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The aim of this study was to develop self- nanoemulsifying drug delivery system (SNEDDS) to improve the transcorneal permeability of voriconazole. A 'mixture design around a reference mixture' approach was applied. This latter included four components, namely, isopropyl myristate, PEG 400, Tween

The development of Al2O3-ZrO2-TiO2 composites targeted for biomedical applications was investigated. A design approach was applied to evaluate how composite formulation could affect the mechanical properties, in terms of hardness, tensile strength and elastic modulus. The statistical analysis based on mixture design model was proposed in order to define an adequate tool to describe the mechanical properties relationships of composite mixture. On the basis of the results, the mixture experimental design showed that the fitted models were adequate to describe mechanical properties of composites. A good compromise between mechanical properties that fit the requirements of bone tissue replacement was defined. Keywords: Mixture experimental design, Al2O3, ZrO2, TiO2, Mechanical properties

The aim of the present study is to optimize the production of antifungal metabolites produced by Bacillus subtilis V26 and to evaluate its efficiency in suppression Botrytis cinerea , the main cause of tomato fruit rot disease. Different media were tested for antifungal metabolite production, including chitosanase, by V26. Both of antifungal and chitosanase activities were highly produced in M13 medium, which was selected for medium optimization by using a three-level three-factor Box Behnken design. The optimum antifungal metabolite production (6200 AU/mL) was achieved at 30 g/L soybean, 200 g/L potato extract and 18.5 mL culture medium volume, and represented more than 93% improvement biofungicide production over the basal medium. The V26 culture supernatant showed a strong growth inhibition activity against B. cinerea at low percentage (9%), causing various morphological mycelia changes. The antifungal activity of V26 was relatively stable to temperature, resistant to proteases and UV treatments. Treatment of tomato fruits by V26 significantly reduced by 79% postharvest decay caused by B. cinerea . B. subtilis V26 could be a potential biological agent for the protection of tomato against postharvest disease. High production of chitosanase and antifungal metabolites by B. subtilis V26 may be useful for various industrial and agricultural applications.

International audience; The aim of this work was to investigate the impact of almond gum as coating agent to decrease the oil absorption and to increase the moisture content of fried potato chips meaning a Box–Behnken design. The studied parameters were: almond gum concentration (0–20 g/L), frying time (30–120 s) and frying temperature (160–190 °C). Results showed that the increase of almond gum concentration up to 20 g/L decreased the oil uptake of potato chips by 34% and increased the moisture by 29.5%. Optimal coating and frying conditions found with RSM were thus achieved with 20 g/L aqueous almond gum, 75 s frying time at 160 °C frying temperature. Additionally, the study of sensorial analysis (color, appearance, crispiness, taste, odor, appetence) showed that the chips coated with almond gum have an overall acceptability better than the uncoated potato chips, and the ones coated with arabic gum. The textural analysis of potato chips showed that the hardness (rigidity) decreased significantly by coating either with almond gum or arabic gum. The results obtained through this work showed that coating with almond gum improves the sensorial and nutritional qualities of potato chips.

VOC-free waterborne hybrid alkyd–acrylic (50/50 wt/wt) dispersions were synthesized by melt condensation reactions between acrylic pre-polymers bearing carboxylic groups and medium-oil alkyd resins, followed by a self-emulsification through the neutralization of the carboxylic groups by an aqueous ammonia solution. A mixture experimental design was used to investigate how formulation components of the hybrid alkyd–acrylic resin affect the properties of the hybrid dispersion in terms of the viscosity of the dispersion, particle size, hydrolytic stability, and coating performance, namely gloss and film hardness. It was found that the content of ionizable monomers is the dominant factor controlling the particle size. This latter was shown to meaningfully affect the gloss of the coating after drying. The viscosity of the dispersion was mainly governed by the content of the soybean oil fatty acid which also controlled the hardness of the coating film after drying. An optimal composition that fits the requirement of paint formulation in terms of particle size, viscosity, hardness, and gloss was defined on the basis of the results of the mixture experimental design.

