There have been reports in the literature regarding the use of
co-cultivation to improve the fermentations and to carry out two
or more transformations in one step (Abouzied and Reddy, 1987).
In the alcoholic beverages industry, the use of autochthonous
yeasts is considered more desirable since they are adapted to the
substrates and usually produce secondary metabolites that are
responsible for the aroma and taste of the drink, although the
yields are often very low (Fleet, 2003; Cedeño-Cruz, 1995). With
henequen, although the production of alcohol from the stems to
derive a drink is commercially exploitable, however, this is not
the case for the production of ethanol as fuel. In earlier investigations
carried out by our group, it was found that the ethanol production
obtained from leaf juice was relatively low, 2.72% v/v
(volume of ethanol per volume of fermentation broth) when fermentation
was performed with Cicy-Ki, in comparison with 6–8%
obtained in the Mexican sugar industry, where fermentations are
carried out with the yeast S. cerevisiae and molasses used as substrate.
When S. cerevisiae was used to ferment henequen leaf juice,
an ethanol production of 4–5% v/v was obtained. Using these preliminary
data a mixture of these yeasts was proposed to improve
yields. It was also possible to determine that henequen leaf juice
contains sugars that can be metabolized to produce alcohol, but
with insufficient concentration to obtain acceptable yields, therefore,
industrial molasses were added. Thus, the raw materials for
the production of ethanol as fuel are two industrial residues: henequen
leaf juice produced by the natural fiber industry and molasses
produced by the sugar industry.