Metabolism of d -Fructose by Arthrobacter pyridinolis

Previous studies showed that Arthrobacter pyridinolis can transport and utilize d -glucose only after prior growth on certain Krebs cycle intermediates. In contrast, we found that d -fructose was taken up and metabolized by A. pyridinolis without special prior conditions of growth. d -Fructose was first converted to d -fructose-1-phosphate by a phosphoenolpyruvate (PEP): D -fructose phosphotransferase. This activity required both supernatant and pellet fractions from d -fructose-grown cells centrifuged at 150,000 × g . The d -fructose-1-phosphate formed was converted to d -fructose-1, 6-diphosphate. Mutants deficient in PEP: d -fructose phosphotransferase and d -fructose-1-phosphate kinase, or d -fructose-1, 6-diphosphatase (FDPase) were unable to grow on d -fructose but retained the normal ability to use d -glucose. Mutants forming reduced amounts of FDPase were completely unable to grow on d -fructose but were still capable of limited growth on Krebs cycle intermediates. A requirement for higher levels of FDPase for growth on d -fructose than for growth on Krebs cycle intermediates was also indicated by the higher specific activities of FDPase in d -fructose-grown cells than in cells grown on l -malate or amino acids.