Fig. 5

Comparison of GadB secretion at 37 °C and GABA production at 50 and 37 °C for BL21(DE3)/pET20b-torA-gadB cells, using BL21(DE3)/pET20b-gadB cells as control. Cells were grown at 37 °C for 36 h for expression and secretion of GadB. Then two portions of 50 mL cell culture were collected. One portion was used as the whole sample; while the other portion was centrifuged, the supernatant was collected as the extracellular sample, and the cell pellets was resuspended in the same volumes of PBS buffer and used as the intracellular sample. At this time point (the 36 h time point), GABA synthesis was initiated by adding 25 g MSG in the broth. pH was adjusted manually to 4.6. GABA productions were determined at different time points. a BL21(DE3)/pET20b-torA-gadB grown at 37 °C produced GABA at 50 °C. b BL21(DE3)/pET20b-torA-gadB grown at 37 °C produced GABA at 37 °C. c BL21(DE3)/pET20b-gadB grown at 37 °C produced GABA at 50 °C. d BL21(DE3)/pET20b-gadB grown at 37 °C produced GABA at 37 °C