Significance of lysogeny for the metabolism of Desulfovibrio spp. strains isolated from aquatic environments of Georgia.

AIMS: Sulphate-reducing bacteria (SRB) are ecologically important group of anaerobic micro-organisms that can reduce sulphate to form hydrogen sulphide-a toxic gas causing iron corrosion on metal surfaces. In this work, SRB strains were isolated from aquatic environments in the country of Georgia to determine their lysogenicity and the role of temperate phages in host metabolism. METHODS AND RESULTS: SRB strains were isolated in samples from the Black Sea coast of Georgia. Based on their genetic, cytological and physiological properties of bacteria, 10 Georgian isolates were assigned to the genus Desulfovibrio. Temperate bacteriophages were induced from three out of ten strains by UV-exposure. Comparison of metal (Fe and Cr) reduction and utilization of various carbon sources by the wild-type (lysogenic) bacterial strains and their UV-irradiated counterparts was done. CONCLUSIONS: Temperate phage in the cells of SRB could alter significant functions of bacteria and may have a contribution in the acquisition of different traits by SRB. SIGNIFICANCE AND IMPACT OF THE STUDY: This article pointed to a significant role for temperate bacteriophages in the metabolism and metabolic potential of host strains of SRB, which were first isolated from the aquatic environment of Georgia.

Genomic characterization of three novel Basilisk-like phages infecting Bacillus anthracis.

BACKGROUND: In the present study, we sequenced the complete genomes of three novel bacteriophages v_B-Bak1, v_B-Bak6, v_B-Bak10 previously isolated from historical anthrax burial sites in the South Caucasus country of Georgia. We report here major trends in the molecular evolution of these phages, which we designate as "Basilisk-Like-Phages" (BLPs), and illustrate patterns in their evolution, genomic plasticity and core genome architecture. RESULTS: Comparative whole genome sequence analysis revealed a close evolutionary relationship between our phages and two unclassified Bacillus cereus group phages, phage Basilisk, a broad host range phage (Grose JH et al., J Vir. 2014;88(20):11846-11860) and phage PBC4, a highly host-restricted phage and close relative of Basilisk (Na H. et al. FEMS Microbiol. letters. 2016;363(12)). Genome comparisons of phages v_B-Bak1, v_B-Bak6, and v_B-Bak10 revealed significant similarity in sequence, gene content, and synteny with both Basilisk and PBC4. Transmission electron microscopy (TEM) confirmed the three phages belong to the Siphoviridae family. In contrast to the broad host range of phage Basilisk and the single-strain specificity of PBC4, our three phages displayed host specificity for Bacillus anthracis. Bacillus species including Bacillus cereus, Bacillus subtilis, Bacillus anthracoides, and Bacillus megaterium were refractory to infection. CONCLUSIONS: Data reported here provide further insight into the shared genomic architecture, host range specificity, and molecular evolution of these rare B. cereus group phages. To date, the three phages represent the only known close relatives of the Basilisk and PBC4 phages and their shared genetic attributes and unique host specificity for B. anthracis provides additional insight into candidate host range determinants.

Correction to: Genomic characterization of three novel Basilisk-like phages infecting Bacillus anthracis.

Following the publication of this article [1], the authors noted two typographical errors: one in Table 1 with regard to the location of the Basilisk Phage, which was incorrectly captured as "Kutaisis, country of Georgia Utah, USA" but should be "Utah, USA".

[New Virulent Bacteriophages Active against Multiresistant Pseudomonas aeruginosa Strains].

The sensitivity of 512 newly isolated Pseudomonas aeruginosa clinical strains to six classes of anti-microbial preparations has been studied. Antibiotic-resistant strains were selected and genotyped. Three new virulent bacteriophages of the families Myoviridae and Podoviridae were isolated against these strains. The parameters of the intracellular phage development cycle were established, and the influence of inactivating factors (temperature, pH, and UV exposure) on phage viability was studied. The molecular weight of the phage genome was determined. Phage DNA restriction analysis and polyacrylamide gel electrophoresis in the presence of envelope protein SDS were carried out. The plating efficacy of phages on 28 genetically distant antibiotic-resistant P. aeruginosa strains was studied. It was established that 26 of them were lysed by phages with a high efficacy. The range of antibacterial action of the studied phages and their mixtures on 427 multi-drug-resistant clinical isolates was assessed. It is shown that including these phages in one multicomponent preparation enhanced their lytic activity.

