Pectolytic bacteria were found in greater numbers in the eutrophic than in the mesotrophic lake. However, higher pectolytic activity was exhibited by the bacteria derived from the mesotrophic lake. In the eutrophic lake higher endo- and exo-PG activity was found in the benthic than in the panktonic bacteria, whereas in the mesotrophic one higher endo-PG activity was exhibited by the planktonic and higher exo-PG activity by the benthic bacteria. The polygalacturonases synthesized by the bacteria of the genera Achromobacter, Bacillus, Pseudomonas, of the group Flavobacterium - Cytophaga and of the family Enterobacteriaceae were active in the pH range 6.0-9.0. The majority of tested strains showed maximum activity at a temperature of 30 degrees C.