Phage typing of Bacillus subtilis and B. thuringiensis

Characterization of Bacillus subtilis bacteriophage BasuTN3 isolated from Thua Nao, a thai fermented soybean food product

The infection of bacteriophage is of great concern in food industry as this can result in complete fermentation failure. In this study, a virulent bacteriophage, named BasuTN3, was isolated from Thua Nao, a Thai fermented soybean. The stability of BasuTN3 was evaluated under various ranges of temperature, pH, chloroform, UV, and disinfectants. The results showed that the isolated BasuTN3 appeared to be specific to its bacterial host, which was identified as Bacillus subtilis strain TN3 based on the 16 S rRNA gene sequence analysis. Under TEM, the BasuTN3 belonged to the family Myoviridae. The isolated BasuTN3 could withstand wide temperature ranges (4-45 °C) and pH conditions (5-11). The BasuTN3 was susceptible to chloroform, UV, and commonly used disinfectants. The results obtained expand the knowledge of the Bacillus bacteriophage diversity in the fermented soybean products and provide useful information for the bacteriophage and its bacterial starter cultures.

A Unique Isolation of a Lytic Bacteriophage Infected Bacillus anthracis Isolate from Pafuri, South Africa

Bacillus anthracis is a soil-borne, Gram-positive endospore-forming bacterium and the causative agent of anthrax. It is enzootic in Pafuri, Kruger National Park in South Africa. The bacterium is amplified in a wild ungulate host, which then becomes a source of infection to the next host upon its death. The exact mechanisms involving the onset (index case) and termination of an outbreak are poorly understood, in part due to a paucity of information about the soil-based component of the bacterium’s lifecycle. In this study, we present the unique isolation of a dsDNA bacteriophage from a wildebeest carcass site suspected of having succumbed to anthrax. The aggressively lytic bacteriophage hampered the initial isolation of B. anthracis from samples collected at the carcass site. Classic bacteriologic methods were used to test the isolated phage on B. anthracis under different conditions to simulate deteriorating carcass conditions. Whole genome sequencing was employed to determine the relationship between the bacterium isolated on site and the bacteriophage-dubbed Bacillus phage Crookii. The 154,012 bp phage belongs to Myoviridae and groups closely with another African anthrax carcass-associated Bacillus phage WPh. Bacillus phage Crookii was lytic against B. cereus sensu lato group members but demonstrated a greater affinity for encapsulated B. anthracis at lower concentrations (<1 × 10⁸ pfu) of bacteriophage. The unusual isolation of this bacteriophage demonstrates the phage’s role in decreasing the inoculum in the environment and impact on the life cycle of B. anthracis at a carcass site.

Complete genome sequence of the virus isolate vB_BthM-Goe5 infecting Bacillus thuringiensis

Bacillus thuringiensis (Bt) is non-pathogenic for humans and serves as a biological control agent in agriculture. Understanding its phages will help to prevent industrial production loss of Bt products and will lead to a better understanding of phages in general. The complete genome of the new B. thuringiensis phage isolate vB_BthM-Goe5 (Goe5) was sequenced, revealing a linear 157,804-bp-long dsDNA chromosome flanked by 2579-bp-long terminal repeats. It contains two tRNAs and 272 protein coding regions, 69 of which could be assigned with an annotation. Morphological investigation, using transmission electron microscopy, revealed Myoviridae morphology. The formation of a double baseplate upon tail sheath contraction indicates a link to the group of SPO1-related phages. Comparative genomics with all Bacillus-related viral genomes available in the NCBI genome database during this investigation indicated that Goe5 was a unique isolate, with Bacillus phage Bastille as its closest relative.

Complete Genome sequence of the nematicidal Bacillus thuringiensis MYBT18246

10.1601/nm.5000 is a rod-shaped facultative anaerobic spore forming bacterium of the genus 10.1601/nm.4857. The defining feature of the species is the ability to produce parasporal crystal inclusion bodies, consisting of δ-endotoxins, encoded by cry-genes. Here we present the complete annotated genome sequence of the nematicidal 10.1601/nm.5000 strain MYBT18246. The genome comprises one 5,867,749 bp chromosome and 11 plasmids which vary in size from 6330 bp to 150,790 bp. The chromosome contains 6092 protein-coding and 150 RNA genes, including 36 rRNA genes. The plasmids encode 997 proteins and 4 t-RNA's. Analysis of the genome revealed a large number of mobile elements involved in genome plasticity including 11 plasmids and 16 chromosomal prophages. Three different nematicidal toxin genes were identified and classified according to the Cry toxin naming committee as cry13Aa2, cry13Ba1, and cry13Ab1. Strikingly, these genes are located on the chromosome in close proximity to three separate prophages. Moreover, four putative toxin genes of different toxin classes were identified on the plasmids p120510 (Vip-like toxin), p120416 (Cry-like toxin) and p109822 (two Bin-like toxins). A comparative genome analysis of 10.1601/nm.5000 MYBT18246 with three closely related 10.1601/nm.5000 strains enabled determination of the pan-genome of 10.1601/nm.5000 MYBT18246, revealing a large number of singletons, mostly represented by phage genes, morons and cryptic genes.

