Bio-Synthesis of GABA by <i>Streptococcus thermophilus</i> QYW-LYS1 Isolated from Traditional Fermented Yoghurt

Thirteen strains of lactic acid bacteria were isolated from the local traditional fermented yoghurt. One of them showed the highest GABA-producing ability in MRS broth with 1% L-glutamate. The strain was identified Streptococcus thermophilus QYW-LYS1 based on morphological characteristics and 16S rDNA sequence determination. The single factor design was applied to optimize culture conditions. The optimal initial cell density, temperature and reaction time were 0.2OD·mL -1 , 34°C and 72h respectively. Under the optimized reaction conditions, the production of GABA was 2.905g/L.The result may contribute to the development of traditional fermented dairy product with functional properties.