Bioconversion of one carbon feedstocks for producing organic acids

doi:10.12211/2096-8280.2024-023

Abstract

Abstract:

Organic acids, as important platform chemicals, have been widely used in food, pharmaceutical, chemical industries and agriculture. Currently, microbial production of organic acids relies primarily on sugars as feedstocks, which may suffer from the competition with food and arable lands. One carbon (C₁) molecules such as CO, CO₂, methane, methanol and formic acid are widespread and inexpensive, which are considered as ideal feedstocks for future bio-manufacturing. Bioconversion of C₁ feedstocks toward the production of organic acids helps mitigate greenhouse effect and realize carbon neutrality. Therefore C₁ sources have been regarded as raw materials of third generation biorefinery, and natural C₁ utilizing microbes attracted increasing attention. Although some microorganisms have native biosynthetic pathway of organic acids, the production efficiency is usually lower than expected. This review summarizes the recent progress on the biosynthesis of organic acids (3-hydroxypropionic acid, lactic acid and succinic acid) from C₁ feedstocks using synthetic biology methods. First, the native C₁ utilizing pathways are summarized, including CO₂, CO, methane, methanol and formic acid. Then the metabolic engineering strategies to improve organic acids production were systematically reviewed, including the optimization of rate-limiting enzymes expression, enhancement of the supply of precursor and cofactor, cofactor engineering, and inhibition of the product degradation. In addition, the challenges, solutions, and prospects of C₁ bioconversion to organic acids are also discussed, and coupling chemical catalysis and biological transformation may provide a promising industrial route for organic acids production. In particular, methanol is an ideal C₁ feedstock with many advantages like convenient storage and transportation, high liquid-to-liquid mass transfer efficiency, and it can also be massively produced from CO₂ by “liquid sunshine” technology. Therefore constructing high efficient methanol cell factory may enable organic acids production from CO₂, a carbon neutral production manner. This review may provide a guidance for C₁ biorefinery and industrial bioproduction of organic acids.

Key words: C₁ biorefinery, metabolic engineering, 3-hydroxyproionic acid, lactic acid, succinic acid

摘要：

有机酸在食品、医药、化工、农业等领域有着广泛的应用。目前有机酸的生产主要以微生物发酵法为主，采用糖类为原料，然而长此以往可能面临“与人争粮”的困境。CO、CO₂、甲烷、甲醇和甲酸等含有一个碳原子的物质被称为一碳（one carbon，C₁）资源，其来源广泛且价格低廉，有望成为生物制造的替代原料，且C₁原料生物转化有助于缓解温室效应、助力“碳中和”目标。本文总结了近年来CO₂、甲烷和甲醇生物合成3种重要有机酸（3-羟基丙酸、乳酸、琥珀酸）的研究进展，主要论述了C₁生物利用途径、有机酸的生物合成途径以及代谢工程策略，也讨论了C₁合成有机酸的挑战及应对措施，并展望了有机酸产业化新路线，尤其是化学催化与生物转化耦合以CO₂为原料合成有机酸。本综述对于C₁生物炼制以及有机酸产业升级具有一定的参考意义。

关键词: C₁生物炼制, 代谢工程, 3-羟基丙酸, 乳酸, 琥珀酸

CLC Number:

Wei YU, Jiaoqi GAO, Yongjin ZHOU. Bioconversion of one carbon feedstocks for producing organic acids[J]. Synthetic Biology Journal, 2024, 5(5): 1169-1188.

禹伟, 高教琪, 周雍进. 一碳生物转化合成有机酸的研究进展[J]. 合成生物学, 2024, 5(5): 1169-1188.

