Use of micro- and ultrafiltration membranes for concentration of laccase-rich enzymatic extract of Pleurotus sajor-caju PS-2001 and application in dye decolorization

Abstract

In the present work, studies of laccase-rich enzymatic extract pretreatment were carried out using granulated activated carbon and/or microfiltration (polyimide hollow fiber membrane, 0.4 µm pore size) prior to ultrafiltration (polyether sulfone spiral membrane, 10 kDa cut-off). Concentration by ultrafiltration without any pretreatment resulted in superior recovery percentage (141%), but under low permeate flow (20 L m−2 h−1) and longer process time. Conversely, a protocol comprising both pretreatments resulted in moderately inferior recovery (109%) and rather higher permeate flux. In order to effectively concentrate about 110 L laccase crude broth, only the microfiltration pretreatment was used, once it decreases overall process time and cost. Volumetric concentration up to a factor of 60 times was obtained, with an enzyme recovery percentage of 183% and an activity concentration factor of 102, producing an extract with laccase activity of ca. 3033 U mL−1. Reaction mixtures containing 150 U mL−1 laccase activity from concentrated enzymatic extracts, associated with 0.3 µmol L−1 mediator syringaldazine granted decolorization percentages of approximately 75% for brilliant green, 68% for acid blue 80 and 52% for reactive red 198.