In this study, a Box–Behnken design was carried out in order to study the effects of coating agent (locust bean gum [LBG]) concentration (0–1%), frying time (30–120 s) and frying temperature (160–190C) on oil content, moisture content and volume of fried potato chips. The fitted mathematical model allowed us to plot isoresponse curves and to determine optimal coating and frying conditions. Results showed that frying temperature was the main factor influencing the oil uptake of potato chips. High-quality potato chips characterized by a low fat content ( 10 10−6 m3) could be obtained by using a LBG concentration of 1% and low frying temperature (10 10−6 m3) were obtained by using a locust bean gum concentration of 1%, low frying temperature (

Summary The resistance-in-series model was used to analyse flux behaviour, which involved the resistances of membrane itself, the fouling and solute concentration polarisation. Response surface methodology was used to establish the relationships between operating parameters and ultrafiltration (UF) efficiency and thus to determine optimal conditions. Experiments were performed according to Box–Behnken design by changing the levels of three parameters, namely transmembrane pressure, feed flow rate and temperature. The fitted mathematical models allowed us to plot isoresponse curves. It was shown that the resistance due to solute concentration polarisation (Rcp) dominated the flux decline (40–74%). The fouling resistance (Rf) varied from 12 to 46%. To optimise simultaneously the three responses studied (Rf, Rcp and permeate limit flux), we applied the desirability function approach which allowed us to determine the best acceptable compromise. The selected UF conditions of the compromise were as follows: three bars, 0.95 L min−1 and 30 °C. Optimal values of Rf, Rcp and permeate limit flux were equal to 18%, 72% and 19 L h−1 m−2, respectively.

This work is directed towards Bacillus amyloliquefaciens strain BLB371 metabolite production for biocontrol of fungal phytopathogens. In order to maximise antifungal metabolite production by this strain, two approaches were combined: random mutagenesis and medium component optimization. After three rounds of mutagenesis, a hyper active mutant, named M3-7, was obtained. It produces 7 fold more antifungal metabolites (1800 AU/mL) than the wild strain in MC medium. A hybrid design was applied to optimise a new medium to enhance antifungal metabolite production by M3-7. The new optimized medium (35 g/L of peptone, 32.5 g/L of sucrose, 10.5 g/L of yeast extract, 2.4 g/L of KH2PO4, 1.3 g/L of MgSO4 and 23 mg/L of MnSO4) achieved 1.62 fold enhancement in antifungal compound production (3000 AU/mL) by this mutant, compared to that achieved in MC medium. Therefore, combinatory effect of these two approaches (mutagenesis and medium component optimization) allowed 12 fold improvement in antifungal activity (from 250 UA/mL to 3000 UA/mL). This improvement was confirmed against several phytopathogenic fungi with an increase of MIC and MFC over than 50%. More interestingly, a total eradication of gray mold was obtained on tomato fruits infected by Botrytis cinerea and treated by M3-7, compared to those treated by BLB371. From the practical point of view, combining random mutagenesis and medium optimization could be considered as an excellent tool for obtaining promising biological products useful against phytopathogenic fungi. Scopus

