Interaction between the production of ethanol and glycerol in fed-batch bioreactors.

During alcoholic fermentation, most of the substrates supplied to the yeasts are converted into ethanol and carbon dioxide generating energy for cell maintenance. However, some of these substrates end up being diverted to other metabolic pathways generating by-products reducing the yield in ethanol production. Glycerol is the most important by-product quantitatively, and its production during fermentation is associated to the production of ethanol.

Yeast biomass production: a new approach in glucose-limited feeding strategy.

The aim of this work was to implement experimentally a simple glucose-limited feeding strategy for yeast biomass production in a bubble column reactor based on a spreadsheet simulator suitable for industrial application. In biomass production process using Saccharomyces cerevisiae strains, one of the constraints is the strong tendency of these species to metabolize sugars anaerobically due to catabolite repression, leading to low values of biomass yield on substrate. The usual strategy to control this metabolic tendency is the use of a fed-batch process in which where the sugar source is fed incrementally and total sugar concentration in broth is maintained below a determined value.

Genome structure of a Saccharomyces cerevisiae strain widely used in bioethanol production.

Bioethanol is a biofuel produced mainly from the fermentation of carbohydrates derived from agricultural feedstocks by the yeast Saccharomyces cerevisiae. One of the most widely adopted strains is PE-2, a heterothallic diploid naturally adapted to the sugar cane fermentation process used in Brazil. Here we report the molecular genetic analysis of a PE-2 derived diploid (JAY270), and the complete genome sequence of a haploid derivative (JAY291).

Study of flocculent yeast performance in tower reactors for bioethanol production in a continuous fermentation process with no cell recycling.

The purpose of this study was to assess the retention ability of 12 different Saccharomyces sp. yeast strains with flocculent characteristics when inoculated in a continuous ethanol fermentation process. The system was comprised of two reactors connected in series with no cell recycling.