Isolation and Characterization of Phages Infecting <i>Bacillus subtilis</i>

Krasowska, Anna; Biegalska, Anna; Augustyniak, Daria; Łoś, Marcin; Richert, Malwina; Łukaszewicz, Marcin

doi:https://doi.org/10.1155/2015/179597

BioMed Research International

On this page

Abstract Introduction Materials and Methods Results Discussion Acknowledgments References Copyright Related Articles

Special Issue

Microbial Diversity for Biotechnology 2014

View this Special Issue

Research Article | Open Access

Volume 2015 | Article ID 179597 | https://doi.org/10.1155/2015/179597

Isolation and Characterization of Phages Infecting Bacillus subtilis

Anna Krasowska,¹Anna Biegalska,¹Daria Augustyniak,²Marcin Łoś,^3,4,5Malwina Richert,⁶and Marcin Łukaszewicz¹

Academic Editor: Dimitrios Karpouzas

Received06 Jul 2014

Revised15 Sept 2014

Accepted25 Sept 2014

Published26 Jul 2015

Abstract

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.

1. Introduction

Recent investigations show that bacteriophages could be used as a means of controlling food-borne pathogens [1–3]. New phages are therefore being isolated and characterized [4, 5]. One of the bacterial genera with the highest prevalence in food industry, which could potentially be controlled by bacteriophages, is Bacillus, which belong to the heterogeneous group of Gram-positive, endospore-forming, facultative anaerobic bacteria [6, 7]. Despite the numerous advantages of Bacillus species in industry applications, they may also cause damage. The pathogenicity of Bacillus anthracis for mammals is well known, and other Bacillus species infections have been documented since the beginning of the last century [8, 9]. Bacillus cereus is considered a pathogenic species causing local infections, bacteremia, septicemia endocarditis and pericarditis, and infection of the central nervous system and respiratory tract [10–15]. Bacillus cereus is the main factor in food poisoning resulting from toxin production [16]. Beside the well-known pathogenic Bacillus species, recent studies have detected the production of enterotoxins and emetic toxin by B. subtilis, B. pumilus, and B. licheniformis, resulting in food-borne illnesses [17–19]. Bacillus subtilis contaminated 25% of samples of food products in The Netherlands (milk, yeast, flour, pasta products, cocoa, chocolate, bakery products, meat products, herbs, and spices) [20] and 12% of raw materials, dough and bread samples in South Africa [21]. Moreover, B. subtilis spore contamination has been found in wheat flour, ropy bread [22], and gelatin [23].

The removal of Bacillus contamination is limited due to its resistance to physicochemical decontaminations methods. Usually the food industry uses physical methods of sterilization or disinfection such as uv, gamma radiation, or high temperature, but, unfortunately, they are often not effective against the highly resistant Bacillus spores [24, 25]. One option for Bacillus contamination treatment could be phagotherapy [26].

Bacteriophages are the largest group of viruses [27, 28]. They are very useful for people in phage therapy [29]. On the other hand, preventive phage therapy may eliminate pathogenic bacteria from food products. Phages are host-specific and infect only specific species or strains [1] with a few exceptions [30]. Although investigations have shown that bacteriophages can aid in successful eradications of food-borne pathogens such as Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, or Campylobacter [1, 31], there are few commercial products, such as LISTEX P100, which have received the GRAS status [32]. Thus, it is necessary to determine the criteria for the application of phages in the control of bacteria in food and therefore all newly isolated phages with the potential application in antibacterial therapy should be characterized in detail. Beside using isolated phages as decontamination agents, they could be used in bacterial detection and serotyping or strain improvement recently described by Petty et al. [33]. However, the commercial application of bacteriophages requires the optimization of culture conditions and detailed determination of the physical and chemical factors influencing phage viability [34, 35]. The first attempts to control Bacillus subtilis infections by phages were carried out by Ackermann et al. [36]. The results showed an extreme heterogeneity of B. subtilis strains. Ackermann’s phagotype system was used by Inatsu et al. [37] for the differentiation of B. subtilis (natto) and other B. subtilis strains isolated from fermented soybean foods [38].

