TABLE 1.

Comparison of n-caproate production via lactate chain elongation by continuously fed reactor microbiome

Substrate	Reactor type	No. of days	pH	Dominant microbiome	RA (%)	Max concn (g liter−1)	Max production (g liter−1 day−1)	Reference or source
Thin stillage + H2	1-Liter reactor (with electro chemical cells)	42	5.4∼5.7	Megasphaera elsdenii	57	2.08	0.58	39
l-Lactate	0.7-Liter AFa (with in-line extraction)	220	5.0	Acinetobacter sp.	62.9	—e	3.03	31
Grass	100-ml reactor (with electrochemical cells)	30	5.5∼6.2	Clostridium IV (related to strain BS-1)	28	4.09	—e	28
Acid whey	0.7-liter CSTRb (with in-line extraction)	90	5.0	Bacteroidales	21.7	—e	1.68	8
Clostridiales	12.6
15× diluted food waste leachate + H2	6.0-liter leach-bed	100	Initial, 7.0d	Clostridium	42	9.59	—e	29
Acid whey	1.0-liter UASBc	400	5.5	Ruminococcaceae	20.5	10.4	3.20	32
Prevotellaceae	17.9
Liquor brewing wastewater	5.0-liter AF	485	6.5	Clostridium IV	25.5	3.59	10.9	33
Xylan + lactate	1.0-liter CSTR	148	5.5	Ruminiclostridium 5	42.3	—e	3.60	49
10–15% (vol/vol) food waste	1.0-liter stirred tank reactor	45	6.0	Caproiciproducensf	32–72	5.4	1.81	27
Lactate	0.9-liter CSTR	194	5.0–6.5	Caproiciproducens	2.0–67.8	8.58	—e	34
dl-Lactate	3.0-liter CSTR	780	6.0	Caproiciproducensg	53.9	33.7	11.5	This study

^aAF, anaerobic filter.

^bCSTR, continuously stirred tank reactor.

^cUASB, upflow anaerobic sludge blanket.

^dOnly the initial pH of each cycle was controlled.

^eNo related data given.

^fCaproiciproducens in this source, formerly Clostridium IV, showed 91 to 95% similarity to Caproiciproducens galactitolivorans.

^gCaproiciproducens related to Ruminococcaceae strain CPB6.