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    New lipase for biodiesel production: Partial purification and characterization of LipSB 25-4
    (Hindawi Publishing Corporation, 2014) Uğur, Aysel; Saraç, Nurdan; Boran, Rukiye; Ayaz, Berk; Ceylan, Özgür; Ökmen, Gülten
    The lipolytic activities of 300 Streptomyces isolates were determined in Tributyrin and Rhodamine-B Agar. Lipase activities were also measured with p-nitrophenyl palmitate (p-NPP) as a substrate. The strain of Streptomyces bambergiensis OC 25-4 used in this study was selected among 300 strains of Streptomyces from MUCC as the best lipase producer. The incubation conditions were optimized and the inoculum amount, incubation period, effect of carbon and nitrogen sources, and rates of MgSO4 and CaCO3 were investigated. LipSB 25-4 (the lipase produced by S. bambergiensis OC 25-4 strain) was partially purified with ammonium sulphate precipitation, dialysis, and gel filtration chromatography 2.73-fold and with 92.12 U/mg specific activity. The optimal pH and temperature for LipSB 25-4 were determined as 8.0 and 50°C, respectively. The lipase has high stability in all pH and temperature values used in this study. While LipSB 25-4 was slightly activated in the presence of ?-mercaptoethanol, it was slightly reduced by PMSF. The enzyme conserved approximately 75% of its activity at the end of 60 h, in the presence of methanol and ethanol. Since LipSB 25-4 displays high activity in the thermophilic conditions and stability in the presence of organic solvents, this lipase can catalyse the biodiesel production from olive oil by the transesterification reactions.
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    Purification and characterization of organic solvent-tolerant lipase from Streptomyces sp. OC119-7 for biodiesel production
    (Elsevier, 2015) Ayaz, Berk; Uğur, Aysel; Boran, Rukiye
    This study determined the lipolytic activity of Streptomyces isolates and then purified and characterized the lipase obtained from Streptornyce.s sp. OC 119-7, the isolate demonstrated to have the high lipolytic activity. Ammonium sulfate precipitation and gel filtration chromatography were used to purify the extracellular alkaline lipase obtained from StTeptornyces sp. OC 119-7, and resulted in 5.52-fold purification with 68.055 U/mg specific activity. The enzyme showed optimal activity at pH 8.0 and 50 degrees C, with stability in a temperature range of 40-60 degrees C and at pHs of >= 7. Enzyme activity was enhanced by the presence of Ca2+ and Mg2+ and inhibited by the presence of Mn2+, Co2+, Cu2+, Zn2+, K+, Na+ and PMSF. OC 119-7 lipase displayed stability against surfactants and organic solvents. Lip0C 119-7 catalyzed transesterification of olive oil with methanol, suggesting that this lipase may be a potential enzymatic catalyst for biodiesel production. (C) 2014 Elsevier Ltd. All rights reserved.