High level extracellular production of a recombinant alkaline catalase in E. coli BL21 under ethanol stress and its application in hydrogen peroxide removal after cotton fabrics bleaching

• The yield of alkali catalase (KatA) in E. coli was the highest level reported so far.
• The yield of recombinant KatA was significantly enhanced by 2% ethanol stress.
• Triton X-100 supplementation could markedly improved extracellular ratio of KatA.
• KatA shows higher H2O2 removal rate and lower cost than traditional process.

The effects of induction parameters, osmolytes and ethanol stress on the productivity of the recombinant alkaline catalase (KatA) in Escherichia coli BL21 (pET26b-KatA) were investigated. The yield of soluble KatA was significantly enhanced by 2% ethanol stress. And a certain amount of Triton X-100 supplementation could markedly improved extracellular ratio of KatA. A total soluble catalase activity of 78,762 U/mL with the extracellular ratio of 92.5% was achieved by fed-batch fermentation in a 10 L fermentor, which was the highest yield so far. The purified KatA showed high stability at 50 °C and pH 6–10. Application of KatA for elimination of H2O2 after cotton fabrics bleaching led to less consumption of water, steam and electric power by 25%, 12% and 16.7% respectively without productivity and quality losing of cotton fabrics. Thus, the recombinant KatA is a promising candidate for industrial production and applications.