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A cryptic plasmid from a soil strain of Bacillus subtilis was found to contain a sequence having features of IS element. Homologous sequences were also found in the chromosome of this strain and in the chromosomes of some other B. subtilis strains.
The ability of Bacillus subtilis exolectin to modulate the effect of antibiotics acting as metabolic inhibitors, which can suppress the biosynthesis of cell wall glycans (ampycillin), replication (mitomycin C) and transcription (rifampycin), have been investigated on mutants of B. subtilis. Extracellular lectin was produced by B. subtilis strains B-7014 isolated from new-born calve's intestines. It was shown that the exolectin displays affinity for to sialic and uronic acids in the decreasing order: mucin, glycuronic acid, N-acetylneuraminic acid, galacturonic acid. It was established by the diffusion method and by determination of minimum inhibitory concentrations (MIC) that B. subtilis exolectin had selective activity as to bacteriostatic effect of antibiotics under study. The activity depended on the antibiotic structure and on mutant genotype defective as to the state of its replication and repair system. The lectin under study had no modulating effect on ampycillin action. There was a tendency to lower the bacteriostatic effect of rifampycin on the growth of strain BD170 (rec+) with the help of exolectin. Only in the case of mitomycin C the significant modulating effect of the bacterial lectin was manifested and its dependence on the mutant genotype was shown. The mutants sensitivity to exolectin effect decreased in the order: BD293 (polC), SB25 (recP), BD224 (recE), BD170 (rec+). Revealed ability of B. subtilis exolectin to protect the action of mitomycin C on growth of mutant BD293 (polC) with defect in the enzyme-DNA polymerase III permits supposing that the process of DNA replication is the most sensitive target for the lectin. The found dependence of modulation of the mitomycin C effect by the bacterial lectin on the genotype of mutants (rec-) demonstrated that the lectin acted following a complex mechanism mediated by a replicative and reparative complex.
A beta-D-fructofuranosidase -- called levanase -- capable of the hydrolysis of sucrose, inulin and levans has been identified in Bacillus subtilis Marburg. This enzyme can not be detected in strain 168. However, sacL mutations -- mapped on the chromosome of strain 168 between the pheA and aroD reference markers -- lead to constitutive levanase synthesis. This synthesis is repressed by carbon sources such as glucose, glycerol or sucrose.
In a previous publication (Narhi, L. O., and Fulco, A. J. (1986) J. Biol. Chem. 261, 7160-7169) we described the characterization of a 119,000-dalton P-450 cytochrome that is strongly induced by barbiturates in Bacillus megaterium. In the presence of NADPH and O2, this single polypeptide can catalyze the hydroxylation of long-chain fatty acids without the aid of any other protein. The gene encoding this unique monooxygenase (cytochrome P-450BM-3) has now been cloned by an immunochemical screening technique. The Escherichia coli clone harboring the recombinant plasmid produces a 119,000-dalton protein that appears to be electrophoretically and immunochemically identical to the B. megaterium enzyme and contains the same N-terminal amino acid sequence. The recombinant DNA product also exhibits the characteristic cytochrome P-450 spectrum and is fully functional as a fatty acid monooxygenase. In E. coli, the synthesis of P-450BM-3 is directed by its own promoter included in the DNA insert and proceeds constitutively at a very high rate but is not stimulated by pentobarbital. However, when the cloned P-450BM-3 gene, either intact or in a truncated form, is introduced back into B. megaterium via an E. coli/Bacillus subtilis shuttle vector, its expression is constitutively repressed but is induced by pentobarbital. This finding demonstrates that the regulatory region of the P-450BM-3 gene that responds to barbiturates is included in the cloned DNA. The evidence also indicates that pentobarbital cannot directly act on the gene to cause induction but presumably interacts with another component such as a repressor molecule that is present in B. megaterium but is absent in the E. coli clone.
An RNA processing activity capable of cleaving Bacillus subtilis phage SP82 early mRNA has been purified to apparent homogeneity from crude extracts of uninfected B. subtilis. The enzyme, a functional monomer of Mr approximately 27,000, cleaves only at the 5' side of adenosine residues at processing sites and is competitively inhibited by double-stranded synthetic RNA polymers. Processed SP82 mRNAs were translated in an Escherichia coli cell-free system and no qualitative or quantitative effects of processing on the synthesis of polypeptides was observed. The processing enzyme does not cleave T7 mRNA, E. coli precursor rRNA, or double-stranded poly(AU). A recombinant plasmid containing portions of two B. subtilis rRNA gene sets was transcribed in vitro and the resulting RNA was cleaved in the spacer region between the 16 S and 23 S rRNA genes. The ability of the B. subtilis processing enzyme to cleave SP82 mRNA and B. subtilis precursor rRNA and the fact that the enzyme has high affinity for double-stranded RNA suggest that it is the functional analog of E. coli RNase III.
127 strains of bacilli sensitive to different phages of Bacillus subtilis were isolated from the soil of Moscow and its country-side. In 6 strains, restriction and modification systems were discovered which differed from these previously described for Bac. subtilis BsuR system. Two strains has identical restriction-modification systems, and one strain possessed two different systems. Using DNA from all 6 strains, it was possible to transform competent cells of Bac. subtilis RUB834. Two of these 6 strains could serve as recipients in transformation and transfection experiments.
The authors report a case of bacteriemia with Bacillus licheniformis in a pregnant woman with coagulation disorders (acute fibrinolysis). Eight blood cultures were positive. Recovery rapidly occurred. The origin of this affection is discussed : a venous mode of entry is possible, either by the use of contaminated infusion fluid, or following several catheterizations.
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.
A novel Bacillus thuringiensis strain highly toxic to mosquitoes was isolated from soil samples in Malaysia. This strain was shown to display a new subfraction of the H-28 flagellar antigen determining a new serovar H28a28c, which was designated serovar jegathesan. Bioassays indicated that Culex quinquefasciatus larvae are the most susceptible to this new isolate, whereas toxicity to Anopheles maculatus and Aedes aegypti larvae was 10 times lower. The potency of this new serotype is also comparable to most of the Malaysian B. thuringiensis H-14 isolates.
A 3279-bp fragment of the Bacillus subtilis chromosome was cloned. This fragment completely restored exonuclease I activity in cells of the Escherichia coli Jm105 strain, which contained the sbcB mutation, and suppressed repair damage in cells of this mutant. The cloned fragment fully complemented a mutation that decreased exonuclease I activity in Bac. subtilis KU647 and KU1020 strains leading to the restoration of enzymatic activity and mutant phenotype suppression. The nucleotide sequence of the Bac. subtilis gene encoding the structure of exonuclease I was determined. The amino-acid sequence of this enzyme proved to have 29.7% homology with the amino-acid sequence of E. coli exonuclease I.
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