Table 1.

Representative examples of chemicals synthesis via anodic electro-fermentations (AEF) and microbial electrosynthesis (MES).

Process	Microbial organism	Substrate	Product	Mechanisms of EET	Genetic modification of host	Title/Yield/Productivity	Reference
AEF
	Shewanella oneidensis	Glycerol	Ethanol; Acetate	Direct electron transfer	Introduction of glycerol utilization module from Escherichia coli and ethanol production module from Zymomonas mobilis	Ethanol titer of 1.28 ± 0.02 g L-1, yield of (52 ± 4) %; Acetate titer of 0.29 ± 0.08 g L-1, yield of (13 ± 6) %	[36]
	Shewanella oneidensis	Glucose	Acetate	Direct electron transfer	Introduction of galactose permease (galP) and glucose kinase (glk) genes from Escherichia coli	No	[33]
	Shewanella oneidensis	Lactate	Acetoin	Direct electron transfer	Deletion of prophages in genome; Introduction of acetolactate synthase and acetolactate decarboxylase from Bacillus subtilis; Knockout of the acetate kinase (ackA) and phosphotransacetylase (pta) genes	Acetoin production rate of 0.91 mgh−1, yield of 52%, titer of 0.24 g L-1	[29]
	Pseudomonas putida	Glucose	2-ketogluconic acid	Direct electron transfer	Overexpression of periplasmic glucose dehydrogenase GCD	2-ketogluconic acid production rate of 0.25 ± 0.02 mmol gCDW−1 h−1	[34]
	Klebsiella pneumoniae	Glycerol	Acetate; 3-HP; 1,3-PDO	Direct electron transfer	No	Acetate titer of 21.7 mM; 3-HP titer of 7.6 mM; 1,3-PDO titer of 45.5 mM	[35]
	Escherichia coli	Lactate	Acetate; Ethanol	Direct electron transfer	Introduction of the Mtr pathway of Shewanella oneidensis MR-1	Acetate production rate of 0.038 mM day−1; Ethanol titer of 40 ± 3 μM	[39]
	Clostridium cellobioparum; Geobacter sulfurreducens	Glycerol	Ethanol	Direct electron transfer	Adaptive evolution of Clostridium cellobioparum	Ethanol titer of 10 g L-1	[40]
	Cellulomonas uda; Geobacter sulfurreducens	Cellobiose	Ethanol	Direct electron transfer	Adaptive evolution and deleted hydrogenase gene of Geobacter sulfurreducens	No	[41]
	Ralstonia eutropha	Fructose	PHB	PMF-mediated electron transfer	No	No	[42]
	Klebsiella pneumoniae	Glycerol	3-HP	2-hydroxy-1,4-naphthoquinone (HNQ)-mediated electron transfer	Overexpression of aldehyde dehydrogenase (AldH)	3-HP titer of 21.5 ± 2.2 mM	[43]
	Escherichia coli	Glucose	Acetoin	Methylene blue-mediated electron transfer	Deletion of the genes that encoding for enzymes of central reactions (ΔfrdA-D ΔadhE ΔldhA Δpta–ack); Introduction of the genes for the acetolactate synthase (alsS) and the acetolactate decarboxylase (alsD) and c-type cytochromes from Shewanella oneidensis	Production of 0.79 mol acetoin per mol glucose	[31]
	Escherichia coli; Methanobacterium formicicum	Glycerol	Ethanol; Acetate	Methylene blue-mediated electron transfer	Introduction of c-type cytochromes CymA, MtrA and STC from Shewanella oneidensis	Ethanol production rate of 12.12 ± 1.70 mgh−1, yield of (35 ± 5) %, titer of 55.25 ± 7.76 g L-1; Acetate production rate of 8.94 ± 0.52 mgh−1, yield of (20 ± 1) %, titer of 40.75 ± 2.37 g L-1	[45]
	Pseudomonas putida F1	Glucose	2-Keto-gluconate	Seven different mediators-based mediated electron transfer	No	2-Keto-gluconate production rate of 1.75 ± 0.33 mgh−1, yield of (90 ± 2) %, titer of 1.47 ± 0.27 g L-1	[44]
