5-Keto-d-fructose

When grown on n-fructose, Gluconobacter cerinus accumulates significant amounts of a dicarbonylhexose in the growth medium (1).The new product was identified as 5-keto-n-fructose by Terada, Tomizawa, Suzuki, and Kinoshita (I), a structure which was also favored by our own chemical studies (2).1 It would seem that the dicarbonylhexose found by Weidenhagen and Bernsee (4) in the culture medium of an Acetobacter strain is indistinguishable from the product of G. cerinus (2).As production of 5KF2 is presumably a common feature for many organisms of the Acetobacter suboxydans and Gluconoacetobatter groups (5-7), it seemed of interest to study some of the characteristics of its production and accumulation in cultures and to survey the bacterial extracts for enzymatic activities associated with hexose oxidation and reduction.Of particular interest are those enzyme systems linked to formation and utilization of 5KF.This communication describes some experiments relating to these questions.