Pectic enzymes of Erwinia carotovora

Abstract

A culture of Erwinia carotovora isolated from rotted Mexican bell pepper liberated methanol practically quantitatively from pectin when growing in a pectin medium. This phenomenon is considered to be positive evidence of pectinesterase activity. Polygalacturonase could not be demonstrated directly in the culture medium containing actively growing cells because the subsequent rapid utilization of galacturonic acid made positive identification of the enzyme uncertain. Because polygalacturonase is insensitive to both fluoride and azide, and the galacturonic acid degrading system is inhibited by these substances, it was possible to demonstrate and study the polygalacturonase in the presence of these metabolic inhibitors. E. carotovora polygalacturonase is active over a wide pH range, the optimum being around 5.8. Its production or secretion into the medium is greatly increased by the addition of pectic substances to the growth medium.