Microbial metabolism of C1 and C2 compounds. The role of glyoxylate, glycollate and acetate in the growth of Pseudomonas AM1 on ethanol and on C1 compounds

摘要

pSuccinate (or a product of succinate metabolism) is a catabolite repressor of some enzymes of the serine pathway (hydroxypyruvate reductase, serine–glyoxylate aminotransferase and glycerate kinase) but not of methanol dehydrogenase nor methylamine dehydrogenase. A mutant (PCT64) of iPseudomonas/i AM1, which is unable to grow on Csub1/sub compounds, lacks glycerate kinase, showing that this enzyme is essential for the operation of the serine pathway. Mutant PCT48, unable to convert acetate into glycollate, has lost the ability to grow both on Csub1/sub compounds and on ethanol. The properties of a third mutant (PCT57) show that iPseudomonas/i AM1 contains enzymes catalysing the conversion of acetate into glyoxylate. Evidence is presented that hydroxypyruvate reductase is involved in the oxidation of glycollate to glyoxylate during growth on ethanol. A scheme is proposed for the conversion of ethanol and of Csub1/sub compounds into glyoxylate in which acetate (or a derivative) and glycollate are intermediates./p