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Table 1 Strains, fermentation media, and control methods of the ten highest-yielding γ-GPA fermentation processes

From: Microbial synthesis of poly-γ-glutamic acid: current progress, challenges, and future perspectives

Starting sources Isolation or improvement methods Fermentation medium components Bioreactor and process controla Yield (g/L) Ref.
B. subtilis ZJU-7 Isolated from fermented bean curd Glucose, l-glutamate, yeast extract, NaCl, CaCl2, MgSO4, MnSO4 10-L bioreactor, 300–800 rpm with 1.5 vvm, pH 6.5, 37 °C 101.1 [49]
B. subtilis NX-2 Using co-fermentation strategy Glutamate, (NH4)2SO4, K2HPO4, MgSO4, MnSO4, and hydrolysis of rice straw 7.5-L bioreactor, 400 rpm with 1.2 vvm, initial pH 7.0, 32 °C 73.0 [50]
B. subtilis NX-2 Isolated from soil samples Glucose, glutamate, (NH4)2SO4, K2HPO4, MgSO4, MnSO4 7.5-L APFB for immobilized fermentation, 32 °C, pH 7.0 71.21 [42]
B. subtilis MJ80 Isolated from soil samples Glutamic acid, starch, urea, citric acid, glycerol, NaCl, K2HPO4, MgSO4, MnSO4 3-L fermenter, 37 °C, 150 rpm with 1 vvm, initial pH 7.0 68.7 [56]
B. subtilis NX-2 Isolated from soil samples Cane molasses and monosodium glutamate waste liquor 7.5-L bioreactor, 400 rpm at 1.2 vvm, 32 °C, pH 7.0 52.1 [55]
B. licheniformis P-104 Isolated from Chinese soybean paste Glucose, sodium glutamate, sodium citrate, (NH4)2SO4, MnSO4, MgSO4, K2HPO4 7-L bioreactor, 500 rpm with 1.5 vvm, 37 °C, pH 7.0, fed-batch 41.6 [43]
B. licheniformis NCIM 2324 Addition of metabolic precursors Glycerol, l-glutamic acid, citric acid, (NH4)2SO4, K2HPO4, MgSO4, MnSO4 250-mL flask, 200 rpm, 37 °C, initial pH 6.5 35.75 [81]
B. methylotrophicus SK19.001 Isolated from soil samples Glucose, yeast extracts, MgSO4, K2HPO4, MnSO4 250 mL flask, 200 rpm, initial pH 7.2, 37 °C 35.34 [51]
B. subtillis HB-1 Isolated from soil samples Glutamate, yeast extract, NaCl, MgSO4, xylose, or corncob fibers hydrolysate 10-L bioreactor, 500 rpm, 37 °C, initial pH 6.5, fed-batch 28.15 [82]
B. licheniformis TISTR 1010 Using different feeding strategies Glucose, citric acid, NH4Cl, K2HPO4, MgSO4, CaCl2, MnSO4, NaCl, Tween-80, 7-L fermenter, 300 rpm and 1 vvm, initial pH 7.4, 37 °C 27.5 [83]
  1. a vvm volumes of air per volume of broth, APFB aerobic plant fibrous-bed bioreactor