Soumya Elabed

The effect of the Thymus vulgaris extracts on the physicochemical characteristics of cedar wood using angle contact measurement

The aim of the study was to investigate the effect of crude extracts of Thymus vulgaris on wood surface physicochemical characteristics. Thus, the Lifshitz-van der Waals (), acid–base (surface tension components ΔGiwi, electron donor () and electron acceptor () parameters of untreated and treated wood were assessed using contact angle measurement. The main results showed that all T. vulgaris extracts are able to change wood surface properties. Indeed, the samples treated with the product obtained by maceration and ultrasound indicated the hydrophilic character (θw = 29.7 ± 0.3°, ΔGiwi = 17. 78 ± 0.48 mJ/m2 and θw = 18.2 ± 0.2°, ΔGiwi = 30.62 ± 0.31 mJ/m2) respectively, and had less contact angle values than that of untreated wood (θw = 86.0 ± 0.2°). In addition, this treatment has made the wood more donor ( = 44.76 ± 0.3 mJ/m2 and  = 53.80 ± 0.3 mJ/m2) than the electron acceptor compared to sample control ( = 2.03 ± 0.04 mJ/m2). Finally, the effect of the extract obtained by ultrasound was found to be more important and significant than those recovered by classical extraction.

Determination of endoglucanase activity of paper decaying fungi from an old library at the ancient Medina of Fez

Paper from an ancient library of the cultural city of Fez (Morocco) is exposed to rapid deterioration by variety of microorganisms, especially cellulolytic fungi. For this, ten isolates fungi previously isolated from historical biodeteriorated paper were screened for their ability to produce endoglucanase (CMCase), amylase, polygalacturonase and ligninase enzymes. The CMCase activity of cellulolytic strains was essayed in liquid media at 25°C for 10 days. Influence of temperature and pH were assessed for the production of CMCase by all the fungus isolated from decaying paper. The research findings from the present study demonstrate that all the tested isolates had cellulase, amylase, pectinase and ligninase activities. It was found that Mucor racemosus PF15, Aspergillus niger, and Aspergillus oryzae exhibited the maximum endoglucanase activity in liquid medium (0.256, 0.236, and 0.216 UI/mL in descending order) for six days. Temperature profiling revealed optimum endoglucanase activity at 25 and 30°C. Maximum activity was observed at pH 5 and pH 6.

Biochemical characterization of a new thermostable lipase from Bacillus pumilus strain

Abstract Objective: Research and characterization of new thermostable lipases from bacterial strains isolated from tannery waters in the old medina of Fez. Methods: Gene which encodes the 16S ribosomal RNA for a bacterial species was amplified via PCR and sequenced (Bacillus pumilus HF544325). The extracellular lipase from B. pumilus is purified by gel filtration (Sephacryl S-200) and cation exchange chromatography (Mono S sepharose cation exchanger). The N-terminal sequences of purified Bacillus pumilus lipase were determined by automated Edman’s degradation, using an Applied Biosystems 470 A protein sequencer equipped with PTH 120A analyser. The activity of lipase was examined within the pH range of 6.0-10.0 and the effect of pH on lipase stability was determined by incubating the lipase fraction in various buffer solutions ranging from 3.0 to 10.0 for 24 h at room temperature. Results: The results showed that Bacillus pumilus is a strain that produce non-inducible lipase. This enzyme has a molecular weight of 27 kDa and presents a maximal activity at pH 8 and 45°C. The 18 N-terminal amino acid residues showed a high degree of homology with other Bacillus lipase sequences. After treatment in 100°C for 5 min, the thermostable enzyme maintains 60% of its activity, which is greater than that those founded in previous works. The enzyme retained 100% of its activity after 30 min incubation at 70°C. Conclusion: This newly isolated lipase is thermostable and it has a significant difference which was observed when the biochemical properties of the Bacillus pumilus lipase were compared to others microbial lipases. The Bacillus pumilus lipase can be considered as a good candidature for industrial and biotechnological applications. Özet Amaç: Çalışmanın amacı Fez şehrinde bulunan tabakhane sularından izole edilen bakteri suşlarından, sıcaklığa dayanıklı yeni bir lipaz enzimini saflaştırarak karakterize etmektir. Metod: Bakteri türleri için 16S ribosomal RNA’yı kodlayan gen PCR ile çoğaltılarak sekanslanmıştır (Bacillus pumilus HF544325). Ekstraselüler lipaz jel filtrasyonu (Sefakril S-200) ve katyon değiştirici kromatografi kullanılarak (Mono S Sefaroz katyon değiştirici) B. pumilus’den saflaştırılmıştır. Saflaştırılan Bacillus pumilus lipazının N-terminal dizisi Edman degredasyon yöntemi (Applied Biosystems 470 A protein sekanslama cihazı ile PTH120A analizör) ile saptanmıştır. Lipaz aktivitesi 6.0-10.0 pH aralığında incelenmiş, pH’nın lipaz enziminin dayanıklılığına olan etkisi lipaz fraksiyonunu pH’sı 3.0 ile 10.0 arasında değişen çeşitli tampon çözeltilerinde 24 saat oda sıcaklığında inkübe ederek araştırılmıştır. Bulgular: Sonuçlar Bacillus pumilus suşunun indüklenmeyen lipaz enzimini ürettiğini göstermektedir. Lipaz enzimi 27 kDa molekül ağırlığına sahip olup, en yüksek aktiviteyi pH 8 ve 45°C’de göstermektedir. Amino ucundaki 18 amino asit diğer Bacillus lipaz dizileri ile yüksek oranda homoloji göstermektedir. Sıcaklığa dayanıklı olan bu enzim 100°C’de 5 dakika muamele edildiğinde aktivitesinin %60’ını korumaktadır. Bu değer daha önce yapılan çalışmalardakinden daha yüksek bir değerdir. Enzim 30 dakika 70°C’de inkübe edildiğinde aktivitesinin tamamını korumaktadır. Sonuç: Yeniz izole edilen lipaz sıcaklığa dayanıklıdır ve diğer mikrobiyal lipazlar ile karşılaştırıldığında biyokimyasal özellikleri bakımından diğerlerinden oldukça farklıdır. Bacillus pumilus lipaz enzimi endüstriyel ve biyoteknolojik uygulamalar için iyi bir aday olarak düşünülebilir.

