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Jaouadi N.Z.,University of Sfax | Rekik H.,University of Sfax | Badis A.,Blida University | Badis A.,National Center for Research and Development of Fisheries and Aquaculture | And 7 more authors.
PLoS ONE | Year: 2013

Dehairing is one of the highly polluting operations in the leather industry. The conventional lime-sulfide process used for dehairing produces large amounts of sulfide, which poses serious toxicity and disposal problems. This operation also involves hair destruction, a process that leads to increased chemical oxygen demand (COD), biological oxygen demand (BOD), and total suspended solid (TSS) loads in the effluent. With these concerns in mind, enzyme-assisted dehairing has often been proposed as an alternative method. The main enzyme preparations so far used involved keratinases. The present paper reports on the purification of an extracellular keratinase (KERUS) newly isolated from Brevibacillus brevis strain US575. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) analysis revealed that the purified enzyme was a monomer with a molecular mass of 29121.11 Da. The sequence of the 27 N-terminal residues of KERUS showed high homology with those of Bacillus keratinases. Optimal activity was achieved at pH 8 and 40°C. Its thermoactivity and thermostability were upgraded in the presence of 5 mM Ca2+. The enzyme was completely inhibited by phenylmethanesulfonyl fluoride (PMSF) and diiodopropyl fluorophosphates (DFP), which suggests that it belongs to the serine protease family. KERUS displayed higher levels of hydrolysis, substrate specificity, and catalytic efficiency than NUE 12 MG and KOROPON® MK EG keratinases. The enzyme also exhibited powerful keratinolytic activity that made it able to accomplish the entire feather-biodegradation process on its own. The kerUS gene encoding KERUS was cloned, sequenced, and expressed in Escherichia coli. The biochemical properties of the extracellular purified recombinant enzyme (rKERUS) were similar to those of native KERUS. Overall, the findings provide strong support for the potential candidacy of this enzyme as an effective and eco-friendly alternative to the conventional chemicals used for the dehairing of rabbit, goat, sheep and bovine hides in the leather processing industry. © 2013 Jaouadi et al. Source


Ben Elhoul M.,University of Sfax | Zarai Jaouadi N.,University of Sfax | Rekik H.,University of Sfax | Bejar W.,University of Sfax | And 6 more authors.
International Journal of Biological Macromolecules | Year: 2015

An alkaline proteinase (STAP) was produced from strain TN650 isolated from a Tunisian off-shore oil field and assigned as Streptomyces koyangensis strain TN650 based on physiological and biochemical properties and 16S rRNA gene sequencing. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) analysis revealed that the purified enzyme was a monomer with a molecular mass of 45125.17-Da. The enzyme had an NH2-terminal sequence of TQSNPPSWGLDRIDQTTAFTKACSIKY, thus sharing high homology with those of Streptomyces proteases. The results showed that this protease was completely inhibited by phenylmethanesulfonyl fluoride (PMSF), diiodopropyl fluorophosphates (DFP), and partially inhibited by 5,5-dithio-bis-(2-nitro benzoic acid) (DTNB), which strongly suggested its belonging to the serine thiol protease family. Using casein as a substrate, the optimum pH and temperature values for protease activity were pH 10 and 70°C, respectively. The protease was stable at pH 7-10 and 30-60°C for 24h. STAP exhibited high catalytic efficiency, significant detergent stability, and elevated organic solvent resistance compared to the SG-XIV proteases from S. griseus and KERAB from Streptomyces sp. AB1. The stap gene encoding STAP was isolated, and its DNA sequence was determined. These properties make STAP a potential candidate for future application in detergent formulations and non-aqueous peptide biocatalysis. © 2015 Elsevier B.V. Source


Mokrane Z.,University of Science and Technology Houari Boumediene | Mokrane Z.,National Center for Research and Development of Fisheries and Aquaculture | Laribi H.,Polytechnic School of Algiers | Touahria N.,University of Science and Technology Houari Boumediene | And 2 more authors.
Cahiers de Biologie Marine | Year: 2015

