Table 6.

Engineered strains of H. bluephagenesis TD01

Engineered strain	Parent strain	Metabolic engineering strategy	Effect on PHA synthesis	Mode of study	References
TD04	TD01	Deletion of prpC gene	CDW of 8.9 g/L containing 70.12% (wt) of P(3HB-co-12.03 mol% 3HV) in presence of 0.5 g/L of propionic acid	Shake flasks	[98]
TD-prpC6prpC7	TD01	Controlled repression of prpC gene using CRISPRi systems	Improved CDW of 14.67 g/L containing 73.78% (wt) P(3HB-co-12.70 mol% 3HV) using 1.0 g/L of propionic acid as co-substrate	Shake flasks	[110]
TD08	TD04	Deletion of three phaZ genes	CDW of 80 g/L containing 70% (wt) of P(3HB-co-8 mol% 3HV) in 0.5 g/L of propionic acid	500-L fermentor	[98]
TD08 (pSEVA341-thrACBilvA)	TD08	Overexpression of thrACB operon and ilvA gene	Synthesis of PHBV with 3HV up to 6 mol% without using 3HV precursor	Shake flasks	[111]
TD08AB	TD08	Chromosomal expression of E. coli scpA-argK-scpB fragment	CDW of 54 g/L containing 57% (wt) P(3HB-co-8 mol% 3HV)	6-L fermentor	[122]
TD08AB (ΔsdhEΔicl)	TD08AB	Deletion of sdhE and icl genes	78% increase in 3HV yield	Shake flasks	[25]
TY194(ΔsdhEΔicl)	TD1.0(ΔprpC)	Integration of scpAB under the control of a Pporin promoter; deletion of sdhE and icl genes	PHBV with 18 mol% 3HV content in presence of waste gluconate and glucose	Shake flasks	[25]
TY194 (ΔsdhE, G7::Pporin-ppc)	TY194 (ΔsdhE)	Integration of ppc and vgb genes under the control of Pporin and P8vgb promoter	PHBV with 25 mol% 3HV from glucose and gluconate	Shake flasks	[25]
TD40	TD01	Integration of orfZ gene of Clostridium kluyveri	Block co-polymer of P3HB4HB with 16 mol% 4HB using GBL as co-substrate	1000-L fermentor	[126]
TDH4	TD01	orfZ expression using moderate promoter	4HB mol% similar to TD40 was achieved by consuming 17% less GBL	7-L fermentor	[127]
TDH5	TD01	orfZ expression using strong promoter	40% higher 4HB mol% than TD40 was achieved from GBL as co-substrate	7-L fermentor	[127]
TDH4-pCD-ΔphaP1	TDH4	Deletion of phaP1 and overexpression of minCD	Synthesis of large P3HB4HB granules of axial length 4 µm from GBL as co-substrate	Shake flasks	[116]
TDWT-D2	TD01	Introduction of double plasmid for expression of orfZ, ogdA, sucD, and 4hbd genes	Incorporation of 0.17 mol% 4HB solely from glucose	Shake flasks	[128]
TD△gabD2-D2	TDWT-D2	Deletion of gabD2 and gabD3	Incorporation of up to 24.9 mol% 4HB	7-L fermentor	[128]
TD68-194	TDG (gabD2 and gabD3 deleted TD01 derivative)	Chromosomal integration of the orfZ and 4hbd-sucD-ogdA genes using HRCGE system	Best 4HB-producing strain with 48.2 g/L CDW containing 75% (wt) P(3HB-co-16 mol% 4HB) solely from glucose	7-L fermentor	[26]
TD08 (pRE112-pMB1-udhA)	TD08	Overexpression of udhA	CDW of 12 g/L containing 92% (wt) PHB	Shake flasks	[98]
TD01PC	TD01	Deletion of phaC gene and integration of the phaCRe downstream of the porin operon	12% increase in PHB yield	Shake flasks	[133]
TDPIΔC (pSEVA341-phaC Re)	TD01ΔphaC	Plasmid expression of phaCRe using inducible promoter	PHB content up to 81% (wt)	Shake flasks	[133]
TDPI (pBBR1-Ppolac-phaCAB)	TDPI (TD01 derivative with lacI gene inserted downstream of the porin operon)	Plasmid expression of phaCABRe using inducible promoter	Increased PHB concentration up to 7 g/L	Shake flasks	[134]
TD-HIGH	TD01	Chromosomal expression of the phaCAB operon	38% enhancement in PHB production	10-L fermentor	[135]
TD01 (tat-vgb)	TD01	Periplasmic expression of vgb with the help of the Tat peptide signal	50% improvement in CDW and PHB concentration	Shake flasks	[137]
TDHCD-R3	TDHCD-Ro (TD01 derivative with ΔpyrF deleted, T7-like RNA polymerase Mmp1 and vgb integrated into genome and harbouring mutagenesis plasmid)	Three rounds of selection in medium containing toxic metabolites	41.7% increase in CDW and 8.2% increase in PHB content	7-L fermentor	[24]
TDHCD-R3-8-3	TDHCD-R3	Plasmid expression of phaCABRe	12.3% increase in PHB content; CDW of 90.5 g/L with 78.8% (wt) PHB	7-L fermentor	[24]