Genomic analysis of Bacillus subtilis lytic bacteriophage ϕNIT1 capable of obstructing natto fermentation carrying genes for the capsule-lytic soluble enzymes poly-γ-glutamate hydrolase and levanase

Bacillus subtilis strains including the fermented soybean (natto) starter produce capsular polymers consisting of poly-γ-glutamate and levan. Capsular polymers may protect the cells from phage infection. However, bacteriophage ϕNIT1 carries a γ-PGA hydrolase gene (pghP) that help it to counteract the host cell's protection strategy. ϕNIT had a linear double stranded DNA genome of 155,631-bp with a terminal redundancy of 5,103-bp, containing a gene encoding an active levan hydrolase. These capsule-lytic enzyme genes were located in the possible foreign gene cluster regions between central core and terminal redundant regions, and were expressed at the late phase of the phage lytic cycle. All tested natto origin Spounavirinae phages carried both genes for capsule degrading enzymes similar to ϕNIT1. A comparative genomic analysis revealed the diversity among ϕNIT1 and Bacillus phages carrying pghP-like and levan-hydrolase genes, and provides novel understanding on the acquisition mechanism of these enzymatic genes.

Isolation and Characterization of Phages Infecting Bacillus subtilis

Bacteriophages have been suggested as an alternative approach to reduce the amount of pathogens in various applications. Bacteriophages of various specificity and virulence were isolated as a means of controlling food-borne pathogens. We studied the interaction of bacteriophages with Bacillus species, which are very often persistent in industrial applications such as food production due to their antibiotic resistance and spore formation. A comparative study using electron microscopy, PFGE, and SDS-PAGE as well as determination of host range, pH and temperature resistance, adsorption rate, latent time, and phage burst size was performed on three phages of the Myoviridae family and one phage of the Siphoviridae family which infected Bacillus subtilis strains. The phages are morphologically different and characterized by icosahedral heads and contractile (SIOΦ, SUBω, and SPOσ phages) or noncontractile (ARπ phage) tails. The genomes of SIOΦ and SUBω are composed of 154 kb. The capsid of SIOΦ is composed of four proteins. Bacteriophages SPOσ and ARπ have genome sizes of 25 kbp and 40 kbp, respectively. Both phages as well as SUBω phage have 14 proteins in their capsids. Phages SIOΦ and SPOσ are resistant to high temperatures and to the acid (4.0) and alkaline (9.0 and 10.0) pH.

Occurrence of Bacillus thuringiensis and their phages in Yemen soil

Bacillus thuringiensis (Bt) isolates were found in all samples of soil in nine Governorates of Yemen. From 384 isolates of Bacillus recovered from these soil samples after acetate selection, 104 isolates (27.1 %) were Bt. Five isolates of Bt were selected and insecticidal activity was tested against Culex pipiens, Callosobruchus maculatus and Spodoptera littoralis. The Bt isolate YH18 gave toxicity to all tested insects larvae. This study extended to isolate phages active against the selected Bt isolates. Five phages were isolated and classified into two groups of tailed phages. Four phages with long non-contractile tails and hexagonal heads (Siphoviridae) and one phage with very short tail and isometric head (Podoviridae). Susceptibility of selected Bt to infect by these phages was studied by spot-test technique. Also the Bt isolate no YH18 was resistant to all tested phages. This is the first report illustrates the diversity and the abundance of Bt and Bt phage in Yemen soil.

The SPO1-related bacteriophages

A large and diverse group of bacteriophages has been termed 'SPO1-like viruses'. To date, molecular data and genome sequences are available for Bacillus phage SPO1 and eight related phages infecting members of other bacterial genera. Many additional bacteriophages have been described as SPO1-related, but very few data are available for most of them. We present an overview of putative 'SPO1-like viruses' and shall discuss the available data in view of the recently proposed expansion of this group of bacteriophages to the tentative subfamily Spounavirinae. Characteristics of SPO1-related phages include (a) the host organisms are Firmicutes; (b) members are strictly virulent myoviruses; (c) all phages feature common morphological properties; (d) the phage genome consists of a terminally redundant, non-permuted dsDNA molecule of 127-157 kb in size; and (e) phages share considerable amino acid homology. The number of phages isolated consistent with these parameters is large, suggesting a ubiquitous nature of this group of viruses.

