Authors: Sarote Sirisansaneeyakul Nisakorn Worawuthiyanan Wirat Vanichsriratana Penjit Srinophakun Yusuf Chisti
Publish Date: 2006/09/06
Volume: 23, Issue: 4, Pages: 543-552
Abstract
Two new effective microbial producers of inulinases were isolated from Jerusalem artichoke tubers grown in Thailand and identified as Aspergillus niger TISTR 3570 and Candida guilliermondii TISTR 5844 The inulinases produced by both these microorganisms were appropriate for hydrolysing inulin to fructose as the principal product An initial inulin concentration of ∼100 g l−1 and the enzyme concentration of 02 U g−1 of substrate yielded 375 g l−1 of fructose in 20 h at 40°C when A niger TISTR 3570 inulinase was the biocatalyst The yield of fructose on inulin was 039 g g−1 Under identical conditions the yeast inulinase afforded 353 g l−1 of fructose in 25 h The fructose yield was 035 g g−1 of substrate The fructose productivities were 19 g l−1 h−1 and 14 g l−1 h−1 for the mold and yeast enzymes respectively After 20 h of reaction the mold enzyme hydrolysate contained 53 fructose and more than 41 of initial inulin had been hydrolysed Using the yeast enzymes the hydrolysate contained nearly 38 fructose at 25 h and nearly 36 of initial inulin had been hydrolysed The A niger TISTR 3570 inulinases exhibited both endoinulinase and exoinulinase activities In contrast the yeast inulinases displayed mainly exoinulinase activity The mold and yeast crude inulinases mixed in the activity ratio of 51 proved superior to individual crude inulinases in hydrolysing inulin to fructose The enzyme mixture provided a better combination of endo and exoinulinase activities than did the crude extracts of either the mold or the yeast individuallyThis research was financially supported by the Department of Biotechnology Faculty of AgroIndustry Kasetsart University Thailand Partial support also came from the Graduate School of Kasetsart University The authors wish to thank the Department of Food Science and Technology Faculty of AgroIndustry Kasetsart University and the Research and Development Institute for Agricultural Systems under Adverse Conditions IASAC Kasetsart University for the kind contributions of chromatographic equipment and Jerusalem artichoke tubers respectively
Keywords: