Production, purification, and biochemical characterization of serine alkaline protease from Penicillium chrysogenium strain X5 used as excellent bio-additive for textile processing

A new ascomycete fungus X5, a hyperproducer (9000 U/mL) of a serine alkaline protease (SAPTEX) was identified as Penicillium chrysogenum. The experimental purification protocol comprises three steps: heat treatment (10 min at 80 degrees C) followed by an ammonium sulfate precipitation (30-50%)-dialysis, and a UNO Q-12 anion exchange chromatography using the FPLC system. The chemical characterizations performed include physicochemical determination and spectroscopic analysis. The MALDI-TOF/MS analysis revealed that the purified enzyme was a monomer with a molecular mass of 43,074.11 Da. The 25 residue NH2-terminal sequence of the enzyme showed high homology with Penicillium proteases. The optimum pH and temperature values for protease activity were pH 10 and 80 degrees C, respectively. Compared to other proteases (SPTC; Flavourzyme (R) 500 L; Proteinase, type XXIII; Proteinase K; and Alcalase (R) 2.4 L), SAPTEX has the highest catalytic efficacy, hydrolysis degree, and a powerful stability toward some commercial detergents. According to morphological, physico-chemical [scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), and FTIR-Fourier transform infrared spectroscopy], and mechanical evaluation, SAPTEX has no destructive impact on fibers after the enzyme treatment and a very slight effect on textile support. Obtained results suggested that SAPTEX may be considered as a potential candidate as a protein stain removal product for textile supports. (C) 2018 Elsevier B.V. All rights reserved.