Aims The aim of this work was to characterize and apply a polygalacturonase of Penicillium janthinellum new strain VI2R3M. Methods and Results The polygalacturonase obtained from P. janthinellum VI2R3M was incubated in cultures of passion fruit peel and was partially purified by ion‐exchange chromatography and gel filtration. The enzyme showed a relative molecular mass of 102·0 kDa, maximum activity at pH 5·0, temperature of 50°C, 100% stablity at 50°C and 80% stablity at pH 3·0–5·0. The apparent Km, Vmax and Kcat values for hydrolyzing polygalacturonic acid were 2·56 mg ml−1, 163·1 U mg−1 and 277 s−1 respectively. The polygalacturonase presented exo activity and was activated by Mg2+. The juices treated with polygalacturonase presented increases in transmittance with reduction in colour. Conclusions The results suggest that the new lineage P. janthinellum VI2R3M presents a high yield of an exo‐polygalacturonase induced by agro‐industrial residues, with excellent activity and stability in acidic pH and at 50°C. Significance and Impact of the Study The use of agro‐industrial residue to obtain the polygalacturonase can contribute to a decrease enzyme production cost. The results of the activity, stability to acidic pH and excellent performance in the clarification of juices show that the enzyme is promising for industrial application.

The second-generation bioethanol employs lignocellulosic materials degraded by microbial cellulases in their production. The fungus Trichoderma reesei is one of the main microorganisms producing cellulases, and its genetic modification can lead to the optimization in obtaining hydrolytic enzymes. This work carried out the deletion of the sequence that encodes the zinc finger motif of the transcription factor ACE1 (cellulase expression repressor I) of the fungus T. reesei RUT-C30. The transformation of the RUT-C30 lineage was confirmed by amplification of the 989 bp fragment relative to the selection marker, and by the absence of the zinc finger region amplification in mutants, named T. reesei RUT-C30Δzface1. The production of cellulases by mutants was compared to RUT-C30 and measured with substrates carboxymethylcellulose (CMC), microcrystalline cellulose (Avicel ® ) and Whatman filter paper (PF). The results demonstrated that RUT-C30Δzface1 has cellulolytic activity increased 3.2-fold in Avicel and 2.1-fold in CMC and PF. The mutants presented 1.4-fold higher sugar released in the hydrolysis of the biomass HIGHLIGHTS  Enhance of Trichoderma reesei RUT-C30∆zface1. Deletion of zinc finger of the repressor transcription factor cellulase ACE1. Optimized fungal strain for the production of cellulase. Greater efficiency in the enzymatic activity and sugarcane hydrolysis. 2 Dudek, D.N.; et al.