Phosphorylated Carbohydrate Esters in Autotrophic Bacteria

Strictly autotrophic bacteria are microorganisms which grow only in the presence of a specific inorganic nutrient from the oxidation of which they obtain their energy and which are able to cover all of their carbon needs from COS.In most cases organic materials are not utilized and may be toxic.One representative of this group of organisms, Thiobacillus thiooxidans, oxidizes sulfur to sulfuric acid as its energy source and no material yet found can replace COZ as a source of carbon for growth.This organism is further remarkable in that it will only grow at a pH of below 6, and produces, during its growth, as much as 5 per cent sulfuric acid without detectable harm to its metabolism.It has recently been shown that cells of this organism were able to survive relatively long periods in the absence of oxidizable sulfur and that under these circumstances it possessed an organic metabolism resulting in the liberation of CO2 (1).LePage (2) was able to demonstrate that during this "endogenous metabolism" a polysaccharide storage product was broken down and O'Kane (3), Vogler and Umbreit (4), and LePage (2) have provided evidence that phosphorylation was somehow involved in this breakdown.It was therefore of considerable interest to determine whether this metabolism followed a pathway similar to that of yeast and muscle or whether a different, and perhaps more primitive, type of phosphorylating metabolism was involved.Two limitations are imposed upon studies of this organism.First, the difficulty of obtaining sufficient amounts of tissue for experiment necessitates the application of micromethods throughout.Second, the usual methods of study of bacterial metabolism are not applicable, since organic materials are not utilized by this organism; i.e., one cannot supply an external source of glucose, for example, and determine the fermentation products.It was therefore necessary to modify existing methods for the determination of the phosphorylated carbohydrate esters and to apply them on a micro scale.In the procedure.employedmost of the compounds are determined by at least two independent measurements.By application of this method it was possible to account for over 90 per cent of the acidextractable phosphorus of the autotrophic cell in terms of known compounds whose identity is clearly established.The results showed that the 263