A newly isolated Bacterium strain UEB CF was selected from southern Tunisia, exhibiting the highest clear zone on agar plates containing barley flour by staining with Congo red. On the basis of 16S rDNA sequence analysis, this strain was identified as Bacillus licheniformis . Its capacity to produce lichenase was assessed under solid-state fermentation (SSF) using pea pomace as an abundant agro-industrial substrate. Cultivation conditions of B. licheniformis UEB CF for lichenase production were optimized using Doehlert design. The impact on enzyme production of four independent variables, namely cultivation time, moisture-to-substrate ratio (L/S), inoculum volume and culture temperature were evaluated by response surface methodology (RSM). A second-order polynomial model was determined by the multiple regression analysis of the experimental data. A statistical analysis showed a satisfactory adjustment of the quadratic model with the experimental data. Contour plots were generated to assess the change in the response surface and to understand the relationship between the enzyme production yield and the culture conditions. A ridge analysis revealed that the optimum values of the tested variables for maximizing enzyme production were as follows cultivation time, 84 h; L/S ratio 4 ml/gs; inoculum volume, 0.8 ml (8 × 10 7 CFU/ml) and culture temperature, 44 °C. The experiment carried out under these conditions led to a lichenase production yield of 280 U/g dry substrate, which was in agreement with the predicted value of 293 ± 49 U/gds by the model.

Statistical experimental designs, involving a Plackett-Burman design followed by a rotatable central composite design were used to optimize the culture medium constituents for Bacillus thuringiensis bioinsecticide production. This was carried out by using firstly an asporogenic strain and extrapolated to some sporeless and sporulating strains. Initial screening of production parameters was performed and the variables with statistically significant effects on delta-endotoxin production were identified: glucose, glycerol, yeast extract and MnSO(4). These variables were selected for further optimization by response surface methodology. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 22.5 g/l of glucose, 4.8g/l of glycerol, 5.8 g/l of yeast extract and 0.008 g/l of MnSO(4). Under these conditions, delta-endotoxin production was 2,130 and 2,260 mg/l into 250 and 1,000 ml flask respectively, which represent more than 38% improvement in toxin production over the basal medium (1,636 mg/l). Such medium composition was shown to be suitable for overproducing delta-endotoxins by sporeless and sporulating strains. Tunisian Ministry of Higher Education, Scientific Research and Technology

The decolorization of direct Solophenyl red 3BL (SR), a polyazo dye extensively used in textile industry was studied. TheFomes fomentariuslaccase alone did not decolorize SR. The natural redox mediator, acetosyringone (AS), was necessary for decolorization to occur. Box-Behnken design was used to evaluate the effects of three parameters, namely, enzyme concentration (0.5–2.5 U mL−1), redox mediator concentration (3–30 μM), and incubation time (1–24 h), on the SR decolorization yield. The fitted mathematical model allowed us to plot response surfaces as well as isoresponse curves and to determine optimal decolorization conditions. The results clearly indicated that the AS concentration was the main factor influencing the SR decolorization yield. The selected optimal conditions were enzyme concentration 0.8 U mL−1, mediator concentration 33 μM, and time 14 h 30 min. These conditions allowed 79.66% of SR decolorization versus 80.70% for the predicted value. These results showed a promising future of applying laccase-AS system for industrial wastewater bioremediation.

The present research studies the optimization of the textural properties of new fiber-enriched biscuit formulae. A mixture design was carried out in order to model the textural properties of dough and biscuit supplemented with Aestivum wheat bran (AWB) and durum wheat bran (DWB). The desirability function was used to determine the coordinates of fiber-enriched biscuit formulae characterized presenting textural properties of dough (hardness, cohesiveness and adhesiveness) and biscuit (maximum peak force) close to those of the commercial product without fiber. Two optimal biscuit formulae (Optimal formula 1 (OM1): 86.66% of wheat flour, 6.67% of DWB and 6.67% of AWB and Optimal formula 2 (OM2): 73.30% of wheat flour, 13.35% of DWB and 13.35% of AWB) were tested at the industrial scale and provided highly acceptable scores from the taste panelists. PRACTICAL APPLICATIONS Consumption of dietary fiber provides health benefits including protection against cardiovascular diseases, cancer and other degenerative diseases. Wheat bran is a readily available and inexpensive source of dietary fiber. In this work, we developed new biscuit formulae enriched with both Aestivum and durum wheat brans. The substitution of wheat flour by wheat brans at their optimum levels led to dietary fiber-enriched biscuits with improved functional and nutritional properties and without undesirable changes in their sensory properties.

