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    Screening of yeast strains for pectinolytic activity: Effects of different carbon and nitrogen sources in submerged fermentations
    (Science Publications, 2015) Oskay M.; Yalçin H.T.
    Twenty yeast strains were screened for pectinolytic activity, among the strains, only nine were positive for pectinase production. The best strain was Kluyveromyces marxianus NRRL-Y-1109 which gave high quantities of pectinase activity, by submerged fermentation. Different parameters such as incubation time, pH (3.5-7), temperature (20-45°C), nitrogen and carbon source, were optimized. The optimal incubation time, temperature and pH for pectinase production were found to be 48 h, 30°C and 6, respectively. Studies were conducted on the production of pectinase in submerged fermentation using agro-industrial residues such as wheat bran, grape waste, brewer's malt, beet molasses and corncob at a concentration of 1.5% (wt./vol.). Under optimized fermentation conditions, maximal enzyme were produced when citrus pectin (4.8 U/mL) was used as the carbon source, but high enzyme production was also obtained on wheat bran (2.2 U/mL) and grape waste (1.8 U/mL) in shaking conditions (120 rpm) for 48 h. Peptone and yeast extract used together as nitrogen source gave best enzyme production. The effects of temperature (30-70°C), pH (3.5-8) and salt concentration (1, 2, 5 and 10%) on the pectinase activity were determined. The optimum activity was obtained when temperature 45°C and pH at 5.5. The enzyme was stable at 45°C for more than 50 min, suggesting that it is relatively thermostable and being of interests for food processing. © 2015 Mustafa Oskay and Hüsniye Tansel Yalçin.