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Microbial lipid production using renewable raw material is considered an alternative for biodiesel production. In this study, several biotopes have been targeted for new oleaginous yeasts isolation. 205 yeast strains were screened to find efficient and more suitable oleaginous yeasts for agro-industrial wastes bioconversion. Using the qualitative fluorometric technique, 12 strains were pre-selected and the morphology of their lipid bodies was studied. The molecular identification showed that our isolates are closely related to six genera of oleaginous yeast. Cultivated on nitrogen limited medium, lipid content of all yeast strains exceeds 20% (w/w), confirming their oleaginous character. The highest lipid yield and content were achieved by Candida viswanathii Y-E4 (3.55 g/L) and Rhodotorula babjevae Y-SL7 (39.17%), respectively. All the lipid profiles analyzed are mainly formed by triacylglycerols of oleic acid. In addition to the lipogenic aptitude, the hydrolytic potential including cellualse and lipase activities was also studied. The highest CMCase (0.11 U/mL) and β-glucosidase (0.55 U/mL) activities were produced by the Trichosporon asahii Y-SL1 strain. However, the highest lipase activity (50 U/mL) was detected in the liquid culture of Yarrowia lipolytica Y-D1P. To minimize the SCO production cost, oleaginous yeasts were evaluated for their capacity to use agro-industrial by-products for lipids and enzymes production. Cultivated on wheat bran acid-hydrolysate, Rhodotorula mucilaginosa Y-MG1 exhibits the highest lipid yield (2.2 g/L). In parallel, a considerable lipid content 64% (w/w) and lipase activity (174.1 U/mL) were achieved by Yarrowia lipolytica Y-D1P and Trichosporon asahii Y-D1 respectively, when the soap stock of pomace olive oil refining was used as carbon source. This study opens up new perspectives in the use of industrial wastes for production of microbial lipids and high-added value products. [ABSTRACT FROM AUTHOR]

A thermophilic fungus , Talaromyces thermophilus that produces a novel thermotolerant extra-cellular β-glucosidase (Bgl.tls), was isolated from Tunisian soil samples. The enzyme was purified from the culture filtrates of T. thermophilus grown on lactose using gel filtration, ion exchange chromatography and FPLC. The monomeric enzyme had a molecular mass of 116.0 kDa and a high specific activity of 1429 UI/mg. Bgl.tls exhibited optimal activity at pH 5.0 and 65 °C. It was also stable over a wide range of pH (4.0–10.0) and stable at 50 °C for 34 h. Bgl.tls retained about 80% of its initial activity after 1.0 hours of preincubation at 60 °C. The Km and Vmax values recorded for p NPG were 0.25 mM and 228.7 µmol min −1 , respectively. Bgl.tls was activated by Mn 2+ , Mg 2+ , Ca 2+ and Co 2+ but obviously inhibited by Fe 2+ and Cu 2+ . It was able to hydrolyze a variety of aryl / alkyl -β-glucosides and disaccharides as well as (1→6) and (1→4)-β-glucosidic linkages and α-glycosidic substrates, thus providing evidence for its broad substrate specificity. The enzyme also displayed high hydrolytic and transglycosylation activities. Overall, this study is the first report on the purification and physicochemical properties of a β-glucosidase secreted by T. thermophilus . The cello-oligosaccharides synthesized by this enzyme within 2 h were mainly cellotriose, cellotetraose and cellopentaose identified by HPLC and ESI-MS techniques. [ABSTRACT FROM AUTHOR]

In this study, we isolated a novel endoglucanase (EG1) that exhibits optimal activity at pH 7 and 50 °C and retained >85% of its activity between pH 5 and 9 and >80% at 60 °C. In addition to its alkali tolerance, this EG1 is a halophilic enzyme as its activity was enhanced to 152% in the presence of 5 M NaCl. In this condition, optimal activity was observed at pH 8 and 70 °C. More interestingly, EG1 was active in the presence of an ionic liquid (IL) (100% and 80% activity in 5% and 10% [Bmim]Cl, respectively). Furthermore, it was extremely stable in the presence of various detergents, especially SDS (10%), which is a very rare property amongst fungal cellulases. All these properties make this enzyme suitable for many applications, mainly in biofuel, textile and detergent industries. [ABSTRACT FROM AUTHOR]

Abstract: A newly isolated thermophilic bacterial strain from Tunisian thermal source was identified as Bacillus sp. and was selected for its ability to produce extracellular levansucrase. Following the optimization of carbon source, nitrogen source, temperature and initial pH of the growth medium in submerged liquid cultures. In fact, sucrose was found to be a good inducer of levansucrase enzymes. The optimal temperature and pH of the levansucrase were 50°C and 6.5, respectively and its activity increased four folds in the presence of 50mM Fe2+. This enzyme exhibited a remarkable stability and retained 100% of its original activity at 50°C for more than 1h at pH 6.5. The half-life of the enzyme was 1h at 90°C. Crude enzyme of Bacillus sp. rich in levansucrase was established for the synthesis of fructooligosaccharides and levan. Bacillus sp. could therefore be considered as a satisfactory and promising producer of thermostable levansucrases. Contrary to other levansucrases, the one presented in the current study was able to produce high levels of levan with high molecular weight at 50°C and having an important effect as a hypoglycemic agent which was demonstrated in our previous publications (Dahech et al., 2011 ) and as a hypo-cholesterolemic agent which will be investigated in further research. [Copyright &y& Elsevier]

