Innovative fermentation strategies for the production of extremophilic enzymes.

A new type of microfiltration (MF) bioreactor, developed in our laboratory, was investigated for use in improving efficiency of the production of extremophilic enzymes. In spite of the difficulties in cultivating hyperthermophiles, we achieved, in 300 h fermentation, more than 38 g/l dry weight of Sulfolobus solfataricus using a MF technique, and we demonstrated that the activity of alcohol dehydrogenase (ADH), as the reporter enzyme, was not affected by cell density. However, hyperthermophile cultivation is difficult to scale up because of evaporation and the very low growth rate.

Effective production of a thermostable alpha-glucosidase from Sulfolobus solfataricus in Escherichia coli exploiting a microfiltration bioreactor.

A microfiltration (MF) membrane bioreactor was developed for an efficient production of a recombinant thermostable alpha-glucosidase (rSsGA) from Sulfolobus solfataricus MT-4. The aim of the membrane bioreactor was to improve the control of the concentration of key components in the growth of genetic engineered microorganisms, such as Escherichia coli. The influence of medium composition was studied in relation to cell growth and alpha-glucosidase production.