Effect of growth temperature on the accumulation of glucose-oxidation products in Pseudomonas fluorescens

The effect of the growth temperature, on the accumulation of glucose-oxidation products, was examined in aerated cultures with carbon excess in two strains of Pseudomonas fluorescens. At low growth temperatures (0 and 5 degrees C), 2-ketogluconate (KG) a-cumulated in the medium as the major oxidation product of glucose (up to 70%) before further metabolism. As the growth temperature was increased, the amount of 2-KG found to accumulate in the medium from glucose oxidation decreased. At a growth temperature of 20 degrees C, up to 25% of the glucose originally added accumulated in the medium as 2-KG. At the optimum growth temperature of 30 degrees C or above, no 2-KG was detected at any time during growth with glucose. Similar results were obtained when gluconate was used as the sole carbon and energy source. The results demonstrated a differential effect of growth temperature on the accumulation of oxidation products from glucose and gluconate. At low growth temperatures the major route for the catabolism of glucose and gluconate was the direct oxidative non-phosphorylated pathway.