[Display omitted] • Two keratinases from strain Cpt20 were purified (KERA-71 and KERB-19) and characterized. • KERA-71 and KERB-19 were monomers with molecular masses of 71 and 19 kDa, respectively. • Both keratinases are active in the neutral to alkaline range and at temperatures >40 °C. • KERA-71 is a potential candidate for feather keratin-biodegradation. • KERB-19 is a good candidate for dehairing activity in leather processing industry. Two novel extracellular keratinases were produced by Actinomadura keratinilytica strain Cpt20. Both enzymes were purified to homogeneity using heat-treatment (60 °C for 30 min) and ammonium sulfate salt fractionation (40 %–70 %), followed by anion-exchange chromatography with fast protein liquid chromatography (FPLC) system. The purified keratinases, designated as KERA-71 and KERB-19, are monomeric and named according to their molecular masses of 71 kDa and 19 kDa, respectively, as estimated via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), zymography, and high-performance liquid chromatography (HPLC). N-terminal residues of both enzymes exhibited high identity with other Actinomadura keratinases. Their hydrolytic activities were significantly inhibited by phenylmethylsulfonyl fluoride (PMSF) and di-iodopropyl fluorophosphates (DFP), classifying them in the serine proteases family. While KERA-71 was ideally active at 50 °C and pH 8, KERB-19 illustrated optimum activity at 40 °C and pH 7. The thermo-activity and thermo-stability of both enzymes were improved with 10 mM Ca2+. Interestingly, the KERA-71 displayed broader substrate specificity, higher catalytic efficiency (k cat / K m), and a high degree of hydrolysis (DH) than actinobacterial keratinases, including KERB-19, KERDZ, KERAK-29, Actinase E, and KERAB. Interestingly, both enzymes exhibited effective keratinase activities with high potential, illustrating their possibility to be used in the process of keratin-containing wastes valorization and leather industry. [ABSTRACT FROM AUTHOR]

• Oleaginous fungi were screened by colorimetric and fluorimetric methods. • Accumulation of SCO in various stress conditions was investigated. • Ex novo lipid synthesis was strongly improved using industrial by-products. • Agro wastes influenced the degree of unsaturation of produced lipids. • PROMETHEE-GAIA algorithm used for the selection of potent substrates and strain. Crude oil is the most important raw material used in chemical industry and for energy supply. Microbial lipids are ideal for various industrial applications as an alternative to conventional fuel. However, the main factor controlling the total production costs is the choice of the growth substrates. For this reason, economically feasible substrate such as agro-industrial residues has been explored. In addition, the most suitable substrates for biodiesel production were selected by PROMETHEE-GAIA analysis on the basis of the fatty acid profile of the produced oils. Six strains were selected as the best lipid producer among twenty-three fungal strains screened by colorimetric methods. The strains identified belong to the genera Fusarium and Mucor. Mucor circinelloides was chosen for comparative evaluation of the accumulation performance with different carbon sources. The use of soap stock of refined soybean oil, waste cooking oils and soap stock of refined olive-pomace successfully resulted in improved lipid yield (4.07, 2.69 and 2.44 g/L) (ρ = 0.001; ρ > 0.05) and the lipid content at 46%, 51% and 44% (ρ = 0.049; ρ < 0.05) respectively. The ability to use low-cost agro industrial raw materials for the production of microbial lipids has been proven. The fatty acid profile of M. circinelloides grown on used cooking oils improved the level of linoleic acid (56.26%) that can be valorized as additive in health and dietary supplements. Glucose, refined olive-pomace oil soap stock, and refined soybean oil have influenced the resulting fatty acid profile and meet the characteristics required for successful biodiesel production. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Oleaginous yeast isolation, identification and characterization. • Study of the effect of nutritional parameters on lipids production. • Simultaneous bioreactor production of triacylglycerols and glycolipids. • Structural elucidation of neutral lipids and glycolipids. • Application of Y-SL7 glycolipid as emulsifying and anticancer agent. Abstract The newly isolated oleaginous yeast, Rhodotorula babjevae Y-SL7, was shown to accumulate high intracellular content of microbial oil (mainly triacylglycerols) and to secret, under the same culture conditions, an atypical glycolipid. This unusual behavior was induced when the strain was subjected to nitrogen limitation and high amount of carbon. A series of analytical methods was adopted in order to structurally characterize the secreted glycolipid. The latter consists of a mixture of 9 molecules formed by a polyol head group, bound through the carboxyl end of an acetylated 3-hydroxy fatty acid with C18 or C16 chain length. In addition of their physicochemical properties such as emulsifying activity on hydrophobic substrates, Y-SL7 glycolipids have shown a therapeutically promising cytotoxic effect against different cancer cell lines. In fact, Y-SL7 strain can be used for the production of triacylglycerols as energetic molecules and for the secretion of a biosurfactant of therapeutic and environmental interest. [ABSTRACT FROM AUTHOR]

