Table 1.
Major strategies and advancements in achieving and enhancing L-valine production
| Host | Main engineering strategy | Culture condition | Performance | References | ||
|---|---|---|---|---|---|---|
| Titer (g L−1) |
Yield (mol mol−1 glucose) |
Productivity (g L−1 h−1) |
||||
| C. glutamicum ATCC 13032 |
Alanine transaminase deactivated, AHAIS, AHAS and TA overexpressed |
3.5 L Fed-batch fermentation 12.5% glucose, 31 °C, 72 h |
31.1 | 0.28 | 0.43 | [11] |
| C. glutamicum ATCC 13032 | Increasing the expression of ptsG | 50 mL shake flask fermentation, 4% glucose, 0.5% maltose, 2% acetate, 48 h | 11.94 | 0.21 | 0.27 | [39] |
| C. glutamicum ATCC 13032 | L-threonine dehydratase and ketopantoate hydroxymethyltransferase deactivated. AHAIR, AHAS and DHAD overexpressed | 100 mL flask batch cultivation, 4% glucose, 30 °C 48 h | 10.7 | ND | 0.22 | [50] |
| C. glutamicum R | Lactate dehydrogenase, alanine transaminase, CoA transferase, phosphotransacetylase, phosphoenolpyruvate carboxylase and acetate kinase deactivated. Variant of AHAIS and AHAS expressed |
50 mL (flask) Fed-batch fermentation, 4% glucose, 33 °C, 24 h (anaerobic condition) |
150 | 0.88 | 6.25 | [66] |
| C. glutamicum ATCC 13869 | L-threonine dehydratase, pyruvate dehydrogenase complex and alanine transaminase deactivated. AHAIR, AHAS and the genes lrp1/brnFE overexpressed | 2 L Fed-batch fermentation, 12% glucose, 30 °C, 96 h | 51 | 0.47 | 0.533 | [68] |
| C. glutamicum R |
Leucine dehydrogenase expression Feedback-resistant muntant AHAS |
50 mL (flask) Fed-batch fermentation, 4% glucose, 33 °C, 24 and 48 h (anaerobic condition) | 172.2 and 227 | 0.63 | 4.09 and 4.72 | [65] |
| C. glutamicum ATCC 13032 |
Deactivating phosphoenolpyruvate carboxylase and quinone oxidoreductase combined with ALE AHAIS, AHAS, DHAD and TA overexpressed |
50 mL flask batch cultivation, 4% glucose, 30 °C, 72 h | 8.9 | 0.22 | 0.012 | [22] |
| C. glutamicum VWB-1 | Applying multiple random mutagenesis |
5 L Fed-batch fermentation, 12% glucose, 31.5 °C 72 h |
29.8 | ND | 0.41 | [41] |
| C. glutamicum ATCC 13032 |
Random mutagenesis and selection Transcriptomic and metabolomics analysis |
5 L Fed-batch fermentation, 5% glucose, 32 °C, 24 h | 44.6 | ND | ND | [46] |
| Brevibacterium flavum JV16 |
Alanine transaminase deactivated, AHAIS, AHAS and TA overexpressed |
3.5 L Fed-batch fermentation, 2.5% glucose, 31 °C, 72 h |
38.8 | 0.37 | 0.53 | [11] |
| Brevibacterium flavumMDV1 | Random mutagenesis by UV and Binary ethylenimine; BEI |
12 L Fed-batch fermentation, 12.5% glucose, 30 °C, 64 h |
68.8 | ND | 1.07 | [12] |
| E. coli W |
L-threonine dehydratase, Isopropyl malate synthase, ketopantoate hydroxymethyltransferase, malate dehydrogenase and pyruvate dehydrogenase phosphofructokinase deactivated (VAMF strain) AHAIS, AHAS, DHAD, TA and gene lrp/ygaZH overexpressed |
100 mL Flask batch cultivation, 2% glucose, 0.3% sodium, 31 °C, 48 h |
7.6 | ND | 0.15 | [17] |
| E. coli W | AHAIS, AHAS variant, DHAD, TA and gene lrp/ygaZH overexpressed in VAMF strain |
2 L Fed-batch fermentation, 2% glucose,, 31 °C, 55 h |
32.2 | ND | 0.58 | [18] |
| E. coli W |
L-threonine dehydratase deactivated AHAIS, AHAS, DHAD, TA and gene lrp/ygaZH overexpressed |
2 L Fed-batch fermentation, 2% glucose,, 31 °C 29.5 h |
60.7 | 0.22 | 2.06 | [19] |
| E.coli DH5α | Heterologous introduction of a feedback-resistant acetolactate acid synthase, exporter, redox cofactor balance, two-stage fed-batch fermentation | 5 L Fed-batch fermentation, glucose concentration below 5 g/L, 37℃, 36 h | 84 | 0.41 | 2.33 | [57] |
| Bacillus subtilis 168 | Pyruvate dehydrogenase complex, L-threonine dehydratase, isopropyl malate synthase and transcription factor σ (sigF) deactivated |
20 mL Flask batch cultivation 3% sucrose, 1% mannitol, 37 °C 24 h |
3.9 | ND | 0.19 | [13] |
ND not determined