Screening for Polyphenol Oxidase in Enologically Important Yeast Cultures.

Swati, Dahariya (2013) Screening for Polyphenol Oxidase in Enologically Important Yeast Cultures. [Student Project Report] (Submitted)

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Abstract

Polyphenol oxidases are enzymes that catalyze the oxidation of phenol compounds using molecular oxygen. The ability of polyphenol oxidases to act on phenolic compounds makes them highly useful biocatalysts for various biotechnological applications. They are commonly found in animals, plants and fungi. Recent genome analysis have shown that polyphenol oxidases are also widespread in yeast species. In the present study, Saccharomyces cerevisiae (ITB), Saccharomyces (S101), Pichia kudriavzeii (P1), AP[C] and Strain C were screened and characterize polyphenol oxidase (PPO) for their pH, temperature, enzyme kinetic, substrate specificity. Further selected organisms were screened for pH and thermal stability. Spectrophotometric method was used to assay the PPO activity, by measuring the initial rate of quinone formation, as indicated by an increase in absorbance. Initial results of activity measurements of samples from intracellular and extracellular extract revealed that the enzyme was intracellular. Further work was carried out with intracellular enzymes. Result of screening revealed the P1 to produce 1.9 g/ 100ml of dry biomass & the enzyme etxracted from Strain C and P1, exhibits the maximum activity at optimum pH 5 & 7 and 20°C & 25°C. The optimum temperature achieved for enzyme production was 25oC for both organisms. Characterization studies indicated that the enzyme showed highest activity at pH 6.0 and 30ºC. Km and Vmax values for the enzyme were determined as 0.21 & 0.17 mM for Strain C and P1, respectively. As for the thermal stability studies, the PPO activity decreased with increasing temperature. Denaturation of this enzyme was measured by loss in activity. Efforts to identify strain C using morphological characters (SEM), FTIR studies and 18sR DNA were carried out. FTIR analysis indicates that the unidentified strain resembles Pichia sp. Further confirmation of molecular analysis is awaited.

Item Type:	Student Project Report
Uncontrolled Keywords:	Polyphenol oxidases, enzymes, Saccharomyces, yeast
Subjects:	600 Technology > 08 Food technology > 29 Microbiological food > 04 Yeast
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	06 May 2014 05:26
Last Modified:	06 May 2014 05:26
URI:	http://ir.cftri.res.in/id/eprint/11544

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