CONSERVATION OF RIBOSOMAL AND MESSENGER RIBONUCLEIC ACID CISTRONS IN BACILLUS SPECIES

Doi, Roy H. (Syracuse University, Syracuse, N.Y.), and Richard T. Igarashi. Conservation of ribosomal and messenger ribonucleic acid cistrons in Bacillus species. J. Bacteriol. 90:384-390. 1965.-Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) fractions from various Bacillus species were tested for interspecies DNA-RNA hybrid formation. DNA preparations from B. subtilis, B. cereus, B. megaterium, B. stearothermophilus, and B. macerans, whose base composition varied from 33 to 50% guanylate + cytidylate content, were used in the hybrid annealing mixtures with pulse-labeled RNA from sporulating cells and from log-phase cells of B. subtilis and B. cereus. Efficient hybridization in these cases was obtained only in homologous annealing situations. When heterologous DNA and RNA preparations were tested for hybrid formation, only 1 to 6% of the homologous hybridization was obtained. Although the efficiency of hybrid formation was low, the results were reproducible. No difference in efficiency of hybrid formation was observed between the messenger RNA from sporulating cells and that from log-phase cells. When B. subtilis ribosomal RNA was placed in annealing mixtures with heterologous DNA, 47.5 to 62.9% of the homologous hybridization was obtained. These results suggest that a small number of identical sequences are present among the Bacillus species. Furthermore, the ribosomal RNA cistrons appear to be more highly conserved relative to other genetic sequences.

SURVEY OF THE BACTERIOCINES OF ENTEROCOCCI

Brock, Thomas D. (Indiana University, Bloomington), Barbara Peacher, and Deborah Pierson. A survey of the bacteriocines of enterococci. J. Bacteriol. 86:702-707. 1963.-A survey has been made of bacteriocine production by a wide variety of well-characterized strains of group D streptococci. On the basis of spectrums and sensitivity to chloroform, heat, and proteolytic enzymes, five distinct bacteriocines can be defined. Type 1 is produced by all Streptococcus zymogenes (S. faecalis var. zymogenes) strains, is active against a wide variety of gram-positive bacteria, and is also a hemolysin. Type 2 is produced by some S. liquefaciens (S. faecalis var. liquefaciens) strains, and acts on many enterococci as well as on certain other lactic acid bacteria. Type 3 is produced by certain strains of both S. faecalis and S. faecium, and inhibits a wide variety of group D streptococci, but is inactive against all other lactic acid bacteria tested except Leuconostoc citrovorum. Type 4 is produced by certain S. faecium strains and resembles in certain ways the type 3 activity, but differs from it in other ways. Type 5 has been found to be produced by only one proteolytic strain of S. zymogenes, and this bacteriocine has a very narrow spectrum. The strain that produces this bacteriocine also produces type 1 activity. No strain is sensitive to a bacteriocine of the type it produces.

PATHWAYS OF GLUCOSE CATABOLISM IN BACILLUS SUBTILIS

Goldman, Manuel (The University of Michigan, Ann Arbor) and Harold J. Blumenthal. Pathways of glucose catabolism in Bacillus subtilis. J. Bacteriol. 86:303-311. 1963.-Under aerobic conditions, resting cells of Bacillus subtilis Marburg C4 catabolized 60 to 70% of glucose by the Embden-Meyerhof pathway and the remainder by the hexose monophosphate pathway; under anaerobic conditions, the percentages were 70 to 80 and 20 to 30, respectively. These estimates, based on two different radio-isotopic procedures, were the same whether the cells were grown in a glucose medium containing a complex, organic nitrogen source (C cells) or a simple inorganic nitrogen source (S cells). In C cells, respiration was inhibited by fluoride, whereas S cells were relatively insensitive to this influence. Factors such as the initial concentration of inorganic phosphate or glucose during growth, and the concentration of inorganic phosphate or even the presence of fluoride during glucose utilization by resting cells, had no major effects on the pathways of glucose catabolism. From an examination of the isotopic distribution in an isolated intermediate, lactic acid, it seems unlikely that the radioisotopic estimates were influenced by such other factors as participation of an Entner-Doudoroff pathway, extensive randomization of C(1) activity into other positions of the hexose molecule, or extensive CO(2) fixation.

