Search

A novel extracellular alkaline protease, called SAPHM, from Bacillus licheniformis strain K7A was purified by four steps procedure involving heat treatment (30 min at 70 °C) followed by ammonium sulfate precipitation (40–70%)-dialysis, UNO Q-12 FPLC, and ZORBAX PSM 300 HPLC, and submitted to biochemical characterization assays. The purified enzyme is a monomer of molecular mass of 30,325.12 Da. It was completely inhibited by phenylmethanesulfonyl fluoride (PMSF)and diiodopropyl fluorophosphates (DFP), which strongly suggested its belonging to the serine protease family. Its sequence of the 26 NH2-terminal residues showed high homology with those of Bacillus proteases. The purified enzyme was optimally active at pH 10 and temperature 70 °C. Its catalytic efficiency was higher than those of Alcalase and Thermolysin. SAPHM exhibited excellent stability to detergents and wash performance analysis revealed that it could remove blood-stains effectively. Data suggest also that SAPHM may be considered as potential candidate for future applications in non-aqueous peptide biocatalysis because it possesses an elevated organic solvent resistance. The sapHM gene encoding SAPHM was cloned, sequenced, and expressed in Escherichia coli strain BL21(DE3)pLysS. The biochemical properties of the extracellular purified recombinant enzyme (rSAPHM) were similar to those of native one. The deduced amino acid sequence showed strong homology with other Bacillus proteases. The highest sequence identity value (97%) was obtained with APRMP1 protease from Bacillus licheniformis strain MP1, with only 9 aa of difference.

The capacities of a biosurfactant producing and polycyclic aromatic hydrocarbon (PAH) utilizing bacterium, namely, strain 1C, isolated from an Algerian contaminated soil, were investigated. Strain 1C belonged to the Paenibacillus genus and was closely related to the specie Paenibacillus popilliae, with 16S rRNA gene sequence similarity of 98.4%. It was able to produce biosurfactant using olive oil as substrate. The biosurfactant production was shown by surface tension (32.6mN/m) after 24h of incubation at 45°C and 150rpm. The biosurfactant(s) retained its properties during exposure to elevated temperatures (70°C), relatively high salinity (20% NaCl), and a wide range of pH values (2–10). The infrared spectroscopy (FTIR) revealed that its chemical structure belonged to lipopeptide class. The critical micelle concentration (CMC) of this biosurfactant was about 0.5g/l with 29.4mN/m. In addition, the surface active compound(s) produced by strain 1C enhanced PAH solubility and showed a significant antimicrobial activity against pathogens. In addition to its biosurfactant production, strain 1C was shown to be able to utilize PAHs as the sole carbon and energy sources. Strain 1C as hydrocarbonoclastic bacteria and its interesting surface active agent may be used for cleaning the environments polluted with polyaromatic hydrocarbons.

The aim of this work was to evaluate the effect of different surfactant type on biodegradation of low molecular weight polycyclic aromatic hydrocarbons (PAHs) (naphthalene and anthracene) in aqueous media by bacterial strain isolated from crude oil-contaminated soil in southern of Algeria. The biodegradative ability of the strain tested was determined by measuring OD 600 and the residual PAH concentration by UV–Vis and GC. The results indicated that 1C strain could degrade both naphthalene and anthracene without addition of surfactants; the degradation rate of PAHs was decreased when surfactants were added. The higher bacterial growth observed in the presence of Tween 80 could be due to the fact that this surfactant can be used as an additional carbon source by 1C strain.

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.

Biosurfactant-producing bacteria were isolated from a crude-oil-contaminated soil in Hassi Messaoud (southern Algeria). Isolates were screened for biosurfactant/bioemulsifier production on different carbon sources (glucose, olive oil, and hexadecane) on the basis of their ability to reduce the surface tension. The highest number of positive isolates (19) was obtained on a medium containing hexadecane as carbon source. Culture broth from all 19 isolates emulsified motor oil and 14 exhibited high emulsion-stabilizing capacity, maintaining 50% of the original emulsion volume for 48 h. The cell-free culture broth of the two best-performing isolates (identified as Ochrobactrum sp. 1C and Brevibacterium sp. 7G) reduced the surface tension below 31.5 mN m −1 . Biosurfactant produced by strains 1C and 7G exhibited tolerance, with slight variations for heat, pH, and salinity, and based on spectral features, they were glycolipids. Furthermore, they exhibited antimicrobial activities against Pseudomonas aeruginosa and Staphylococcus aureus .

A biosurfactant-producing bacterium (Staphylococcus sp. strain 1E) was isolated from an Algerian crude oil contaminated soil. Biosurfactant production was tested with different carbon sources using the surface tension measurement and the oil displacement test. Olive oil produced the highest reduction in surface tension (25.9 dynes cm(-1)). Crude oil presented the best substrate for 1E biosurfactant emulsification activity. The biosurfactant produced by strain 1E reduced the growth medium surface tension below 30 dynes cm(-1). This reduction was also obtained in cell-free filtrates. Biosurfactant produced by strain 1E showed stability in a wide range of pH (from 2 to 12), temperature (from 4 to 55 °C) and salinity (from 0 to 300 g l(-1)) variations. The biosurfactant produced by strain 1E belonged to lipopeptide group and also constituted an antibacterial activity againt the pathogenic bacteria such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis. Phenanthrene solubility in water was enhanced by biosurfactant addition. Our results suggest that the 1E biosurfactant has interesting properties for its application in bioremediation of hydrocarbons contaminated sites.