Complete Nucleotide Sequence and Molecular Characterization of Bacillus Phage TP21 and its Relatedness to Other Phages with the Same Name

Three different Bacillus bacteriophages designated TP21 are known from the literature. We have determined the sequence and structure of the TP21-L genome, and compared it to the other phages. The genome is 37.5 kb in size, possesses fixed invariable genome ends and features the typical modular organization of a temperate siphovirus. TP21-L is neither identical to TP21 isolated by Thorne (TP21-T), as shown by a PCR-based approach nor to TP21 isolated by He et al. (TP21-H), as estimated from phage dimensions. For reasons of clarity, we suggest renaming the different TP21 isolates.

Functional viral metagenomics and the next generation of molecular tools

The enzymes of bacteriophages and other viruses have been essential research tools since the first days of molecular biology. However, the current repertoire of viral enzymes only hints at their overall potential. The most commonly used enzymes are derived from a surprisingly small number of cultivated viruses, which is remarkable considering the extreme abundance and diversity of viruses revealed over the past decade by metagenomic analysis. To access the treasure trove of enzymes hidden in the global virosphere and develop them for research, therapeutic and diagnostic uses, improvements are needed in our ability to rapidly and efficiently discover, express and characterize viral genes to produce useful proteins. In this paper, we discuss improvements to sampling and cloning methods, functional and genomics-based screens, and expression systems, which should accelerate discovery of new enzymes and other viral proteins for use in research and medicine.

Aggregates of bacteriophage 0305phi8-36 seed future growth

Lytic bacteriophage 0305φ8-36 forms visually observed aggregates during plaque formation. Aggregates intrinsically lower propagation potential. In the present study, the following observations indicate that lost propagation potential is regained with time: (1) Aggregates sometimes concentrate at the edge of clear plaques. (2) A semi-clear ring sometimes forms beyond the plaques. (3) Formation of a ring is completely correlated with the presence of aggregates at the same angular displacement along the plaque edge. To explain this aggregate-derived lowering/raising of propagation potential, the following hypothesis is presented: Aggregation/dissociation of bacteriophage of 0305φ8-36 is a selected phenomenon that evolved to maintain high host finding rate in a trade-off with maintaining high rate of bacteriophage progeny production. This hypothesis explains ringed plaque morphology observed for other bacteriophages and predicts that aggregates will undergo time-dependent change in structure as propagation potential increases. In support, fluorescence microscopy reveals time-dependent change in the distance between resolution-limited particles in aggregates.

Identification of the nonA and nonB loci of Bacillus subtilis Marburg permitting the growth of SP10 phage

Mutational inactivation of both nonA and nonB genes are required for the permissiveness of Bacillus subtilis Marburg cells to infection by phage SP10. By transformational analysis of the nonA strain with DNAs from gently lysed protoplasts carrying the integrative plasmid pMUTIN (em) insertions in every 20 kb along the whole chromosome, we have identified the nonA to be the cured state of endogenous prophage SPbeta. Direct DNA sequencing, on the other hand, revealed one nonsense mutation of nonB in ydiR, which is a component gene of the intrinsic restriction system BsuMR of B.subtilis Marburg. Introduction of the wild type ydiR into the nonB strain at aprE locus resulted in complementation of nonB. Furthermore, as the SP10 genome was found to possess multiple BsuM target sites, it is considered that SP10 can infect and multiply in B.subtilis cells, which are SPbeta free and possess a defective BsuMR restriction system.

Characterization of poly-gamma-glutamate hydrolase encoded by a bacteriophage genome: possible role in phage infection of Bacillus subtilis encapsulated with poly-gamma-glutamate

Some Bacillus subtilis strains, including natto (fermented soybeans) starter strains, produce a capsular polypeptide of glutamate with a gamma-linkage, called poly-gamma-glutamate (gamma-PGA). We identified and purified a monomeric 25-kDa degradation enzyme for gamma-PGA (designated gamma-PGA hydrolase, PghP) from bacteriophage PhiNIT1 in B. subtilis host cells. The monomeric PghP internally hydrolyzed gamma-PGA to oligopeptides, which were then specifically converted to tri-, tetra-, and penta-gamma-glutamates. Monoiodoacetate and EDTA both inhibited the PghP activity, but Zn(2+) or Mn(2+) ions fully restored the enzyme activity inhibited by the chelator, suggesting that a cysteine residue(s) and these metal ions participate in the catalytic mechanism of the enzyme. The corresponding pghP gene was cloned and sequenced from the phage genome. The deduced PghP sequence (208 amino acids) with a calculated M(r) of 22,939 was not significantly similar to any known enzyme. Thus, PghP is a novel gamma-glutamyl hydrolase. Whereas phage PhiNIT1 proliferated in B. subtilis cells encapsulated with gamma-PGA, phage BS5 lacking PghP did not survive well on such cells. Moreover, all nine phages that contaminated natto during fermentation produced PghP, supporting the notion that PghP is important in the infection of natto starters that produce gamma-PGA. Analogous to polysaccharide capsules, gamma-PGA appears to serve as a physical barrier to phage absorption. Phages break down the gamma-PGA barrier via PghP so that phage progenies can easily establish infection in encapsulated cells.

