title: Pectinolytic enzymes secreted by yeasts from tropical fruits.
abstract: Three hundred yeasts isolated from tropical fruits were screened in relation to secretion of pectinases. Twenty-one isolates were able to produce polygalacturonase and among them seven isolates could secrete pectin lyase. None of the isolates was able to secrete pectin methylesterase. The pectinolytic yeasts identified belonged to six different genera. Kluyveromyces wickerhamii isolated from the fruit mangaba (Hancornia speciosa) secreted the highest amount of polygalacturonase, followed by K. marxianus and Stephanoascus smithiae. The yeast Debaryomyces hansenii produced the greatest decrease in viscosity while only 3% of the glycosidic linkages were hydrolysed, indicating that the enzyme secreted was an endo-polygalacturonase. The hydrolysis of pectin by polygalacturonase secreted by S. smithiae suggested an exo-splitting mechanism. The other yeast species studied showed low polygalacturonase activity.
authors.affiliation: Biology Department, Federal University of Lavras, MG, Brazil.
authors.forename: Evânia Geralda
authors.initials: EG
authors.lastname: da Silva
authors.forename: Maria
authors.initials: M
authors.lastname: de Fátima Borges
authors.forename: Clara
authors.initials: C
authors.lastname: Medina
authors.forename: Roberta Hilsdorf
authors.initials: RH
authors.lastname: Piccoli
authors.forename: Rosane Freitas
authors.initials: RF
authors.lastname: Schwan
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000302:isolation & purification / Q000378:metabolism; D005638:Fruit / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D011096:Polygalacturonase / Q000302:isolation & purification* / Q000378:metabolism; D011133:Polysaccharide-Lyases / Q000302:isolation & purification* / Q000378:metabolism; D015003:Yeasts / Q000201:enzymology*
chemical_list: D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; D011096:Polygalacturonase; D011133:Polysaccharide-Lyases; C027349:pectin lyase