Two slow-growing, Gram-negative, non-motile, non-spore-forming, coccoid bacteria (strains F60 T and F965), isolated in Austria from mandibular lymph nodes of two red foxes (Vulpes vulpes), were subjected to a polyphasic taxonomic analysis. In a recent study, both isolates were assigned to the genus Brucella but could not be attributed to any of the existing species. Hence, we have analysed both strains in further detail to determine their exact taxonomic position and genetic relatedness to other members of the genus Brucella. The genome sizes of F60 T and F965 were 3 236 779 and 3 237 765 bp, respectively. Each genome consisted of two chromosomes, with a DNA G+C content of 57.2 %. A genome-to-genome distance of .80 %, an average nucleotide identity (ANI) of 97 % and an average amino acid identity (AAI) of 98 % compared with the type species Brucella melitensis confirmed affiliation to the genus. Remarkably, 5 % of the entire genetic information of both strains was of non-Brucella origin, including as-yet uncharacterized bacteriophages and insertion sequences as well as ABC transporters and other genes of metabolic function from various soil-living bacteria. Core-genome-based phylogenetic reconstructions placed the novel species well separated from all hitherto-described species of the genus Brucella, forming a long-branched sister clade to the classical species of Brucella. In summary, based on phenotypic and molecular data, we conclude that strains F60 T and F965 are members of a novel species of the genus Brucella, for which the name Brucella vulpis sp. nov. is proposed, with the type strain F60 T (5BCCN 09-2 T 5DSM 101715 T ).Abbreviations: AAI, average amino acid identity; ANI, average nucleotide identity.The GenBank/EMBL/DDBJ accession numbers for the genome sequences (chr1 and chr2) of strains F60 T and F965 are LN997863-LN997864 and LN998033-LN998034, respectively, and can be retrieved from the European Nucleotide Archive under

Expression of cloned gene E of bacteriophage PhiX174 induces lysis by formation of a transmembrane tunnel structure in the cell envelope of Escherichia coli. Ultrastructural studies of the location of the lysis tunnel indicate that it is preferentially located at the septum or at polar regions of the cell. Furthermore, the diameter and shape of individual tunnel structures vary greatly indicating that its structure is not rigid. Apparently, the contours of individual lysis tunnels are determined by enlarged meshes in the peptidoglycan net and the force produced at its orifice, by the outflow of cytoplasmic content. Once the tunnel is formed the driving force for the lysis process is the osmotic pressure difference between cytoplasm and medium. During the lysis process areas of the cytoplasmic membrane which are not tightly attached to the envelope are extended inward by the negative pressure produced during lysis. After cell lysis external medium can diffuse through the lysis tunnel filling the inner cell space of the still rigid bacterial ghosts.

Biochemical and genetic studies have suggested that a transmembrane tunnel structure penetrating the inner and outer membranes is formed during the lytic action of bacteriophage 4X174 protein E. In this study we directly visualized the lysis tunnel by using high-magnffication scanning and transmission electron microscopy.

Summary The double‐stranded (ds)DNA virus φCh1 infects the haloalkaliphilic archaeon Natrialba magadii. The complete DNA sequence of 58 498 bp of the temperate virus was established, and the probable functions of 21 of 98 φCh1‐encoded open reading frames (ORFs) have been assigned. This knowledge has been used to propose functional modules each required for specific functions during virus development. The φCh1 DNA is terminally redundant and circularly permuted and therefore appears to be packaged by the so‐called headful mechanism. The presence of ORFs encoding homologues of proteins involved in plasmid replication as well as experimental evidence indicate a plasmid‐mediated replication strategy of the virus. Results from nanosequencing of virion components suggest covalent cross‐linking of monomers of at least one of the structural proteins during virus maturation. A comparison of the φCh1 genome with the partly sequenced genome of Halobacterium salinarum virus φH revealed a close relationship between the two viruses, although their host organisms live in distinct environments with respect to the different pH values required for growth.

SummaryA novel archaeal bacteriophage, ⌽Ch1, was isolated from a haloalkalophilic archaeon Natronobacterium magadii upon spontaneous lysis. The phage-cured strain N. magadii (L13) was used to demonstrate infectivity of phage ⌽Ch1. The turbid-plaque morphology and the fact that N. magadii cells isolated from plaques were able to produce phage indicated that ⌽Ch1 is a temperate phage. The phage morphology resembles other members of Myoviridae-infecting Halobacterium species. In solution below 2 M NaCl, the phage lost its morphological stability and infectivity. One-and two-dimensional SDS-PAGE of phage particles revealed at least four major and five minor proteins with molecular masses ranging from 15 to 80 kDa and acidic isoelectric points. Southern blot analysis of chromosomal DNA of a lysogenic N. magadii strain showed that ⌽Ch1 exists as a chromosomally integrated prophage. The phage particles contain both double-stranded, linear DNA (approx. 55 kbp) as well as several RNA species (80-700 nucleotides). Hybridization of labelled RNA fragments to total DNA from N. magadii and ⌽Ch1 showed that the virion-associated RNA is host encoded. Part of the phage DNA population is modified and restriction analysis revealed evidence for adenine methylation. Phage ⌽Ch1 is the first virus described for the genus Natronobacterium, and the first phage containing DNA and RNA in mature phage particles.