Oxidative quenching of spruce thermomechanical pulp fiber autofluorescence monitored in real time by confocal laser scanning microscopy - Implications for lignin autofluorescence

Confocal laser scanning microscopy (CLSM) was used to monitor real-time lignin autofluorescence intensities from different cell wall compartments of spruce fibers during oxidation by laccase-2,2'-azinobis-3ethylbenzthiazoline-6-sulfonate (ABTS) treatment. CLSM data revealed an instant emission quenching from all cell wall compartments, including those not physically accessible to enzyme or ABTS, followed by an additional decrease simultaneously in all cell wall compartments over a 45 min time course. The importance of site-to-site excitation energy transfer in lignin efficient over long distance is suggested.