International Journal of Biological Macromolecules 94 (2017) 221–232 Contents lists available at ScienceDirect International Journal of Biological Macromolecules j ourna l h o mepa ge: www.elsevier.com/locate/ijbiomac Characterization of a novel protease from Aeribacillus pallidus strain VP3 with potential biotechnological interest Sondes Mechri a , Mouna Ben Elhoul Berrouina a , Maroua Omrane Benmrad a , Nadia Zaraî Jaouadi a , Hatem Rekik a , Emna Moujehed a , Alif Chebbi b , Sami Sayadi b , Mohamed Chamkha b , Samir Bejar a , Bassem Jaouadi a,∗ a Laboratory of Microbial Biotechnology and Engineering Enzymes, Centre of Biotechnology of Sfax, University of Sfax, Road of Sidi Mansour Km 6, P.O. Box 1177, Sfax 3018, Tunisia b Laboratory of Environmental Bioprocesses, LMI COSYS-Med, Centre of Biotechnology of Sfax, University of Sfax, Road of Sidi Mansour Km 6, P.O. Box 1177, Sfax 3018, Tunisia a r t i c l e i n f o Article history: Received 28 August 2016 Accepted 16 September 2016 Available online 5 October 2016 Keywords: Protease Aeribacillus pallidus Geothermal oil-field a b s t r a c t The present study investigates the purification and physico-chemical characterization of an extracellular protease from the Aeribacillus pallidus strain VP3 previously isolated from a geothermal oil-field (Sfax, Tunisia). The maximum protease activity recorded after 22 h of incubation at 45 ◦ C was 3000 U/ml. Pure enzyme, designated as SPVP, was obtained after ammonium sulfate fractionation (40–60%)-dialysis fol- lowed by heat-treatment (70 ◦ C for 30 min) and UNO Q-6 FPLC anion-exchange chromatography. The purified enzyme is a monomer of molecular mass about 29 kDa. The sequence of the 25 NH 2 -terminal residues of SPVP showed a high homology with those of Bacillus proteases. The almost complete inhi- bition by PMSF and DIFP confirmed that SPVP is a member of serine protease family. Its optima of pH and temperature were pH 10 and 60 ◦ C, respectively. Its half-life times at 70 and 80 ◦ C were 8 and 4 h, respectively. Its catalytic efficiency was higher than those of SAPCG, Alcalase Ultra 2.5 L, and Thermolysin type X. SPVP exhibited excellent stability to detergents and wash performance analysis revealed that it could remove blood-stains effectively and high resistance against organic solvents. These properties make SPVP a potential candidate for applications in detergent formulations and non-aqueous peptide biocatalysis. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Extremophilic microorganisms are adapted to surviving in eco- logical niches such as high temperatures in volcanic springs, at low temperatures in polar regions, at high pressure in the deep sea, at very low and high pH values (pH 0 ± 3 or pH 10 ± 12), or at very high salt concentrations (5 ± 30%). In the last decade, vari- ous hyperthermophilic bacteria and archaea capable to grow under extreme temperatures have been isolated. These microorganisms produce novel organic compounds and stable biocatalysts that function under these conditions comparable to those prevailing in many industrial processes. Thanks to their ability to propagate under the conditions where other organisms either can not grow or grow little, microorganisms living in extreme environments, ∗ Corresponding author. E-mail addresses: bassem.jaouadi@cbs.rnrt.tn, bassem.jaouadi@yahoo.fr (B. Jaouadi). termed extremophiles, have always gained a significant attention from scientists. In particular, they are a source of several enzymes with unconventional biochemical and molecular characteristics. The literature indicates that these extremophiles are considered as an important source of enzymes with unconventional biochemical and molecular characteristics, and unique metabolic capabilities are the major points of attractions in biotechnological applications [1,2]. Thus, as per earlier report, search for new robust biocatalysts producing microbes from extreme must be an endless task [3]. The enzymes isolated from those microorganisms have been reported to be thermostable and active not only at high temperatures but also in the presence of organic solvents and detergents [4]. Some of the enzymes from extremophiles have already been purified and their genes successfully cloned in mesophilic hosts [4,5]. Petroleum reservoirs constitute a group of unique habitat, as they present an unusual combination of extreme environmen- tal conditions, including temperature, pressure, and salinity. It is also known that petroleum composition varies widely among reservoirs, which has an impact on the microbial life include [6]. http://dx.doi.org/10.1016/j.ijbiomac.2016.09.112 0141-8130/© 2016 Elsevier B.V. All rights reserved.