Biochemical characterization of a thermoactive and thermostable lipase from a newly isolated Trichosporon coremiiforme strain

Nonstop demand for greatly thermostable and thermoactive active lipase encourages the research for the new enzyme sources. In this study, a strain of Trichosporon coremiiforme was isolated from the traditional tannery in the city of Fez in Morocco, lipase production and their lipolytic activity was studied. Pure T. coremiiforme lipase (TCL) was obtained after ammonium sulfate fractionation, G-75 gel filtration and cation exchanger chromatography (Mono-S), having a molecular weight of 67 kDa. TCL presents a maximal activity at pH 8 and 50°C. After a 5 min treatment at 80°C, the enzyme maintained 50% of its activity, which is so far as is known. TCL previously characterized is found to be stable between pH 5 and 10 after 60 min incubation. TCL hydrolyses the long chains triacylglycerols more efficiently than the short ones. A specific activity of 1800 U/mg was measured on tributyrin or olive oil emulsion as substrate. This newly isolated lipase can be considered as a good candidature for industrial and biotechnological applications. Keywords : Trichosporon coremiiforme , lipase, purification, thermoactive African Journal of Biotechnology Vol. 12(28), pp. 4503-4511

Wicherhamomyces anomalus biofilm supported on wood husk for chromium wastewater treatment

A Wickeramomyces anomalus biofilm supported on wood husk was used to remediate water bodies contaminated with chromium (Cr), in batch and open systems. The favorable adhesion ability of the chromium-resistant yeast strain on the wood husk was predicted by XDLVO theory and confirmed by environmental scanning electronic microscopy. The chromium decontamination was then optimized in a batch mode using a central composite design (CCD). Analysis of variance (ANOVA) showed a high coefficient of determination (R2) value of 0.93-0.91 for Cr(VI) and total Cr removal, respectively, ensuring a satisfactory fitting of the second-order regression model to the experimental data. In batch system, the concentration of biomass exhibited the minimal effect on the process. An acidic pH of 3.72 and 5.48, an initial chromium concentration of 10 and 16.91 mg/L and a support dose of 6.95 and 8.20 g/L were optimal for Cr(VI) and total Cr removal, respectively. The breakthrough curves were determined in open system for different initial chromium concentrations. The study of glucose concentration effect on the yeast extracellular polymeric substances (EPS) production showed that a medium exempt of glucose allowed maximal EPS production and minimal chromium removal efficiency, while 20 g/L glucose concentration of presented the optimal condition for chromium removal.

Correlation between cell surface physicochemical properties of bacterial strains and their chromium removal potential

Abstract Physicochemical characterization of microbes has gained recently a great interest by scientific community. It is proved of extreme importance in several fields of science and technology applications such as bioremediation. In this work, we investigated the establishment of a possible correlation between chromium removal capacity of seven bacterial strains isolated from contaminated sites with industrial wastes including tanning processing and their cell surface physicochemical properties. Thus, hydrophobicity and donor/acceptor electrons character were obtained using contact angle measurements. Statistical analysis showed a high significant positive correlation between hexavalent chromium (Cr(VI)) removal by the strains and their acceptor electron character γ+(r = 0.90). While significant negative correlation between the Cr(VI) removal potential and the ΔGiwi value (r = −0.844) and also with their donor electron character γ− (r = −0.746) were observed. These results may contribute to determine a selectrion criteria of bacteria that can be operated in bioremediation applications.

Characterization in vitro studies and antibacterial properties on a sol-gel derived silver incorporated bioglass

The SiO2-CaO, SiO2-CaO-P2O5 and SiO2-CaO-P2O5-Ag2O glass systems were synthesized by the sol-gel technique and characterized with different techniques such as X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), and Environmental Scanning Electron Microscopy (ESEM). In vitro bioactivity tests were performed in Simulated Body Fluid (SBF). The antibacterial action of 65S5Ag (65%SiO2 + 24%CaO + 6%P2O5 + 5% Ag2O) is attributed exclusively to the leaching of Ag+ ions from the glass matrix. The activity of SiO2-CaO-P2O5-Ag2O was compared with that of its binary and ternary counterpart glass system. The concentrations of Ag-bioglass, in the range of 0.05 mg/mL of culture medium, were found to inhibit the growth of these bacteria.