The genetically transformed roots of red beet have been shown, for the first time, to produce very high levels of peroxidase (POD; EC 1.11.1.7) accounting for 1.21 x 106 Units L
-1. Of the ten clones established using different strains of
Agrobacterium rhizogenes
, one was that from the strain LMG-150, three each from A 2/83, A 20/83 and A4. All the clones showed true integration of T-DNA when tested by PCR and Southern hybridization methods. Each clone differed significantly from the others in growth, hormone dependency and POD production where LMG-150 produced highest biomass (140 g FW L
-1) as well as POD (ranging from 8000-9000 U g
-1 FW and 1.18 x 10
6 U L
-1 with a specific activity of 600 U mg
-1 protein) on hormone-free medium, both in shake-flask as well as in bioreactor with a further enhancement to 1.21 x 106 U L
-1 upon the addition of extra calcium chloride (5 mM). PAGE with active staining showed 4 distinct bands of R
m 0.06, 0.16, 0.25, 0.38 and 0.46 in the biomass and bands at R
m 0.06, 0.16, 0.25 and one extra band of R
m 0.575 in the spent medium where isozymes of R
m 0.38 and 0.46 were totally absent. The pH optima and other properties were grossly comparable with the standard horse-radish POD (HRP) with better thermal stability than HRP and therefore, the present source appears to offer a cheaper and additional alternative for the commercial production of POD.
