A novel detergent-stable protease from Penicillium chrysogenium X5 and its utility in textile fibres processing

Background and aim: The use of enzymes in the textile industry is an example of white/industrial biotechnology, which allows the development of environmentally friendly technologies in fibre processing and strategies to improve the final product quality. The consumption of energy and raw-materials, as well as increased awareness of environmental concerns related to the use and disposal of chemicals into landfills, water or release into the air during chemical processing of textiles are the principal reasons for the application of enzymes in finishing of textile materials. Owing to the quality of the workforce, political stability, economic, and geographical approximation with Europe, textile sector has a significant importance in the Tunisian economy. The aim of this study is to isolate a new fungi protease, with excellent proprieties in order to be used as a bio-additive in detergent formulation with any destructive effect on textile supports.

Methods: The ITS rDNA gene-sequencing was used to identify the fungus strain X5. The biochemical and chemical characterization of the pure enzyme were investigated though physico-chemical and kinetic determination as well as spectroscopy analysis.

Results: A new extracellular thermostable serine alkaline protease (SAPTEX) was purified to homogeneity and biochemically characterized from P. chrysogenium X5 as a monomer with 43 kDa. The experimental purification protocol comprises three steps: heat treatment followed by an ammonium sulfate precipitation, and a FPLC/UNO Q-12 anion exchange chromatography. The optimum pH and temperature values for protease activity were pH 10 and 80°C, respectively. Compared to other proteases (SPTC; Flavourzyme® 500L; Proteinase, type XXIII; Proteinase K; and Alcalase® 2.4L), SAPTEX has the highest catalytic efficacy, hydrolysis degree, and a powerful stability toward some commercial detergents. According to morphological, physico-chemical, and metrological evaluation, SAPTEX has no destructive impact on fibers after the enzyme treatment and a very slight effect on textile support. Data suggested that SAPTEX may be considered a potential candidate as a protein stain removal product from textile supports.

Conclusion: Overall, the findings indicate that SAPTEX is bestowed with a number of promising properties that may be considered as potential candidate for protein stain removal from textile supports in the textile processing applications.