Production and characterization of biosurfactant by free and immobilized cells from Ochrobactrum intermedium isolated from the soil of southern Algeria with a view to environmental application

In this paper, biosurfactant production by free and immobilized cells of Ochrobactrum intermedium has been studied. This bacterium strain was isolated from an Algerian crude oil-contaminated soil; hexadecane was used for the production as the sole carbon and energy source. The process was monitored by measuring the surface tension and emulsification index E24 for one week at 37 °C and neutral pH. For the production by immobilized cells, the concentrations of sodium alginate, calcium chloride and biomass were optimized. Results showed that O. intermedium entrapped in calcium alginate beads is able to preserve its viability and produce biosurfactants but with an effect on the production kinetics due to diffusional limitations of the alginate beads with greater stability with up to 75%. The product biosurfactant reduced the surface tension below 33 and emulsification index were 68%–93% after 48 and 72 h with free and immobilized cells, respectively. Also, the product belongs to the family of glycolipids and showed stability in a wide range of pH (2–12), temperature (25–120 °C), and to high salinity. Both products by strain O. intermedium, based on spectral features, have a chemical structure identical to that of glycolipids. The production yield of biosurfactant versus concentration of the hexadecane is 1292 g/g. Second, the surfactants are able to promote the solubility of polycyclic aromatic hydrocarbons (PAHs). Results show that the use of biosurfactant, produced by the isolated bacterial strain O. intermedium, obtained a better solubility of naphthalene and phenanthrene

Catalase Activity in Brown Mussels (Perna perna) under Acute Cadmium, Lead, and Copper Exposure and Depuration Tests

Brown mussels (Perna perna) were exposed to cadmium (Cd), lead (Pb), and copper (Cu) concentrations under acute exposure and exposure-depuration tests for the estimation of biochemical biomarker catalase (CAT). The acute tests showed accumulated Cd, Pb, and Cu in Perna perna correlated linearly with the exposure concentrations (R2=0.794, R2=0.891, and R2=0.985 for Cd, Pb, and Cu, resp.). The results of CAT increased significantly in tissues of treatment mussels after 72 h exposure when compared to control. The values of total protein were disturbed in exposed groups when compared with control. These results suggest that metabolites and catalase activity were affected by heavy metal exposures. Analysis using the Spearman rank correlation coefficient showed that the CAT activity appeared to have a significant positive correlativity (Rs=0.921, Rs=0.949, and Rs=0.949 for Cd, Pb, and Cu, resp.) with the accumulated Cd, Pb, and Cu concentrations, respectively. The result of exposure-depuration tests showed that there is a general tendency for CAT to decrease in depuration phase, suggesting that the induction of catalase is metal and/or mixture of metals dependent

Effect of keratinacious substrates on the keratinase KERUS of <i>Br. brevis</i> strain US575 after 28 h of incubation.

<p>Values represent the means of three replicates, and ± standard errors are reported.</p

Flow sheet for KERUS purification.

a<p>The experiments were conducted three times and ± standard errors are reported.</p>b<p>One keratin unit is defined as an increase of 0.1 absorbance at 440 nm per minute, using keratin azure as a substrate under the experimental conditions used.</p>c<p>Amounts of protein were estimated by the method of Bradford <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0076722#pone.0076722-Sambrook1" target="_blank">[21]</a>.</p

Effects of pH and temperature on the activity and stability of KERUS, NUE, and KOROPON.

<p>Effects of pH on the activity (A) and stability (B) of KERUS, NUE, and KOROPON. The activity of the enzyme at optimum pH was taken as 100%. Buffer solutions used for pH activity and stability are presented in Section 2. Effects on the thermoactivity (C) and the thermostability of KERUS (D), NUE (E), and KOROPON (F). The enzyme was pre-incubated in the absence or presence of CaCl₂ at various temperatures ranging from 30°C to 60°C. Residual protease activity was determined from 0 h to 72 h at 6 h intervals. The activity of the non-heated enzyme was taken as 100%. (G) Hydrolysis curves of chicken feather-meal proteins treated with various purified enzymes. The purified proteases used were: KERUS (♦), NUE (▪), and KOROPON (Δ). Each point represents the mean (n = 3) ± standard deviation.</p

Kinetic parameters of purified keratinolytic proteases: KERUS, NUE, and KOROPON for the hydrolysis of protein, ester, and synthetic peptide substrates.

<p>Values represent the means of three replicates, and ± standard errors are reported.</p