The Biological oxidation of carbohydrates

Abstract

The biologic oxidation of 0.1% sucrose in percolating filters was studied in presence of different amts. of phosphate, and with NH4Cl and NE4HCO3 as the source of N; the filter medium consisted of broken glass. In other exps., using gravel filter medium; the effect of organic P compounds on the rate of oxidation of the organic matter present in beet sugar factory press water was studied: in presence of N compounds (a) readily available to microorganisms and (b) available only with difficulty. The amt. of phosphate required to insure rapid oxidation of the sugar depended on the size and grade of filter medium. With a medium which did not become choked, a 0.1% sugar solution required for complete oxidation 15 parts P2O5 and 22 parts N per million; when the filter matured, these amts. could be reduced to 3 and 10 respectively. When NH4CI was used as the source of N, the oxidation of sugar was accompanied by pronounced reductions in pH values, owing to NHs being assimilated by microorganisms and HC1 being liberated. Intermediate compounds of sugar and phosphate were absent from all parts of the filters. The organic compounds of P in press water are only slowly available to microorganisms; in the absence of available P such as K2HPO4, the rate of oxidation by biologic filtration of the organic matter in press water may be limited by the rate at which the P becomes available. The full effect of available P is shown only in presence of an adequate supply of available N.