Pectinase Production by Bacteria Associated with Improved Preservative Permeability in Sitka Spruce: Synthesis and Secretion of Polygalacturonate Lyase by Cytophaga johnsonii

Cytophaga johnsonii synthesized a polygalacturonate lyase which produced random cleavage of galacturonic acid polymers. No pectin methyl-esterase or hydrolytic pectinase activities could be detected in cultures of the organism. Polygalacturonate lyase synthesis was inducible and also subject to repression by glucose and other compounds. Galacturonic acid was the most effective inducer; lower activities were obtained with citrus pectin, polygalacturonic and polypectic acids. Glucose repression of lyase synthesis was not alleviated by 5 mM-adenosine-3'.5'-cyclic-monophosphate. Enzyme production was growth-linked and ceased when batch cultures entered the stationary phase. In steady-state chemostat cultures lyase activity was maximal at a dilution rate ( D ) of 0.19 h^-1. Polygalacturonate lyase was both cell-bound and free in the supernatant medium. The proportion of free enzyme increased throughout the batch growth cycle and in chemostat cultures over 70% of the activity was cell free at dilution rates below 0.05 h^-1.