The metabolism of biphenyl structures in lignin by the soil bacterium (Pseudomonas paucimobilis SYK‐6)

In the soil bacterium (Pseudomonas paucimobilis SYK‐6), the metabolism of DDVA (biphenyl structure of lignin) and syringic acid (characteristic aromatic ring in hardwood lignin) proceeds via a common intermediate, 3‐methylgallic acid. Protocatechuate is also an intermediate in the metabolism of vanillate and p‐hydroxybenzoic acid. 3‐Methylgallic acid and protocatechuate are the final aromatic intermediates in lignin microbial degradation and these compounds are substrates of protocatechuate‐4,5‐dioxygenase, which is a key enzyme in obtaining metabolic energy from various structures of lignin in this bacterium.