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Extracellular inulinases from Penicillium janczewskii, a fungus isolated from the rhizosphere of Vernonia herbacea (Asteraceae)

Pessoni, R.A.B., Figueiredo-Ribeiro, R.C.L., Braga, M.R.
Journal of applied microbiology 1999 v.87 no.1 pp. 141-147
Penicillium, Vernonia, enzymes, filtrates, fructose, fungi, hydrolysis, inulin, pH, raffinose, rhizosphere, sucrose, syrups, temperature
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.