A series of batch assays were undertaken in order to evaluate
the capability of LE37, LE58 and C. butyricum to produce H2 from
different carbon and energy sources, including sugars identified
in the composition of S. obliquus biomass [15,21]. It is known that
S. obliquus is able to store sugars in the form of intracellular starch
and that glucan and xylan may also exist in the microalgae cell
walls, as well as extracellular polymeric substances [26].
Amongst both mixed cultures, the highest H2 volumetric
productions were 241 and 242 mL/g and were attained by LE37
in the fermentations of starch and sucrose, respectively (Fig. 1a).
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