Talaromyces thermophilus lipase (TTL) was found to hydrolyze monogalactosyl diacylglycerol (MGDG) and digalactosyl diacylglycerol (DGDG) substrates presented in various forms to the enzyme. Different assay techniques were used for each substrate: pHstat with dioctanoyl galactolipid-bile salt mixed micelles, barostat with dilauroyl galactolipid monomolecular films spread at the air-water interface, and UV absorption using a novel MGDG substrate containing α-eleostearic acid as chromophore and coated on microtiter plates. The kinetic properties of TTL were compared to those of the homologous lipase from Thermomyces lanuginosus (TLL), guinea pig pancreatic lipase-related protein 2 and Fusarium solani cutinase. TTL was found to be the most active galactolipase, with a higher activity on micelles than on monomolecular films or surface-coated MGDG. Nevertheless, the UV absorption assay with coated MGDG was highly sensitive and allowed measuring significant activities with about 10 ng of enzymes, against 100 ng to 10 μg with the pHstat. TTL showed longer lag times than TLL for reaching steady state kinetics of hydrolysis with monomolecular films or surface-coated MGDG. These findings and 3D-modelling of TTL based on the known structure of TLL pointed out to two phenylalanine to leucine substitutions in TTL, that could be responsible for its slower adsorption at lipid-water interface. TTL was found to be more active on MGDG than on DGDG using both galactolipid-bile salt mixed micelles and galactolipid monomolecular films. These later experiments suggest that the second galactose on galactolipid polar head impairs the enzyme adsorption on its aggregated substrate. [ABSTRACT FROM AUTHOR]

• An oleaginous fungus was isolated for its potential lipid production. • Lipid accumulation by the fungus was improved using different conditions. • The fungus can grow on a variety of low cost carbon sources. • The produced lipids can be used as a potential feedstock for biodiesel production. A newly isolated oleaginous fungus called E4-2 and identified as Fusarium verticillioides was selected as a potential source of lipid production using glucose as carbon source and a mixture of ammonium chloride and yeast extract as nitrogen sources. A maximum lipid accumulation of 1.88 g/L and a lipid cell content of 38% were obtained at optimal pH and temperature equal to 5 and 30 °C, respectively. Moreover, the E4-2 strain can grow on a variety of low-cost agro-waste carbon sources. Interestingly, waste cooking oils (1.67 g/L) and soap stock of refined olive oil pomace (1.25 g/L) were optimal for a maximum lipid accumulation. Gas chromatography analysis of the extracted lipids revealed that, similar to some vegetal oils, the prominent fatty acid (FA) constituents were C18:1 (34.65%), C18:2 or ω6 (30.78%) and C16:0 (25.61%) with a high ω6 content. More interestingly, the ω3 content rose from 0.86 to 1.71 when culture temperature was set from 30 to 25 °C. The predictive determination of biodiesel properties from fatty acids profile suggests that E4-2 lipids may favorably be used for biodiesel production. All these characteristics argue in favor of the great biotechnological potential of the lipids produced by our strain. [ABSTRACT FROM AUTHOR]

Barley hull hydrolysate was used as the fermentation feedstock of Trichosporon cutaneum CTM-30125 yeast strain for production of microbial lipid as the potential raw material of biodiesel. An effective hydrolysis process based on the combination of dilute acid hydrolysis and enzymatic saccharification was developed to maximize recovery of total sugars. On synthetic media, CTM-30125 can assimilate glucose and xylose simultaneously and accumulated intracellular lipid up to 43.6% (w/w). However, when grown on acid barley hull hydrolysate (ABHH) the lipid content was low (16.6% w/w) and a detoxification step was required. Overtiming by Ca(OH)2 treatment and adsorption by activated charcoal improved the fermentability of ABHH significantly by removing the inhibitors and reducing the nitrogen content. The solid fraction resulting from the acid treatment of the barley hull was treated with hydrolytic enzyme complex produced by the hyper-cellulolytic fungal strain Trichoderma reesei Rut C-30. Enzyme production and hydrolytic conditions were optimized to enhance the saccharification. The structural changes in native and treated raw material were monitored using FTIR spectra. Detoxified ABHH and enzymatic hydrolysate were successively fermented by the CTM-30125 strain in fed-batch bioreactor without addition of external nitrogen source. A total biomass of 17.5 g/L with a lipid content of 38.2% (corresponding to a lipid yield of 6.7 g/L) could be achieved after 168 h of culture. The relative fatty acid composition indicates the presence of increased levels of saturated (41.2%) and monounsaturated (52.5%) fatty acids in the oil, making it ideal for biodiesel production. [ABSTRACT FROM AUTHOR]

