Fermentative hydrogen production from glucose and starch using pure strains and artificial co-cultures of Clostridium spp.

Table 4 Fermentation end products (molar concentrations) obtained during the starch fermentation performed at fixed optimal pH values (third sequence)

Strain/co-culture	Formate (mM)	Lactate (mM)	Acetate (mM)	Butyrate (mM)	H₂ yield (mol H₂/mol hexose)	Biogas production rate (L biogas/ h) ^a
C. beijerinckii DSM 1820	−4.34	−3.18	1.25	4.0	^b	0.28
C. butyricum CWBI 1009	0.09	−0.91	4.21	8.63	2.91	0.35
C. pasteurianum DSM525	4.96	−10.63	2.62	10.22	1.79	0.42
C. felsineum DSM 794	3.77	−28.62	8.98	1.04	^b	0.24
Co-culture 1	1.06	−14.47	0.12	6.76	2.08	0.95
Co-culture 2	−0.42	−4.08	3.19	14.08	1.6	1.3
Co-culture 3	9.04	−6.49	8.22	17.81	2.32	1.05

^a Maximum biogas production rate.
^b This strain produced H₂ mainly from the lactate and/or formate present in the medium, therefore it was not possible to correctly calculate the H₂ yield per mole of hexose consumed.

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