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1.  Enzymatic transesterification of palm stearin and olein blends to produce zero-trans margarine fat 
BMC Biotechnology  2012;12:48.
Food industries aim to replace trans fat in their products by formulations having equivalent functionality and economic viability. Enzymatic transesterification can be a technological option to produce trans free fats targeting commercial applications.
Palm stearin and palm olein blends in different ratios were enzymatically transesterified in a solvent free system using a Rhizopus oryzae lipase immobilised onto CaCO3 to produce a suitable fat for margarine formulation. Slip melting points and triacylglycerols profiles were evaluated upon transesterification. Results indicated that all transesterified blends had lower slip melting points than their non transesterified counterparts. Furthermore, the triacylglycerols profile showed a decrease in the concentration of the high melting point triacylglycerols. The rheological analysis showed that margarine prepared with the transesterified blend showed a better spreadability than that of a control margarine prepared with non transesterified fat. Adding powder of dry bark orange to margarine preparation improved its colour and fairly affected its spreadability and rheological behaviour. The margarine prepared with transesterified fat displayed a rheological behaviour that was comparable to that of commercial sample.
This study is an ecofriendly approach to the utilization of relatively low value bioresources like palm stearin and palm olein for making margarine free of trans fatty acids that are now implicated as risk factor for heart diseases.
PMCID: PMC3469396  PMID: 22889174
2.  Decolorization of the azo dye Acid Orange 51 by laccase produced in solid culture of a newly isolated Trametes trogii strain 
3 Biotech  2012;3(2):115-125.
This study concerns the decolorization and detoxification of the azo dye Acid Orange 51 (AO51) by crude laccase from Trametes trogii produced in solid culture using sawdust as support media. A three-level Box–Behnken factorial design with four factors (enzyme concentration, 1-hydroxybenzotriazole (HBT) concentration, dye concentration and reaction time) combined with response surface methodology was applied to optimize AO51 decolorization. A mathematical model was developed showing the effect of each factor and their interactions on color removal. The model predicted that Acid Orange 51 decolorization above 87.87 ± 1.27 % could be obtained when enzyme concentration, HBT concentration, dye concentration and reaction time were set at 1 U/mL, 0.75 mM, 60 mg/L and 2 days, respectively. The experimental values were in good agreement with the predicted ones and the models were highly significant, the correlation coefficient (R2) being 0.9. Then the desirability function was employed to determine the optimal decolorization condition for each dye and minimize the process cost simultaneously. In addition, germination index assay showed that laccase-treated dye was detoxified; however in the presence of HBT, the phytotoxicity of the treated dye was increased. By using cheap agro-industrial wastes, such as sawdust, a potential laccase was obtained. The low cost of laccase production may further broaden its application in textile wastewater treatment.
Electronic supplementary material
The online version of this article (doi:10.1007/s13205-012-0076-2) contains supplementary material, which is available to authorized users.
PMCID: PMC3597134
Crude laccase; Synthetic textile dyes; Mediators; Optimization; Box–Behnken; Decolorization; Detoxification
3.  Optimization of Acid Protease Production by Aspergillus niger I1 on Shrimp Peptone Using Statistical Experimental Design 
The Scientific World Journal  2012;2012:564932.
Medium composition and culture conditions for the acid protease production by Aspergillus niger I1 were optimized by response surface methodology (RSM). A significant influence of temperature, KH2PO4, and initial pH on the protease production was evaluated by Plackett-Burman design (PBD). These factors were further optimized using Box-Behnken design and RSM. Under the proposed optimized conditions, the experimental protease production (183.13 U mL−1) closely matched the yield predicted by the statistical model (172.57 U mL−1) with R2 = 0.914. Compared with the initial M1 medium on which protease production was 43.13 U mL−1, a successful and significant improvement by 4.25 folds was achieved in the optimized medium containing (g/L): hulled grain of wheat (HGW) 5.0; KH2PO4 1.0; NaCl 0.3; MgSO4(7H2O) 0.5; CaCl2 (7H2O) 0.4; ZnSO4 0.1; Na2HPO4 1.6; shrimp peptone (SP) 1.0. The pH was adjusted at 5 and the temperature at 30°C. More interestingly, the optimization was accomplished using two cheap and local fermentation substrates, HGW and SP, which may result in a significant reduction in the cost of medium constituents.