β-amylase extracted from Pergularia tomentosa was characterized by 1.98 U/mg protein of enzyme activity and a molecular weight of 24 KDa. Enzyme was immobilized onto a matrix of titanium dioxide-based materials incorporated to cellulose acetate butyrate and copolymer of acrylonitrile-acrylamide, and its specific activity was 0.34 U/mg protein. A newly kinetic mechanism of a plant enzyme was studied by the means of the variation of the conversion degree α in function of the temperature increase. Modified Prout-Tompkins topochemical equation described the kinetic process of the free and the immobilized β-amylase. The specific nature of the process was determined by plans and enzyme activity. The current rate was responsible for the behavior of active centers. The apparent rate constant and the power factor were depending on the temperature. The topochemical process of the free β-amylase was explained by the influence of the current rate decrease with 2.8% at 60 °C by the pre-exponential factor and the inhibition of the enzyme due to the obtained product. With immobilization, the decrease of the current rate of the process, 7.91% at 70 °C, was due to the change in the number and the accessibility of active centers on the surface. [ABSTRACT FROM AUTHOR]

This work aims at realizing an optimal hydrolysis of pretreated Alfa fibers ( Stipa tenacissima ) through the use of enzymes produced from Talaromyces thermophilus AX4, namely β- d -glucosidase and xylanase, by a solid state fermentation process of an agro-industrial waste (wheat bran supplemented with lactose). The carbon source was firstly selected and the optimal values of three other parameters were determined: substrate loading (10 g), moisture content (85%) and production time (10 days); which led to an optimized enzymatic juice. The outcome was then supplemented with cellulases of T. reesei and used to optimize the enzymatic saccharification of alkali-pretreated Alfa fibers (PAF). The maximum saccharification yield of 83.23% was achieved under optimized conditions (substrate concentration 3.7% ( w/v ), time 144 h and enzyme loading of 0.8 FPU, 15 U CMCase, 60 U β- d -glucosidase and 125 U xylanase).The structural modification of PAF due to enzymatic saccharification was supported by the changes of morphologic and chemical composition observed through macroscopic representation, FTIR and X-Ray analysis. [ABSTRACT FROM AUTHOR]

The present study investigates the hypolipidemic effects of sulphated polysaccharide obtained from Codium fragile (CFSP) in induced obese rats (HFD). The results showed an increase in body weight of HFD rats by 21.56% as compared to control normal rats. Moreover, serum lipase activity underwent an increase which led to an increase in the levels of total cholesterol (T-Ch), triglycerides (TG) and low density lipoprotein cholesterol (LDL-Ch) in serum associeted with a decrease in the level of high density lipoprotein cholesterol (HDL-Ch) in untreated HFD rats. This diet has disrupted the antioxidant status by decreasing the activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX)) and subsequently an increase in thiobarbituric acid reactive substances (TBARS) level in liver and kidney of obese rats. All these disturbances are significantly corrected by CFSP administration with no fatty deposits in the liver and a protective effect against renal histological alteration. This confirms the important role of this polysaccharide in the fight against oxidative stress and the prevention of hyperlipidemia. [ABSTRACT FROM AUTHOR]

A sulphated polysaccharide from brown algae Sargassum vulgare (SVSP) was extracted and examined with respect to chemical, structural characterization and hypolipidemic effects. SVSP consisted mainly of sulphate and total sugars with low levels of lipids and proteins. Its structure was studied by nuclear magnetic resonance (RMN), gas chromatography-mass spectrometry (GC–MS), infra-red spectroscopic, differential scanning calorimetry and X-ray diffraction analysis. Allowing us therefore to revealed that SVSP was composed of glucose, rhamnose, xylose, galactose, mannose and arabinose with XRD pattern that was typical for a semi-crystalline polymer and complexities of the spectra reflected its homogeneous structure. The administration of SVSP to obese rats is effective in lowering the body weight and inhibiting the lipase activity leading to notable regulation of lipid profile, increasing the activities of antioxidant enzymes, limiting lipid peroxidation; and protects liver-kidney functions proved by a decrease in the levels of toxicity parameters in blood, confirmed by histological study. [ABSTRACT FROM AUTHOR]

This new study aimed to evaluate for the first time the effect of Cymodocea nodosa extract (CNE) on α-amylase activity, hyperglycemia and diabetes complications in the alloxan-induced diabetic rats. The in vitro evaluation and oral administration of CNE to surviving diabetic rats inhibited key enzyme related to hyperglycemia as α-amylase, helped to protect the β cells of the rats from death and damage confirmed by oral glucose test tolerance (OGTT), which leads to decrease in blood glucose level by 49% as compared to untreated diabetic rats. The CNE also decreased the triglyceride, low density lipoprotein (LDL) cholesterol and total cholesterol rates in the plasma of diabetic rats by 46%, 35%, and 21%, respectively, and increased the high density lipoprotein (HDL) cholesterol level by 36%, which helped maintain the homeostasis of blood lipid. When compared to those of the untreated diabetic rats, the superoxide dismutase, catalase, and glutathione peroxidase levels in the pancreas, liver and kidney of the rats treated with this supplement were also enhanced significantly. Moreover, a significant decrease was observed in the lipid peroxidation level in the tested organs of diabetic rats after CNE administration. This positive effect of CNE was confirmed by histological study. Overall, the findings presented in this study demonstrate that CNE has both a promising potential with a valuable hypoglycemic and hypolipidemic functions. [ABSTRACT FROM AUTHOR]

