Benzene toxicity and yield improvement in a cis-benzeneglycol production processe

We carried out experiments designed to increase the production of cis-benzeneglycol from benzene by a mutant strain of Pseudomonas. Factors affecting the production were the temperature, the nitrogen source and it's concentration, the concentration of iron ions, and the benzene concentration. At a benzene concentration of 33% of saturation vapor pressure, the cis-benzeneglycol production was not stable, but this benzene concentration was not toxic to the cells. In a culture under 10% of saturation vapor pressure the cells kept producing cis-benzeneglycol for over 100 h.

The decrease in cis-benzeneglycol production observed production at high benzen partial pressure (33%) could not be accounted for by the combined effects of an inhibition of enzyme production and a rapid turn-over of the enzyme, but by a specific inactivation of the enzyme. Possible mechanisms of inactivation were discussed which could explain the specific inactivation of the benzene dioxygenase: generation of polyphenols or generation of oxygen radicals.