Anthrax-specific "AP 50-like" phages isolated from Bacillus cereus strains.

Phages exerting a specific action on Bacillus anthracis were isolated from mitomycin C-induced concentrated lysates of 5 Bacillus cereus strains producing megacin A (phospholipase A). In electron micrographs the phages closely resembled the anthrax-specific, lipid containing phage AP 50 isolated earlier from soil sample. The phages were similar to AP 50 also in their antigenic and chemical structure, host range and sensitivity to organic solvents, detergents and caesium chloride. The DNA character of AP 50 nucleic acid was shown by agarose gel electrophoresis. AP 50 and related phages seem to represent a separate group of phages acting on Bacillus strains.

Characteristics of phage AP50, an RNA phage containing phospholipids.

A bacteriophage specific for Bacillus anthracis was isolated and designated as AP50. The nucleic acid of phage AP50 is RNA and the virion contains five different phospholipids. Some physical and biological characteristics of the phage, including morphology, were examined. To the best of our knowledge, this RNA bacteriophage containing phospholipids is the first to be isolated for a Gram-positive host.

Mapping the uroporphyrinogen decarboxylase, coproporphyrinogen oxidase and ferrochelatase loci in Bacillus subtilis.

Three genes hemE, hemF, hemG taking part in the porphyrin biosynthesis of Baccillus subtilis were mapped by two- and three-factor transduction crosses. The gene hemE determines uroporphyrinogen decarboxylase (EC 4.1.1.37) the gene hemF coproporphyrinogen oxidase (EC 1.3.3.3) and the gene hemG ferrochelatase (EC 4.99.1.1) enzymes. The loci hemE, hemF, hemG, are not linked to hemA locus and located near the argC and metD loci.

Studies on megacinogeny in Bacillus cereus. I. Multiplication of phage wx causing lysogenic conversion to megacin A (phospholipase A) production.

Phage wx capable of reconverting Bacillus cereus strain W derivatives, cured to lose megacin A (phospholipase A) production into megacin A-producing cultures, exhibits unusual kinetics of multiplication; its clear mutant, phage wxc, behaves similarly. The phages are not adsorbed by stationary phase indicator bacteria. As sonicated bacteria fail to inactivate the phages, the absence of adsorption cannot be attributed to an undersurface localization of the receptors. Multiplying bacteria exert a slow and slight degree of phage adsorption. Cells inhibited by chloramphenicol produce no receptors. It has been assumed that the receptor, produced from a precursor involved in bacterial cell synthesis, either absorbs the phage in the nascent state or is incorporated in the cell and loses its phage-adsorbing capacity.

Studies on megacinogeny in Bacillus cereus. II. Bacillus cereus isolates characterized by prophage-controlled production of megacin A (phospholipase A).

Five out of a number of Bacillus cereus strains isolated from soil produced high titre specific bacteriocin (megacin A) in mitomycin C-induced cultures. In the course of cultivation with ethidium bromide, the strains gave off segregants not producing bacteriocin (cin-). The lysate of two wild strains formed plaques on the corresponding cin- bacteria. The two phages (wx23 and wx26) were identical in antigenic structure with phage wx was present in the lysate of B. cereus strain W, and converted cin- derivatives into cultures producing megacin A (phospholipase A). The phages produced plaques at 26 degrees C but not at 37 degrees C. In the lysates of the remaining three strains phages were not detected with biological and morphological methods; these cultures have been assumed to carry defective prophage genome. As the corresponding prophages are responsible for the determination of inducible phospholipase A production, phages named wx seem to form a separate group of B. cereus phages.

Electron microscopy of phages liberated by megacin A producing lysogenic Bacillus megaterium strains.

Mitomycin C was added at fairly high concentration (5-10 mug/ml) to exponentially growing cultures of selected strains of Bacillus megaterium. Lysis of the bacteria followed, associated by liberation of phage and megacin A production. In contrast, a low concentration (0.5 mug/ml) of mitomycin induced only megacin A production. Electron microscopic examination of the lysates induced by 5-10 mug/ml of mitomycin in 19 strains of B. megaterium showed them all to contain phages; most of the strains proved polylysogenic. Their lysates contained distinct complete phages of different structures and dimensions. A few strains released defective phage particles. The significance of the electron microscopic findings is discussed in relation to megacinogeny.

Genetic and biochemical analysis of haemin dependent mutants of Bacillus subtilis.

Numerous porphyrin auxotrophic mutants have been isolated from the 168 trpC2 strain of Bacillus subtilis by selection with streptomycin. Some of them could be supplemented with ALA while the majority grew only in the presence of haemin. Among the latter strains, the syntropism test allowed to distinguish two groups different in phenotype, viz., feeders accumulating ALA and non-feeders accumulating instead of ALA other porphyrin intermediates. On the basis of transductional studies, feeders and non-feeders could be divided into two and four groups, respectively. Biochemical investigation revealed that, with one exception, one enzyme of the porphyrin biosynthesis was coordinated to each hem locus. The following genes were identified:hemB yields ALA-dehydrase;hemC yields PBG-deaminase; hemE yields uroporphyrinogen decarboxylases; hemF yields coproporphyrinogen oxidase; hemG yields protoporphyrin-iron-chelatase.