Nine indigenous cachaça
Saccharomyces cerevisiae strains and one wine strain were compared for their trehalose metabolism characteristics under non-lethal (40°C) and lethal
(52°C) heat shock, ethanol shock and combined heat and ethanol stresses. The yeast protection mechanism was studied through
trehalose concentration, neutral trehalase activity and expression of heat shock proteins Hsp70 and Hsp104. All isolates were
able to accumulate trehalose and activate neutral trehalase under stress conditions. No correlation was found between trehalose
levels and neutral trehalase activity under heat or ethanol shock. However, when these stresses were combined, a positive
relationship was found. After pre-treatment at 40°C for 60 min, and heat shock at 52°C for 8 min, eight strains maintained
their trehalose levels and nine strains improved their resistance against lethal heat shock. Among the investigated stresses,
heat treatment induced the highest level of trehalose and combined heat and ethanol stresses activated the neutral trehalase
most effectively. Hsp70 and Hsp104 were expressed by all strains at 40°C and all of them survived this temperature although
a decrease in cell viability was observed at 52°C. The stress imposed by more than 5% ethanol (v/v) represented the best condition
to differentiate strains based on trehalose levels and neutral trehalase activity. The investigated
S. cerevisiae strains exhibited different characteristics of trehalose metabolism, which could be an important tool to select strains for
the cachaça fermentation process.
Keywords Heat shock proteins - Indigenous yeasts -
Saccharomyces cerevisiae
- Stress - Trehalose - Trehalase