The aim of this work was to isolate and characterize Bacillus bacteriophages in view of their potential application in phagotyping, strain improvement, and eradication of unwanted Bacillus strains in food industries. We have isolated four bacteriophages with different specificity to 20 B. subtilis strains. Detailed data on their morphology, thermal and pH stability, genome size, and capsid protein mass are described for bacteriophages specified for four representative B. subtilis strains.

2. Materials and Methods

2.1. Bacillus Strains and Bacteriophages

The origins of bacteriophages used in this study as well as their host strains are shown in Table 1. Bacillus strains 10 (isolated from soil), SWV215 [39], B3 [40], and ATTC6633 [41] were used for detailed investigation (Table 1). Bacillus strains were maintained as frozen stocks at −80°C in 1.5%, nutrient broth (Biocorp, Poland) with 2% agar-agar (BioShop, Canada Inc) supplemented with 15% (v/v) of glycerol. For experiments, the strains were cultured on the nutrient agar and then cultured overnight in a liquid nutrient broth. The Bacillus subtilis-specific bacteriophages SUBω, SPOσ, SIOΦ (Acc. number KC699836), and ARπ were isolated from soil supplemented with a liter of Bacillus subtilis cultures. After a week, soil samples (1 g) were suspended in water, shaken (200 rpm/30 min), and centrifuged (4500 rpm/10 min), and the supernatant was filtered through a polyethersulfone (PES) 0.22 μm Millipore filter. Phage propagation was performed as follows: 45 mL of filtered soil samples and 5 mL culture of Bacillus strain grown overnight in nutrient broth were added to 20 mL of fresh nutrient broth and incubated for 24 h at 37°C. The suspension was centrifuged (4500 rpm/10 min) and the supernatant was filtered through a PES 0.22 μm Millipore filter. The bacteriophage titer in the filtrate was assessed using the double-agar layer technique of Adams [42].

Phage stocks were prepared in nutrient broth and then stored at 4°C.

2.2. Electron Microscopy

A high-titer phage lysate filtered through a PES 0.22 μm Millipore filter was centrifuged at 25,000 ×g for 60 min, and the pellet was washed twice in ammonium acetate (0.1 M, pH 7.0). A portion of the resuspended sediment was deposited on carbon-coated Formvar films, stained with 1% uranyl acetate for 30 s, and examined in a Philips CM 100 (Philips CM 100, Japan) transmission electron microscope at 80 kV with 39,000x magnification. The phage size was determined from the average of five to seven independent measurements using T4 phage tail (114 nm) as the magnification control.

2.3. Thermal Treatment

The thermal resistance of all bacteriophages was determined at 23, 50, 60, 70, 80, 90, and 100°C in a temperature-controlled thermo-block (Labnet International. Inc.), at 121°C in an autoclave, at 4°C and −20°C in a standard refrigerator, and at −80°C in a low temperature freezer (REVCO Sanyo, Japan). Equal volumes of phage (10⁷ pfu/mL in sterile water) were incubated for 1, 2, 5, 10, 15, 30, 60, and 180 min at 4°C and then placed in an ice bath or thawed. Samples were assayed to determine surviving pfu using the double-agar layer technique [42].

2.4. pH Treatment

The influence of pH on the bacteriophages was assayed in CP (citrate-phosphate) buffer (0.2 M Na₂HPO₄/0.1 M citrate) within the pH range of 2.0 to 8.0 and in carbonate buffer (0.2 M H₂CO₃/0.2 M NaHCO₃) within the pH range of 9.0 to 11.0. Experiments were carried out at room temperature (25°C) for 1 and 6 h. Samples were assayed to determine pfu using the double-agar layer technique [42].

2.5. Host Range Determination

The host range of bacteriophages was assayed according to Yang et al. [43] as follows: 10⁸ bacterial cells were mixed with molten 0.6% agar and the mixture was poured on 2% solid agar to make double layer agar plates. After solidification, 10 μL of bacteriophage (>10⁶ pfu/mL) was spotted on each plate with each of the different Bacillus strains, incubated, and the presence of lysed plates was examined to determine host range.

