Metabolic engineering of Aureobasidium melanogenum 9-1 for overproduction of liamocins by enhancing supply of acetyl-CoA and ATP.

In this study, it was found that reducing consumption of acetyl-CoA in mitochondria, peroxisome and lipid biosynthesis could not obviously enhance liamocin biosynthesis by engineered strains of Aureobasidium melanogenm 9-1, but decreased cell growth of the mutants. On the contrary, expression of heterologous PTA gene for phosphotransacetylase in PK pathway and native ALD gene for acetaldehyde dehydrogenase and ACS gene encoding acetyl-CoA synthetase in the PDH bypass pathway reduced liamocin biosynthesis. However, expression the PK gene for phosphoketolase, the PDC gene encoding pyruvate decarboxylase and VHb gene coding for Vitreoscilla hemoglobin (VHb) in the glucose derepression mutants could greatly enhance liamocin production. The resulting strain V33 could produce 55.38 g/L of liamocin and 25.10 g/L of cell dry weight from 117.27 g/L of glucose within 168 h of 10-liter fermentation, leading to the yield of 0.47 g/g of glucose, the productivity of 0.33 g/L/h and rate of glucose utilization of 0.70 ± 0.01 g/L/h. This was a new and efficient strategy for overproduction of liamocin by A. melanogenm.