This corresponds to a maximum H2 yield from starch of 1.75 mol/-
mol glucose equivalents, which is an intermediate value between
2.2 mol/mol hexose obtained under optimised conditions by Lin
and co-workers [27] and 1.19 mol/mol glucose obtained in the fermentation of pre-treated corn starch [28]. The H2 yield from
sucrose was 3.35 mol/mol, that is higher than other values
reported with mesophilic mixed cultures, such as 2.39 and
1.8 mol H2/mol sucrose [29,30], or even with a pure culture of C.
butyricum CGS5 (2.78 mol H2/mol sucrose) [31]. These results show
that in general mixed cultures can produce H2 in similar or even
higher yields than pure cultures. Evidently, this only occurs as long
as the selective pressure of the production process (i.e., operational
conditions such as temperature and pH) allows the growth and
supremacy of hydrogenogenic microorganisms in the culture
[32]. H2 production by the consortium LE58 from xylose or xylan
as carbon and energy source reached 132 and 178 mL/g, respectively