2.6. Adsorption Rate, Latent Time, and Phage Burst Size

Experiments were performed as described previously [42, 44, 45] with slight modifications. Equal volume of phages (10⁶–10⁷ pfu/mL) was added to 0.9 mL of overnight cultures of host bacterial species and incubated at 37°C for 5 min. After incubation, the mixture was diluted to 10⁻⁵ and filtered through a PES 0.22 μm Millipore filter. The number of free phages in the filtrate was determined in duplicate, using the double-agar layer method.

To determine the phage latent time and burst size a one-step experiment was carried out according to the previous descriptions [46] with modifications. To 0.9 mL of overnight cultures of host bacteria was added 0.1 mL of the bacteriophage suspension. The bacteria were allowed to adsorb the bacteriophages for 5 min at 37°C; the mixture was diluted to 10⁻⁵ or 10⁻⁴ and further incubated for 135 min at 37°C. Samples were taken at 10 min intervals and phage titer was determined by the double layer-agar plate method. Burst size was calculated as the ratio of the final amount of liberated phage particles to the initial number of infected bacterial cells during the latent period [42].

2.7. Phage DNA Extraction

Phage particles were partially purified by PEG precipitation [47]. High titer suspensions (10¹⁰ pfu/mL) of filtered phage lysate were mixed with NaCl (1 M final conc.) and incubated on ice for 1.5 h. Then PEG 8000 was added to a final concentration of 10% and the mixture was incubated on ice for 2.5 h. This was followed by the centrifugation of precipitated phages (10 000 g, 4°C, 20 min). Pellets were suspended in 10 mM TE buffer (pH 8.0) or TM buffer (10 mM Tris-HCl, 100 mM NaCl, 10 mM MgCl₂; pH 7.4). The residual PEG and bacterial debris were next removed by gentle extraction for 30 s with an equal volume of chloroform, followed by centrifugation at 3000 ×g, 4°C for 15 min.

2.8. Pulsed-Field Gel Electrophoresis PFGE

Determination of bacteriophage genome size by PFGE was performed according to Lingohr et al. [48]. Purified phage particles in 10 mM TE buffer (pH 8.0) were incorporated in 1 : 1 proportion into 2% low-melting agarose in 10 mM TE. The solid gel plugs were incubated for 2.5 h at 54°C in 1 mL of phage lysis buffer containing 50 mM pH 8.0 Tris-HCl, 50 mM EDTA, 1% (w/v) SDS, and 100 μg/mL (final conc.) of proteinase K (phages SUBω, SPOσ, SIOΦ) or 1 mg/mL of proteinase K (phage ARπ). The plugs were washed at least 4 times in 10 mM Tris/EDTA buffer (TE, pH 8.0) and pulsed-field gel electrophoresis (PFGE) was performed (Bio-Rad, UK) in 1% agarose in 0.5X TBE buffer (pH 8.3). The PFGE parameters were as follows: 0.5X TBE buffer; 6 V/cm, initial switch time 1 s; final switch time 15 s; run time 16 h; temperature 12°C. Gels were stained with ethidium bromide followed by destaining in miliQ water. The genome size was determined with BioRad Quantity One software, using the Low Range PFG marker (New England BioLabs, UK) as a standard.

2.9. Preparation of Phage Structural Proteins and SDS-PAGE

Concentrated phage particles in TM buffer were extracted with chloroform (1 : 1 v/v) and, after gentle mixing, were centrifuged at 3000 ×g, 4°C for 15 min. Partly purified phage particles in the aqueous phase were pelleted by ultra-centrifugation (Beckman Coulter) at 50 000 rpm at 4°C for 60 min. The pellets were resuspended in 1X Laemmli loading buffer (62.5 mM Tris-HCl, 2% SDS (w/v), 5% β-mercaptoethanol (v/v), 10% glycerol (v/v), 0.04% (w/v) bromophenol blue; pH 6.8), boiled for 5 min, and separated on the SDS-PAGE 12% gel. All gels were run at 40 mA using a mini Protean apparatus (BioRad) and Laemmli buffer. Gels were stained with Gel Code Blue stain reagent (Thermo Scientific). Biorad Quantity One software was used for the molecular analysis of the phage structural proteins based upon a PageRuler prestained protein ladder plus (Fermentas).

