Skip to main content

Table 2 Exemplar engineering of homologous and heterogeneous hosts

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

Strains Engineering methods Fermentation medium Production (g/L) Ref.
B. licheniformis WX-02 Expression of glr gene encoding glutamate racemase Glucose, l-glutamic acid, sodium citrate, NH4Cl, MgSO4, K2HPO4, CaCl2, ZnSO4, MnSO4 14.38 [75]
B. amyloliquefaciens LL3 Double-deletion of genes pgdS and cwlO Sucrose, (NH4)2SO4, MgSO4, KH2PO4, K2HPO4 7.12 [84]
B. amyloliquefaciens LL3 Deletion of genes (rocR, rocG, gudB, odhA) Sucrose, (NH4)2SO4, MgSO4, KH2PO4, K2HPO4, 5.68 [85]
B. subtilis ISW1214 Bearing the plasmid-borne PGA synthetic system Sucrose, NaCl, MgSO4, KH2PO4, NaHPO4,xylose 9.0 [47]
E. coli BL21 Cloning and overexpressing γ-PGA biosynthesis genes Glucose, yeast extract, l-glutamic acid, (NH4)2SO4 3.7 [76]
E. coli JM 109 Co-expressing γ-PGA synthetase and glutamate racemase LB medium supplemented with l-glutamate or glucose 0.65 [48]
B. amyloliquefaciens Deletions of genes (epsA-O, sac, lps, pta, pgdS, cwlO, luxS, and rocG gene, expression of synthetic small regulatory RNAs which repressed the rocG and glnA gene Sucrose, (NH4)2SO4, MgSO4, KH2PO4, K2HPO4 20.3 [86]
B. subtilis PB5249 Knockout of genes (pgdS and ggt) l-glutamic acid, citric acid, glucose, NH4Cl, K2HPO4, MgSO4·7H2O, FeCl3·6H2O, CaCl2·2H2O, MnSO4·H2O, pH 6.5 40 [87]
Bacillus licheniformis WX-02 Enhanced expression of pgdS gene Glucose, sodium glutamate, sodium citrate, NH4Cl, MgSO4, K2HPO4, CaCl2, ZnSO4, MnSO4 20.16 [88]
Corynebacterium glutamicum Cloning and expressing γ-PGA biosynthesis genes Glucose, (NH4)2SO4, KH2PO4, MgSO4·7H2O, FeSO4·7H2O, MnSO4·4H2O, soy protein hydrolysate, thiamine hydrochloride, CaCO3 18 [54]
  1. Despite some progress, γ-PGA production remains low in these strains