Extrato e farinha de yacon como fontes de carbono para produção de inulinase pela levedura Kluyveromyces marxianus NRRL Y-7571

Abstract

The yacon (Smallanthus sonchifolius) is a herbaceous plant of the Asteraceae family that has received much attention for being a rich source of fructo- oligosaccharides, which are considered functional ingredients. However there are few studies in the literature that use this plant as substrate for substances production of industrial interest by fermentation. This work aimed to study the production of enzyme inulinase by Kluyveromyces marxianus NRRL Y-7571 by batch fermentation using the crude extract and flour of yacon tubers. Were investigated the effects of extract and flour of yacon concentrations as carbon source, corn steep liquor as nitrogen source and pH on the inulinase and biomass production, utilizing the Central Composite Rotational (CCR) design 22. Maximum enzymatic activity was 36.1 U/ mL and biomass was 8.95 g/L obtained in the condition of 7% of yacon flour and 2% of corn steep liquor. For the yacon extract the best fermentation condition was 55% and pH 5.5, reaching enzymatic activity of 14.48 U / mL and biomass of 9.03 g/ L. Partial characterization of inulinase, produced in both substrates, showed that the optimum pH was reached at 4.0 and optimum temperature at 60 ºC. The results of thermal stability tests showed that the enzyme retained more than 95% of its enzymatic activity for 3 hours at 45 °C and above 90% for 4 hours at 50 °C. The analysis showed that the responses have adjusted well to the statistical model, especially taking into account the great variability inherent in biological processes involving enzymes and micro-organisms, especially when using complex substrates such as fermentation substrates.