Isolation of acetic acid-tolerant Baker’s yeast variants in a turbidostat

A commercial baker’s yeast was subjected to selection in a continuous turbidostat cultivation with increasing concentration of acetic acid. The final acetic acid content in fresh medium was 0.6% or 0.8% v/v. Two of seven selected variants were stable over 15 sequential shake flask cultivations without selection pressure. After laboratory scale production of baker’s yeast, one of the variants also showed increased acetic acid tolerance in sour dough. The overall raising power (mL CO₂/h) in sour dough was improved 36%.