P11: Study of bacterial contamination in ethanol mills in Brazil using next generation sequencing

Brazil is one of the largest ethanol producers in the world, producing on average about 24 billion liters annually. The plants producing ethanol in Brazil use a non-sterile fermentation process resulting in bacterial contamination during fermentation. Bacterial contaminations up to 10⁵ CFU/ml in the plants are acceptable and above 10⁸CFU/mL results in reduction of fermentation efficiency.

In order to study bacteria contaminations in the process of ethanol production we performed metagenomic analysis of plants in 2012 using 16S sequence. Previous studies using Sanger sequencing methodology was conducted by our group during the 2010 harvest, which showed the predominance of Lactobacillus sp. and Weisella sp. and the presence of species that had not yet been described in literature, such as: Arthrobacter sp. and Methylobacteriumsp. However to obtain this data it was necessary to culturing the samples in various media, which may result in loss of uncultured bacterias, fact that does not occur using NGS methodology.

The results obtained from NGS confirm the predominance of lactobacilli in fermentation, and the presence of other contaminants not previously described: Megasphaera elsdenii, Prevotella oris, Prevotella stercorea, Escherichia fergusonii, among others. Each analysis allows detection of species in very small concentrations, since more than 50,000 hits are analyzed at a time.

The innovative use of this technology will enable a more efficient prevention of bacterial contamination. The detection of bacteria in low concentrations will lead to a better understanding of the population dynamics of these contaminants and correlation with environmental factors and productivity measures.