A POSSIBLE EFFECT OF CELLULOSE-DECOMPOSITION ON SOIL BACTERIAL FLORA

Abstract

Soil bacterial flora was studied in soil suspensions supplied with cellulose powder. Cellulose decomposers proliferated comparatively soon after addition of the cellulose powder. Following the proliferation of the cellulose decomposers, counts of total numbers of non-cellulolytic bacteria increased in proportion to the amount of added cellulose powder. Bacteriological characterization of the isolated bacterial strains revealed that gram-negative bacteria, especially pseudomonad groups, increased their populations in soil suspensions with the added cellulose powder. On the other hand, the bacillus group did not increase even under such conditions. Most of the predominant gram-negative bacteria could grow by utilizing glucose or cellobiose as the sole source of carbon. At the final stage of the experimental period, the predominance of the gram-negative bacteria diminished, and these organisms were partly replaced by bacteria which were unable to utilize glucose or cellobiose. The change in pH of the soil suspensions and the pattern of accumulation of reducing sugars were also followed. A fungus predominated temporarily during the decomposition of cellulose when the pH of the soil suspension was lowered.