Biotechnol.Bioeng.; (1991) 38, 3, 217-23

A new biosensor for specific determination of sucrose using an oxidoreductase of Zymomonas mobilis and invertase

Park-J-K; Ro-H-S; +Kim-H-S

A biosensor for sucrose analysis was constructed by coating a pH electrode with a gelatin membrane support carrying co-immobilized yeast beta-D-fructofuranosidase (EC-3.2.1.26) and permeabilized Zymomonas mobilis ATCC 31821 cells (with glucose-fructose-oxidoreductase activity). Electrode response was measured using a pH meter coupled with an IBM PC by a peripheral interface card. The biosensor showed a linear response up to 70 g/l sucrose. The following optimum conditions were determined: 1,000 U beta-D-fructofuranosidase/ml gelatin mixture; 0.083 g dry cell wt./ml gelatin mixture; 20 mM MES buffer at pH 6.2; and an operating temp. of 35 deg. In order to avoid the problem of interference by compounds which exist simultaneously with sucrose in food samples, sucrose samples containing glucose and fructose were pretreated with glucose-oxidase (EC-1.1.3.4) in order to eliminate glucose, and sucrose concentration was determined by the steady-state method. The biosensor exhibited excellent precision during analysis of sucrose in beverage samples. The biosensor was stable for at least 7 days during operational conditions. (17 ref)