Robust microorganisms for biofuel and chemical production from municipal solid waste

Table 2 Key fermentation yield parameters for eight species grown on OMSW fibre hydrolysate

Species	Strain	Product	Time (h)	Glucose used (%)	Xylose used (%)	Total sugars (used)^a	Mean ± SD					Yield per tonne (kg/t)^e	Theoretical max. yield (kg/t)^f
Species	Strain	Product	Time (h)	Glucose used (%)	Xylose used (%)	Total sugars (used)^a	Final CDW (g/L)	Product titre (g/L)	Productivity (g/L/h)^b	P/S (g/g)^c	Percentage yield (%)^d	Yield per tonne (kg/t)^e	Theoretical max. yield (kg/t)^f
P. putida	NCIMB8249	None	72	73.1	n/a	63.4	2.5 ± 0.4	n/a	n/a	n/a	n/a	n/a	n/a
C. saccharoperbutylacetonicum	DSM14923	Butanol	48	5.6	0.0	4.4	0.7 ± 0.1	n/d	n/a	n/a	n/a	n/a	n/a
G. thermoglucosidasius	DSM2542	Ethanol	48	20.3	47.5	26.0	0.4 ± 0.1	n/d	n/a	n/a	n/a	n/a	n/a
E. coli	LW06	Ethanol	48	99.1	61.6	91.0	9.0 ± 0.8	10.9 ± 0.5	0.46 ± 0.02	0.17 ± 0.01	34 ± 2	55	70
S. pombe	JB953	Ethanol	48	99.8	n/a	99.8	3.3 ± 0.1	14.9 ± 1.9	0.31 ± 0.04	0.26 ± 0.03	51 ± 7	74	101
Z. mobilis	DSM424	Ethanol	24	98.4	n/a	98.4	1.3 ± 0.2	17.5 ± 0.3	0.73 ± 0.01	0.35 ± 0.01	69 ± 1	87	136
S. cerevisiae	ATCC200062	Ethanol	24	99.3	n/a	99.3	2.5 ± 0.1	18.1 ± 1.3	0.75 ± 0.06	0.36 ± 0.03	70 ± 5	90	139
R. opacus	MITXM-61	TAG	72	99.5	100.0	99.6	32.7 ± 0.4	15.2 ± 1.1	0.21 ± 0.02	0.23 ± 0.02	72 ± 5	76	91

TAG, Triacylglycerol; n/a, not applicable; n/d, not detected; ± SD, standard deviation of triplicate measurements
The equations used to calculate these variables are given in Additional file 1: Additional Methods
^aPercentage of metabolically available sugars consumed based on initial d-glucose and d-xylose concentrations
^bGrams of product produced per litre of fermentation medium per hour, also known as process productivity, (g/L/h)
^cProduct to substrate yield ratio (grams of product per gram of sugar fermented)
^dProduct titre attained by fermentation, given as a percentage of the theoretical maximum fermentation yield from sugars. Assuming theoretical maxima of 0.316 g/g sugar for triacylglycerol and 0.511 g/g for ethanol. Note that these figures may be overestimates as only the major carbon sources d-glucose and d-xylose were accounted for. Less abundant sugars or unaccounted carbon sources could have contributed to the yield
^ekg of product that could be produced from one tonne of OMSW fibre, based on observed conversion efficiencies
^fkg of product that could be produced from one tonne of OMSW fibre, assuming complete conversion of sugars in hydrolysis

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