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.

Comments on substrate exhaustion during Klebsiella pneumoniae growth

The behavior of the bacterium Klebsiella pneumoniae in the condition of substract exhaustion, in different adaption levels, was studied. The objective was to stablish a substrate exhaustion indicator, for the study of 2,3-butanediol production from eucalyptus hemicellulosic hydrolizate, in fed-batch process. The bacterium was acclimatized in synthetic medium containing 0, 10 and 20 (per cent) of nontreated hydrolizate. The results showed that pH and dissolved oxygen are afected when different levels of adaption are used and that the best substrate exhaustion indicator is the increase of the percentage of dissolved oxygen in the medium.