Effect of Pectin on Bacterial Growth

Abstract

Several years ago we became interested in pectin when it was suggested 1 that this substance appeared to exert a germicidal action on intestinal organisms. We have tried various technics for studying different concentrations of numerous commercial pectins of different grades at various H-ion concentrations. From these studies we have developed a testing technic that appears to be satisfactory.

It is necessary to test different pectins under the same conditions to obtain comparable results. Since the higher the concentration the more difficult it is to dissolve the pectin and since the more insoluble pectins are dissolved only by severe heat treatment, which tends to break down the pectin molecule, we have standardized on a 1% pectin solution in nutrient broth. However, we have tested the more soluble pectins at concentrations up to 5% with similar results.

Each pectin was dissolved with minimum heat treatment in sterile nutrient broth of pH 6.5. These pectin broths had low pH's, ranging from 5.5 to 3.9. At the “natural” pH thus obtained, we studied the growth of Esch. coli. Similar studies were conducted on each pectin broth adjusted to pH 6.5, which adjustment was made at room temperature to eliminate degradation of the pectin by heat and alkali. As controls for each pectin, we used nutrient broth adjusted to the corresponding “natural” pH and also nutrient broth adjusted to pH 6.5.