Nisakorn Worawuthiyanan

Kasetsart University, Krung Thep, Bangkok, Thailand

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Publications (2)1.35 Total impact

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    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 ∼100g l−1 and the enzyme concentration of 0.2Ug−1 of substrate, yielded 37.5gl−1 of fructose in 20h at 40°C when A. niger TISTR 3570 inulinase was the biocatalyst. The yield of fructose on inulin was 0.39gg−1. Under identical conditions, the yeast inulinase afforded 35.3gl−1 of fructose in 25h. The fructose yield was 0.35gg−1 of substrate. The fructose productivities were 1.9g l−1h−1 and 1.4gl−1h−1 for the mold and yeast enzymes, respectively. After 20h 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 25h and nearly 36% of initial inulin had been hydrolysed. The A. niger TISTR 3570 inulinases exhibited both endo-inulinase and exo-inulinase activities. In contrast, the yeast inulinases displayed mainly exo-inulinase activity. The mold and yeast crude inulinases mixed in the activity ratio of 5:1 proved superior to individual crude inulinases in hydrolysing inulin to fructose. The enzyme mixture provided a better combination of endo- and exo-inulinase activities than did the crude extracts of either the mold or the yeast individually.
    World Journal of Microbiology and Biotechnology 03/2007; 23(4):543-552. · 1.35 Impact Factor
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    ABSTRACT: Inulin is an industrially important fructan. Inulin hydrolysis by inulinases has been applied in the production of fructose in a single step. In previous studies, Aspergillus niger TISTR 3570 and Candida guilliermondii TISTR 5844 were screened and selected as the best producers of inulinases. The productions of fructose from inulin using inulinases produced from these two microorganisms were investigated in this study. It was found that the inulinases from Aspergillus niger TISTR 3570 showed both exo-and endo-activities which rapidly cleave the high inulin, while the inulinases from Candida guilliermondii TISTR 5844 only showed exo-activity which sequentially splits off fructose from nonreducing end of inulin. From different mechanism, the production of fructose from inulin using mixed-inulinases from Aspergillus niger TISTR 3570 and Candida guilliermondii TISTR 5844 in 1:1 inulinase activity ratio was investigated. The results showed that the maximum yield (Y F/S = 0.56 g/g) was obtained from this system, which were 1.44 and 1.60 times higher than those of the single-inulinases, Aspergillus niger TISTR 3570 and Candida guiliermondii TISTR 5844, respectively. These results suggested a great potential of application to sweetener industry. Objectives The aims of this study were to study the production of fructose from inulin using inulinases from selected strains and to investigate the efficient of fructose production by using the mixed-inulinases.