Toxic effects of acrylic acid on Clostridium propionicum and isolation of acrylic acid-tolerant mutants for production of acrylic acid

This work presents a systematic investigation of the toxic effects of acrylic acid on the growth of Clostridium propionicum and the isolation of acrylic acid-tolerant mutants. The results suggest that addition of acrylic acid prolonged the lag phase of the fermentation and reduced the initial-specific growth rate, as well as the final cell concentration. Moreover, the toxic effect of acrylic acid was sensitive to the pH value. The minimal inhibition concentration of acrylic acid increased from 1.11 to 31.25 mM when the pH value rose from 5.8 to 7.4. In addition, the molar concentration ratio of products (acetic acid:propionic acid) was enhanced with the supplementation of acrylic acid. The highest ratio was 0.7:1 when acrylic acid was 20.83 mM at pH 7.4. Two acrylic acid-tolerant mutants were isolated, which could still grow at a high concentration (43.06 mM) of acrylic acid. These strains could be instrumental for improved bioproduction of acrylic acid.