The intracellular teichoic acid from Lactobacillus arabinosus 17-5.

It has been shown that extracts of certain bacteria contain both glycerol teichoic acid and ribitol teichoic acid, although the walls of these organisms contain only the ribitol compounds (Armstrong, Baddiley, Buchanan, Carss & Greenberg, 1958). The conclusion that glycerol teichoic acids occur in an unspecified region beneath the wall was substantiated in a more extensive survey (Baddiley & Davison, 1961; and unpublished work) in which separated walls and cell contents of many bacteria were examined. It was found that glycerol or ribitol teichoic acids may occur in considerable amounts in a number of walls, but in some cases neither compound is present. On the other hand, smaller amounts of glycerol teichoic acids were isolated from the cell contents of very nearly all the organisms studied in these Laboratories. It is now thought that a small amount of glycerol teichoic acid may well occur in the cell contents of all Gram-positive bacteria. In the many cases examined, the only method used so far for the reliable detection of these compounds is actual isolation, followed by hydrolysis and identification of hydrolysis products. The isolation procedure is difficult and probably not quantitative; consequently, in the few cases where no teichoic acid was observed it is possible that the amount is small or that other substances interfere with the isolation. The general term 'intracellular teichoic acid' is applied to these compounds on the understanding that they occur in a region enclosed by the cell wall. The structure of only one of the intracellular compounds has been studied in detail. That from Lactobacillus casei A.T.C.C. 7469 was isolated in an impure state from the cell contents of the organism and was identified as a glycerol 1,3-phosphate polymer bearing D-alanine ester residues at position 2 on most of the glycerol residues (Kelemen & Baddiley, 1961). Unlike the ribitol teichoic acids, this compound apparently contains no sugar residues, although the presence of considerable amounts of carbohydrate impurities would have prevented the detection of small numbers of sugar residues attached to the teichoic acid. The increasing recognition that teichoic acids possess serological properties (Baddiley & Davison, 1961; Haukenes, Ellwood, Baddiley & Oeding,