Evaluation of rheological performance of a local modified bitumen by Styrene Butadiene Styrene polymer used in wearing course

In road construction, bitumen is the binder that gathered the different aggregates of road pavements. Bitumen, as a viscoelastic material, influences considerably the rheological behavior of bitumen concrete. The bitumen used in Algeria, showed its limits face to the traffic, which is increasing continuously. This research aims to valorize SBS polymer in wearing course by modifying a pure 35/50 bitumen. The present paper aims to study the polymer derived from styrene and butadiene (SBS) from the company Kraton Polymers International Ltd in the modification of a bitumen to improve its mechanical characteristics.To this end, the incorporation of SBS polymer was carried out according to two contents: 5.0 and 7.5% (by weight of asphalt), the objective being to evaluate the influence of this type of polymer on the rheological properties of the bitumen ordinary road including viscosity and modulus.The results reveal that the bitumen modified with 7.5% of SBS has better mechanical performance on the rigidity and the elasticity compared to the conventional bitumen. Recommendations have been made to implement a bitumen modification system to improve its quality and therefore the durability of bituminous pavements in the south of Algeria

Biochemical properties of a new thermo- and solvent-stable xylanase recovered using three phase partitioning from the extract of Bacillus oceanisediminis strain SJ3

The present study investigates the production and partial biochemical characterization of an extracellular thermostablexylanase from the Bacillus oceanisediminis strain SJ3 newly recovered from Algerian soil using three phasepartitioning (TPP). The maximum xylanase activity recorded after 2 days of incubation at 37 °C was 20.24 U/ml in thepresence of oat spelt xylan. The results indicated that the enzyme recovered in the middle phase of TPP system usingthe optimum parameters were determined as 50% ammonium sulfate saturation with 1.0:1.5 ratio of crude extract:t-butanol at pH and temperature of 8.0 and 10 °C, respectively. The xylanase was recovered with 3.48 purificationfold and 107% activity recovery. The enzyme was optimally active at pH 7.0 and was stable over a broad pH range of5.0–10. The optimum temperature for xylanase activity was 55 °C and the half-life time at this temperature was of 6 h.At this time point the enzyme retained 50% of its activity after incubation for 2 h at 95 °C. The crude enzyme resist tosodium dodecyl sulfate and β-mercaptoethanol, while all the tested ions do not affect the activity of the enzyme. Therecovered enzyme is, at least, stable in tested organic solvents except in propanol where a reduction of 46.5% wasobserved. Further, the stability of the xylanase was higher in hydrophobic solvents where a maximum stability wasobserved with cyclohexane. These properties make this enzyme to be highly thermostable and may be suggested asa potential candidate for application in some industrial processes. To the best of our knowledge, this is the first reportof xylanase activity and recoverey using three phase partitioning from B. oceanisediminis

Three phase partitioning, a scalable method for the purification and recovery of cucumisin, a milk-clotting enzyme, from the juice of Cucumis melo var . reticulatus

Cucumisin [EC 3.4.21.25] was first purified from Cucumis melo var. reticulatus juice by three-phase parti-tioning (TPP). Optimum purification parameters of the TPP system were determined as 60% ammoniumsulfate saturation with 1.0:1.25 ratio of crude extract: t-butanol at pH and temperature of 8.0 and 20◦C,respectively. Cucumisin was purified with 4.61 purification fold and 156% activity recovery. The molecularweight of the recovered cucumisin was determined as 68.4 kDa and its isoelectric point is 8.7. OptimumpH and temperature of cucumisin were pH 9.0 and 60–70◦C, respectively. The protease was very stable at20–70◦C and a pH range of 2.0–12.0. Km and Vmax constants were 2.24 ± 0.22 mgmL−1and 1048 ± 25 Mmin−1, respectively. The enzyme was stable against numerous metal ions and its activity was highlyenhanced by Ca2+, Mg2+, and Mn+2. Cucumisin activity was 2.35-folds increased in the presence of 5 mM ofCaCl2. It was inactivated by Co2+, Cd2+, Zn2+and Fe2+and dramatically by PMSF. Cucumisin milk-clottingactivity was highly stable when stored under freezing (−20◦C) compared at 4◦C and 25◦C. Finally, TPPrevealed to be a useful strategy to concentrate and purify cucumisin for its use as a milk-clotting enzymefor cheese-making

