Abstract:

The original strain of Actinobacillus succinogenes 130Z was illuminated under ultraviolet light for gene mutagenesis, and two mutant strains resistant to fluoroacetic acid alone or in combination with allyl alcohol were screened. The 72 h fermentation broths of the original strain and the two mutant strains were centrifugated to harvest the supernatants, which were sampled for organic acid composition determination, the measurement of related enzyme activities and metabolic flux analysis. The malate dehydrogenase (MDH) from the fluoroacetic acid-resistant mutant strain was increased by 159.2% and the mutant strain resistant to both fluoroacetic acid and allyl alcohol showed increases in MDH activity by 165.8% and in pyruvate carboxylase (PC) activity by 1226.4% but 78.0% decrease in alchol dehydrogenase (ADH) activity as compared to the original strain. The utilization rate of glucose in the original strain was lower, utilizing 100 g of glucose to produce 47.0 g of succinic acid, which was 25% lower than that in the bi-resistant mutant strain, producing 58.8 g of succinic acid through utilizing 100 g of glucose in 1 L of the medium (namely 58.8 g/L succinic acid yield).

Key words: breeding, pyuvate carboxylase, malate dehydrogenase, alcohol dehydrogenase, Actinobacillus succinogenes