	Corynebacterium glutamicum Zymomonas mobilis	Glucose Glucose	l-lysine; Ethanol	Ferricyanide-mediated electron transfer; Methylene blue, neutral red, methyl naphthoquinone, 1,4- riboflavin, tempol, humic acid, and butanedisulfonate-mediated electron transfer	Feedback-deregulated mutant Overexpression of redox-related genes ZMO0899, ZMO1116, and ZMO1885	l-lysine titer of 2.9 Mm, production rate of 0.2 mmol L−1h−1 Bioelectricity generation 2.0 mWm−2; Ethanol titer ~42.5 g L-1	[30]
MES
	Geobacter sulfurreducens	CO2; Succinate	Glycerol	Direct electron transfer	No	Glycerol titer of 8.7 ± 0.3 mM	[47]
	Sporomusa ovate	CO2	Acetate	Direct electron transfer	No	No	[48]
	Clostridium pasteurianum DSM 525	Glucose; Glycerol	Butanol; 1,3-propandiol	Direct electron transfer	No	Butanol titer of 1.00 ± 0.20 g L-1 from glucose; 1,3-propandiol titer of 4.74 g L-1 from glycerol	[49]
	Shewanella oneidensis MR-1	Acetoin	2,3-butanediol	Direct electron transfer	Heterologous expression of a light-driven proton pump (PR) and butanediol dehydrogenase (Bdh); Knockout of hydrogenase gene ΔhyaBΔhydA	2,3-butanediol titer of 0.03 mM	[52]
	Shewanella oneidensis MR-1	CO2; Fumarate; Pyruvate	H2; Lactate; Formate; Succinate	Methyl viologen-mediated electron transfer	No	Accumulated 242 ± 24 nmol of H2; ~9100 nmol lactate (93% yield); ~1600 nmol of formate (16% yield); ~8300 nmol succinate (70% yield)	[53]
	Clostridium pasteurianum	Glycerol	1,3‐propanediol; n‐butanol	Neutral red and brilliant blue-mediated electron transfer	No	BuOH yields of 0.35 mol mol-1 glycerol in NR-mediated BES; 1,3‐PDO yields of 0.41 mol mol-1 glycerol in BB-mediated BES	[54]
	Escherichia coli	Acetophenone	(R)-1-phenylethanol	Methyl viologen-mediated electron transfer	Genetically introduction of cytochromes MtrA, CymA, and STC and heme exporter proteins ccmA-H from Shewanella oneidensis; Heterogenous expression of alcohol dehydrogenase from Lactobacillus brevis	(R)-1-phenylethanol yield of (39.4 ± 5.7) %	[55]
	Escherichia coli	Glucose	Succinate	Neutral red-mediated electron transfer	Heterogenous expression of mtrABC, fccA and cymA from Shewanella oneidensis MR-1	Succinate yield of 1.10 mol mol-1 glucose	[57]
	Saccharomyces cerevisiae	Dhea	7α–OH–DHEA	Neutral red and 7α-hydroxylase-mediated electron transfer	Heterogenous expression of 7α-hydroxylase	7α–OH–DHEA titer of 288.6 ± 7.8 mg L−1	[56]
	Ralstonia eutropha	CO2	Isopropanol	H2-mediated electron transfer	No	Isopropanol titer of 216 mgL−1	[59]
	Ralstonia eutropha	CO2	PHB; Isopropanol; C4 and C5 alcohols	H2-mediated electron transfer	No	PHB titer of ~700 mgL−1; Isopropanol titer of ~600 mgL−1; C4+C5alcohols titer of ~220 mgL−1	[60]
	Xanthobacter autotrophicus	N2 and H2O	NH3	H2-mediated electron transfer	No	NH3 concentration of ~0.8 mM	[61]
	Sporomusa ovate; Methanococcus maripaludis	CO2	Acetate; CH4	H2-mediated electron transfer	No	Acetate titer of 0.2–0.3 mM; CH4 titer of 0.2–0.3 mM;	[62]
	Sporomusa ovate	CO2	Acetate	H2-mediated electron transfer	No	Acetate titer of 6.4 ± 1.1 g L−1	[64]
	Ralstonia eutropha	CO2	3-methyl-1-butanol (3 MB); Isobutanol	Formate-mediated electron transfer	Introduction of genes alsS, ilvC, ilvD, kivd, and yqhD; Knockout of PHB synthesis gene cluster (phaC1, phaA and phaB1)	3 MB and isobutanol titer of 140 mgL−1	[25]
	Ralstonia eutropha	CO2	PHB	Formate and neutral red-mediated electron transfer	Heterologous expression of the ribulose-1,5-bisphosphate carboxylase (Rubisco) from Synechococcus elongatus PCC7942	PHB titer of 485 ± 13 mgL−1	[65]