Partial Characterization of Xylanase Produced by Caldicoprobacter algeriensis, a New Thermophilic Anaerobic Bacterium Isolated from an Algerian Hot Spring

To date, xylanases have expanded their use in many processing industries, such as pulp, paper, food, and textile. This study aimed the production and partial characterization of a thermostable xylanase from a novel thermophilic anaerobic bacterium Caldicoprobacter algeriensis strain TH7C1T isolated from a northeast hot spring in Algeria. The obtained results showed that C. algeriensis xylanase seems not to be correlated with the biomass growth profile whereas the maximum enzyme production (140.0 U/ml) was recorded in stationary phase (18 h). The temperature and pH for optimal activities were 70 °C and 11.0, respectively. The enzyme was found to be stable at 50, 60, 70, and 80 °C, with a half-life of 10, 9, 8, and 4 h, respectively. Influence of metal ions on enzyme activity revealed that Ca+2 enhances greatly the relative activity to 151.3 %; whereas Hg2+ inhibited significantly the enzyme. At the best of our knowledge, this is the first report on the production of xylanase by the thermophilic bacterium C. algeriensis. This thermo- and alkaline-tolerant xylanase could be used in pulp bleaching process

Characterization of a purified thermostable xylanase from Caldicoprobacter algeriensis sp. nov. strain TH7C1T

The present study investigates the purification and biochemical characterization of an extracellular thermostable xylanase (called XYN35) from Caldicoprobacter algeriensis sp. nov., strain TH7C1T, a thermophilic, anaerobic strain isolated from the hydrothermal hot spring of Guelma (Algeria). The maximum xylanase activity recorded after 24 h of incubation at 70 °C and in an optimized medium containing 10 g/L mix birchwood- and oats spelt-xylan was 250 U/mL. The pure protein was obtained after heat treatment (1 h at 70 °C), followed by sequential column chromatographies on Sephacryl S-200 gel filtration and Mono-S Sepharose anion-exchange. Matrix assisted laser desorption ionization–time of flight mass spectrometry (MALDI–TOF/MS) analysis indicated that the purified enzyme is a monomer with a molecular mass of 35,075.10 Da. The results from amino-acid sequence analysis revealed high homology between the 21 NH2-terminal residues of XYN35 and those of bacterial xylanases. The enzyme showed optimum activity at pH 11 and 70 °C. While XYN35 was activated by Ca2+, Mn2+, and Mg2+, it was completely inhibited by Hg2+ and Cd2+. The xylanase showed higher specific activity on soluble oat-spelt xylan, followed by beechwood xylan. This enzyme was also noted to obey the Michaelis–Menten kinetics, with Km and kcat values on oat-spelt xylan being 1.33 mg/mL and 400 min−1, respectively. Thin-layer chromatography soluble oat-spelt xylan (TLC) analysis showed that the final hydrolyzed products of the enzyme from birchwood xylan were xylose, xylobiose, and xylotriose. Taken together, the results indicated that the XYN35 enzyme has a number of attractive biochemical properties that make it a potential promising candidate for future application in the pulp bleaching industry

Partial Characterization of Xylanase Produced by Caldicoprobacter algeriensis, a New Thermophilic Anaerobic Bacterium Isolated from an Algerian Hot Spring

To date, xylanases have expanded their use in many processing industries, such as pulp, paper, food, and textile. This study aimed the production and partial characterization of a thermostable xylanase from a novel thermophilic anaerobic bacterium Caldicoprobacter algeriensis strain TH7C1T isolated from a northeast hot spring in Algeria. The obtained results showed that C. algeriensis xylanase seems not to be correlated with the biomass growth profile whereas the maximum enzyme production (140.0 U/ml) was recorded in stationary phase (18 h). The temperature and pH for optimal activities were 70 °C and 11.0, respectively. The enzyme was found to be stable at 50, 60, 70, and 80 °C, with a half-life of 10, 9, 8, and 4 h, respectively. Influence of metal ions on enzyme activity revealed that Ca+2 enhances greatly the relative activity to 151.3 %; whereas Hg2+ inhibited significantly the enzyme. At the best of our knowledge, this is the first report on the production of xylanase by the thermophilic bacterium C. algeriensis. This thermo- and alkaline-tolerant xylanase could be used in pulp bleaching process