Table 1 Metabolic engineering strategies for enhancing citric acid production in A. niger

Engineering carbon utilization

 TNA 101ΔagdA

ΔagdA

CGMCC10142

172.7, ↑8.68%

2.40

0.96^a

↓52.95% (residual sugar)

Liquefied corn medium, 180 g/L total sugar, 72 h

[66]

 OG1

ΔagdA, ↑glaA

CGMCC10142

185.7, ↑16.87%

2.58

1.03^a

↓88.24% (residual sugar)

Liquefied corn medium, 180 g/L total sugar, 72 h

[66]

Enhancing citric acid biosynthesis pathway

 50-2-12

↑pfkA, ↑pki

NW129/NW131

55, no change

0.33

0.64^b

–

Synthetic medium, 140 g/L glucose, 168 h

[62]

 55-14

↑citA

NW129/NW131

46, ↓16.36%

0.27

0.52^b

–

Synthetic medium, 140 g/L glucose, 168 h

[63]

Enhancing precursor supplement pathway

 acl1-acl2

↑acl1, ↑acl2

ATCC1015

42, ↑32%

0.35

0.42^a

–

Synthetic medium, 100 g/L glucose, 120 h

[67]

 Δacl

Δacl1

AB4.1

increased

–

0.043^b

Succinate, Oxalate, Glycerol

–

[68]

 Frds (V)-FumRs

↑Frds1, ↑FumRs

N402

29.5, ↑59.46%

0.10

0.46^b

Oxalate

Synthetic medium, 50 g/L glucose, 14 days

[69]

Removal of by-product formation

 NW185

ΔgoxC17, ΔprtF28

NW131

90, ↑63.64%

0.375

0.64^a

No oxalate

Synthetic medium, 140 g/L glucose, 240 h

[64]

Reducing feedback inhibition

 Δ1–3

ΔggsA

ATCC11414

115, ↓4.17%

–

0.82^a

–

Shu and Johnson medium, 140 g/L sucrose

[71]

 TE23

↑mt-pfkA10

A158

~120, ↑ ~ 85%

0.4

0.80^a

–

Synthetic medium, 150 g/L sucrose, ~ 300 h

[72]

Engineering Mn²⁺ response and morphology

 Brsa-25-3

↓Brsa-25

ATCC11414

2.5, ↑ ~ 35%

0.042

–

–

Synthetic medium, 140 g/L glucose, 60 h in tested tube

[77]

 chsC-3

↓chsC

CBS513.88

180.3, ↑3.56%

2.50

1.02^a

–

Liquefied corn medium, 177 g/L total sugar, 72 h

[78]

Regulating the respiratory chain

 CGMCC5751

Adding 0.2 mg/L antimycin A

CGMCC5751

151.67, ↑19.89%

2.11

0.82^a

–

Liquefied corn medium, 184 g/L total sugar, 72 h

[75]

 CGMCC5751

Adding 0.1 mg/L DNP

CGMCC5751

135.78, ↑7.32%

1.89

0.74^a

–

Liquefied corn medium, 184 g/L total sugar, 72 h

[75]

 CGMCC10142-72

↑AOX1

CGMCC10142

163.1, ↑2.52%

2.27

0.89^a

–

Liquefied corn medium, 184 g/L total sugar, with 0.2 μg/mL antimycin A, 72 h

[76]

 CGMCC10142-102

↑AOX1

CGMCC10142

169.1, ↑6.29%

2.35

0.92^a

–

Liquefied corn medium, 184 g/L total sugar, with 0.2 μg/mL antimycin A, 72 h

[76]

 CGMCC10142-3-4

ΔAOX1

CGMCC10142

140.1, ↓11.95%

1.95

0.76^a

–

Liquefied corn medium, 184 g/L total sugar, with 0.2 μg/mL antimycin A, 72 h

[76]

 CGMCC10142-4-10

ΔAOX1

CGMCC10142

125.6, ↓20.75%

1.74

0.68^a

–

Liquefied corn medium, 184 g/L total sugar, with 0.2 μg/mL antimycin A, 72 h

[76]