2.10. Statistical Analysis

All experiments were performed at least in triplicate. For the statistical analysis of data obtained, Microsoft Excel 2007 (SD and -test) and R (ANOVA) programs were applied. Standard deviation was included in figures. Statistical significance was determined using Student’s -test. The significance level was set at .

3. Results

3.1. Phage Isolation

Bacillus subtilis-specific bacteriophages were isolated from soil inoculated with four distinct (isolated from different locations) B. subtilis strains: 10, B3, ATTC 6633, and SWV215. All isolated phages formed clear plaques with the strains used for isolation. Phage titers ranged from 10¹⁰ for SUBω and SPOσ to 10¹³ for SIOΦ (Table 2).

3.2. Phage Typing

Twenty Bacillus subtilis strains were used to determine the specificity of the four isolated bacteriophages: SUBω, SPOσ, SIOΦ, and ARπ (Table 1). Phage SUBω infected all Bacillus strains tested with the exception of B. subtilis 10. For B. subtilis 168, B20, KT20, B24, and PCM 486 the resulting plaques were hazy. Phage SPOσ did not form plaques with B. subtilis 10 and KT20 strains, but formed distinct clear plaques with all other strains. Phage SIOΦ formed plaques with B. subtilis strains 168, 10, KT20, and PCM 2226 but clear plaques were observed only with Bacillus strains 10 and PCM 2226. Phage ARπ did not form plaques with strains ATCC 6633, SWV215, 10, PCM1938, PCM 2226, PCM 2189, and PCM 2224. Clear plaques were observed for P22 and 172 strains and for B3 and its mutants (Table 1).

3.3. Phage Morphology

The phages belonged to two morphotypes. Three phages (SIOΦ, SUBω, and SPOσ) were classified to Myoviridae because of the appearance of icosahedral heads and contractile tails with necks, collars, and base plates (Figures 1(a), 1(b), and 1(c)). Phage head and tail length also indicated relationship to the Myoviridae (Table 3).

(a) SIOΦ

(b) SUBω

(c) SPOσ

(d) ARπ

Bacteriophage ARπ had icosahedral heads and noncontractile, long tails (Figure 1(d), Table 3) and is thus morphologically similar to phages belonging to Siphoviridae family.

3.4. Thermal and pH Stability Test

The thermal stability test was carried out to determine the heat resistance of tested phages at pH 7.0. All phages were stable after 180 min at −80°C, −20°C, 4°C, 23°C, 30°C, 37°C, and 50°C, and all phages retained 100% infection activity after a 1 min incubation at 90°C, 100°C, and 121°C (data not shown). An ANOVA test was done and the interaction between the types of phage tested parameters was found statistically important. Thus, it can be said that the inactivation rate of the phages varies for different types of phages.

Phage SIOΦ lost total activity after 2 min at 80°C, 30 min at 70°C, and at 60°C only 1% of original activity was observed after a 3 h incubation period. Phage SUBω lost its infective ability after 1 min at 80°C, 5 min at 70°C, and 180 min at 60°C. Phage SPOσ was inactive after 2 min at 80°C, 15 min at 70°C, and 60 min at 60°C, respectively. Phage ARπ lost its activity after 2 min at 80°C, 10 min at 70°C, and 3 hours at 60°C (Figures 2(a), 2(b), 2(c), and 2(d)).

(a)

(b)

(c)

(d)

Optimal pH was determined by testing the stability of phages at different pH after 60 min (data not shown) and 6 h of incubation at room temperature (25°C). After 1-hour incubation at pH 2.0 all tested phages lost infective ability. Statistically significant differences between tested phages were found. Phage SPOσ seems to be extremely stable in the pH range 6.0–8.0; after a 6 h incubation the SPOσ activity was reduced from 10⁷ to 10⁴ pfu/mL at pH 3.0 and pH 4.0 (Figure 3(c)). At alkaline pH of 10.0 and pH 11.0 the activity was reduced by one order of magnitude (Figure 3(c)).

