Studies on Glucose Isomerase of Bacteria

A bacterial strain, HN-56, having an activity of d-glucose isomerization was isolated from soil, and was identified to be similar to Aerobacter aerogenes (Kruse) Beijerink. d-Glucose-isomerizing activity was induced when HN-56 was precultured in the media containing d-xylose, d-mannose, lactate, especially d-mannitol. Paper chromatography showed that the ketose formed in reaction system containing d-glucose was d-fructose alone. The optimum pH for the reaction was 6.5~7.0. Sulfhydryl reagents inhibit the reaction, but metal inhibitors affect little if any. With the washed living cells as enzyme source, only arsenate could accumulate d-fructose. In addition, the cells grown with d-mannitol and d-mannose showed no activity of d-xylose isomerase.