Higher SDS Concentrations Research Articles

AMWEst, a new thermostable and detergent-tolerant esterase retrieved from the Albian aquifer

A fosmid library was constructed with the metagenomic DNA from the high-temperature sediment-rich water of the Albian aquifer (Algeria). Functional screening of this library was subsequently done looking for genes encoding lipolytic enzymes. We identified a novel gene named AMWEst (1209 base pairs) encoding a protein of 402 amino acids with a predicted molecular weight of 43.44 kDa and conferring esterase activity. AMWEst was successfully overexpressed in the yeast mesophilic host Saccharomyces cerevisiae, and the expression system used proved to be efficient and produced sufficient activity for its biochemical characterization. Multiple sequence alignment indicated that AMWEst contained a conserved pentapeptide motif (Gly120-His121-Ser122-Gln123-Gly124). The optimum pH and temperature of the recombinant esterase AMWEst were 8 and 80 °C, respectively. Additionally, AMWEst showed higher activity towards short carbon substrates and showed maximum activity for p-nitrophenyl hexanoate (C6). Notably, AMWEst has a remarkable thermostability, and the enzyme retains almost maximum activity at 70 °C after incubation for 1 h. Moreover, enzyme activity was enhanced by high concentrations of SDS and Triton X-100 detergents.Key points• A novel thermostable esterase has been retrieved through functional metagenomics• The esterase is detergent-tolerant, which is attractive for some applications• The esterase can be expressed in a yeast mesophilic host to enhance its yield

Enhanced performance of algal-bacterial aerobic granular sludge in comparison to bacterial aerobic granular sludge for treating surfactant-containing wastewater

Increasing amounts of surfactants are used and emitted into the environment due to the COVID-19 pandemic, posing potential threats to ecological health. Algal-bacterial aerobic granular sludge (A-BAGS), with the advantages of compact structure, high-efficient nutrient uptake, and high tolerance to harsh conditions, was attempted in this study to treat surfactant-containing wastewater at relatively high concentrations. The treatment performance was also compared to bacterial AGS (BAGS). Results showed that A-BAGS is preferable for treating wastewater containing a high SDS concentration (30 mg/L), achieving nutrient removal efficiency of 86.3 % for organic carbon, 60.5 % for total nitrogen, and 58.7 % for total phosphorus within a short duration, compared to 70.1 %, 52.8 % and 42.3 % in BAGS reactor. Besides, the removal rate of ammonia nitrogen by A-BAGS was much faster than that of BAGS. The above results confirmed that A-BAGS is a promising technology for treating surfactant-containing wastewater with high nutrient removal efficiency being maintained.

Proteomics-Based Analysis and Diagnosis of Formalin-Fixed Paraffin-Embedded Amyloidosis Samples.

Amyloidosis is a group of rare pathologies characterized by abnormal folding and deposition of susceptible proteins in tissues and organs. Diagnosis of amyloidosis often relies on immunohistochemistry of formalin-fixed paraffin-embedded (FFPE) patient samples; however, dependency on antibodies for protein staining is one of the major pitfalls of this approach, especially for the detection of rare amyloidosis types. In recent years, mass spectrometry-based proteomics has emerged as a promising alternative for adequate detection and amyloid typing, despite the fact that preparing FFPE samples for proteomics remains a challenging task. Major hurdles are removal of formalin-induced protein cross-links and water-insoluble paraffin prior to mass spectrometry analysis. With the recent development of the suspension trapping protocol, enabling the use of high concentrations of SDS, these obstacles can be overcome. In this chapter, we describe the implementation of suspension trapping for FFPE sample processing and its application to analyze human amyloidosis samples, comparing a standard procedure with probe sonication with a more advanced workflow based on ultrasonication.

Influence of seawater on interfacial Properties, foam performance and aggregation behaviour of Fluorocarbon/Hydrocarbon surfactant mixtures