[Distribution and transcription of determinants homologous to the alpha-hemolysin (hlY) gene in the genomes of HLY- and HLY+ staphylococci]. / Raspredelenie i transkriptsiia determinant, gomologichnykh genu alpha-gemolizina (hlY), v genomakh HLY- i HLY+ stafilokokkov.

The molecular organization of the alpha-hemolysin gene from Staphylococcus aureus strain O15 has been studied. Hybridization of the DNA from this strain with the [32P]-labeled cloned fragment containing alpha-hemolysin gene has shown the studied gene to be unique in the genome of the strain. Sequences homologous to the gene were not found to be dispersed along the genome of Staphylococcus aureus O15. The presence of alpha-hemolysin gene in some Staphylococcus epidermidis strains has been monitored. The strains 1413, 303 have been demonstrated to contain no gene for alpha-hemolysin. The hemolysin genes were found in the genomes of the strains 159, 169, 180 by DNA hybridization technique. In the genome of the strain 180 the long region including the right end of alpha-hemolysin gene is deleted. Hybridization with the net RNA of these strains shows the absence of transcription of intact as well as deleted alpha-hemolysin genes.

[Cloning of alpha-hemolysin gene from Staphylococcus aureus strain 015]. / Klonirovanie gena alpha-gemolizina shtamma Staphylococcus aureus 015.

The genomic library of Staphylococcus aureus O15 has been constructed on the EMBL-3 vector. The synthetic oligonucleotide probes to N- and C-end regions of alpha-hemolysin permitted identification of the recombinant bacteriophage clone RS-1 containing a gene for this protein. The restriction map of the cloned fragment has been constructed for restriction endonucleases SalGI, EcoRV, PstI, PvuII. Expression of the alpha-hemolysin gene in phagolysate of the recombinant clone RS-1 (1000 units per ml) has been demonstrated.

The virulent bacteriophage IRA of Salmonella typhimurium: cloning of phage genes which are potentially lethal for the host cell.

Morphological and biological properties of Salmonella typhimurium phage IRA were studied. The phage is a member of the Styloviridae family and exhibits a very wide spectrum of lytic activity. Molecular cloning of phage genes whose expression is lethal for the host cell has been performed and consequences of gene expression have been investigated. Expression of recombinant plasmid pKI71 causes structural changes of the cell wall and also degradation of host DNA while plasmid DNA remains intact. Expression of pKI72 blocks normal cell division. The possibility of applying such recombinant clones in marking pathways of microbial contamination in water areas is proposed.

[Restriction endonuclease Sau 6782]. / Restriktiruiushchaia éndonukleaza Sau 6782.

Data are described on identification, isolation and purification of restricting endonuclease Sau 6782 as well as on estimation of the enzyme recognition site. Conditions were developed for growing of Staphylococcus aureus 6782 strain, which enabled to produce a maximal yield of the restricting activity containing minimal level of nucleases. The procedure for isolation and purification of restrictase Sau 6782 involved affinity chromatography on Blue Sepharose and cation exchange chromatography on phosphocellulose PII. The enzyme preparation obtained was free from impurities of unspecific nucleases. The yield of the Sau 6782 restrictase constituted 1,000 un from 1 g of the culture cells. Restrictase Sau 6782 recognized the nucleotide sequence 5'...GATC...3' and was the isoshizomere of the Sau 3A enzyme.

[Modification of the modification-restriction system in staphylococci]. / Identifikatsiia sistem modifikatsii-restriktsii u stafilokokkov.