The objective of this current study was to investigate the possible hyperlipidemic and antioxidative effects of Cystoseira crinita sulfated polysaccharide (CCSP) in rats fed with a high-fat diet, exhibited an inhibitory activity on pancreatic lipase in vitro . In vivo administration of this extract to HFD-rats lowered body weight and potentially inhibited key enzymes of lipid metabolism and absorption as lipase activity in both plasma and small intestine, which led to a notable decrease of blood LDL- cholesterol (LDL-Ch) and triglycerides (TG) levels, and an increase in HDL-cholesterol (HDL-Ch) levels in HFD-rats. CCSP was also observed to protect the liver-kidney functions efficiently, by decreasing of aspartate transaminase (AST), alanine transaminase (ALT), lactate dehydrogenase (LDH) and Creatine phosphokinase (CPK) activities and creatinine, albumin, T-bilirubin, uric acid, and urea rates in plasma. The histological analysis of liver and kidney tissues further established the positive effect of CCSP. [ABSTRACT FROM AUTHOR]

A sulfated polysaccharide was successfully isolated from Cymodocea nodosa (CNSP). This is the first report that indicates the chemical composition, structural characterization, functional and antihypertensive properties of this polysaccharide. The CNSP consisted mainly of sulfate (23.17%), total sugars (54.90%), galactose (44.89%), mannose (17.30%), arabinose (12.05%), xylose (9.18%), maltose (1.07%) and uronic acid (11.03%) with low water activity (0.49). CNSP had an XRD pattern that was typical for a semi-crystalline polymer with homogeneous structure. It also displayed an important anti-hypertensive activity (IC 50 = 0.43 mg ml) with a dose-dependent manner using a synthetic substrate, N-hippuryl-His-Leu hydrate salt (HHL). Overall, the results indicate that CNSP have attractive chemical, functional and biological properties, with a preliminary structural may have a backbone of branched 6-O-sulfated (1 → 4) galactosidic linkages, which can be considered in the future as alternative additive in various foods, cosmetic and pharmaceutical preparations. [ABSTRACT FROM AUTHOR]

Obesity is a serious health problem that increases the risk of many complications, including diabetes and cardiovascular disease. This study aims to evaluate, for the first time, the effects of oxaziridine 3 on lipoprotein lipase activity in the serum of rats fed with a high-fat diet (HFD) on body weight, lipid profile and liver-kidney functions. The administration of oxaziridine 3 to HFD-rats lowered body weight and inhibited the lipase activity of obese rats leading to notable decrease of T-Ch, TGs and LDL-Ch levels accompanied with an increase in HDL-Ch concentration in serum. Moreover, the findings of this study revealed that oxaziridine 3 helped to protect liver tissue from the appearance of fatty cysts. Additionally, oxaziridine 3 administration to HFD-rats induces antioxidant activity proven by the increase of superoxide dismutase (SOD) and catalase (CAT) activities and the decrease in Thiobarbituric acid reactive substances (TBARS) levels. It also induces the protection of liver-kidney functions confirmed by a decrease in the levels of toxicity parameters in blood. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate the purification and biochemical characterization of a new extracellular alkaliphilic and thermostable pectate lyase (Pel-20) isolated from Actinomadura keratinilytica strain Cpt20. Pure protein was obtained after sequential chromatographies on a fast performance liquid chromatography (FPLC) and high performance liquid chromatography (HPLC) columns. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) analysis revealed that the purified enzyme was a monomer with a molecular mass of 34125.11-Da. The enzyme had an NH 2 -terminal sequence of GFATNQGGTTGGAGGTLS, thus, sharing high homology with actinomycetes pectate lyase family. The results showed that this enzyme was completely inhibited by EDTA, which supports its belonging to the pectate lyase superfamily. It showed optimum activity at pH 10.5 and 70 °C. The thermoactivity and thermostability of Pel-20 were enhanced in the presence of 1 mM Ca 2+ . Its half-life times at 70, 80, 90, and 100 °C were 18, 12, 7, and 2 h, respectively. Its kinetic parameters, K m and V max values were 0.45 mM and 21,700 U/mg, respectively. Low-esterified pectin was the optimum substrate for the Pel-20. However, higher-esterified pectin was also weakly cleaved. Overall, the alkaliphilicity and thermostability properties of Pel-20 make it a potential candidate for future application in industrial bioprocesses. [ABSTRACT FROM AUTHOR]