• Adding seawater lowers surface activity and adsorption kinetics of SDS/FS-50 mixtures. • Ca 2+ , Mg 2+ and K + have greater adverse effects on foaming ability than Na + in seawater. • Dual effects of salts on foam stability are observed at different surfactant concentrations. • Spontaneous transition from vesicle to micelle is observed after mixing SDS and FS-50. In this work, the influence of seawater on interfacial properties, foam performance and aggregation behaviour of fluorocarbon/hydrocarbon surfactant mixtures was systematically investigated. Two model foaming solutions containing different surfactants (nonionic APG, anionic SDS, and amphoteric FS-50) were prepared by deionized water and seawater, respectively. Multi-scale methods including surface tension measurements, foam ageing tests and cryogenic-transmission electron microscopy (cryo-TEM) were used. The results show that the addition of seawater reduces the equilibrium surface tension, foaming ability and adsorption kinetics of SDS/FS-50 mixtures. Among the counterions in seawater, Na + can lower the surface tension and slightly improve the foaming ability, while the presence of Ca 2+ , Mg 2+ and K + allows the formation of surfactant precipitate to weaken the foaming ability of the solution. It turns out that seawater has dual effects on foam stability and the defoaming/stabilizing effects of seawater are related to ionic surfactant concentrations. Besides, it is confirmed that the spontaneous transition from single-lamellar vesicle to rod-like micelle occurs after mixing FS-50 with SDS in the deionized water, while only multi-lamellar vesicles and surfactant crystals can be observed in the seawater. The aggregation behaviour strongly affects solution viscosity as well as foam performance. At high SDS concentrations, the surfactant precipitate/aggregate can inhibit the liquid drainage process and improve foam stability.

Quality Comparison of Decellularized Omentum Prepared by Different Protocols for Tissue Engineering Applications.

Objective Decellularized greater omentum (GOM) is a good extracellular matrix (ECM) source for regenerative medicine applications. The aim of the current study was to compare the efficiency of three protocols for sheep GOM decellularization based on sufficient DNA depletion and ECM content retention for tissue engineering application. Materials and Methods In this experimental study, in the first protocol, low concentrations of sodium dodecyl sulfate (SDS 1%), hexane, acetone, ethylenediaminetetraacetic acid (EDTA), and ethanol were used. In the second one, a high concentration of SDS (4%) and ethanol, and in the last one sodium lauryl ether sulfate (SLES 1%) were used to decellularize the GOM. To evaluate the quality of scaffold prepared with various protocols, histochemical staining, DNA, and glycosaminoglycan (GAGs) quantification, scanning electron microscopy (SEM), Raman confocal microscopy, Bradford assay, and ELISA were performed. Results A comparison of DNA content showed that SDS-based protocols omitted DNA more efficiently than the SLES- based protocol. Histochemical staining showed that all protocols preserved the neutral carbohydrates, collagen, and elastic fibers; however, the SLES-based protocol removed the lipid droplets better than the SDS-based protocols. Although SEM images showed that all protocols preserved the ECM architecture, Raman microscopy, GAGs quantification, total protein, and vascular endothelial growth factor (VEGF) assessments revealed that SDS 1% preserved ECM more efficiently than the others. ConclusionThe SDS 1% can be considered a superior protocol for decellularizing GOM in tissue engineering applications.

Understanding the Photochemical Properties of Polythiophene Polyelectrolyte Soft Aggregates with Sodium Dodecyl Sulfate for Antimicrobial Activity.

The threat of antibiotic-resistant bacteria is an ever-increasing problem in public health. In this report, we examine the photochemical properties with a proof-of-principle biocidal assay for a novel series of regio-regular imidazolium derivative poly-(3-hexylthiophene)/sodium dodecyl sulfate (P3HT-Im/SDS) materials from ultrafast sub-ps dynamics to μs generation of reactive oxygen species (ROS) and 30 min biocidal reactivity with Escherichia coli (E. coli). This broad series encompassing pure P3HT-Im to cationic, neutral, and anionic P3HT-Im/SDS materials are all interrogated by a variety of techniques to characterize the physical material structure, electronic structure, and antimicrobial activity. Our results show that SDS complexation with P3HT-Im results in aggregate materials with reduced ROS generation and light-induced anti-microbial activity. However, our characterization reveals that the presence of non-aggregated or lightly SDS-covered polymer segments is still capable of ROS generation. Full encapsulation of the P3HT-Im polymer completely deactivates the light killing pathway. High SDS concentrations, near and above critical micelle concentration, further deactivate all anti-microbial activity (light and dark) even though the P3HT-Im regains its electronic properties to generate ROS.