In the present study, we search to improve the viscoelastic properties of wheat flour characterized by a low bread-making quality. Six regulators were tested: broad bean flour, gluten, monodiglyceride (MDG), ascorbic acid, sodium alginate and a mixture of amylase and xylanase. A hybrid design was carried out in order to study the effect of these regulators on the alveographic properties of wheat flour dough. Two alveographic responses (W: deformation energy and P/L: elasticity-to-extensibility ratio) were studied and simultaneously optimized via the desirability functions. An optimal mixture, containing 13.17 g/kg of broad bean flour, 15.13 g/kg of gluten, 0.155 g/kg of ascorbic acid, 3.875 g/kg of MDG, 2.75 g/kg of sodium alginate and 0.3 g/kg of enzyme mixture, was obtained and tested in a Tunisian flour. It led to a dough characterized by a W = 274 × 10−4 J and P/L = 0.74 versus 191 × 10−4 J and 0.40, respectively, for the Tunisian flour without improvers. PRACTICAL APPLICATIONS In this work, we developed a new flour improver mixing formula intended to be used with wheat flour characterized by a low bread-making quality. This improver mixture is in powder form and contains 13.17 g of broad bean flour, 15.13 g of gluten, 0.155 g of ascorbic acid, 3.875 g of monodiglyceride, 2.75 g of sodium alginate and 0.3 g of enzyme mixture per kilogram of wheat flour. The incorporation of this improver mixture in low bread-making quality wheatflour leads to an increase of its deformation energy (W) of about 43% and produces large volume bread.

In a previous paper, we showed that the preparation of sulfated diethanolamide of fatty acids is easy to carry out without organic solvents when using olive pomace oil as starting material; the reaction yield was, however, highly variable as a function of factor levels. The purpose of this research is to look for the optimal experimental conditions. We started by applying a supersaturated experimental design to screen for important factors among a list of 31 potentially influential factors in 18 experiments. Thus, we constructed a two-level supersaturated design as a half fraction of a 36-experiment Hadamard matrix and used it for this screening purpose. Multiple regression methods namely stepwise selection procedure, ridge regression and all-subset regressions were used to analyze the supersaturated design results according to a four step procedure. Results indicated that six factors, namely, molar ratio SO 3 /ester, amidation time, amide addition rate, alkali reagent, alkali concentration, and amidation temperature, were very influential factors. Three other factors were moderately influential: neutralization temperature, sodium methanoate amount, and methanol amount. In future research, these factors will be further studied in order to perform robustness tests of the process.

Phenolic compounds of pomegranate juice, which are responsible for haze formation and browning during storage, could be selectively removed by combined enzyme-ultrafiltration process. The pomegranate juice was treated with Fomes fomentarius laccase at various enzyme concentrations (0.5–5 U/mL), temperatures (20–50C) and times (30–300 min). The effect of these enzymatic treatments on total phenol content and clarity of the juice were evaluated using a central composite design. The optimum treatment conditions were: enzyme concentration 5 U/mL; time 300 min; and temperature 20C. Their application led to a 40% reduction of total phenols but induced a threefold decrease of the juice clarity. This drawback was overcome by ultrafiltration of the laccase-treated juice. The pomegranate juice obtained was clear, stable and characterized by total phenolics = 864 mg/L, clarity (A650 nm × 1,000) = 86 and color (A420 nm × 1,000) = 236 versus 1,681, 127 and 382, respectively, for untreated juice. PRACTICAL APPLICATIONS The tendency for hazes to develop in pomegranate juices during storage is a persistent problem in the fruit juice industry. In this work, laccase treatment optimized by response surface methodology followed by ultrafiltration was used to clarify the pomegranate juice. The application of the optimum enzymatic treatment conditions (enzyme concentration 5 U/mL; time 300 min; and temperature 20C) followed by ultrafiltration (cutoff value 15 KDa) decreases the total phenolics of about 50% and the antioxidant capacity of about 20% and, increases the clarity of about 30% versus untreated juice.

