From Glucose to Green Chemistry: Breakthrough in Microbial Production of Tartaric Semialdehyde

L-(+)-tartaric acid (L-TA) is a crucial hydroxy carboxylic chelator with extensive applications in the food and pharmaceutical industries. The synthesis of L-TA from renewable biomass presents a promising approach to mitigating environmental impact and advancing green energy initiatives. Previous studies revealed that a mutant transketolase (TKTA_M) could catalyse the production of tartaric semialdehyde, a precursor to L-TA. This study focuses on the development of a Gluconobacter oxydans cell factory for tartaric semialdehyde production, employing a combination of metabolic engineering and a modular strategy. The genetically modified G. oxydans T strain exhibited robust expression of the tktA_M gene. The optimal pH and temperature for this strain were determined to be 6.0°C and 30°C, respectively. Under these conditions, the strain produced 32.21 ± 0.74 g/L of tartaric semialdehyde from glucose. Implementation of a "Push-Pull" strategy enhanced tartaric semialdehyde production, resulting in a 23.85% increase in the G. oxydans T02 cell growth. In CSLP medium with 100 g/L glucose, the fermentation process yielded 48.88 ± 2.16 g/L of tartaric semialdehyde and 7.72 ± 1.56 g/L of residual 5-KGA after 48 h. This resulted in a tartaric semialdehyde productivity rate of 1.018 g/L·h, representing an 87.82% improvement over flask fermentation. This study demonstrates a straightforward and efficient microbial process for the oxidation of glucose to tartaric semialdehyde, indicating its potential for industrial-scale production and facilitating the synthesis of L-TA from renewable resources.