Using low-shear aerated and agitated bioreactor for producing two specific laccases by trametes versicolor cultures induced by 2,5-xylidine: Process development and economic analysis.

Laccase isoforms from basidiomycetes exhibit a superior redox potential compared to commercially available laccases obtained from ascomycete fungi, rendering them more reactive toward mono-substituted phenols and polyphenolic compounds. However, basidiomycetes present limitations for large-scale culture in liquid media, restraining the current availability of laccases from this fungal class. To advance laccase production from basidiomycetes, a newly designed 14-L low-shear aerated and agitated bioreactor provided enzyme titers up to 23.5 IU/mL from Trametes versicolor cultures. Produced enzymes underwent ultrafiltration and LC/MS-MS characterization, revealing the predominant production of only two out of the ten laccases predicted in the T. versicolor genome. Process simulation and economic analysis using SuperPro designer® suggested that T. versicolor laccase could be produced at US$ 3.60/kIU in a 200-L/batch enterprise with attractive economic parameters and a payback period of 1.7 years. The study indicates that new bioreactors with plain design help to produce low-cost enzymes from basidiomycetes.

Recovery of Peniophora cinerea laccase using aqueous two-phase systems composed by ethylene oxide/propylene oxide copolymer and potassium phosphate salts.

Aqueous two-phase systems (ATPSs) composed by UCON (ethylene oxide/propylene oxide copolymer) and potassium phosphate salts were for the first time evaluated in the recovery of Peniophora cinerea laccase from complex fermented medium. The ATPSs were obtained by combining the random copolymer UCON with KH2PO4, potassium phosphate buffer pH 7 or K2HPO4. According to the results, protein partition occurred predominantly toward the saline phase (bottom phase) of the ATPSs, while some contaminants such as pigments partitioned mainly to the top phase. In preliminary tests, it was found that the salt with the lowest pH value (KH2PO4, pH 4.6) stimulated the enzyme activity, while the other salts (pH between 7.0 and 9.5) caused a strong inhibition. However, the salt inhibition was not observed in the equilibrium phases of the UCON-Potassium phosphate ATPSs. The laccase recovery was high for all the biphasic systems, but the highest value (134%) was obtained when using UCON combined with KH2PO4. When compared to conventional concentration and purification methods (lyophilization, ammonium sulfate precipitation, ultrafiltration, and ion exchange chromatography), ATPS was demonstrated to be an efficient alternative for P. cinerea laccase recovery from fermented medium.

Identification of iron-regulated cellular proteins, Fe3+-reducing and -chelating compounds, in the white-rot fungus Perenniporia medulla-panis.

In this paper, we present the responses of the white-rot fungus Perenniporia medulla-panis to iron availability with regard to alterations in growth, expression of cellular proteins, Fe3+-reducing activity, and Fe3+ chelators production. Iron supplementation stimulated fungal growth but did not result in a significant increase in biomass production. Catechol and hydroxamate derivatives were produced mainly under iron deficiency, and their productions were repressed under iron supplementation conditions. Perenniporia medulla-panis showed several cellular proteins in the range of 10-90 kDa. Some of them showed negative iron-regulation. Iron-supplemented medium also repressed both cell surface and extracellular Fe3+-reducing activities; however, the highest cell surface activity was detected at the initial growth phase, whereas extracellular activity increased throughout the incubation period. No significant production of chelators and extracellular Fe3+-reducing activity were observed within the initial growth phase, suggesting that the reduction of Fe3+ to Fe2+ is performed by ferrireductases.