(a)

(b)

(c)

(d)

Bacteriophage ARπ was the most sensitive to acid and alkaline conditions and only showed 100% activity at pH 7.0 and pH 8.0 (Figure 3(d)). Similar results were observed after only 1 hour incubation (data not shown).

Phages SIOΦ and SUBω had 100% activity in the pH range of 6.0–8.0 and SIOΦ had reduced activity at pH 4.0, 5.0, and 9.0 from 10⁷ to 10², 10³, and 10³, respectively (Figures 3(a) and 3(b)).

Phage SIOΦ was the most active in the adsorption (50%) to the B. subtilis 10 strain. The one-step growth curve of SIOΦ indicated that the latent period was 55–65 min and the estimated burst size was ~74 phage particles per infected bacterial cell (Table 4). Phage SPOσ was less active. It was adsorbed by only 7.5% of the B. subtilis SWV215 strain. The latent period of SPOσ was 75–85 min and the estimated burst size was ~23 phage particles per infected bacterial cell (Table 4). The latent periods of phages SUBω and ARπ were the same as that of phage SIOΦ, but the adsorption was lower (12%) and growth times were shorter (30 min). A difference between phages SUBω and ARπ was observed in their burst size: for SUBω it was only ~8 phage particles per infected bacterial cell while for ARπ it was ~37 phage particles (Table 4).

3.5. Phage Genome Size Estimated by PFGE

The size of the intact genomic DNA of the four phages in this study was estimated by pulse-field electrophoresis (PFGE). For phages SIOΦ, SUBω, and SPOσ belonging to Myoviridae family the size of their genomes was, respectively, 154, 154, and 25 kbp (Figure 4). The genome size of Arπ, the only phage from Siphoviridae family, was 40 kbp (Figure 4). The determined genome size values are comparable with values estimated by ICTV for the indicated phage families.

3.6. Protein Composition

SDS-PAGE was used to determine the content of structural proteins of phage particles. Virions of phages SIOΦ, SUBω, and SPOσ contained structural proteins with predominant protein bands corresponding, respectively, to ~52 kDa (SIOΦ), ~45, 31 kDa (SUBω), and 45 kDa (SPOσ) (Figure 5). Phage ARπ contained at least 14 structural proteins and was found to produce three major protein bands at molecular masses of approximately 42, 37, and 31 kDa (Figure 5).

4. Discussion

Bacillus has a high prevalence in nature and ability to form heat-resistant endospores; hence it is difficult to eradicate it from, for example, fermented food, and the constant presence of beneficial microorganisms is critical to maintaining the expected food quality. Bacteriophages are host-specific natural enemies of bacteria and the efficient eradication of bacterial pathogens with the use of phages is an effective way to control harmful bacteria [2, 49].

Bacteriophages may have distinct applications, such as biocontrol (eradication) of unwanted species (strains), improvement (selection) of strains used for production, and strain typing. All these applications depend on phage specificity [50]. Both a wide and a narrow host range may be useful. While a rather narrow host range will enable distinction of closely related strains in strain typing, a rather wide host range will be beneficial for biocontrol. In comparison to biocontrol, application of bacteriophages for improvement and selection of industrial strains has been poorly described. In fact, it is well known that in a large-scale production phage infection may lead to the collapse of the production, as it was in the case of acetone-butanol fermentation [51]. Thus, in industrial practice either various strains are used every month or a cocktail of strains is used for inoculum. Rotation of strains with various resistance decreases the risk of accumulation of bacteriophages infecting producer strain in industrial environment [52].