BACKGROUND: The agro-industries generate thousands of tons of by-products, such as bran or pulps, each year. They are, at best, used for cattle feeding. Through biocracking, this biomass may constitute a renewable source for various molecules of interest for the industry. For instance, ferulic acid, a compound showing antioxidant ability, is found in abundance in cereal bran. Its release depends mainly on the breaking of its ester linkage to other constitutive elements of the cell wall, such as arabinoxylans. Response surface methodology was used to evaluate the effects of ferulic acid esterase (FAE) and xylanase activities, as well as incubation time and temperature, on ferulic acid extraction yield from wheat bran. Under optimized conditions, the composition of the hydrolysate and of residual bran were compared to native bran. RESULTS: Experiments carried out under the predicted optimal conditions (FAE amount, 27 U g−1; xylanase amount, 304 U g−1; incubation time, 2 h; and temperature, 65 °C) led to an extraction yield of 52.8%, agreeing with the expected value (51.0%). The crude ferulic acid fraction was purified with Amberlite XAD16, leading to a final concentration of 125 µg mL−1 of ferulic acid in ethanol. The antioxidant capacity of this purified fraction was evaluated by the DPPH· scavenging method: it exhibited better efficiency (EC50 = 10.6 µmol L−1 in ferulic acid) than the ferulic acid standard (EC50 = 13.7 µmol L−1). CONCLUSION: These results confirm the potential of wheat bran valorization in the field of natural antioxidant extraction, possibly viable in an industrial scheme. Copyright © 2009 Society of Chemical Industry

The sequential simplex method and its derivatives, the modified and the super modified simplex methods, are used to optimize on-line the levels of the parameters of an injection moulding process (producing bottle caps) in order to minimize the process cycle time and to reduce the rejects. Nine process parameters are selected to conduct the optimization: screw rotation speed, back pressure, injection rate, injection pressure, cooling time, holding pressure, holding time, nozzle temperature and opening stroke. Optimum conditions are achieved using 17 experiments only. The obtained results clearly show that the process cycle time is very sensitive to the effect of two parameters: cooling time and holding pressure. Low levels of these two parameters are needed in order to minimize cycle time. In addition, the evaluation of rejects in the course of the simplex evolution shows that this additional response is also sensitive to the same parameters. In order to minimize rejects, these two parameters have to be set to low levels. Finally, this study allows us to conclude that the simplex method may be easily used and reused on-line to drive the process continuously towards its optimal conditions without any disruption of production or additional operating costs.

Sulfated diethanolamides of fatty acids are known to be effective lime soap dispersing agents. However, their preparation from fatty acids via fatty amides requires the use of organic solvents due to the high viscosity of both fatty amides and sulfated fatty amides. This study shows that the preparation of sulfated fatty amides is relatively easy when using olive pomace oil as the raw material. The latter, is converted into sulfated fatty amides by performing the following steps: saponification, hydrolysis, esterification, amidation, and sulfation. In the final step, the mixture obtained has sufficient fluidity, due to its high linoleic acid amide content, to obviate the use of organic solvents, as usually suggested in the literature. Characterization of the product was carried out by chemical analyses, FTIR, 13C NMR, GC, and HPLC. It was shown that the yield of the amidation reaction is about 80%, and that of the sulfation reaction can exceed 100% against the pure amide (more than one sulfate group could be linked to one amide molecule). On the other hand, the Borghetty test showed that the product is an effective dispersant with a lime soap dispersing power equal to five.