EXCRETION AND DEGRADATION OF RIBONUCLEIC ACID BY BACILLUS SUBTILIS

Demain, A. L. (Merck & Co., Inc., Rahway, N.J.), R. W. Burg, and D. Hendlin. Excretion and degradation of ribonucleic acid by Bacillus subtilis. J. Bacteriol. 89:640-646. 1965.-Bacillus subtilis MB-1480 was found to produce several 5'-ribonucleotides in the extracellular medium, in addition to the previously found 5'-guanosine monophosphate and guanosine diphosphate. The nucleotides accumulated after excretion of high-molecular-weight ribonucleic acid (RNA) and subsequent extracellular breakdown. Excretion of RNA paralleled growth closely, and was accompanied by deoxyribonucleic acid (DNA) and protein excretion. The process occurred in the absence of visible lysis. Whereas extracellular DNA was stable, the other macromolecules were degraded after excretion. With extracellular DNA as a measure of maximal lysis, it was calculated that the major part of the extracellular RNA must have been excreted by cells which had not undergone lysis.

LINKAGE RELATIONSHIPS OF GENES CONTROLLING ISOLEUCINE, VALINE, AND LEUCINE BIOSYNTHESIS IN BACILLUS SUBTILIS

Barat, M. (Centre National de la Recherche Scientifique, Gif-sur-Yvette, Seine et Oise, France), C. Anagnostopoulos, and A.-M. Schneider. Linkage relationships of genes controlling isoleucine, valine, and leucine biosynthesis in Bacillus subtilis. J. Bacteriol.90:357-369. 1965.-In Bacillus subtilis, the genetic loci controlling isoleucine and valine biosynthesis are not all clustered. Some of them were located on two distinct transforming deoxyribonucleic acid "molecules." One of these molecules (the "ileilva(2-4)-met segment") carries the threonine deaminase and the dihydroxy acid dehydrase loci linked to methionine markers. The other (the "ilva(1-3)-leu segment") bears the reductoisomerase locus and one or more loci involved in leucine synthesis. A phenylalanine marker was also shown to be weakly linked to this latter group. In transduction mediated by phage PBS-1, these groups are transferred jointly with other gene clusters. The phage appears to convey chromosome fragments considerably longer than the transforming "molecules." The genetic maps of both the above segments were extended by transduction. Some groups previously studied by transformation can be placed in the following linear order: the ile-ilva(2-4)-met segment, the cluster of loci involved in aromatic amino acid synthesis (try segment), and a lysine locus. An arginine locus is cotransduced with the phe-ilva(1-2)-leu segment. Recombination frequencies between linked markers are much lower in transduction by this phage than in transformation.

SEROLOGICAL RELATIONSHIPS AMONG BETA-LYSIN, PLAKIN, AND LEUKIN

Donaldson, D. M. (Brigham Young University, Provo, Utah), R. S. Jensen, B. M. Jensen, and A. Matheson. Serological relationships among beta-lysin, plakin, and leukin. J. Bacteriol. 88:-1049 1055. 1964.-beta-Lysin is a substance which has been separated from normal serum and which is bactericidal for a variety of gram-positive bacteria including Bacillus subtilis. Purified beta-lysin is not denatured at 97 C for 15 min. The bactericidal activity of six of nine beta-lysin preparations was unaltered at 97 C for 30 min and was depressed 50% in the other three preparations. After 120 min at 97 C, the bactericidal activity was between 13 and 25% of normal. beta-Lysin was completely inactivated at 120 C for 15 min. Antisera prepared in guinea pigs against purified rabbit beta-lysin neutralized the bactericidal activities of purified beta-lysin, normal rabbit serum, platelet extracts, and purified plakin. This serological relationship between beta-lysin and plakin was also demonstrated by the observation that antisera against platelets neutralized the bactericidal activities of serum, platelet extracts, and purified beta-lysin. When anti-beta-lysin serum was tested against crude bactericidal extracts of leukocytes and purified leukin, no neutralization of these bactericidal substances was measurable. The results of this study are in accord with conclusions made in previous studies that platelets are a primary source of serum beta-lysin and that leukocytes contribute little, if any, to this type of serum bactericidal activity. Ouchterlony tests, in combination with the neutralization studies, indicated that the antigen-antibody system involved in the neutralization of beta-lysin may be a nonprecipitating system.