The digestive system of teleost fish has a high structural diversity based on modes, living environments and diets. This study aims to qualitatively and quantitatively determine the diet of Scorpaena notata and describe the adaptation of the histological structure of the digestive tract with enzymatic secretion compared to the nature of ingested prey. This study was performed using three approaches: histology of different parts of the digestive tract, stomach contents analysis, and enzymatic assay. A total of 350 small red scorpion fish individuals were collected from small landings in the region of Algiers. The composition of the diet shows that S. notata is a macrophagous species with a large alimentary spectrum of prey. The diet consists of decapoda brachyura, other crustaceans and fishes. A digestive enzymology test reveals that the activity of chitinolytic enzymes is particularly high in the scorpion fish stomach in general; the major preys are known by their carapace rich on chitin. This result was obtained by the extraction of crude chitinases from the offal of these fish. It was confirmed by the histological structure of the lamina propria of the stomach mucosa showing a dense glandular exocrine serous form, when the intestinal structure are much less dense at the mucosa. Source


Ferradji F.Z.,Blida University | Ferradji F.Z.,National Center for Research and Development of Fisheries and Aquaculture | Mnif S.,University of Sfax | Badis A.,Blida University | And 5 more authors.
International Biodeterioration and Biodegradation | Year: 2014

Petroleum and naphthalene (example of PAHs) degrading Streptomyces spp. isolates AB1, AH4, and AM2 were recovered from surface soils at Mitidja plain (North of Algeria). The degradation efficiencies were examined by HPLC and GC-MS analysis and the results showed that the biosurfactant producing isolates AB1, AH4 and AM2 could remove 82.36%, 85.23% and 81.03% of naphthalene after 12 days of incubation, respectively. During naphthalene degradation, a slight decrease in pH values was recorded for the three studied strains. Degradation metabolites were identified using GC-MS analysis of ethyl acetate extracts of the cell free-culture. The metabolism of degradation proceeds via the phthalic acid pathway for the three strains. Moreover, the selected strains showed an important degradation of the aliphatic fraction present in crude oil after 30 days of incubation. The finding suggests that the selected strains are suitable candidates for practical field application for effective in situ bioremediation of hydrocarbon-contaminated sites. © 2013 Elsevier Ltd. Source


Zarai Jaouadi N.,University of Sfax | Rekik H.,University of Sfax | Ben Elhoul M.,University of Sfax | Zohra Rahem F.,Blida University | And 8 more authors.
International Journal of Biological Macromolecules | Year: 2015

The present paper reports on the purification and characterization of an extracellular keratinase (KERQ7) newly purified from Bacillus tequilensis Q7. Pure protein was obtained after ammonium sulfate fractionation (30-60%), followed by Mono S Sepharose cation-exchange chromatography. MALDI-TOF/MS analysis revealed that the purified enzyme was a monomer with a molecular mass of 28,355.07-Da. The sequence of the 21 N-terminal residues of KERQ7 showed high homology with those of Bacillus keratinases. Optimal activity was achieved at pH 7 and 30°C. KERQ7 was completely inhibited by PMSF and DFP, which suggests that it belongs to the serine keratinase family. KERQ7 displayed higher levels of hydrolysis and catalytic efficiency than Basozym® CS 10, Koropon® SC 5K, and Pyrase® 250 MP. The kerQ7 gene encoding KERQ7 was cloned, sequenced, and expressed in Escherichia coli BL21(DE3)pLysS. The biochemical properties of the extracellular purified recombinant enzyme (rKERQ7) were similar to those of native KERQ7. The deduced amino acid sequence showed strong homology with other Bacillus keratinases. The highest sequence identity value (97%) was obtained with KERUS from Brevibacillus brevis US575, with only 7 aa of difference. These properties make KERQ7 a potential promising and eco-friendly enzymatically enhanced process for animal hide bating in the leather processing industry. © 2015 Elsevier B.V. Source

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