Effects of cadmium towards yeast fermentation, and the use of vinasse to atenuate the toxic effects

Author(s)

Samuel Mariano Gislon da Silva

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2001-10-30
• Advisor: Luiz Carlos Basso

Abstract

The study was carried out in order to evaluate the capability of different cadmium concentrations to affect some alcoholic fermentation parameters, inclusive in cell recycling conditions, and the vinasse capability in order to attenuate the cadmium toxicity. Toe yeast were grown in yeast extract + dextrose medium with or without vinasse and in sugar-cane medium with or without vinasse. The measured parameters were yeast growth, trehalose and glycogen accumulation, alcohol and glicerol production, residual glucose and frutose in vine, fermentation rate, cell cadmium concentration, damages of the citoplasmatic membrane, cell viability and budding rate. The increase of cadmium levels showed a reduction on trehalose accumulation, yeast growth and cell viability. Watch ali levels studied have accumulation of cadmium at yeast. Vinasse showed low toxicity, demonstrated by growth and trehalose reduction, but protected yeast cells very effectively against the toxic effects of cadmium. ln the concentration of 0,025 mmol L-1 of cadmium, damages of the cellular wall were observed. Y east viability decreased in parallel with trehalose content, apparently in response to cadmium toxicity. Therefore, trehalose concentrations may be an important indicator of cadmium stress on yeast (AU)