Selection of Pycnoporus cinnabarinus strains for laccase production.

A comparison of Pycnoporus cinnabarinus strains for laccase production was carried out. A dikaryotic strain, I-937 strain, producing a high level of laccase (9500 U l(-1)) was selected. The study of the life cycle in vitro of this dikaryotic strain led to isolation of monokaryons. Forty-eight monokaryotic strains were isolated and screened for laccase production. One of these strains, ss3, produced a higher level of laccase than the parental strain I-937. The maximum production reached 29000 U l(-1) in medium supplemented with ferulic acid.

Pycnoporus cinnabarinus laccases: an interesting tool for food or non-food applications.

The effects of the addition of ferulic acid and ethanol in P. cinnabarinus ss3 culture medium in fermentor were compared in 15-L fermentor. In the presence of 30 g l(-1) ethanol, laccase activity (270,000 U/L1) was 3-fold higher as compared with ferulic acid-induced cultures, and 150-fold higher as compared with non-induced cultures, respectively. High-quality flax pulp was bleached in a totally-chlorine free (TCF) sequence using a laccase-mediator system constituted by laccase from Pycnoporus cinnabarinus and 1-hydroxybenzotriazole (HBT) as mediator. Up to 90% delignification and strong brightness increase were attained after the laccase-mediator treatment followed by H2O2 bleaching. This TCF sequence was further improved by applying H2O2 under pressurized O2. In this way, up to 82% ISO brightness was obtained (compared with 37% in the initial pulp and 60% in the peroxide-bleached control) as well as very low kappa number. A positive evaluation of the laccase has been also performed in a food application. The colour of a tea-based beverage was significantly improved by incubating an infusion of green tea with the Pycnoporus laccase.

Design and scale up of a process for manganese peroxidase production using the hypersecretory strain Phanerochaete chrysosporium I-1512.

Manganese peroxidase (MnP) production was performed in a airlift bioreactor in which Phanerochaete chrysosporium I-1512, an MnP hypersecretory strain, was immobilized on a stainless steel mesh. Production was scaled up from a 2.5-L bench scale to a 100-L bioreactor. The yield of MnP was increased 2-fold and reached 6600 U L(-1). These results indicate the feasibility of MnP production on a medium scale, which promises sufficient MnP availability for its use in pulp bleaching at industrial scale.

Isolation of a new laccase isoform from the white-rot fungi Pycnoporus cinnabarinus strain ss3.

Two extracellular laccase isoforms (Lac I and Lac II) produced by the white-rot fungus Pycnoporus cinnabarinus from the monokaryotic strain ss3 were purified from ferulic-acid-induced liquid culture medium using ammonium sulphate precipitation, followed by anion-exchange chromatography on a Mono Q column. Strain ss3 is the first generation of the parental strain P. cinnabarinus I-937. The new isolated isoform, Lac II, consists of an 86,000 molecular weight protein as determined by SDS polyacrylamide gel electrophoresis. The N-terminal amino acid sequences of both isoforms were determined, and compared to known laccase protein sequences of other organisms.