Distinct laccase expression and activity profiles of facilitate degradation of benzo[a]pyrene.

A isolate from the Changbai Mountain showed promising activity in degrading benzo[a]pyrene (BaP), which is a high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH) compound. It was hypothesized that the isolate encode BaP-degrading enzymes, among which laccase is mostly sought after due to significant commercial potential. Genome of the isolate was sequenced and assembled, and seven laccase homologues were identified () as candidate genes potentially contributing to BaP degradation. In order to further identify the BaP responsive laccases, time-course transcriptomic and proteomic analyses were conducted in parallel on the isolate upon BaP treatment. Homologous laccases showed distinct expression patterns. Most strikingly, TvLac5 was rapidly induced in the secreted proteomes (secretomes), while TvLac2 was repressed. Recombinant laccase expression and biochemical characterization further showed corresponding enzymatic activity profiles, where TvLac5 was 21-fold more effective in BaP degradation compared to TvLac2. Moreover, TvLac5 also showed 3.6-fold higher BaP degrading activity compared to a commercial laccase product of origin. Therefore, TvLac5 was concluded to be a BaP-responsive enzyme from showing effective BaP degradation activity.