RADIOAUTOGRAPHIC EVIDENCE FOR EQUATORIAL WALL GROWTH IN A GRAM-POSITIVE BACTERIUM

Abstract

Studies of bacterial wall growth, employing fluorescent antibodies to label specific areas of the growing walls, have suggested that in Gram-positive bacteria wall growth occurs by the intercalation of newly synthesized wall materials into discrete, specific equatorial zones of the preexistent wall (2, 3, 5, 11) . In the Gram-positive bacterium, Diplococcus pneumoniae, choline is required for growth. It has been shown that choline becomes incorporated solely into the cell wall teichoic acid of this organism (8, 6) . When deprived of choline, these cells can incorporate the amino alcohol analogue, ethanolamine, into teichoic acid in lieu of choline . Ethanolamine-grown cells exhibit several unusual properties, all of which are reversible upon restoration of choline to the culture medium (6, 9) . Among these deviant properties is the inability of daughter cells to completely separate after division . Thus, continued growth with ethanolamine as the sole available amino alcohol results in the eventual formation of long coccal chains instead of diplococci . This chaining phenomenon was exploited in the experiments to be described, in which radioautographic techniques were employed to provide new evidence for zonal wall growth . Media