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Articles by E.H.M. Melo
Total Records ( 2 ) for E.H.M. Melo
  M.C.B. Pimentel , A.B.F. Leao , E.H.M. Melo , W.M. Ledingham , J.L. Lima Filho and J.F. Kennedy
  The immobilization of Penicillium citrinum lipase by covalent bond onto ferromagnetic azide-Dacron showed 73% of specific lipase activity retention with 7.3 mg protein/g support. There was no change in either optimal temperature (37°C) or pH (8.0-8.5) after immobilization. The thermal stability of ferromagnetic azide-Dacron-Penicillium citrinum lipase derivative was significant, retaining 86.8% of lipolytic activity while the soluble enzyme retained only 34.2% after 1 h at 45°C, this represented an improvement of 154% in the thermal stability. This lipase did not show inhibition by isopropanol. Both soluble and immobilized Penicillium citrinum lipases showed a kinetic of Michaellis-Menten to hydrolysis of 4-nitrophenyl palmitate of (4NPP) at 37°C and pH 8.0. The values of KM were for soluble enzyme of 233 μM and immobilized derivative of 276 μM. This immobilized derivative showed a good operational stability keeping about 75% of initial activity after its reuse for 5 times. Also, it was stable to storage at 4°C in Tris-HCl buffer pH 7.2 with a half-life of 25 days. Immobilized Penicillium citrinum lipase was able to catalyse the synthesis of triolein using glycerol and olive oil as substrates free of organic solvent, with 80% of conversion after 20 h at 40°C.
  M.M. Camargo de Morais , S.A.F. Ramos , M.C.B. Pimentel , E.H.M. Melo , M.A. Morais Jr , J.F. Kennedy and J.L. Lima Filho
  A Brazilian strain of Penicillium citrinum produced a lipopolysaccharide with emulsifier properties during cultivation on mineral medium, containing ammonium sulfate as nitrogen source, with 1% (v/v) olive oil as the carbon source. The maximal emulsifier production (1.6 U mL-1) was obtained after 60 h of cultivation and the biomass reached 7.5 g L-1 at the end of fermentation. The production yield i.e. the amount the carbon source utilized for product synthesis was 54% and the best emulsifying activity was observed for xylene and diesel oil when compared to other carbohydrates tested. The emulsifier was shown to be stable to a wide range of pH and temperature values and was shown to contain D-galactose, D-glucose and D-xylose (8.2:1.0:5.3) with a total carbohydrate content of 43%. The presence of salts stimulated the emulsification activity, suggesting potential for its application in industrial waste or marine remediation.
 
 
 
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