Ligninolytic enzyme production and polyphenolic compound extraction by liquid-state culture of Phanerochaete chrysosporium ATCC 24275 was investigated by employing apple pomace sludge and synthetic medium. Different physico-chemical and biological parameters namely viscosity, zeta potential and particle size, viability and enzyme production were investigated. The ligninolytic enzyme production was higher in apple pomace sludge (45 U/I of laccase, 220 U/I of MnP and 6.5 U/I of LiP) than in synthetic medium (17 U/I of laccase, 37 U/I of MnP and 6 UP). These maximal activities were found during the stationary and decline phase. It was also found that enzyme production was strongly correlated with P. chrysoporium viability in both synthetic medium and apple pomace sludge. Moreover, physico-chemical parameters, such as particle size, zeta potential and viscosity were strongly correlated to the viability of P. chrysosporium and to the ligninolytic enzyme production. An increase in polyphenol content extracted by acetone (383-720 mg GAE/I) was observed during fermentation of apple pomace and it was found that the polyphenol content extracted by ethanol increased similar to 1.5 fold until 67 h of fermentation and later it decreased. It was found that antioxidant activity increased to 35% and eventually decreased based on the change in the polyphenol content. (C) 2012 Elsevier Ltd. All rights reserved.