Ali Ghasemian; Mohammadtaghi Asadollahzadeh; Ahmadreza Saraeian; Hossein Resalati; Mohammad Taherzadeh
Abstract
Abstract Toxic compounds and inhibitors in lignocellulosic hydrolysates such as acetic acid and phenolic compounds are the major challenge for biochemical conversion of lignocellulosic materials into biofuels like bioethanol. In this study, the performance of four filamentous fungi Rhizopus oryzae, Mucor ...
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Abstract Toxic compounds and inhibitors in lignocellulosic hydrolysates such as acetic acid and phenolic compounds are the major challenge for biochemical conversion of lignocellulosic materials into biofuels like bioethanol. In this study, the performance of four filamentous fungi Rhizopus oryzae, Mucor indicus, Neurospora intermedia and Aspergilus oryzae on the fungal biomass production, sugar and acetic acid consumption as well as ethanol production was investigated in synthetic mediums containing 0, 3, 5 and 7 g/L acetic acid. The fungal biomass obtained after 48 and 72 hours cultivation showed that the rate of the fungi growth and lag phase decreased and increased by acetic acid addition into the medium, respectively. The inhibitory effect of acetic acid on M. indicus growth was higher than those of other fungi, i.e., its biomass production decreased significantly at higher concentration of acetic acid (5 g/L), while A. oryzae showed pretty good tolerance to acetic acid. The results indicated that the effect of acetic acid on the fungal biomass and ethanol production was dependent on acetic acid concentration and the fungus type which can affect positively and/or negatively on the fermentation. The ethanol concentration from A. oryzae and R. oryzae cultivation in the medium containing acetic acid was decreased and increased, respectively. According to the fermentation results, the medium containing 7 g/L acetic acid was enough to stop the fungi growth and ethanol production.
Behzad Shareghi; Maryam Kazemi Nafchi
Volume 5, Issue 1 , September 2016, , Pages 1-8
Abstract
Abstract Peroxidases are a group of oxidoreductases that are produced by a number of microorganisms and plants, and catalyse the reduction of peroxides. Peroxidases are widely used in clinical biochemistry and enzyme immunoassay. Horseradish peroxidase isoenzyme C (HRP) is one of the characterized peroxidases. ...
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Abstract Peroxidases are a group of oxidoreductases that are produced by a number of microorganisms and plants, and catalyse the reduction of peroxides. Peroxidases are widely used in clinical biochemistry and enzyme immunoassay. Horseradish peroxidase isoenzyme C (HRP) is one of the characterized peroxidases. The structure of the enzyme is largely alpha helical. Kinetics studies of peroxidase enzyme were performed using a spectrophotometer UV-Vis fitted with electronic control system at 35oC and 45oC and pH4 and in the presence ethanol and butanediol. Kinetic parameters show that ethanol and butanediol organic solvents becomes caused the increase of maximum speed (VMAX) and activity of the enzyme. Organic solvents have effect on electrostatic interactions of proteins because their dielectric constant with water is different. In general, reduce properties of polar solvents and decreased dielectric constant becomes caused the increases electrostatic repulsion, leading to the opening of the proteins. Enzymes activity in such organic environments increases stability, activity or facilitate reactions that are difficult to perform in aquatic environments.
