MORPHOLOGICAL CHANGES OF RECOMBINANT S. cerevisiae CELLS DURING ADAPTIVE EVOLUTION

Saccharomyces cerevisiae is the main microorganism used for ethanol production. During second generation ethanol production, using lignocellulosic biomasses as carbon sources, the yeast is exposed to different growth inhibitors. In this context, this work aims to evaluate morphological changes in the recombinant strain S. cerevisiae MDS 130 during an adaptive evolution study. Exposure to different cultivation conditions, including increasing content of hemicellulosic hydrolysate in the medium as well as ethanol concentrations, were evaluated. Samples of each batch condition were collected during the evolution and characterized by its viability. The images obtained were used to estimate the cells average area by the software ImageJ. It allowed to evaluate changes in cell morphology as a function of the culture conditions. However, no significant changes were observed in population morphology, which can be justified by the high variability in cell population. So, the average size of the cell population was similar throughout the adaptation process, which lasted 120 days.