Progress in metabolic engineering of biosynthesis of 3-hydroxypropionic acid / 生物工程学报

As an important platform compound, 3-hydroxypropionic acid (3-HP) can be used as a substrate to synthesize a variety of biological products with commercial potential. The titer of 3-HP by wild-type bacteria is low, which severely limits the large-scale application and production of 3-HP. By modifying the genes related to the metabolic pathway, engineered bacteria using cheap substrates as carbon sources are constructed, the aim of reducing production cost and increasing output is realized. In this paper, the recent progress in the synthesis of 3-HP by metabolic engineering at home and abroad is reviewed. The advantages and disadvantages of glycerol pathway, malonyl-CoA pathway and beta-alanine pathway for synthesis of 3-HP are also summarized and analyzed, and the future development of 3-HP is prospected.

Biocatalytic access to β-alanine by a two-enzyme cascade synthesis / 生物工程学报

Enzymatic synthesis is an important way to produce β-alanine, but the biological method is expensive generally because of the high price of substrate. In this paper, a two-step enzymatic cascade system was developed, combining L-aspartase from Escherichia coli DH5α and L-aspartate α-decarboxylase from Corynebacterium glutamicum. This system catalyzes Fumarate and ammonia to β-alanine. The optimal ratio of AspA and PanD was 1:80 (W/W), and the concentration of AspA was 10 μg/mL, at 37 ℃ and pH 7.0. When the concentration of Fumarate was 100 mmol/L, the reaction reached its equilibrium after 8 h, and the yield of β-alanine was 90 mmol/L (7 g/L). The yield of β-alanine can reach 126 mmol/L (9.8 g/L) when the concentration of Fumarate increased to 200 mmol/L. Extending reaction time, the conversion rate did not change obviously. Using this two-step enzymatic cascade system, β-alanine from cheaper substrate Fumarate can be obtained.