IMPROVING BIOCHEMICAL PROCESSES FOR THE PRODUCTION OF SUSTAINABLE FUELS AND CHEMICALS
Location: Renewable Product Technology Research Unit
Title: Laccases from Aureobasidium pullulans
Submitted to: Enzyme and Microbial Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 20, 2013
Publication Date: June 10, 2013
Citation: Rich, J.O., Leathers, T.D., Anderson, A.M., Bischoff, K.M., Manitchotpisit, P. 2013. Laccases from Aureobasidium pullulans. Enzyme and Microbial Technology. 53(1):33-37.
Interpretive Summary: In this research we identified novel sources of the enzyme, “laccase,” involved in biomass degradation. Unique versions of this enzyme are needed for expanded industrial and bioremediation applications. We characterized enzymes produced by new microbial isolates and found that they differed from those of previously studied enzymes, including possessing relatively high thermal stability. This information will facilitate future research to develop additional uses for these enzymes.
Laccases are polyphenol oxidases (EC 22.214.171.124) that have numerous industrial and bioremediation applications. Laccases are well known as lignin-degrading enzymes, but these enzymes can play numerous other roles in fungi. In this study, 41 strains of the fungus Aureobasidium pullulans were examined for laccase production. Enzymes from A. pullulans were distinct from those from lignin-degrading fungi and associated with pigment production. Laccases from strains in phylogenetic clade 5, which produced a dark vinaceous pigment, exhibited a temperature optimum of 50-60 ºC and were stable for an hour at 50 ºC, unlike enzymes from the lignin-degrading fungi Trametes versicolor and Pycnoporus cinnabarinus. Laccase purified from A. pullulans strain NRRL 50381, a representative of clade 5, was glycosylated but had a molecular weight of 60-70 kD after Endo H treatment. Laccase purified from strain NRRL Y-2568, which produced a dark olivaceous pigment, was also glycosylated, but had a molecular weight of greater than 100 kD after Endo H treatment.