Analysis of metabolite profiles of Saccharomyces cerevisiae strains suitable for butanol production.

Butanol has advantages over ethanol as a biofuel. Although butanol is naturally produced by some Clostridium species, clostridial fermentation has inherent characteristics that prevent its industrial application. Butanol-producing Saccharomyces cerevisiae strains may be a solution to this problem.

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.

Artisanal cachaça and brewer's spent grain as sources of yeasts with promising biotechnological properties.

Aims: This study aimed to characterize yeasts isolated from the environment of artisanal cachaça production and brewer's spent grain-bearing in mind their further application in bioprocesses.

Methods And Results: Cell morphology, growth and fermentative parameters, and karyotyping were employed for the selection and grouping of yeast strains. The results showed that from 134 yeast strains studied, 14·2% exhibited cells with snowflake morphology, which is not appropriate for bioethanol production.

The expanding large-spored Metschnikowia clade: Metschnikowia matae sp. nov., a yeast species with two varieties from the Brazilian Atlantic Forest.

Fifty-two yeast isolates from flowers and associated nitidulid beetles of the Brazilian Atlantic Forest (Mata Atlântica) region were found to represent a new species in the large-spored Metschnikowia clade. The species is heterothallic, haploid, and allogamous, and produces asci with two aciculate ascospores that can reach 80 μm in length, as is typical in the clade. Analysis of sequences of the ribosomal RNA gene cluster indicates that the new species is closely related to Metschnikowia lochheadii, which ranges across Central America to northern Brazil, occurs as an adventive species in Hawaii, but is rarely found in central Brazil.

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.