Microbial ecology applied to fuel ethanol production from sugarcane.

The production of fuel ethanol in sugarcane biorefineries is a nonaseptic industrial operation, which employs cell recycling and the use of adapted Saccharomyces cerevisiae strains. Microbial contaminants are present and, depending on the conditions, may lead to process performance deterioration. Past studies have identified the main microbial species present in this environment, using culture-dependent techniques. A few recent studies started to deploy culture-independent techniques to better understand this microbiota and its dynamics. In both cases, lactic acid bacteria have been identified as the main contaminating microorganisms. Less than a handful of reports are available on the interactions between yeast and contaminating bacteria, using synthetic microbial communities, proposing that interactions are not necessarily always detrimental. The present mini-review aims at systematizing the current knowledge on the microbiota present in the alcoholic fermentation environment in sugarcane biorefineries and setting the ground and claiming the need for a microbial ecology perspective to be applied to this system, which in turn might lead to future process improvements.