Sustainable production of 4-aminobutyric acid (GABA) and cultivation of Chlorella sorokiniana and Chlorella vulgaris as circular economy

The 4-aminobutyric acid (GABA) is important to produce bio-nylon 4 in biorefineries. First, a glutamate decarboxylase (GAD) was propagated in three different Escherichia coli strains to achieve 100% conversion from 1 M monosodium glutamate after optimization of the process. To make the process greener and more efficient, in situ CO2 adaptation and citrate feeding strategies to maintain the optimal pH value and 498 g/L of GABA was obtained....