The ability of a noncommercial immobilized lipase from Staphylococcus xylosus (SXLi) to catalyze the transesterification of tyrosol and ethyl acetate was investigated. Response surface methodology was used to evaluate the effects of the temperature (40-60 degrees C), the enzyme amount (50-500 UI), and the ethyl acetate/hexane volume ratio (0.2-1) on the tyrosol acetylation conversion yield. Two independent replicates were carried out under the optimal conditions predicted by the model (reaction temperature 54 degrees C, enzyme amount 500 UI, and volume ratio ethyl acetate/hexane 0.2). The maximum conversion yield reached 95.36 +/- 3.6%, which agreed with the expected value (96.8 +/- 3.7%). The ester obtained was characterized by spectroscopic methods. Chemical acetylation of tyrosol was performed, and the products were separated using HPLC. Among the eluted products from HPLC, mono- and diacetylated derivatives were identified by positive mass spectrometry. Tyrosol and its monoacetylated derivative exert similar antiradicalar activity on 2,2-diphenyl-1-picrylhydrazyle.

The present research studies the optimization of the preparation of a hydrotrope (mixture of sodium toluenesulfonate and sodium xylenesulfonates) for liquid detergents using experimental designs. The preparation is carried out by selective sulfonation of toluene and xylene present in the BTX fraction of a natural gas. The optimization of five responses has been carried out in two steps. First, we carry out an asymmetrical screening design 2 1 3 6 //18 to select from seven factors, those factors which have significant influence on the amount of residual sodium sulfate in the product and on the total conversion of toluene and xylenes. Secondly, we carry out a Box–Behnken design to optimize three retained factors (temperature, molar ratio of acid to toluene plus xylenes, and the amount of desulfation agent), using response surface methodology. In addition, and in order to reach near-optimal sulfonation conditions, we use the desirability functions to optimize the five responses simultaneously. This allows us to determine for the whole process, sulfonation conditions leading to a high yield of toluene and xylene conversion and acceptable amounts of residual sodium sulfates and sodium benzenesulfonate.

The present research studies the formulation and optimization of a self-leveling composition for floor toppings. This formulation is, in particular, based on a fluoroanhydrite which is a by-product of a Tunisian plant for fluorhydric acid preparation; it also contains aggregates, a neutralizing agent, a hydration accelerator and, especially, a plasticizer prepared by sulfonation of the lignin extracted from the black liquor of a Tunisian esparto grass soda pulping process. The optimization of four responses (plasticity, compressive strength, initial and final setting times) has been carried out in two steps. First, we obtain a coarse composition with a relatively acceptable rheological properties. Second, we carry out a mixture design in the surroundings of the retained composition aimed at obtaining a product with the required characteristics formulated by the users of this kind of materials. To this end, the evolution of the plasticity and the setting times of the fresh mortar and the compressive strength of the hardened mortar in a four-component system with constraints were analyzed using a mathematically independent variable approach. Finally, and in order to reach a near-optimal composition, we use the desirability functions to optimize the four responses simultaneously. This allows us to determine the coordinates of a composition which is characterized by high plasticity, acceptable compressive strength and relatively rapid setting times.

The objective of the work described in this first paper of a series is an investigation of the preparation of a sulfonated esparto grass lignin (SEL) and its behavior as a plasticizing–water-reducing agent for cement–water systems. SEL is prepared by extracting the lignin from the black liquor of a soda esparto grass pulping process and then sulfonating it with a mixture of sodium sulfite and formaldehyde. Analyses and characterization of SEL carried out with high-performance size exclusion chromatography (HPSEC), reversed phase chromatography (RPC), infrared spectrometry and chemical methods show that both the molecular weight average and the combined sulfur content are relatively high. Moreover, HPSEC shows that SEL has a relatively more uniform molecular weight distribution (MWD) than the commercial products obtained from the sulfite wood pulping process. On the other hand, SEL could reduce the water content, improve the workability and compressive strength of mortars. SEL also permits a very low rate of slump loss of cements without excessive extension of the final set time.

