Deoxyribonucleic acid studies in the genus Caryophanon.

The deoxyribonucleic acid (DNA) of 36 isolates of Caryophanon latum and 3 isolates designated Caryophanon tenue, obtained from geographically diverse regions, has been examined for guanine plus cytosine (mol % G+C) base composition, genome size, and for relative reassociation levels. The isolates were found to be homogenous and group-specific in their base composition, with C. latum DNA ranging from 44.0 to 45.6 mol % G+C, and C. tenue from 41.2 to 41.6 mol % G+C. Genome size determined for representative isolates confirmed the distinction of the two groups. The genome size ranged from 1100 to 1200 X 10(6) daltons for C. latum and from 900 to 1000 X 10(6) daltons for C. tenue. DNA:DNA hybridization studies revealed relative reassociation levels as follows: C. latum to C. latum, 78-94%, C. tenue to C. tenue, 82-94%; and C. latum to C. tenue, 13-30%. Finally, based on genome size and mol % G+C similarities, DNA:DNA hybridization experiments between two strains of Lactobacillus and C. latum and C. tenue were performed. These experiments revealed essentially no polynucleotide sequence similarity between the Lactobacillus and Caryophanon isolates used.

Ultrastructural effects of lysozymes on the cell wall of Caryophanon latum.

When Caryophanon latum was exposed to egg white lysozyme in isotonic sucrose and observed by phase-contrast microscopy, protoplasts emerged along the length of the trichomes, apparently at sites corresponding to cross septa. Electron microscopy of sections revealed that this enzyme initially attacked the core of the septal peptidoglycan and delamination of septa resulted. The inner densely staining layer of the lateral and polar wall (considered to contain peptidoglycan as the major component) remained intact except for destruction at the advancing tip of partial septa; protoplasts or cell debris could escape from the gaps formed at developing septa. Treatment of intact trichomes with pronase, a lipase - phospholipase C mixture, EDTA, glutaraldehyde, or heat, before exposure to egg white lysozyme did not alter this pattern nor did it render the remaining peptidoglycan more susceptible to attack. The wall material external to the peptidoglycan was solubilized by pronase. The peptidoglycan remaining after lysozyme treatment was not morphologically changed by treatment with pronase. Lysozyme derived from Chalaropsis hydrolyzed incomplete septa initially, while the lateral and polar wall and complete septa were degraded later. Therefore, it is most probable that the inner dense layer does contain the peptidoglycan component and that some biochemical maturation distinguishes the substrate for these enzymes in the lateral wall and septa.

Growth and ultrastructure of Rhodomicrobium vannielii as a function of light intensity.

Cells of Rhodomicrobium vannielii were grown in a controlled environment at several different light intensities. Differential rates of bacteriochlorophyll (BChl) synthesis and specific BChl contents were inversely related to the light intensity. On the other hand, the specific rate of growth-before reaching a maximal value-was directly related to the intensity of the light. Thin sections of cells grown at moderately low light showed the typical peripherally located, symmetrically distributed lamellate system, whereas an asymmetrical distribution of a less extensive lamellate system occurred in cells grown at high light intensities. It is proposed that a limited number of individual units of the lamellate system are originally derived from inward folds of the cytoplasmic membrane, and that subsequent lamellae arise by proliferation, including possible forking and definite folding back, of the few original lamellar membranes.