RESUMEN
Eleven Bacillus isolates from the surface and subsurface waters of the Gulf of Mexico were examined for their capacity to sporulate and harbor prophages. Occurrence of sporulation in each isolate was assessed through decoyinine induction, and putative lysogens were identified by prophage induction by mitomycin C treatment. No obvious correlation between ability to sporulate and prophage induction was found. Four strains that contained inducible virus-like particles (VLPs) were shown to sporulate. Four strains did not produce spores upon induction by decoyinine but contained inducible VLPs. Two of the strains did not produce virus-like particles or sporulate significantly upon induction. Isolate B14905 had a high level of virus-like particle production and a high occurrence of sporulation and was further examined by genomic sequencing in an attempt to shed light on the relationship between sporulation and lysogeny. In silico analysis of the B14905 genome revealed four prophage-like regions, one of which was independently sequenced from a mitomycin C-induced lysate. Based on PCR and transmission electron microscopy (TEM) analysis of an induced phage lysate, one is a noninducible phage remnant, one may be a defective phage-like bacteriocin, and two were inducible prophages. One of the inducible phages contained four putative transcriptional regulators, one of which was a SinR-like regulator that may be involved in the regulation of host sporulation. Isolates that both possess the capacity to sporulate and contain temperate phage may be well adapted for survival in the oligotrophic ocean.
Asunto(s)
Fagos de Bacillus/genética , Bacillus/fisiología , Lisogenia , Agua de Mar/microbiología , Bacillus/genética , Bacillus/virología , Fagos de Bacillus/efectos de los fármacos , Fagos de Bacillus/fisiología , Bacillus anthracis/efectos de los fármacos , Bacillus anthracis/genética , Secuencia de Bases , ADN Viral/genética , Genoma Bacteriano , Genoma Viral , Integrasas/genética , Lisogenia/efectos de los fármacos , Microscopía Electrónica de Transmisión , Mitomicina/farmacología , Datos de Secuencia Molecular , Océanos y Mares , Profagos/efectos de los fármacos , Profagos/genética , Profagos/fisiología , Esporas Bacterianas/efectos de los fármacos , Esporas Bacterianas/genética , Proteínas Virales/genética , Activación Viral/efectos de los fármacos , Activación Viral/genética , Activación Viral/fisiología , Integración Viral/efectos de los fármacos , Replicación Viral/efectos de los fármacos , Replicación Viral/genéticaRESUMEN
Most bacterial cells carry prophage genomes either integrated into the host DNA or present as repressed plasmids. Methods are described for the induction of prophages using Mitomycin C, and for the isolation of prophage-cured bacterial cell lines.
Asunto(s)
Bacteriófagos/genética , Bacteriófagos/aislamiento & purificación , Lisogenia/genética , Antibióticos Antineoplásicos/farmacología , Lisogenia/efectos de los fármacos , Lisogenia/efectos de la radiación , Mitomicina/farmacología , Profagos/efectos de los fármacos , Profagos/genética , Profagos/efectos de la radiación , Rayos UltravioletaRESUMEN
1. The mutagenic and genotoxic effects of mate (Ilex paraguariensis) aqueous solutions were analyzed in bacterial cells. 2. Mate solutions showed mutagenic activity in the Ames test (TA97, TA98, TA100 and TA102 strains) at concentrations of 20 to 50 mg/plate (mutagenic factors of 3.5 to 5.6) and genotoxic activity in the inductest (WP2s (lambda) strain), with a maximal phage induction at concentrations of 10 to 20 mg/plate. Above these concentrations the mate solutions were cytotoxic. 3. Addition of 5 U/ml catalase, 20 microliters/ml S9 rat liver microsomal fraction, 100 mM thiourea or 10 mM dipyridyl completely inhibited the lysogenic induction produced by mate; however, the addition of 1,000 U/ml superoxide dismutase was almost ineffective. 4. Oxygen reactive species may be present in mate solutions playing an essential role in its genotoxicity.