PMCID: PMC3349213  PMID: 22593695
4.  Enhanced decolourization of the azo dye Sirius rose BB by laccase–HBT system 
3 Biotech  2011;2(2):149-157.
Response surface methodology (RSM) was applied to optimize the decolourization of the diazo dye Sirius rose BB (SR) by crude laccase from the white-rot fungus Trametes sp. strain CLBE55. A Box–Behnken design using RSM with six variables, namely pH, incubation temperature, enzyme (laccase) concentration, 1-hydroxybenzotriazol (HBT) concentration, dye concentration and incubation time was used in this study to determine significant correlations between the effects of these variables on the decolourization of Sirius rose. The optimum concentrations of HBT, dye and laccase were 0.5 mM, 60 mg/L and 0.1 U/mL, respectively, to obtain maximum decolourization of Sirius rose (approx. 99.5% in 150 min at 45 °C, pH 3). A quadratic model was obtained for dye decolourization using this design. Experimental values were in good agreement with values predicted by the model, giving highly significant correlations.
PMCID: PMC3376867
Laccase; Dyes; Box–Behnken; Decolourization; Response surface
5.  Immobilized Rhizopus oryzae lipase catalyzed synthesis of palm stearin and cetyl alcohol wax esters: Optimization by Response Surface Methodology 
BMC Biotechnology  2011;11:68.
Waxes are esters of long-chain fatty acids and long-chain alcohols. Their principal natural sources are animals (sperm whale oil) and vegetables (jojoba) which are expensive and not easily available. Wax esters synthesized by enzymatic transesterification, using palm stearin as raw material, can be considered as an alternative to natural ones.
Palm stearin is a solid fraction obtained by fractionation of palm oil. Palm stearin was esterified with cetyl alcohol to produce a mixture of wax esters. A non-commercial immobilized lipase from Rhizopus oryzae was used as biocatalyst. Response surface methodology was employed to determine the effects of the temperature (30-50°C), the enzyme concentration (33.34-300 IU/mL), the alcohol/palm stearin molar ratio (3-7 mol/mol) and the substrate concentration (0.06-0.34 g/mL) on the conversion yield of palm stearin. Under optimal conditions (temperature, 30°C; enzyme concentration, 300 IU/mL; molar ratio 3 and substrate concentration 0.21 g/mL) a high conversion yield of 98.52% was reached within a reaction time of 2 h.
Response surface methodology was successfully applied to determine the optimum operational conditions for synthesis of palm stearin based wax esters. This study may provide useful tools to develop economical and efficient processes for the synthesis of wax esters.
PMCID: PMC3145570  PMID: 21682865
6.  Purification and biochemical characterization of a secreted group IIA chicken intestinal phospholipase A2 
Secretory phospholipase A2 group IIA (IIA PLA2) is a protein shown to be highly expressed in the intestine of mammals. However, no study was reported in birds.
Chicken intestinal group IIA phospholipase A2 (ChPLA2-IIA) was obtained after an acidic treatment (pH.3.0), precipitation by ammonium sulphate, followed by sequential column chromatographies on Sephadex G-50 and mono-S ion exchanger. The enzyme was found to be a monomeric protein with a molecular mass of around 14 kDa. The purified enzyme showed a substrate preference for phosphatidylethanolamine and phosphatidylglycerol, and didn't hydrolyse phosphatidylcholine. Under optimal assay conditions, in the presence of 10 mM NaTDC and 10 mM CaCl2, a specific activity of 160 for purified ChPLA2-IIA was measured using egg yolk as substrate. The fifteen NH2-terminal amino acid residues of ChPLA2-IIA were sequenced and showed a close homology with known intestinal secreted phospholipases A2. The gene encoding the mature ChPLA2-IIA was cloned and sequenced. To further investigate structure-activity relationship, a 3D model of ChPLA2-IIA was built using the human intestinal phospholipase A2 structure as template.
ChPLA2-IIA was purified to homogeneity using only two chromatographic colomns. Sequence analysis of the cloned cDNA indicates that the enzyme is highly basic with a pI of 9.0 and has a high degree of homology with mammalian intestinal PLA2-IIA.
PMCID: PMC3040156  PMID: 21284884

Results 1-6 (6)