We found four bacteriophages with different specificity toward twenty Bacillus subtilis strains (Table 1). The classification of bacteriophages is in most cases based on morphological criteria and rarely on molecular data, for example, nucleotide sequence homology [53]. Considering the morphology, 96% of all bacteriophages belong to the order Caudovirales and this order is subdivided into three families: the Myoviridae (25%), characterized by a contractile tail; the Siphoviridae (61%) with a noncontractile tail; and the Podoviridae (14%) with a short, noncontractile tail [54, 55]. In 2009 the International Committee on the Taxonomy of Viruses (ICTV) proposed the creation the Myoviridae subfamily Spounavirinae with genera of SPO1-like viruses and Twort-like viruses and eight phage species [56]. Recently, Klumpp et al. [57] proposed a revision of current taxonomic organization of the family Myoviridae and evaluated new members of this group. In this work we isolated three phages, SIOΦ, SUBω, and SPOσ, which morphologically belong to the Myoviridae family and phage ARπ which is classified in the Siphoviridae family (Figure 1). The genomes of SIOΦ and SUBω are 154 kbp each and are similar to the other phages of Bacillus subtilis such as SPO1 (145.7 kbp), SP8, SP82G, H1, 2C, Φe, or Φ25 (~150) [57]. SIOΦ has only four capsid proteins like the ΦH-like viruses; however, viruses of the ΦH type have a mere 59 kbp genome [58]. Bacteriophage SPOσ has a genome size of 25 kbp and ~14 capsid proteins and these features allow it to fall into the group of P2-like or Mu-like viruses but, unfortunately, viruses in this class have Gram-negative bacteria as hosts [58]. ARπ phage genome is sized 40 kbp and it has ~14 capsid proteins. On the basis of these characteristics it can be classified as N₁₅-like virus but the very long tail (342 nm) excludes it from the known classification [58]. The bacteriophages with the longest tails in Siphoviridae family belong to ΦM₁-like viruses (210 nm) and their tail is terminated with a knob as in ARπ phage.

The use of bacteriophages in biotechnological processes requires the knowledge of their characteristics such as the host range, latent period, growth time, or the resistance to stress conditions, for example, different temperatures or pH. Temperature plays a crucial role in bacteriophage survival, capacity for attachment, and the length of the latent period [59]. SIOΦ, SUBω, SPOσ, and ARπ bacteriophages retain a stable activity following 3 hours at temperatures ranging from −80°C to 50°C (Figure 2). Phages SIOΦ, SPOσ, and ARπ proved to be resistant to high temperatures and all of them survive after 2 min at 80°C, 5 min or longer at 70°C, and 180 min (except for 60 min for SPOσ) at 60°C (Figure 2). In general, members of Myoviridae and Siphoviridae families are considered to be resistant to large temperature fluctuations [35].

Acidity and alkalinity of the environment are other important factors influencing phage stability. SIOΦ and SPOσ phages are the most resistant to acid (4.0) and alkaline (9.0 and 10.0) pH; ARπ phage is the least resistant to pH fluctuations. The optimum pH values for all investigated phages were 7.0 and 8.0 (Figure 3). Lasobras et al. [60] have suggested that members of Siphoviridae family are the most resistant to adverse conditions. However, phage Arπ, which we morphologically classified as a member of Siphoviridae, is only active in a narrow pH range (6.0–8.0).

Bacteriophage SIOΦ had the highest percent adsorption to the Bacillus host (50%) and released the largest number of particles (~74) from host cells (Table 4) and its phage titer was the highest (10¹³) (Table 2). Due to high activity at low and high temperature and pH, SIOΦ seems to be the best candidate for use in industry.

The literature contains many descriptions of experiments conducted under different conditions and hence with varying results. Some Bacillus subtilis phages such as SP02c1 or SP82 have a higher percent of adsorption than our phages [61] while, on the other hand, phage SPO1 has the same burst size as SIOΦ [62].

At least one of the characterized isolated bacteriophages was lytic for each tested strain of Bacillus subtilis. Thus, they could be suitable for the phagotyping of this bacterial species.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

Acknowledgments

This work was supported by grants from the Polish National Centre for Research and Development KB/48/13639/IT1-B/U/08, Grant EU POIG.01.01.02-00-016/2008, grant of the Ministry of Science and Higher Education (Poland) and the European Union within European Regional Development Fund, through Innovative Economy Grant (POIG.01.01.02-00-008/08), and by Wroclaw Centre of Biotechnology, programme The Leading National Research Centre (KNOW) for years 2014–2018.

