An Application of a Bioreactor with Flocculated Cells of Halophilic Micrococcus Varians Subsp. Halophilus Which Preferentially Adsorbed Halophilic Nuclease H to 5’-Nucleotide Production

Abstract

A bioreactor system was designed with the flocculated cells of halophilic Micrococcus varians subsp. halophilus which immobilized halophilic nuclease H on the surface, for the production of flavouring agent, 5’-guanylic acid (5’-GMP). As the bacterium produced an extracellular 5’-nucleotidase as well as the nuclease H, selective inactivation of the 5’-nucleotidase contaminated in the column was necessary to obtain high yields of 5’-GMP from RNA. A fact that the exogenous nuclease H was preferentially adsorbed on the flocculated cells over the 5’-nucleotidase was advantageous to the production. Desalting treatment of the flocculated cells in the presence of 80 mM MgSO₄ preferentially inactivated 5’-nucleotidase, and the RNA degradation in the presence of 0.25 mM ZnSO₄ greatly improved the yield. Furthermore, Ca-enzyme-complex which was formed by adding CaC1₂ to the supernatant of the culture at 25^°C was applied to the bioreactor.