Evaluation of stress factors in the metabolism of Pedra-2 yeast

Abstract

The objective of this study was to evaluate the composition of the fermentation substrate as well as the effect of stress factors on the metabolism of Pedra-2 yeast. An exploratory survey was conducted for the composition of fermentable carbohydrates present in sugarcane juice. For the analyses of mineral and metal content, acid digestion of organic matter was used, determined by flame atomic absorption whit a spectroscope. The pre-inoculum was prepared whit 0.10g of the freeze-dried yeasts that were inoculated and diluted in sterile saline solution. The bioreactor with 125mL Erlenmeyer flasks, in which 50mL of sterilized sugarcane broth was added and adjusted to concentrations of 18, 25 and 32°Brix, to which the yeast colonies were inoculated with the help of a platinum loop and incubated at 30 and 40°C. Samples were collected at different times to evaluate biomass production through spectrophotometry at 570nm and cell viability by counting in a Neubauer chamber with methylene blue dye. The present study points out that the associated stress factors interfere with the studied microorganism's metabolism.

Keywords

• temperature
• sugar concentration
• saccharomyces cerevisiae
• fermentation process.