Alfa fibres, which are generally extracted from the leaf of a plant belonging to the Poaceae family ( Stipa tenacissima L), originating from the center of Tunisia, are mainly used for pulp and paper applications. Their potential use as reinforcement in polymer composites requires the understanding of their microstructure and mechanical properties and a proper control of fibre extraction and transformation processes. This work investigates the morphology of the alfa plant (leaves and fibres) through optical and electron microscopy. The extraction process combining mechanical, chemical and enzymatic stages and the reaction time of the enzymes have been optimised to achieve the highest mechanical properties of fibres. The effect of enzymatic treatments (laccase, pectinases and xylanases) on the morphological, chemical composition and mechanical properties of alfa fibres was investigated and the effectiveness of enzymatic treatments has been evaluated. The chemical compositions of alfa are correlated with its mechanical properties. The result indicates that the tensile properties of isolated fibres were greatly improved when an optimised enzymatic-based process is used to separate the fibres from the leaves. Using pectinase and xylanase activities, results show really high mechanical properties, with an average rigidity and strength up to, respectively, 66 GPa and 1300 MPa, which make alfa fibre promising reinforcements for load-bearing composite materials. This work also showed that enzymes offer an attractive and eco-friendly approach to efficiently extract high-performance plant fibres. [ABSTRACT FROM AUTHOR]

Abstract: Crude extracts from the fruit of Lycium shawii, a plant collected from the south of Tunisia, were screened for their in vitro antioxidant, antimicrobial and antifungal activities. The dried fruits were extracted with EtOH and an aqueous suspension of the obtained EtOH extract was partitioned successively with CHCl3, CH2Cl2, EtOAc and n-BuOH, leaving residual water extract. Total phenolic content of extracts from these fruits were also determined. β-Carotene bleaching assay and Folin–Ciocalteu reagent were used to determine total antioxidant activity and total phenols of fruit extracts. Total phenolic and flavonoid contents varied from 100 to 377mg GAE/g DW and 3.3–110.6mgquercetin/gDW, respectively. Several extracts showed high antioxidant capacity and an antimicrobial activity against different strains. This is, to our knowledge, the first report on the detail chemical composition, antioxidant and antimicrobial activities of L. shawii extracts. The results provided evidence that the studied fruit might indeed be potential sources of natural antioxidant and antimicrobial agents. [Copyright &y& Elsevier]

Abstract: A newly isolated bacterial strain from Tunisian thermal source was selected for its ability to produce extracellular levanase when grown on levan substrate. The optimization of carbon source, nitrogen source, temperature and initial pH of the growth medium in submerged liquid cultures were investigated. In fact, levan was found to be a good inducer of levanase enzymes. The optimal temperature and pH of the levanase activity were 40̊C and 6.4, respectively. This enzyme exhibited a remarkable stability and retained 75% of its original activity at 55̊C for more than 1h at pH 6.4. Crude enzyme of the strain rich in levanase was established for the hydrolysis of levan in order to produce fructooligosaccharides with variable degrees of polymerization which could be used in important fields such medicine, food-processing industry and cosmetic. The extracellular levanase of the strain was then, partially purified as determined by SDS-PAGE. The purification was achieved by ammonium sulfate precipitation, gel filtration and DEAE cellulose chromatographies. [Copyright &y& Elsevier]

Abstract: A strain of Bacillus licheniformis with high exopolysaccharide (EPS) production ability was isolated and identified. A new type of EPS was isolated from the strain fermentation and its structural characteristics were investigated and elucidated by partial and total acid hydrolysis, Fourier transform infrared, and 1H and 13C NMR spectroscopy including 2D 1H, COSY, NOESY, XHCOR and HMBC experiments. Based on obtained data, the EPS was found to be a levan composed of linear chains of (2→6)-linked β-d-fructofuranosyl residues with connections β (2→6). [Copyright &y& Elsevier]

Abstract: Levan polysaccharide, a type of fructan, has been shown to favorably affect diabetes type 2 and hypercholesterolemia. Recent reports have indicated that excessive oxidative stress contributes to the development of atherosclerosis linked metabolic syndrome. The objective of this current study was to investigate the possible protection against oxidative stress linked atherosclerosis. A group of twenty four male rats was divided into four subgroups; a normal diet group (Control), normal rats received levan (L), a high-cholesterol diet group (Chol) and a high-cholesterol diet with 5% (w/w) levan group. After the treatment period, the plasma antioxidant enzymes and lipid profiles were determined. Our results show that treatment with levan positively changed plasma antioxidant enzyme activities by increasing superoxide dismutase (SOD) and catalase (CAT) by 40% and 28%, respectively, in heart. Similarly, the treatment of Chol fed groups with levan positively changed lipid profiles by decreasing total cholesterol, triglycerides and LDL-cholesterol by 50%, 38.33% and 64%, respectively. Thus may have potential antioxidant effects and could protect against oxidative stress linked atherosclerosis. [Copyright &y& Elsevier]

