Bacillus amyloliquefaciens CotA degradation of the lignin model compound guaiacylglycerol--guaiacyl ether

The cotA gene from Bacillus amyloliquefaciens MN-13 was cloned and expressed in Escherichia coli Transetta. Nucleotide sequence analysis showed an open reading frame of 1542bp encoding a polypeptide comprised of 513 amino acids. The degradation of lignin model compounds by recombinant CotA was investigated by HPLC-MS with guaiacylglycerol--guaiacyl ether as the substrate. The compounds including guaiacol, 3-(4-hydro-3-methoxyphenyl)-3-oxo-propanol and 4-hydro-3-methoxy acetophenone detected by HPLC-MS verified the rupture of -O-4 bond and oxidation C bond of guaiacylglycerol--guaiacyl ether by CotA. 4-vinylguaiacol and 1-(4-hydroxy-3-methoxyl phenyl)-1-(2-methoxyl) phenoxyl ethylene were first time found in the degradation products of guaiacylglycerol--guaiacyl ether. The appearance of 4-vinylguaiacol and 4-hydro-3-methoxy acetophenone confirmed the cleavage of C-C bond. 1-(4-hydroxy-3-methoxyl phenyl)-2-(2-methoxyl) phenoxyl ethylene was coupled by the radical reaction of 4-vinylguaiacol with guaiacol. Otherwise, no corresponding degradation product was found to give a proof of cleavage of C-C bond in guaiacylglycerol--guaiacyl ether by CotA.