Biochemical process

A process for the production of a compound comprising a 1,2-dihydroxycyclohexa-3,5-diene ring which process comprises the steps of:

• (1) growing a mutant strain in a growth medium at a temperature in the range 25.degree. C. to 35.degree. C. and at a pH within the range 5.5 to 8.0 in the presence of oxygen or an oxygen containing gas, the said mutant strain comprising (a) an enzyme for producing cyclic dihydroxy compounds from aromatic compounds;
• (b) being incapable of growing on benzene or toluene, and (c) being obtained by mutation of a strain of Pseudomonas putida selected from the group consisting of NCIB 11680 and NCIB 11767 which is able to grow on benzene or toluene, the said growth medium comprising an aqueous mineral salts solution and a suitable source of carbon for cell growth, the concentration of said source being maintained between 1% w/w and 5% w/w;
• (2) supplying to the cells of the said mutant strain suspended in a suitable medium, after the growth period, an aromatic compound and a compound which functions as a source of energy for metabolising the aromatic compound, the said suitable medium being capable of supporting little or no growth of the cells of the said mutant strain and lacking, or containing little of, one or more elements essential for growth, of the cells of said strain the said aromatic compound having one or more aromatic rings, each of which may bear one or more substituents which may be hydrocarbyl groups having up to four carbon atoms, or heteroatoms or hetero-groups, at least one of the said one or more aromatic rings having a hydrogen atom attached to adjacent carbon atoms in the aromatic rings, the concentration of the said source of energy in the said suitable medium being maintained at between 0.05% w/v and 0.5% w/v, and the concentration of the said cells in the said suitable medium being from 1 to 30 grams dry weight of cells per liter of medium;
• (3) allowing the said mutant strain to convert the aromatic compound into a compound comprising a 1,2-dihydroxycyclohexa-3,5-diene ring at an oxygen tension which is greater than 1% of saturation;
• (4) removing the said cells by centrifugration, flocculation or both;
• and
• (5) isolating the compound comprising (a) 1,2-dihydroxycyclohexa-3,5-diene ring from the medium.