Production of medium-chain carboxylic acids by Megasphaera sp. MH with supplemental electron acceptors

Table 1 The fermentation products according to various electron acceptors by Megasphaera sp. MH using fructose

Electron acceptor (EA, 100 mM)	Fermentation products (g/L)^a
Electron acceptor (EA, 100 mM)	Butyrate (C4)	Pentanoate (C5)	Hexanoate (C6)	Heptanoate (C7)	Octanoate (C8)	O.D._max
Without supplementary EA	0.3 ± 0.0	0.0 ± 0.0	0.9 ± 0.1	0.1 ± 0.0	0.6 ± 0.0	2.9 ± 0.2
Acetate (C2)	0.9 ± 0.1	0.2 ± 0.2	4.4 ± 0.0	0.1 ± 0.0	0.6 ± 0.0	5.5 ± 0.6
Propionate (C3)	0.2 ± 0.0	4.1 ± 0.3	0.2 ± 0.0	2.0 ± 0.1	0.1 ± 0.0	5.4 ± 0.3
Butyrate (C4)	1.6 ± 0.1^b	0.2 ± 0.0	6.3 ± 0.0	ND	0.6 ± 0.0	3.9 ± 0.0
Acetate based (dual electron acceptors)^c
Acetate(C2) +propionate(C3)	1.0 ± 0.0	5.7 ± 0.1	1.5 ± 0.1	2.7 ± 0.1	0.2 ± 0.0	6.4 ± 0.4
Acetate(C2) + butyrate (C4)	2.5 ± 0.1^b	0.3 ± 0.0	9.7 ± 0.2	ND	0.6 ± 0.0	6.2 ± 0.5
Acetate(C2) + pentanoate (C5)	0.2 ± 0.0	5.8 ± 0.1^b	ND	3.6 ± 0.1	0.2 ± 0.0	2.2 ± 0.0
Acetate(C2) + hexanoate (C6)	1.6 ± 0.0	0.2 ± 0.0	8.7 ± 0.0^b	ND	1.2 ± 0.0	2.0 ± 0.0

The italic numbers indicate higher production than in mPYF without supplementary electron acceptors
ND not detected
^aThe value is average of duplicates
^bThe value is undefined as products or non-used electron acceptor
^cEach concentration was 100 mM except hexanoate (50 mM) and total concentration of extracellular electron acceptors was 200 mM (for acetate + hexanoate, 150 mM)

ISSN: 2731-3654