Inhibition of bacteriophage PBS2 replication in Bacillus subtilis by phleomycin

How to Tackle Bacteriophages: The Review of Approaches with Mechanistic Insight

Bacteriophage-based applications have a renaissance today, increasingly marking their use in industry, medicine, food processing, biotechnology, and more. However, phages are considered resistant to various harsh environmental conditions; besides, they are characterized by high intra-group variability. Phage-related contaminations may therefore pose new challenges in the future due to the wider use of phages in industry and health care. Therefore, in this review, we summarize the current knowledge of bacteriophage disinfection methods, as well as highlight new technologies and approaches. We discuss the need for systematic solutions to improve bacteriophage control, taking into account their structural and environmental diversity.

SP-10 bacteriophage-specific nucleic acid and enzyme synthesis in Bacillus subtilis W23

Bacillus subtilis W23 was infected with a clear-plaque variant of SP-10 phage, namely, SP-10c. Exogenous thymidine was not incorporated into phage DNA (even in the presence of deoxyadenosine), nor was there any transfer of thymidine nucleotides from bacterial to viral DNA. The lytic program was unaffected by concentrations of 5-fluorodeoxyuridine sufficient to reduce bacterial DNA synthesis by greater than 95%. Although these data are consistent with the interpretation that thymidine nucleotides are excluded from phage DNA, formic acid digests of SP-10c DNA contained what appeared to be the four conventional bases; however, adenine and thymine were not recovered in equimolar yields. DNA-RNA hybridization and hybridization competition experiments were done. Synthesis of host RNA started to wane moments postinfection and stopped completely by 36 min. SP-10c coded for discrete classes of early and late RNA. The possibility of discrete subclasses of early RNA exists. Replication of the bacterial genome appeared to terminate 12 min postinfection. Degradation of the host DNA to acid-soluble material started at 36 min and, by the end of the latent period, greater than 90% of the host chromosome was hydrolyzed. Four apparent phage-coded enzymes have been identified. A di- and triphosphatase degraded dUTP, dUDP, dTTP, and dTDP (and, to a lesser extent, dCDP and d CTP) to the corresponding monophosphates; the enzyme had no apparent activity on dATP and dGTP. SP10c also coded for a DNA-dependent DNA polymerase, lysozyme, and a nuclease that degrades native bacterial DNA. Judging from the dependence of enzyme synthesis on the time of addition of rifampin (an inhibitor of the initiation of RNA synthesis), messengers for the di- and triphosphatase, as well as the nuclease, are transcribed from promoters that start to function 6 min postinfection. Promoters for polymerase and lysozyme did not become functional until 8 and 16 min postinfection, respectively.

CIBA 36278-Ba" chemotherapy and toxicology in laboratory animals

Phleomycin (PM) induces rapid solubilization of deoxyribonucleic acid (DNA), inhibition of cellular mass increase, and loss of viability when added either to growing cultures of Escherichia coli B or an endonuclease I-defective derivative of B. Nonetheless, bacteriophage of the T-even series are produced, albeit to a reduced extent, when PM is added with phage or after infection to E. coli cells. Bacteriophage T4 infection inhibits the ability of PM to bring about the solubilization of DNA; this effect appears to account for most of the resistance of T-even phage replication to PM. The patterns of inhibition of phage yields obtained when PM is added at infection suggest that glucosylation of T-even phage DNA may also have a protective effect. However, PM induces the solubilization of glucosylated and nonglucosylated DNA at approximately the same rate and thermal denaturation studies indicate that the antibiotic binds both types of DNA equally well. The latter experiments also provided evidence that PM dissociates from DNA at temperatures greater than 80 C.