SDS triggered transformation of highly hydrophobic Pluronics® nanoaggregate into polymer-rich and surfactant-rich mixed micelles

This work reveals the role of sodium dodecylsulphate (SDS, anionic surfactant) in altering the phase behaviour and aggregation characteristics of five very hydrophobic polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) triblock copolymers containing 10% PEO but with different molecular weight. These copolymers are molecularly dissolved in water at ≤15–20 °C and exist as unstable vesicular structure at temperature close to cloud point (CP) >20 °C. SDS enhanced the aqueous solubility and CP of copolymers in water; progressive addition of SDS triggered the transformation of unstable vesicles into spherical mixed micelles. A correlation between the molecular orbital energy levels of Pluronics® and SDS is well comprehended using computational simulation approach where the perception of SDS stabilized Pluronics® micelles is predicted and correlated with optimized parameters. The size/ shape of copolymer-surfactant mixed nanoscale aggregates was evaluated using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The scattering studies showed the presence of spherical mixed aggregates, whose size expanded with increase in hydrophobicity of Pluronics®. In high SDS concentration regime, SANS analysis uncovered the diminishing size of vesicles into spherical mixed aggregates. The nanoscale Pluronics®-SDS mixed micelles remained stable in water where this investigation discloses the conceivable ability of orange-OT solubilization using UV–vis spectroscopy.

Application of enhanced electrokinetic remediation by coupling surfactants for kerosene-contaminated soils: Effect of ionic and nonionic surfactants

Electrokinetic (EK) by coupling surfactants is an enhanced promising remediation technology to eliminate hydrophobic organic contaminants (HOCs) from low-permeable soils. It is also applied to remediate kerosene-contaminated soils using anionic (SDS) and non-ionic (Tween 80) surfactants at different concentrations. There was negligible removal efficiency (40%) of kerosene during traditional EK without any enhancement technique. In the present study, the application of 0.005M and 0.01M SDS in EK-SDS-1 and EK-SDS-2 improved the removal efficiency to 50 and 55%, respectively towards the anode. Furthermore, the use of Tween 80 in EK-Tw80-1 and EK-Tw80-2 at 0.1 and 1% concentrations was able to raise kerosene removal gradually from 45% to 52% towards the cathode. These findings suggest that higher concentrations of SDS and Tween 80 contribute to the more effective elimination of kerosene. Thus, in EK-SDS-Tw80-V1.5 and EK-SDS-Tw80-V2, SDS and Tween 80 were used simultaneously at higher concentrations, which led to 63 and 67% kerosene removal, respectively. Considering the maximum removal in EK-SDS-Tw80-V2, the energy consumption in EK-SDS-Tw80-V2 was 178 KWh/m3 due to the higher voltage gradient; whereas without increased voltage in EK-SDS-Tw80-V1.5, this amount was decreased to 84 KWh/m3. It is to be mentioned that the electro-osmotic flow (EOF) played a significant role in minimizing kerosene concentration during the EK process, particularly when combined with surfactants.

Immobilisation of Candida rugosa lipase on a highly hydrophobic support: A stable immobilised lipase suitable for non-aqueous synthesis

Lipase from Candida rugosa (CrL) was immobilised on highly hydrophobic, octadecyl methacrylate resin (Lifetech™ ECR8806M) via interfacial adsorption. The aim was to produce a stable biocatalyst suitable for use in a range of lipid-modifying reactions. Immobilisation was carried out in 10 mM phosphate buffer (pH 6.0) over 24 h at 21 °C. High protein binding of 58.7 ± 4.9 mg/g dry support accounted for ∼53 % of the applied protein. The activity recovery against tributyrin was 74.0 ± 1.1 %. The specific activity of immobilised CrL against tributyrin was considerably higher than that of Novozym® 435, at 1.79 ± 0.05 and 1.08 ± 0.04 U/mg bound protein, respectively. Incubation with high concentrations (10 % w/v) of both Triton X-100 and SDS resulted in only a small reduction in immobilised lipase activity. Solvent-free synthesis of glycerides by the FFA-saturated immobilised CrL was successful over 6 reaction cycles, with no apparent loss of activity.