Asunto(s)
Magnoliopsida/toxicidad , Mutación , Animales , Catalasa/farmacología , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Lisogenia/efectos de los fármacos , Microsomas Hepáticos/efectos de los fármacos , Pruebas de Mutagenicidad , Ratas , Especies Reactivas de Oxígeno , Salmonella typhimurium/efectos de los fármacos , Salmonella typhimurium/genética , Salmonella typhimurium/aislamiento & purificación , Tiourea/farmacología , Factores de TiempoRESUMEN
Because of the importance of stannous chloride in various fields of human endeavour, the potential genotoxicity of this reducing agent was evaluated by measurement of either the inactivation or the induction of SOS responses in bacteria. Escherichia coli strains used in this work (wild type, uvrA, recA, lexA and uvrA recA) were treated with stannous chloride; the wild type was found to be the most resistant and the double mutant, the most sensitive strain. As these strains present mutations on specific genes for the repair of DNA, stannous chloride would appear to be capable of inducing and/or producing lesions in DNA and, thus, can be considered to be a potential genotoxic agent. This capability was confirmed by the lysogenic induction of E. coli K12 (lambda) (Inductest) and by microscopic observation of E. coli B filamentation.
Asunto(s)
Pruebas de Mutagenicidad/métodos , Mutágenos/toxicidad , Compuestos de Estaño/toxicidad , Reparación del ADN/genética , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Escherichia coli/crecimiento & desarrollo , Lisogenia/efectos de los fármacosRESUMEN
Mutagenesis induced by several genotoxic agents has been reported to be inhibited by cobaltous chloride. In order to study the effects of this metal in some SOS functions we evaluated mutagenesis, lysogenic induction and phage reactivation in Escherichia coli cells treated with CoCl2. We detected that cobaltous chloride, when present in the plating medium, was able to block mutagenesis and lysogenic induction promoted by UV irradiation. We also found that CoCl2 blocked protein synthesis, so we propose that this effect can be responsible for the antimutagenic and antilysogenic effects of this metal. On the other hand, if the cells were treated for a short period of time with CoCl2, in the absence of Mg, we observed that cobaltous chloride per se was able to promote lysogenic induction as well as to enhance the phage reactivation induced by UV irradiation. We conclude that depending on experimental conditions, cobaltous chloride may act either as an inhibitor or as an inducer of the SOS functions.
Asunto(s)
Antimutagênicos/farmacología , Cobalto/farmacología , Respuesta SOS en Genética/efectos de los fármacos , Proteínas Bacterianas/biosíntesis , Escherichia coli , Cinética , Lisogenia/efectos de los fármacos , Magnesio/farmacologíaRESUMEN
Reductone (HOCH2-CO-CHO), a keto-aldehyde formed, in alkaline pH, by thermal degradation of reducing sugars, blocks cellular respiration and macromolecular biosynthesis, inactivates far-UV (254 nm)-irradiated wild-type E. coli cells, and causes DNA strand breaks. So it may be supposed to be an inducer of SOS functions. Indeed, when Salmonella tester strains TA98, TA100 and TA102 were treated with reductone solutions, without metabolization, a mutagenic effect was detected for all of them. Besides, reductone induced lysogenic E. coli cells and cell filamentation, as measured by the Inductest and the SOS Chromotest. So reductone must be considered a genotoxic drug.
Asunto(s)
Proteínas de Escherichia coli , Malonatos/toxicidad , Malondialdehído/toxicidad , Mutágenos , Proteínas Bacterianas/genética , Escherichia coli/efectos de los fármacos , Glucosa , Calor , Lisogenia/efectos de los fármacos , Malondialdehído/análogos & derivados , Respuesta SOS en Genética/efectos de los fármacos , Salmonella typhimurium/efectos de los fármacosRESUMEN
Four strains of Azospirillum brasilense, including strain 7000 (ATCC 29145) and five strains of A. lipoferum, including strain Br17 (ATCC 29709) were examined for the presence of plasmids. All the strains were found to harbour 1 to 5 plasmids whose molecular weight ranged from 3.5 to over 300 Md. No obvious relationship between the plasmids and phenotypic properties was established as yet, in particular N2 fixation, substrate utilization, drug resistance and lysogenic state. Six out of the 9 strains were lysogenic and phage production was inducible by mitomycin C. An icosahedric phage was purified from strain 7000.