Intrinsic Activity of Inulinase from Kluyveromyces marxianus ATCC 16045 and Carbon and Nitrogen Balances

Bernardo Onagar Yépez Silva-Santisteban¹, Attilio Converti²* and Francisco Maugeri Filho<sup>1

1</sup>Department of Food Engineering, FEA-University of Campinas, Campinas, SP, CEP 13083-970, CP 6121, Brazil
²Department of Chemical and Process Engineering »G.B. Bonino«, University of Genoa, Via Opera Pia 15, I–16145 Genoa, Italy

Article history:
Received October 19, 2005
Accepted February 17, 2006

Key words:
carbon source, nitrogen source, inulinase production, Kluyveromyces marxianus

Summary:
Kluyveromyces marxianus ATCC 16045 was cultivated in a batch on minimal medium to overproduce inulinase. The fermented broth was purified by fast protein liquid chromatography and ultrafiltration, and a pure enzyme fraction was obtained. SDS-PAGE electrophoresis allowed calculating molecular mass of 59 kDa, while nitrogen determination by the micro-Kjeldahl method allowed evaluating intrinsic inulinase activity of 879 IU/mg. These results were then used to perform material balances of the fermentation process, which suggested that no more than 0.1 % either of carbon or nitrogen initially present in the medium were incorporated in the extracellular inulinase released under different cultivation conditions. The information obtained in this study can be used for future proposal of metabolic models describing inulinase overproduction by this yeast.

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