Abstract: The Talaromyces thermophilus strain produces only one form of lipase called TTLI. When the culture medium was concentrated and stored at 4°C during a few days, we noticed the appearance of a second short form of lipase named TTLII. This second form was purified to homogeneity using gel filtration and FPLC-Anion exchange chromatography. The NH2-terminal 24 amino acid residues were found to be identical to those of TTLI. The treatment of the TTLI with endoglycosidase H decreased its apparent molecular weight from 39 to 30kDa which corresponds to the molecular weight of TTLII. This difference was mostly attributed to the N-glycosylation of the enzyme. In fact, the glycan chain content and concavaline A–Sepharose affinity column confirmed that the TTLII was completely deglycosylated. Compared to TTLI, the TTLII activity was completely decreased over a broad range of temperature and pH. Furthermore, the deglycosylation of the enzyme reduced its specific activity by 50% toward different substrates; strongly suggest that the N-glycans are determinants for optimal catalytic activity and thermal stability of this enzyme. Covalent immobilization of the enzymes on supports suggests the involvement of the glycan moiety in enzyme–polymer interactions. In the case of TTLI the glycan moiety can constitute an extra site for the covalent linkage of the enzyme on the carrier. [Copyright &y& Elsevier]

Abstract: Biobleaching studies of kraft pulp with cellulase-free xylanase produced by Talaromyces thermophilus and commercial laccase were done in order to investigate their potential applications in various industries. The efficacy of xylanase in reducing the amount of bleaching agent needed was demonstrated by using 20 IU xylanase per gram of oven-dried pulp at 3% concentration prior to the bleaching at pH 7.0 and 70 °C for 120 min of treatment. This amount of xylanase acts on hemicelluloses; it releases chromophores and reduced sugars, and shows the further, decrease in kappa number of pulp without much change in viscosity. Also, a commercial laccase used at 40 IU per gram of oven-dry pulp at 3% concentration exhibited the optimum bleach boosting of the pulp at pH 7.0 and 50 °C after 180 min of treatment. Enzymatic treatment of pulp with the two enzymes (xylanase and laccase) required a smaller amount of chlorine to obtain the same results when pulp was treated with chlorine only. Enzymatic pretreatment of pulp followed by a chemical treatment with 3% NaOCl makes it possible to obtain the same results with chemicals at 7% NaOCl, resulting in 42% reduction in chlorine consumption. [Copyright &y& Elsevier]

Abstract: Levan polysaccharide, a type of fructan, has been shown to have industrial applications as a new industrial gum in the fields of cosmetics, foods like dietary fiber and pharmaceutical goods. The objective of this current study was to investigate the possible hypolipidemic and antioxidative effects of levan in rats fed with a high-cholesterol diet. Animals were allocated into four groups of six rats each: a normal diet group (Control), normal rats received levan (L), a high-cholesterol diet group (Chol) and a high-cholesterol diet with a daily dose of levan equivalent to 5%. Treated hypercholesterolemic rats were administrated with levan in drinking water through oral gavage for 60 days. After the treatment period, the plasma antioxidant enzymes and lipid profiles were determined. Our results show that treatment with levan polysaccharide positively changed plasma antioxidant enzyme activities and lipid profiles (total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides) in cholesterol-rats, and thus may have potential hypolipidemic and antioxidant effects. Levan could protect against oxidative stress linked atherosclerosis and decrease the atherogenic index. [Copyright &y& Elsevier]

Abstract: A genomic bank from Talaromyces thermophilus fungus was constructed and screened using a previously isolated fragment lipase gene as probe. From several clones isolated, the nucleotide sequence of the lipase gene (TTL gene) was completed and sequenced. The TTL coding gene consists of an open reading frame (ORF) of 1083bp encoding a protein of 269 Aa with an estimated molecular mass of 30kDa. The TTL belongs to the same gene family as Thermomyces lanuginosus lipase (TLL, Lipolase®), a well known lipase with multiple applications. The promoter sequence of the TTL gene showed the conservation of known consensus sequences PacC, CreA, Hap2-3-4 and the existence of a particular sequence like the binding sites of Oleate Response Element (ORE) and Fatty acids Responsis Element (FARE) which are similar to that already found to be specific of lipolytic genes in Candida and Fusarium, respectively. Northern blot analysis showed that the TTL expression was much higher on wheat bran than on olive oil as sole carbon source. Compared to the Lipolase®, this enzyme was found to be more efficient for the hydrolysis and the synthesis of esters; and its synthetic efficiency even reached 91.6% from Waste Cooking Oil triglycerides. [Copyright &y& Elsevier]

Abstract: This study aimed to evaluate the effect of a polysaccharide named levan, which was produced by new isolated bacteria, on oxidative stress and hyperglycemia in alloxan-induced diabetic rats. Levan polysaccharide was given in drinking water for 60 days at a daily dose equivalent to 2%. The oral administration of levan in diabetic rats caused a decrease in glucose level in plasma and an increase of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities in both pancreas and liver. Furthermore, a protective action against hepatic and pancreatic toxicity in diabetic rats was clearly observed. Furthermore, a significant decrease in hepatic and pancreatic indices toxicity was observed, i.e., alkalines phosphatases (ALP), aspartate and lactate transaminases (AST and ALT), lactate deshydrogenases (LDH) activities and the thiobarbituric acid-reactive substances (TBARs). These beneficial effects of levan were confirmed by histological findings in hepatic and pancreatic tissues of diabetic rats. This study demonstrates for the first time that levan is efficient in inhibiting hyperglycemia and oxidative stress induced by diabetes and suggests that administration of levan may be helpful in the prevention of diabetic complications associated with oxidative stress. [Copyright &y& Elsevier]

