Screening of Yeast Strains for Pectinolytic Activity: Effects of Different Carbon and Nitrogen Sources in Submerged Fermentations | Science Publications

摘要

> >Twenty yeast strains were screened for pectinolyticactivity, among the strains, only nine were positive for pectinase production.The best strain was Kluyveromyces marxianus NRRL-Y-1109 which gave highquantities of pectinase activity, by submerged fermentation. Differentparameters such as incubation time, pH (3.5-7), temperature (20-45°C), nitrogen and carbon source, were optimized. Theoptimal incubation time, temperature and pH for pectinase production were foundto be 48 h, 30°C and 6, respectively.Studies were conducted on the production of pectinase in submerged fermentationusing agro-industrial residues such as wheat bran, grape waste, brewer's malt,beet molasses and corncob at a concentration of 1.5% (wt./vol.). Underoptimized fermentation conditions, maximal enzyme were produced when citruspectin (4.8 U/mL) was used as the carbon source, but high enzyme production wasalso obtained on wheat bran (2.2 U/mL) and grape waste (1.8 U/mL) in shakingconditions (120 rpm) for 48 h. Peptone and yeast extract used together asnitrogen 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 activitywere determined. The optimum activity was obtained when temperature 45°C and pHat 5.5. The enzyme was stable at 45°C for more than 50 min, suggesting that itis relatively thermostable and being of interests for food processing.