Bacteria and Viruses by Britannica Educational Publishing

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Capsules can be seen under a light microscope by placing the cells in 16 7 Bacterial Morphology and Reproduction 7 The capsular material surrounding these bacteria (Acinetobacter calcoaceticus) is revealed in a suspension of India ink and viewed through a light microscope (magnified about 2,500×). H. Taylor and E. Juni, “Pathways for Biosynthesis of a Bacterial Capsular Polysaccharide,” Journal of Bacteriology (May 1961) a suspension of India ink. The capsules exclude the ink and appear as clear halos surrounding the bacterial cells.

20 7 Bacterial Morphology and Reproduction 7 Cytoplasm Although bacteria differ substantially in their surface structures, their interior contents are quite similar and display relatively few structural features. Indeed, all bacterial cells are filled with a semifluid substance known as cytoplasm. Within the cytoplasm, however, lies the bacterium’s genetic material, the code that ultimately determines the uniqueness of every type of bacteria. The components necessary for the translation of the genetic material into proteins, as well as various storage vessels, are also found in the cytoplasm.

Consequently, endospores do not possess metabolic activity until nutrients become available, at which time they are able to differentiate from spores into vegetative cells. Only one spore is formed inside each bacterial cell during sporulation. The formation of a spore begins with invagination of the cytoplasmic membrane around a copy of the bacterial chromosome, thus separating the contents of the smaller cell from the mother cell. The membrane of the mother cell engulfs the smaller cell within its cytoplasm, effectively providing two concentric unit membranes to protect the developing spore.

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