Abstract: This study aims to examine the effects of polysaccharide levan on oxidative stress and hyperglycemia in alloxan-induced diabetic rats. Levan, used in this study, was a microbial levan synthetisized by a non pathogenic bacteria recently isolated and identified as Bacillus licheniformis. Animals were allocated into four groups of six rats each: a control group (Control), diabetic group (Diab.), normal rats received levan (L) and diabetic rats fed with levan (DL). Treated diabetic rats were administrated with levan in drinking water through oral gavage for 60 days. The administration of polysaccharide levan in diabetic rats caused a significant increase in glycogen level by 52% and a decrease in glucose level in plasma by 52%. Similarly, the administration of polysaccharide levan in diabetic rats caused a decrease in the thiobarbituric acid-reactive substances (TBARS) by 31%, 41%, 39% and 25%, an increase in superoxide dismutase (SOD) by 40%, 50%, 44% and 34%, and in catalase (CAT) by 18%, 20%, 12% and 18% in liver, kidney, pancreas and heart, respectively. Furthermore, a significant decrease in hepatic and renal indices toxicity was observed, i.e. alkalines phosphatases (ALP), aspartate and lactate transaminases (AST and ALT) activities, total bilirubin, creatinine and urea levels by 19%, 31%, 32%, 36%, 37% and 23%, respectively. The results show that administration of polysaccharide levan can restore abnormal oxidative indice near normal levels. This study demonstrates, for the first time, that polysaccharide levan is efficient in inhibiting hyperglycemia and oxidative stress induced by diabetes and suggests that levan supplemented to diet may be helpful in preventing diabetic complications in adult rats. [Copyright &y& Elsevier]

Abstract: The filamentous fungus Penicillium occitanis produces a complete set of cellulolytic enzymes needed for efficient solubilization of native cellulose. Cellobiohydrolase I (CBHI), the most abundant cellulolytic enzyme produced by this micro-organism, has been purified and characterized. In this report, the cDNA encoding this enzyme, isolated from a cDNA bank of P. occitanis, and the equivalent genomic sequence have been cloned. DNA sequencing revealed that the cbh1 gene is intronless and has an open reading frame of 1587bp encoding a putative polypeptide of 529 amino acids. This polypeptide has a predicted molecular mass of 52.5kDa and consists of a fungal cellulose binding module (CBM) and a catalytic module, linked together by a serine–threonine-rich region. Northern blot analysis showed that cbh1 mRNA expression is partially constitutive since, besides being highly induced by cellulose, it is slightly repressed by glucose. Comparative investigation of different cellobiohydrolases I 3D structures by molecular modelling showed that poor hydrogen bonding, together with a more open configuration of the active site account for the weak binding and the relative insensitivity of P. occitanis CBHI to product inhibition. [Copyright &y& Elsevier]

• Biodiesel-derived crude glycerol characterization. • Oleaginous yeast selection for crude glycerol bioconversion. • Statistical optimization of yeast culture conditions to enhance lipid yield. • Kinetics of biomass and lipid production under optimal conditions. • Microbial lipid profile and biodiesel characterization. In recent years, much attention has been paid to microbial lipids as promising raw materials for biodiesel production. The use of industrial by-products as carbon sources seems to be a feasible strategy for cost-effective lipid fermentation with oleaginous microorganisms on a large scale. In this work, biodiesel-derived crude glycerol was used as a renewable feedstock for microbial lipid production. Chemical characterization has shown that used crude glycerol sample is mainly composed of 64.5 % glycerol, 5.9 % methanol, 11 % water and 5.8 % ash in addition to other impurities. This industrial waste was used as only carbon source in the culture media of 13 oleaginous yeast strains. Candida viswanathii Y-E4 stood out above the other strains, achieving a higher amount of biomass and lipid content (17.2 g/L and 41 %, respectively). Culture conditions were optimized using response surface methodology to enhance the Y-E4 lipid yield. Box-Behnken model was performed to determine the optimum levels of three independent variables and the eventual effect of their interactions on the response. Under optimal conditions, the total biomass of 26.6 g/L with lipid content of 51.9 % (corresponding to a lipid yield of 13.6 g/L) could be achieved after 166 h of culture. The characterization of obtained lipid showed that fatty acids composition and lipid profile were very different between pure and crude glycerol based cultures, with a predominance of long-chain fatty acids, particularly polyunsaturated fatty acids such as linoleic acid (45 %). The predictive determination of biodiesel properties suggests that this oil may effectively be used for biodiesel manufacture. The current study, therefore, opens new perspectives in relation to the valorization of biodiesel-derived crude glycerol, through completely eco-friendly processes. [ABSTRACT FROM AUTHOR]