In a previous study, we presented a new method for preparing a mixture of sodium toluenesulfonates (STS), sodium xylenesulfonates (SXS), sodium benzenesulfonate (SBS) and Na 2 SO 4 by sulfonating the BTX fraction of a Tunisian natural gas. Such mixtures can be used as a hydrotrope agent for concentrated liquid detergents. In the present work, we performed a mixture design in order to study the effect of each of these four components on the clear point and the viscosity of a liquid detergent, and therefore, to determine the conditions allowing to improve the effectiveness of the hydrotrope. Twenty-eight combinations of the 4 components out of 51 candidate points are selected by the Nemrod-W software according to the D-optimal criterion to fit two polynomial models. The statistical study shows that the fitted models were adequate to describe the clear point and the viscosity responses. Optimal conditions allowing to lower the two responses are then looking for by examining the response surface both as a contour plot, and as three-dimensional surface plot and the response trace. We prove that Na 2 SO 4 exhibits a harmful negative effect, while SXS and STS exhibit, respectively, a strong and moderate positive effect on both clear point and viscosity responses. As expected, SBS has a harmful effect on the two responses but the magnitude of this effect is lesser than that predicted by the preliminary experiments carried out with SBS alone. This phenomenon is explained by the formation of heteroassociation between SBS, STS and SXS similar to what is found in surfactants. The effectiveness of the hydrotrope, obtained by sulfonation of the BTX fraction of the Tunisian natural gas, is really improved by removing sulfates either by adding lime to precipitate gypsum, or isopropanol to reduce the solubility of Na 2 SO 4 .

Experimental design methodology was used to determine significant factors affecting the extraction yield of soluble and insoluble fibres fromAgave americanaL. and in second time to find optimum conditions leading to the highest yield. Results clearly indicated that the temperature, the powder to water (P/W) ratio, and the agitation speed were the most important factors influencing fibres extraction yield which increased with temperature, P/W ratio, and agitation speed. Ionic strength affected significantly soluble fibre extraction yield and was the most important factor among nonsignificant ones influencing insoluble fibres extraction yield. Then, a Box-Behnken design was carried out to maximise fibres extraction. Selected optimal conditions were temperature: 90°C; P/W ratio: 0.1625; agitation speed: 400 rpm; and ionic strength: 1.5 g/L. These conditions yielded 93.02% and 80.46% of insoluble and soluble fibres, respectively. Concentrates showed high fibres purity and good functional properties.

A new Bacillus strain degrading starch, named Bacillus sp. UEB-S, was isolated from a southern Tunisian area. Amylase production using solid-state fermentation on millet, an inexpensive and available agro-resource, was investigated. Response surface methodology was applied to establish the relationship between enzyme production and four variables: inoculum size, moisture-to-millet ratio, temperature, and fermentation duration. The maximum enzyme activity recovered was 680 U/g of dry substrate when using 1.38 × 10(9) CFU/g as inoculation level, 5.6:1 (ml/g) as moisture ratio (86%), for 4 days of cultivation at 37 degrees C, which was in perfect agreement with the predicted model value. Amylase was purified by Q-Sepharose anion-exchange and Sephacryl S-200 gel filtration chromatography with a 14-fold increase in specific activity. Its molecular mass was estimated at 130 kDa. The enzyme showed maximal activity at pH 5 and 70 degrees C, and efficiently hydrolyzed starch to yield glucose and maltose as end products. The enzyme proved its efficiency for digesting raw cereal below gelatinization temperature and, hence, its potentiality to be used in industrial processes.