The effect of sodium dodecyl sulfate concentration on the aggregation behavior of Aβ (1–42) peptide: Molecular dynamics simulation approach

Beta-amyloid (1–42) is the most effective peptide in the formation of inter-synaptic aggregate structures. These complex structures lead to disruption of the neural network and the development of Alzheimer's disease. Here, the effect of sodium dodecyl sulfate concentration on Aβ (1–42) structure has been investigated by molecular dynamics simulation. The calculations were performed at concentrations lower than and above than the critical micelle concentration. Two single and six peptide systems were used for each concentration. Calculations were also repeated in the absence of sodium dodecyl sulfate. The secondary structure of Aβ (1–42) was calculated in the designed systems. The results showed that the dominant secondary structure in monomeric systems is the helix. Also, the calculation of the Aβ (1–42) secondary structure shows that the behavior of the peptides is heterogeneous in the hexamer systems. The length of the Lys28-Ala42 salt bridge was calculated in different systems as criterion of peptide toxicity. The results showed that the length of the salt bridge is increased at both SDS concentrations. The radial distribution function was used to investigate the interaction of the peptide with SDS. The result revealed that the distribution of SDS molecules around the amyloid-β peptide residues is great in the presence of low SDS concentration. Also, the interaction intensity between the peptide and SDS at low SDS concentrations is higher than that at high SDS concentration.

Tunable stability of oil-containing foam systems with different concentrations of SDS and hydrophobic silica nanoparticles

Experiment and molecular dynamics simulation were carried out to study the tunable stability of oil-containing SDS-stabilized Nitrogen-in-water foam. The experimental results show that the foam stability could be tuned by the concentrations of SDS and modified SiO2 nanoparticles. In the foam systems with a low SDS concentration (0.2 wt.%), the foams show poor stability and the foam stability was almost not affected by the addition of modified SiO2 nanoparticles. The foam stability was greatly improved at moderate SDS concentration (0.5 wt.%), it enhanced first and then weakened with the increase of modified SiO2 concentration, and the half-life time achieved a maximum value of 1292 s at 0.05 wt.% modified SiO2. However, at high SDS concentration (0.8 wt.%), the foam stability was pretty good except for when the modified SiO2 concentration is too high (>0.2 wt.%). The microscopic mechanism was obtained by investigating the structural and dynamic properties of the foam film. The simulation work showed consistent results of foam stability with the experimental results. Moreover, it also revealed that the concentration and configuration of SDS will affect its interaction with SiO2 and oil molecule, which is critical to foam stability.

Bacterial amphiphiles as amyloid inducers: Effect of Rhamnolipid and Lipopolysaccharide on FapC fibrillation

Pseudomonas species export the amyloid-forming protein FapC to strengthen bacterial biofilm. P. species also produce the biosurfactant rhamnolipid (Rhl) and its outer membrane contains lipopolysaccharide (LPS). Given the possible contacts between FapC, Rhl and LPS, we here investigate how Rhl and LPS affect FapC fibrillation compared with SDS, known to promote fibrillation of proteins at sub-micellar concentrations. Micelles of all three surfactants help FapC bypass the nucleation lag phase, leading to rapid fibrillation, which persists even at high concentrations of micelles and incorporates almost all available FapC monomers. Fibrils formed at high micellar concentrations of Rhl and SDS seed fibrillation at low surfactant concentrations while retaining the original fibril structure. FapC interacts strongly with SDS to form a dense network of narrow fibrils. Small angle X-ray scattering (SAXS) analyses reveal that surfactants reduce the population of intermediates in the fibrillation process and detect a fast aggregation step over the first 2–4 h which precedes the main fibrillation monitored by Thioflavin T. An additional SAXS-detected rearrangement of early aggregates occurs after 4–10 h. At high Rhl concentrations, the micelles are decorated with protein fibrils. SDS induces FapC fibrillation so efficiently that epigallocatechin-3-gallate (EGCG) is unable to inhibit this process. However, EGCG stimulates FapC oligomer formation and inhibits fibrillation both on its own and in the presence of Rhl and LPS. This oligomer could be modelled as a compact core with a flexible shell. This suggests that EGCG can override the natural amyloid-stimulatory properties of these biosurfactants and thus target biofilm.

Improvement of the electro-bioremediation process of a non-polar herbicide-polluted soil by means of surfactant addition

