This study examined glucose metabolism pathways in Candida 107, a lipid-accumulating yeast. The researchers discovered that phosphofructokinase, previously thought to be absent, is actually present but extremely labile and only detectable in toluene-treated cells. Using radioactive glucose labeling ([1-14C]glucose and [6-14C]glucose), they determined that approximately 60% of glucose is metabolized through the pentose phosphate cycle, with the remaining 40% via the Embden-Meyerhof pathway. The researchers also identified low-level activity of phosphoketolases acting on xylulose 5-phosphate and fructose 6-phosphate. The Entner-Doudoroff pathway was absent. These findings revise previous conclusions about the metabolic capabilities of this oleaginous yeast and suggest that glucose metabolism occurs through multiple pathways. The results indicate similar metabolic patterns likely exist in related lipid-accumulating yeasts like Rhodotorula species, though the specific mechanisms underlying lipid accumulation remain unclear.

Key findings

• Phosphofructokinase is present in Candida 107 but is extremely labile, detectable only in toluene-treated cells and destroyed by cell disruption
• Approximately 60% of glucose is metabolized via the pentose phosphate cycle with 40% via the Embden-Meyerhof pathway, as determined by radioactive glucose labeling
• Low-level phosphoketolase activity was detected acting on both xylulose 5-phosphate and fructose 6-phosphate, contributing an unmeasured amount to glucose metabolism
• The Entner-Doudoroff pathway is absent in Candida 107
• These findings contradict previous conclusions that the yeast lacks phosphofructokinase and suggest lipid accumulation mechanisms remain unexplained