lines of Research

Climate change is presumably humankind's most important challenge. Bioethanol from sugarcane is a liquid fuel that replaces gasoline, with the benefit of releasing up to 90% less greenhouse gases in its production/utilization cycle. There are ~350 biorefineries in Brazil, in which the yeast Saccharomyces cerevisiae converts sugarcane sugars (sucrose, glucose and fructose) into ethanol. Due to the non-aseptic nature of the process, contaminating microbes, such as bacteria, co-inhabit the fermentation environment, contributing to the creation of a particular microbiome. The presence of contaminants has consequences, such as decreased ethanol yields and increased use of antimicrobials, compromising the economic and environmental sustainability of the whole process. 

The elucidation of the interactions between yeast and contaminating species, which are still very poorly understood, has the potential to lead to improved industrial performance, via e.g. the use of targeted antimicrobials or tailor-made microbial consortia including probiotic (or beneficial) bacteria. Several parallels can be made between the alcoholic fermentation microbiome encountered in sugarcane biorefineries and other, better studied microbiomes, such as those found in the human gut, in soils, in foods, etc.

We are particularly interested in the following questions: 1) what makes the Saccharomyces cerevisiae strains used in bioethanol production different from other strains of the same species, for example those used in the production of beer, wine and baker’s yeast or even from wild strains found in nature? 2) How do yeast cells found inside industrial fermenters  relate ecologically to other microorganisms that contaminate the process, such as lactic acid bacteria? 3) Can we correlate the dynamics of the microbial populations in these biorefineries with process conditions?

To try to answer these questions, we are using metagenomics, bioinformatics, synthetic microbial consortia and other theoretical and experimental approaches in microbial ecology.