The optimization of lichenase production by Bacillus sp. UEB-S in solid state fermentation (SSF) with millet as solid support, was carried out using response surface methodology (RSM) based on Doehlert design. Four variables (inoculum volume, millet-to-moisture ratio temperature and duration of fermentation) were regarded as factors in the optimization process. The maximum enzyme activity predicted by the model was 684 +/- 90 U/g of dry substrate when using 1.5 x 10(9) CFU/g as inoculation level and 6.16:1 (mL/g) as moisture ratio, for 4.6 days of cultivation at 35 degrees C. Using these conditions, 503 U/g of enzyme activity was experimentally obtained, which is in agreement with the predicted one (525 +/- 76 U/g). The enzyme was stable toward non-ionic surfactants and oxidizing agents. In addition, it showed a good stability and compatibility with a wide range of commercial solid detergents suggesting that lichenase from UEB-S is a potential candidate in detergent formulation. (C) 2012 Elsevier B.V. All rights reserved.

Un traitement de surface consiste par apport superficiel de matiere, ou par transformation du substrat, a conferer une fonction technique ou esthetique au materiau. Plus que jamais, le secteur des traitements de surface doit faire face a l’amelioration de la qualite du traitement, la reduction des couts, et le respect des normes environnementales. Pour atteindre cet objectif au nombre de parametres imposants, le recours a la methodologie des plans d’experience est de plus en plus courant. Apres une precision sur la terminologie, une etude quantitative des effets des facteurs et de leurs interactions est deployee. Plusieurs plans factoriels y sont utilises : factoriels complets, factoriels fractionnaires, ou de Taguchi. Le criblage des facteurs, issus lui aussi de plans d’experience, consiste a determiner dans un domaine d’etude fixe les facteurs reellement influents.

Statistical approaches were employed for the optimization of different cultural parameters for the production of laccase by the white rot fungus Fomes fomentarius MUCL 35117 in wheat bran-based solid medium. first, screening of production parameters was performed using an asymmetrical design 2533//16, and the variables with statistically significant effects on laccase production were identified. Second, inoculum size, CaCl2 concentration, CuSO4 concentration, and incubation time were selected for further optimization studies using a Hoke design. The application of the response surface methodology allows us to determine a set of optimal conditions (CaCl2, 5.5 mg/gs, CuSO4, 2.5 mg/gs, inoculum size, 3 fungal discs (6 mm Ø), and 13 days of static cultivation). Experiments carried out under these conditions led to a laccase production yield of 150 U/g dry substrate.

Actinomycetes form an enormous reservoir of secondary metabolites and enzymes. The potential for exploiting rare actinomycetes is highlighted by the discovery of novel compounds from strains of Spirillospora and Nocardioides. Novel compounds of well known classes of antibiotics, such as polyenes, continue to be discovered. For compounds containing a chromophore, the analysis by high-performance liquid chromatography coupled with a diode-array detector enables the elimination of producers of known compounds and facilitates the discovery of novel compounds or derivatives. The complexity of the regulatory mechanisms is illustrated by glutamine synthetase. The characterization of thermostable amylolytic, lignolytic, peroxidase and neuramidase activities, and the isolation of novel cellulolytic actinomycetes clearly demonstrate the potential of Actinomycetes as producers of enzymes.

In the present work the characterization of a fluoroanhydrite which is a by-product of a Tunisian plant for fluorhydric acid preparation and a formulation of a self-leveling composition for floor toppings were reported. The fluoroanhydrite was characterized by x-ray diffraction (XRD), Infra-red (IR) and differential scanning calorimetry (DSC) techniques. These analyses confirmed that the by-product is the anhydrite II. The formulation was mainly, based on a fluoroanhydrite. It also contains aggregates such as a neutralizing agent, a hydration accelerator and a plasticizer. The optimization of four responses (plasticity, compressive strength, initial and final setting times) has been carried out using preliminary experiments. This retained composition aimed at obtaining a product with the required characteristics requested by the users of this kind of material. The optimized formula has the following composition: 39.85% binder (ICF-Fluoroanhydrite; particle size 1200 μm), 39.85% aggregates (silica sand), 4.40% neutralizing agent (CaCO3), 0.52% hydration accelerator (K2SO4), 0.23% plasticizer (sodium lingosulfonate) and 15.15% water.