Figures/Tables 6

Fig. 1 The utilization pathways of C1 sources

Table 1 Bio-production of organic acids from C1 feedstocks

产物	宿主	底物	培养条件	产量/(g/L)	得率/%	生产强度/[g/(L·d)]	参考文献
3-HP	蓝细菌	CO₂	MM，摇瓶， 50 mL发酵体积	0.67	2.6	0.07	[50]
	蓝细菌	CO₂	MM，摇瓶， 20 mL发酵体积	0.84	8.0	0.14	[47]
	甲基弯菌	甲烷	MM，发酵罐， 50 mL发酵体积	0.06	2.4	0.03	[48]
	扭脱甲基杆菌	甲醇	MM，摇瓶， 50 mL发酵体积	0.07	2.0	0.04	[51]
	扭脱甲基杆菌	甲醇	MM，发酵罐， 1.8 L发酵体积	0.86	3.1	0.21	[52]
	多形汉逊酵母	甲醇	MM，摇瓶， 50 mL发酵体积	7.10	14.2	1.20	[53]
	巴斯德毕赤酵母	甲醇	MM，发酵罐， 300 mL发酵体积	48.20	23.0	3.70	[49]
L-乳酸	蓝细菌	CO₂	MM，摇瓶， 80 mL发酵体积	1.00	N.A.	0.03	[54]
	甲烷氧化菌	甲烷	MM，摇瓶， 2 mL发酵体积	0.60	N.A.	0.15	[55]
	多形汉逊酵母	甲醇	MM，摇瓶， 50 mL发酵体积	3.80	8.0	0.69	[56]
D-乳酸	蓝细菌	CO₂	MM，发酵罐， 100 mL发酵体积	1.30	N.A.	0.13	[57]
	甲基单胞菌	甲烷	MM，摇瓶， 12.5 mL发酵体积	1.20	24.5	0.20	[58]
	巴斯德毕赤酵母	甲醇	CM，摇瓶， 5 mL发酵体积	3.50	22.0	0.87	[59]
琥珀酸	蓝细菌	CO₂	MM，发酵罐，发酵体积未知	0.93	N.A.	0.19	[60]
	蓝细菌	CO₂	MM，摇瓶， 40 mL发酵体积	0.63	N.A.	0.32	[61]
	蓝细菌	CO₂	MM，摇瓶，发酵体积未知	1.80	N.A.	0.60	[62]
	蓝细菌	CO₂	MM，发酵罐， 1 L发酵体积	2.50	N.A.	0.23	[63]
	甲基单胞菌	甲烷	MM，发酵罐， 3.2 L发酵体积	0.20	7.9	0.04	[64]

Fig. 2 Biosynthetic pathway and engineering strategies for 3-HP production from C1 feedstocksZWF1—Glucose-6-phosphate dehydrogenase gene; GND1—6-Phosphogluconate dehydrogenase gene; EcPDH—Escherichia coli pyruvate dehydrogenase complex gene; ACC1—Acetyl-CoA carboxylase gene; FAA1—Fatty acyl-CoA synthetase gene; POX1—Fatty acyl-CoA oxidase gene; FAS—Fatty acid synthase gene; MmACL—Mouse ATP-citrate lyase gene; ScIDP2—Saccharomyces cerevisiae isocitrate dehydrogenase gene; MCR-C—Malonyl-CoA reductase C-terminal gene; MCR-N—Malonyl-CoA reductase N-terminal gene

Fig. 3 Biosynthetic pathway and engineering strategies for lactic acid production from C1 feedstocksGPD1/2—Glycerol-3-phosphate dehydrogenase 1/2 genes; ADH—Alcohol dehydrogenase gene; PDC1/5/6—Pyruvate decarboxylase 1/5/6 genes; ALDH—Aldehyde dehydrogenase gene; L-LDH—l-lactate dehydrogenase gene; D-LDH—D-lactate dehydrogenase gene; CYB2—L-lactate dehydrogenase (cytochrome) gene; DLD1—D-lactate dehydrogenase gene; Ady2—Acetate transporter; Jen1—Monocarboxylate/H+ symporter; LldP—D-lactate transporter

Fig. 4 Biosynthetic pathway and engineering strategies for succinic acid production from C1 feedstocksPYC—Pyruvate carboxylase gene; PPC—Phosphoenolpyruvate carboxylase gene; PCK—Phosphoenolpyruvate carboxykinase gene; MAE—Malic enzyme gene; MDH—Malate dehydrogenase gene; FUM—Fumarase gene; FRD—Fumarate reductase gene; SDH—Succinate dehydrogenase gene

Fig. 5 Combination of CO2 reduction and methanol bioconversion is a potential approach for industrial production of organic acids

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