenyl metabolism; (4) ferulate metabolism; (5) tetrahydrofolate-dependent O-demethylation system for lignin compound degrdation; (6) protocatechuate 4，5-cleavage pathway; (7) multiple pathways for 3-O-methylgallate metabolism．