Synthesis of cellulose by Acetobacter xylinum. 4. Enzyme systems present in a crude extract of glucose-grown cells

Mutagenesis induced by high hydrostatic pressure treatment: a useful method to improve the bacterial cellulose yield of a Gluconoacetobacter xylinus strain

“…For BC biosynthesis, the following four enzymatic steps were Note temperature during all the HHP treatments was 25°C reported as the major pathways: Phosphorylation of D-glucose by glucokinase (Benziman and Rivertz 1972); transphosphorylation of glucose 6-phosphate to glucose 1-phosphate by phosphoglucomutase (Gromet et al 1957); synthesis of uridine-5 0 -diphosphateglucose by pyrophosphorylase (Valla et al 1989) and polymerization of uridine-5 0 -diphosphateglucose by cellulose synthase (Aloni et al 1983;Ross et al 1987). We suggest research to investigate the effects of HHP treatment on the four enzymatic steps of strains should be carried out in future research.…”

Comparative Carbohydrate Metabolism and a Proposal for a Phylogenetic Relationship of the Acetic Acid Bacteria

“…The oxidative behaviour of resting bacteria represents only the overall activity of the enzyme systems which have been studied in previous papers. The core of their intermediary carbon catabolism appears to consist of three essential parts: (i) Hauge, King & Cheldelin (1955), Kitos et al (1958) and Gromet, Schramm & Hestrin (1957) showed the presence of the hexose monophosphate oxidative cycle in Gluconobacter suboxydans and Acetobacter xylinum. Unpublished work in our laboratory with many other strains has confirmed these results.…”

The glucose dehydrogenase activity of the nad‐linked glucose 6‐phosphate dehydrogenase from Acetobacter xylinum

“…This makes both glucose and glucose-6-P potential physiological substrates for the enzyme. In this connection it should be noted that glucose oxidation by the enzyme is small, compared to that catalyzed by the particulate pyridine nucleotide-independent glucose dehydrogenase present in these cells [2], and at best could account for no more than 10% of the in viva rate of glucose oxidation to gluconate [13]. On the other hand, the activity of the enzyme towards glucose-6-P is essential for the operation of the pentose cycle, especially in the utilization of sugars such as fructose, the metabolism of which does not involve gluconate formation [2, 131. The inhibitory effect of glucose on the G6PDH reaction could account for the accumulation in the medium of significant amounts of glucose-6-P during the utilization of glucose by resting cells A. xylinum [our unpublished experiments].…”

“…Entry into the cycle takes place by means of specific hexokinases and in several other ways in which the primary conversion of glucose to gluconate plays a part [2,4]. A. xylinum was found to possess two distinct glucose 6-P dehydrogenases: an NAD-specific enzyme, which is optimally active at pH 5.6 and is inhibited by ATP, and an NADP-specific enzyme which is optimally active at pH 8.2 and is insensitive to ATP [S].…”