Divergent structure of the ComQXPA quorum-sensing components: molecular basis of strain-specific communication mechanism in Bacillus subtilis

In Bacillus subtilis, the ComQXPA quorum-sensing system controls cell density-dependent phenotypes such as the production of degradative enzymes and antibiotics and the development of genetic competence. Bacillus subtilis (natto) NAF12, a mutant defective in poly-gamma-glutamate (gamma-PGA) production, was derived from B. subtilis (natto) NAF4 by Tn917-LTV1 insertional mutagenesis. Determination of the mutant DNA sequences flanking the Tn917-LTV1 insert revealed that the insertion had inactivated comP in this mutant, indicating that gamma-PGA synthesis in B. subtilis (natto) is under the control of the ComP-ComA signal transduction system. A comparison of the amino acid sequences revealed striking variation in the primary structures of ComQ (44% identity), ComX (26%) and the sensor domain of ComP (36%) between B. subtilis (natto) NAF4 and B. subtilis 168. In contrast, the amino acid and nucleotide sequences of the kinase domains of ComP and of the ComA response regulator share 95% and 100% identity respectively. The comP genes of NAF4 and 168 restored the impaired competence of B. subtilis BD1658 (comP:cat) and gamma-PGA production of B. subtilis (natto) NAF12 (comP:Tn917-LTV1) to only 15% of the level achieved by the respective parent comP genes. However, when introduced together with the cognate comQ and comX genes, the comP genes restored the relevant defect of the heterologous comP mutants nearly to wild-type levels. Analogous to the comCDE system of Streptococcus strains and the agrBCDE system of Staphylococcus aureus, the concerted variation in the comQXP genes appears to establish specific intercellular communication between B. subtilis strains sharing the same pheromone system.

Updating the H-antigen classification of Bacillus thuringiensis

The classification of Bacillus thuringiensis strains has been revised and updated based on flagellar antigens which have been in use for many years. Sixty-nine serotypes and 13 sub-antigenic groups have now been identified, giving 82 serovars among the 3500 B. thuringiensis isolates of the IEBC Collection. The number of serovars has gradually increased with the total number of strains. The biochemical characters used have also been investigated and their value assessed for identification of B. thuringiensis at the subspecies level. A crystal analysis was carried out in terms of morphology, delta-endotoxin profiles and larvicidal activity for the newly identified serovars. It was found that atypical crystals, some with novel components, are becoming more common. No insect susceptible to these serovars has been discovered among known target species. The number of cross-reacting H-antigens among B. cereus strains is increasing and may be of biological significance.

Bacillus cereus in a whey process

A cheese dairy and its whey manufacturing line were examined for Bacillus cereus. Colonies typical of B. cereus were detected in 120 (17%) samples out of 720 analysed. Only 3% of the sampled raw milk contained B. cereus ( > or = 10 cfu ml(-1)) whereas in evaporated whey concentrate B. cereus was present in 76% of the samples. Nitrate reductase negative and weakly casein hydrolysis isolates were rare in raw milk and the early parts of the process but these defective biotypes became increasingly frequent towards the end of the whey process. The composition of whole cell fatty acids of B. cereus isolates originating from the whey part of the process was different from that of the type strain and of the isolates originating from the raw materials of cheese making. The B. cereus strains in concentrated whey were 100% similar to the type strain in 16S rDNA sequence (500 bp) although they were not or only poorly recognized as B. cereus by a commercial whole cell fatty acid library. All of B. cereus isolates in raw milk were sensitive to one or more of the B. cereus group phages (n = 17) whereas 43% of the isolates from the whey process were sensitive to none. None of the 23 strains originating from the whey processing lines grew at < or = 8 degrees C. although strains with minimum growth temperatures of 5.3 degrees C and 7.0 degrees C were present in the raw materials. Our results indicate that the B. cereus population of the warm ( > 30 degrees C) parts of the cheese dairy process was separate from that of cold (2 degrees C to 4 degrees C) part of the process.