Oxyfluorfen is a non-polar herbicide that may cause severe soil pollution. The present work studies the possible improvement due to surfactant addition in the efficiency of electro-bioremediation of a clay soil polluted which such a non-polar, low-mobility pollutant. Two-week-long batch electro-bioremediation experiments were performed in a bench-scale device. Oxyfluorfen-polluted soil (20 mg kg−1) was inoculated with an acclimated microbial culture, and several experiments were performed using different surfactant concentrations in the electrode wells (0.0, 2.5, 5.0, 10.0 and 20.0 g L−1 of SDS, sodium dodecyl sulphate). Experiments were performed under 1.0 V cm−1 and electrode polarity reversal. It was observed that the electro-osmotic flow (EOF) increased with SDS concentration and that SDS was successfully distributed across the soil, probably improving the oxyfluorfen mobility. Additionally, microbiological activity was fully maintained during the experiments. Electro-bioremediation without SDS removed 14% of the oxyfluorfen, while under 2.5 g L−1 SDS, the efficiency increased to 22% because of an expected improvement in the contact between the different species in the soil. However, higher SDS concentrations (between 10.0 and 20.0 g L−1) caused a decrease in the oxyfluorfen removal efficiency, as SDS is an easily biodegradable compound and was preferably used as substrate by the microbial culture instead of oxyfluorfen. Additionally, the use of high concentrations of SDS was clearly inefficient, as high amounts of the surfactant were lost through the EOF, and even low amounts of oxyfluorfen were removed to the electrode wells, which means that ex situ treatment of the polluted water would be needed.

Synthesis of cationic alkylated chitosans and an investigation of their rheological properties and interaction with anionic surfactant

Two methods were used to alkylate high MW chitosan with glycidyltrimethylammonium chloride (GTAC) in order to produce chitosan derivatives that are water-soluble throughout the pH range. In addition, a novel chitosan derivative was created by alkylating one of the products with the GTAC analogue Quab 342 containing C12 alkyl chains. The phase behaviour and rheological characteristics of the chitosan derivatives were studied in the presence of anionic surfactant. The derivatives were found to form soluble complexes at low and high SDS concentrations and that the Quab 342 derivative was able to form gels.

Gas–liquid flow of sub-millimeter bubbles at low void fractions: Experimental study of bubble size distribution and void fraction

This work studies gas–liquid flow of small bubbles (<1 mm) at low void fractions (<10−1) that is encountered in human bloodstream during Decompression Sickness and is also relevant to two-phase applications such as flow boiling in macro-channels. Two fundamental parameters are experimentally investigated: Bubble Size Distribution (BSD) and void fraction. Experiments are conducted in co-current upward bubbly flow. Water and blood simulant are used as test liquids, while bubble size is controlled using prescribed surfactant (SDS) concentrations. BSDs are determined employing digital image analysis of bubbly flow images captured at three radial positions across the flow cross-section. Volumetric and cross-sectional area averaged void fraction is measured at three axial locations along the flow by Differential Pressure (ΔP) and Electrical Resistance Tomography (ERT), respectively. BSDs are well-fitted by the log-normal distribution. ERT and ΔP measurements are in fair agreement, with void fraction being practically equal along the flow. The influence of gas/liquid phase velocities and surfactant concentration on the measured void fraction and BSDs’ average value and width is discussed in detail. Interestingly, high SDS concentration in blood simulant results in the formation of bubble clusters, whose role on the examined parameters is investigated.

CHARACTERIZATION OF CELLULASE PREPARATION OF BACILLUS SP.G4 ISOLATED FROM THE TERMITES GUT

The Bacillus sp. strain G4 isolated from termites gut can produce cellulase with high activity in rice bran medium after 72 h of incubation at 37 °C. The crude enzymewas collected by centrifugation at 6,000 rpmfor 15 minutes. The precipitation of cellulasewith ammonium sulfate 60 – 90 % saturation and acetone at the concentration 60 % – 90 % was studied. Results showed that ammonium sulfate 90 % saturation gave cellulase with highest purification factor 8.87 but the yield was only 59.9 %, whereas acetone at 90 % concentration gave highest yield 83.57 % with purification factor 4.38. CMCase activity of cellulasepreparation obtained by acetone precipitation at 90 % was optimum at pH 7 and 60 °C. Furthermore, CMCase was stable at pH 6.0 - 7.0 and at temperature lower than 50 °C. The CMCase was activated by ion Ca2+ but inhibited by Co2+, Zn2+, Cu2+, Fe2+, and was not affected by Mg2+ and Ba2+. The CMCase was inhibited by high concentration of SDS while EDTA and Tween 80 played activated role.

Formulation and Composition Effects in Phase Transitions of Emulsions Costabilized by Cellulose Nanofibrils and an Ionic Surfactant.

