Abstract
The effect of environmental parameters on the growth and the tyrosine phenol-lyase content of Erwinia herbicola was investigated. On mineral medium containing glycerol, l -tyrosine increased the enzyme content 23-fold. When the l -tyrosine was also the carbon source, bacterial growth was 300 times greater than the basal level. On a rich medium, tyrosine phenol-lyase production was strongly dependent on pH and aeration. Catabolite repression and induction both probably control enzyme content.