Comparison of the Key Enzymes of Hyphomicrobium sp. 53-49 under Various Growth Conditions: Aerobic, Denitrifying and Autotrophic

Abstract

For Hyphomicrobium 53-49 capable of growing under various conditions, aerobic methanol, anaerobic methanol (with denitrification), autotrophic (H₂-O₂-CO₂), aerobic ethanol and aerobic acetate, investigation and comparison of the specific activities of the following enzymes were performed: alcohol dehydrogenase (NAD-ethanol linked and NAD-methanol linked), primary alcohol dehydrogenase, formaldehyde dehydrogenase (NAD-GSH linked and DCPIP linked), formate dehydrogenase, serine hydroxymethyl transferase, hydroxypyruvate reductase, isocitrate lyase (icl), malate lyase, malate dehydrogenase, ribulosebisphosphate (RuBP) carboxylase, phosphoenolpyruvate (PEP) carboxykinase (ADP linked), PEP carboxylase (phosphorylating), pyruvate carboxylase (NADH linked and NADPH linked) and α-ketoglutarate carboxylase (NADH linked and NADPH linked). On the basis of the data obtained, it was concluded that during growth on methanol, aerobically and anaerobically, the icl⁺ serine pathway operated, while during autotrophic growth on H₂-O₂-CO₂, CO₂ was incorporated through the RuBP pathway and others, and during growth on ethanol or acetate, neither the serine pathway nor the RuBP pathway operated. The organism changed its metabolism through the regulation of the metabolic enzymes according to the growth conditions.