Cellulose nanofibrils (CNF) offer great prospects as a natural stabilizer of colloidal dispersions and complex fluids for application in food, pharma, and cosmetics. In this study, an ionic surfactant (sodium dodecyl sulfate, SDS) was used as emulsifier of oil-in-water and water-in-oil emulsions that were further costabilized by addition of CNF. The adsorption properties of SDS in both, CNF dispersions and emulsions, as well as the influence of composition (CNF and SDS concentration) and formulation (ionic strength, oil, and CNF types) on the phase behavior were elucidated and described in the framework of Windsor systems. At low salinity, the phase transition of emulsions containing CNF and SDS at low concentrations was controlled by molecular transfer in the oil-in-water system. Irregular droplets and "bi-continuous" morphologies were observed at medium and high salinity for systems containing high CNF and SDS concentrations. Water-in-oil emulsions were only possible at high salinity and SDS concentrations in the presence of small amounts of CNF. The results revealed some subtle differences in CNF interfacial activity, depending on the method used for their isolation via fiber deconstruction, either from microfluidization or aqueous counter collision. Overall, we propose that the control of emulsion morphology and stability by addition of CNF opens the possibility of developing environmentally friendly complex systems that display high stability and respond to ionic strength following the expectations of classical emulsion systems.

Coarse-grained modeling of the oil–water–surfactant interface through the local definition of the pressure tensor and interfacial tension

Mesoscopic simulations are conducted to study the dodecane–water interface in the presence of an increasing quantity of sodium dodecyl sulfate. Dissipative Particle Dynamics and Molecular Dynamics using the MARTINI force field were used to model the dodecane–SDS–water system through a coarse-grained description. We have used a full description of the water and oil phases to study the structure of the interface. We have calculated the interfacial tension at the dodecane–water interface and established the accuracy of the calculation by checking the mechanical equilibrium and the stability of the interface. The local components of the pressure tensor are calculated along the interface by comparing both atomistic and molecular definitions. Both coarse-grained models give a good description of the system structure, with SDS molecules located at the interfaces. Increasing the number of SDS results in a drastic decrease in the interfacial tension and a saturation of the interface with SDS molecules. Higher SDS concentrations do not affect the interface structure, as it is saturated. The limiting value of the interfacial tension is very low and corresponds to the formation of a SDS film between the dodecane and water phases. Both coarse-grained potentials studied in this work are suitable for the study of surfactants in equilibrium with an oil–water interface. They provide a good description of the dodecane–SDS–water system and quantitative results for interfacial tension and interfacial concentrations. © 2017, Springer-Verlag Berlin Heidelberg.

Structure and properties of aqueous dispersions of sodium dodecyl sulfate with carbon nanotubes

The dispersing action of the surfactant (sodium dodecyl sulfate, SDS) on the carbon nanotubes (CNT) in aqueous medium has been studied. Electron microscopy, molecular docking, NMR and IR spectroscopies were applied to determine the physical-chemical properties of CNT dispersions in SDS—water solutions. It was established that micellar adsorption of the surfactant on the surface of carbon material and solubilization of SDS in aqueous medium contribute to improving CNT dispersing in water solutions. It was shown that the non-polar hydrocarbon radicals of a single surfactant molecule form the highest possible number of contacts with the graphene surface. Upon increase of the SDS in solution these radicals form micelles connected with the surface of the nanotubes. At the sufficiently high SDS concentration the nanotube surface becomes covered with an adsorbed layer of surfactant micelles. Water molecules and sodium cations are concentrated in spaces between micelles. The observed pattern of micellar adsorption is somewhat similar to a loose bilayer of surfactant molecules.

CHARACTERIZATION OF TYROSINASE ENZYME FROM NATIVE BACILLUS MEGATERIUM SP. STRAIN M36

Tyrosinase is a type 3 copper-containing enzyme that catalyzes the conversion of l-tyrosine to L-DOPA and finally to melanin. In this study tyrosinase enzyme from native Bacillus megaterium sp. strain M36, was produces, characterized and used to produce L-DOPA. The M36 tyrosinase enzyme showed optimum monophenolase and diphenolase activity at pH 7.5 and conserved its maximum activity over than 95 % at pH ranging from 6.5 to 8.0. The M36 tyrosinase enzyme showed optimum monophenolase and diphenolase activity at 40 °C also, the enzyme conserved 100% of its original activity at 4-45 °C. The M36 tyrosinase enzyme was inhibited strongly by β-mercaptoethanol and about 90% by 5mmol of EDTA (a chelating agent). Although the enzyme was activated at the presence of 1mM SDS, it was strongly inhibited at high concentration of SDS (above 15mM). In TLC analysis, the transformation of L-tyrosine to L-DOPA was conspicuously detected.