title: Extracellular inulinases from Penicillium janczewskii, a fungus isolated from the rhizosphere of Vernonia herbacea (Asteraceae).
abstract: Extracellular inulinases from Penicillium janczewskii were obtained from the filtrate of 12 day-old cultures supplemented with inulin from Vernonia herbacea. Crude filtrates and partially-purified enzyme preparations (peaks I and II) were active on inulin, sucrose and raffinose. The apparent M(r) of the enzymes from peaks I and II were 48 and 66 kDa, respectively. The apparent K(m) (mmol l-1) values of peak I were 0.43 for inulin and 18.7 for sucrose; for peak II they were 0.87 and 18.5 for inulin and sucrose, respectively. Their temperature and pH optima were 55 degrees C and 5.0, respectively. Both peaks catalysed the hydrolysis of beta-(2,1) fructans more rapidly than beta-(2,6) fructans. Free fructose was the predominant product released from inulin, indicating that these enzymes display exo-inulinase activity. In view of these characteristics, the yield and the high specific activity towards beta-(2,1) fructans, inulinases from P. janczewskii can be utilized for the preparation of fructose syrup from inulin.
authors.affiliation: Seção de Fisiologia e Bioquímica de Plantas, Instituto de Botânica de São Paulo, Brazil.
authors.forename: R A
authors.initials: RA
authors.lastname: Pessoni
authors.forename: R C
authors.initials: RC
authors.lastname: Figueiredo-Ribeiro
authors.forename: M R
authors.initials: MR
authors.lastname: Braga
mesh_terms: D019659:Asteraceae / Q000382:microbiology*; D005630:Fructans / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D010407:Penicillium / Q000201:enzymology* / Q000302:isolation & purification*; D018517:Plant Roots / Q000382:microbiology*; D011887:Raffinose / Q000378:metabolism; D013379:Substrate Specificity; D013395:Sucrose / Q000378:metabolism; D013696:Temperature
chemical_list: D005630:Fructans; D013395:Sucrose; D006026:Glycoside Hydrolases; C023086:inulinase; D011887:Raffinose