Production of useful oligosaccharides from unused polysaccharides by microbial enzymes

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Oligo-saccharides attract much attention for their physiological function such as anticarious activity, prevention of constipation and of accumulation of plasma cholesterol, and low calorie sweetener etc. It has also been shown that oligo-saccharides are excellent health-care compounds for plants and microbes. As the importance of oligo-saccharides is recognized, it is apparent that development of their production methods becomes important. Thus, we initiated to study oligo-saccharides production by microbial processes using inexpensive starting materials such as inulin and levan. We isolated many microbes degrading inulin or levan from soil samples, and screened oligo-saccharides producers.1. Oligo-saccharides production from inulin : Arthrobacter sp.H65-7 producing difructose anhydride III (DFA III) was shown to convert DFA III into inulobiose by an intracellular DFA III-degrading enzyme. Inulobiose production from DFA III is possible with whole cell reaction. Streptomyces rochei E87 was found to produce an extracellular enzyme degrading inulin into inulotriose in an exo-manner. We have purified this enzyme and clarified its enzymatic properties.2. Oligo-saccharides production from levan : Streptomyces exfoliatus F3-2 and Arthrobacter nicotinovorans SG9 were found to produce levanbiose and DFA IV,respectively. Levanbiose-producing enzyme was purified and its enzymatic properties were investigated.3. Oligo-saccharides production by transfer reaction of degrading enzyme : Arthrobacter sp.MS9 produces a levanbiose-producing enzyme that transfer fructose residue of inulobiose to reducing-terminal fructose of inulobiose by beta2-6 linkage forming a novel trisaccharide.