Increasing Acid Tolerance of an Engineered Lactic Acid Bacterium <i>Pediococcus acidilactici</i> for L-Lactic Acid Production

oleh: Zhao Yan, Mingxing Chen, Jia Jia, Jie Bao

Format: Article
Diterbitkan: MDPI AG 2022-02-01

Deskripsi

Acid tolerance of the lactic acid bacterium (LAB) is crucially important for the production of free lactic acid as a chemical monomer by simplified purification steps. This study conducts both metabolic modification and adaptive evolution approaches on increasing the acid tolerance of an engineered <i>Pediococcus acidilactici</i> strain. The overexpression of the genes encoding lactate dehydrogenase, recombinase, chaperone, glutathione and ATPase did not show the observable changes in acid tolerance. On the other hand, the low pH adaptive evolution showed clear improvement. The L-lactic acid generation and cell viability of the adaptively evolved <i>P. acidilactici</i> were doubled at low pH up to 4.0 when wheat straw was used as carbohydrate feedstock. However, the further decrease in pH value close to the pKa (3.86) of lactic acid led to a dramatic reduction in L-lactic acid generation. This result shows a partially successful approach on improving the acid tolerance of the lactic acid bacterium <i>P. acidilactici</i>.