Glucose dehydrogenase activity in Acinetobacter species

Abstract

A study of D-glucose oxidation by Acinetobacter species was carried out. Glucose-oxidizing strains were found distributed among almost all Acinetobacter species. 14C-glucose oxidation kinetics by non-proliferating cells with separation of oxidation products (14C-gluconate) by DEAE-cellulose paper chromatography was studied. Inhibition of glucose dehydrogenase (GDH) activity by 11 carbohydrates (mono- and disaccharides) and determination of the kinetic parameters showed that glucose oxidation was due to the action of membrane-bound GDH (inactive in vivo on disaccharides). On the basis of GDH inhibition patterns obtained, two groups were individualized. The first group of strains (identified as A. calcoaceticus, A. baumannii, A. lwoffii, A. johnsonii and Acinetobacter species 3, 9, 10 and 11) showed a greater affinity for glucose than the second group (A. haemolyticus, A. junii and Acinetobacter species 6 and 12). Restoration of GDH activity after addition of pyrroloquinoline quinone (PQQ) was studied in 187 strains previously found unable to oxidize glucose. GDH activity of 150 out of 166 strains identified as A. baumannii, A. johnsonii, A. lwoffii and Acinetobacter species 11 and 12 was restored. Eighteen of 21 strains identified as A. haemolyticus and Acinetobacter species 6 were unable to produce acid from glucose after addition of PQQ. Our results confirm that the former taxonomic scheme for the genus Acinetobacter (2 species differing only by glucose oxidation) is untenable and that, accordingly, identification of Acinetobacter strains at the species level must be performed using more modern methods, i.e. carbon source utilization tests.