Synthesis of Fructan and Oligosaccharides by Microbial and Plant Fructosyltransf erasest

It was observed that a considerable amount of fructosyltransferase, levansucrase, was produced when microorganisms (Bacillus subtilis, Bacillus natto, Zymomonas mobilis, etc.) were grown on a medium containing sucrose and the activity was found in culture filtrate and cells. But most of the activity was retained by the cells together with viscous levan in the case of Bacillus natto. The cells harvested and washed with buffer after cultivation were able to be used as reactors repeatedly for the production of levan by soaking in sucrose solution. A complete liberation of the enzyme from the cells was achieved by treating with 2 M sodium chloride solution. Oligosaccharides synthesized from sucrose in the presence of some acceptor sugars were useful for screening of microorganisms which produce exo-type carbohydrases such as a-glucosidase. Low molecular weight levan synthesized under the condition of high concentration of sodium chloride (2 M) was also useful for screening the microorganisms which produced levanbiose-producing enzyme because of its few branchings. The low molecular levan may be useful as a carbon source for finding enzyme having special specificity such as producing cyclic f ructan. Sucrase (β-fructofuranosidase) obtained from microorganisms produced mainly 1-kestose except yeast invertase, which produced mainly 6-kestose; levansucrase produced three types of kestose (1-kestose, neokestose and 6-kestose) and levan, regardless of enzyme source.