A new system of host specificity of DNA, called Sau67 according to the available nomenclature, was identified in Staphylococcus aureus 6782 strain by means of cross titration with staphylophage 729 considering that the phage exhibited the highly effective absorption properties. A total preparation of Sau67 methylases was isolated using ammonium sulfate fractionation. The enzyme preparation contained methylases of cytosine and adenine, where the activity of adenine methylases constituted only for 5% of the total methylase activity. As shown by kinetics of methylation low content of unspecific cellular nucleases was found in the St. aureus 6782 strain; these reasons are important for isolation of restricting endonucleases containing in the strain. 100 micrograms of protein of the total enzymatic fraction enabled to methylate the acceptory DNA at the maximal rate within 1.5 hr of incubation in phosphate buffer, pH 7.9. The fraction of cytosine methylases free of adenine methylating activity was obtained after chromatography on Sepharose blue with NaCl concentration stepwise gradient.

[New type of DNA structural organization in the composition of bacteriophage Sb-1 particles]. / Novyi tip strukturnoi organizatsii DNK v sostave chastits bakteriofaga Sb-1.

Spectrophotometric melting and chemical modification procedures were used for comparative study of parameters of DNA structure in particles of phages Sb-1 and FI-5 possessing spherical symmetry of the heads. Like in other phages of this morphological group, some part of DNA structure in FI-5 phage particles is disarrayed and has changed reactive capacity of basic aminogroups. Another type of DNA structural organization in situ was found with staphylococcal phage Sb-1. According to the results of melting process and pattern of interaction with 4.5% formaldehyde, DNA in particles of this phage throughout had base stacking. Basic aminogroups of DNA in situ are most likely completely involved in intramolecular complementary interactions and are not subjected to oximethylation under reaction conditions.

[Characteristics of the primary and secondary DNA structure of staphylococcal phage SB-1]. / Kharakteristika pervichnoi i vtorichnoi struktury DNK stafilokokkovogo faga SB-1.

Equilibrium centrifugation, spectral analysis of thermal denaturation and direct chemical determinations showed staphylococcal phage Sb-I DNA to be characterized by a standard set of nitric bases (28.5 mol.2./% G-C). No abnormal bases or other extracomponents were found. From the differential spectral analysis of melting interval it is concluded that G-C pairs are distributed along DNA molecule in a Gauss type. Spectrophotometric and thermodynamic parameters of melting show phage Sv-I DNA to have a typical double-stranded structure. DNA is characterized by enthalpies of conformational transitions of spiral=glome delta H=11.4 cal/g and delta H = 9.7 cal/g for 1 x SSC and 0.1 x SSC diluents, respectively.

[Peculiarities of primary and secondary structure of phage FI-1 DNA]. / Osobennosti pervichnoi i vtorichnoi struktury DNK faga Fi-1

The composition of nitrous bases of phage FI-1 DNA was studied. As is evidenced from the values of buoyant density in CsCl (p=1,7093 g/cm(3)), melting temperature (T degrees m=86,05 degrees), spectral parameters and direct chromatographic determination, the DNA analysed contains 41,5 mole% pairs of guanine-cystosine. 5-hydroxymethylcytosine and other anomalous bases were not found. Chemical identification and jaxtposition of data of buoyant density in CsCl and Cs2SO4 (p=1,4466 g/cm(3)) and T degrees m. showed the presence of the extra-sugar component in DNA, most likely in the form of hentibiose. Spectral character of thermal denaturation of DNA in different solvents is indicative of the double helixity of its structure. DNA is characterized by enthalpies of conformational transitions "helix coil" (deltaH=12,3 kcal/g) and (deltaH=10 kcal/g) for the solvents, 1 x SSC, and 0,1 x SSC, correspondingly. The presence of extra-sugar in DNA with standard set of nitrous bases is discussed.

[Effect of the composition of the nutrient medium on the synthesis of acid-fast alpha-amylase by different strains of Aspergillus]. / Vliianie sostava pitatel'noi sredy na biosintez kislotoustoichnivoi Al'fa-amilazy razlichnymi vidami gribov Aspergillus.

The capacity of 86 strains of the Aspergillus fungus to synthesize acid stable alpha-amylase was examined. The strains of Asp. niger showing a high capacity of synthesizing the enzyme were isolated. Repeated cultivation of the selected cultures on the Minoda agar medium led to a 200% increase in the enzyme activity in the submerged culture. Addition of sodium nitrate to the Minoda medium during submerged cultivation allowed a 3-fold increase of the synthesis of acid stable alpha-amylase.