References

S. Hagens and M. J. Loessner, “Application of bacteriophages for detection and control of foodborne pathogens,” Applied Microbiology and Biotechnology, vol. 76, no. 3, pp. 513–519, 2007.
View at: Publisher Site | Google Scholar
S. Guenther, D. Huwyler, S. Richard, and M. J. Loessner, “Virulent bacteriophage for efficient biocontrol of listeria monocytogenes in ready-to-eat foods,” Applied and Environmental Microbiology, vol. 75, no. 1, pp. 93–100, 2009.
View at: Publisher Site | Google Scholar
L. Y. Brovko, H. Anany, and M. W. Griffiths, “Bacteriophages for detection and control of bacterial pathogens in food and food-processing environment,” in Advances in Food and Nutrition Research, H. Jeyakumar, Ed., chapter 6, pp. 241–288, Academic Press, New York, NY, USA, 2012.
View at: Google Scholar
J.-H. Lee, H. Shin, B. Son, S. Heu, and S. Ryu, “Characterization and complete genome sequence of a virulent bacteriophage B4 infecting food-borne pathogenic Bacillus cereus,” Archives of Virology, vol. 158, no. 10, pp. 2101–2108, 2013.
View at: Publisher Site | Google Scholar
N. Bandara, J. Jo, S. Ryu, and K.-P. Kim, “Bacteriophages BCP1-1 and BCP8-2 require divalent cations for efficient control of Bacillus cereus in fermented foods,” Food Microbiology, vol. 31, no. 1, pp. 9–16, 2012.
View at: Publisher Site | Google Scholar
H. Shin, N. Bandara, E. Shin, S. Ryu, and K.-P. Kim, “Prevalence of Bacillus cereus bacteriophages in fermented foods and characterization of phage JBP901,” Research in Microbiology, vol. 162, no. 8, pp. 791–797, 2011.
View at: Publisher Site | Google Scholar
T. Nagai and F. Yamasaki, “Bacillus subtilis (natto) bacteriophages isolated in Japan,” Food Science and Technology Research, vol. 15, no. 3, pp. 293–298, 2009.
View at: Publisher Site | Google Scholar
W. E. Farrar Jr., “Serious infections due to “non-pathogenic” organisms of the genus bacillus. Review of their status as pathogens,” The American Journal of Medicine, vol. 34, no. 1, pp. 134–141, 1963.
View at: Publisher Site | Google Scholar
J. McFarland, “Bacillus anthracis similis,” Zentralbl Bakteriol Parasitenkd Abt I, vol. 24, pp. 556–557, 1898.
View at: Google Scholar
A. Akesson, S. A. Hedstrom, and T. Ripa, “Bacillus cereus: a significant pathogen in postoperative and post-traumatic wounds on orthopaedic wards,” Scandinavian Journal of Infectious Diseases, vol. 23, no. 1, pp. 71–77, 1991.
View at: Publisher Site | Google Scholar
D. Barrie, J. A. Wilson, P. N. Hoffman, and J. M. Kramer, “Bacillus cereus meningitis in two neurosurgical patients: an investigation into the source of the organism,” Journal of Infection, vol. 25, no. 3, pp. 291–297, 1992.
View at: Publisher Site | Google Scholar
D. J. Cotton, V. J. Gill, D. J. Marshall, J. Gress, M. Thaler, and P. A. Pizzo, “Clinical features and therapeutic interventions in 17 cases of Bacillus bacteremia in an immunosuppressed patient population,” Journal of Clinical Microbiology, vol. 25, no. 4, pp. 672–674, 1987.
View at: Google Scholar
C. S. Block, M. L. Levy, and V. U. Fritz, “Bacillus cereus endocarditis—a case report,” South African Medical Journal, vol. 53, no. 4, pp. 556–557, 1978.
View at: Google Scholar
J. E. Carbone and J. L. Stauffer, “Bacillus cereus pleuropulmonary infection in a normal host,” The Western Journal of Medicine, vol. 143, no. 5, pp. 676–677, 1985.
View at: Google Scholar
C. P. Craig, W.-S. Lee, and M. Ho, “Bacillus cereus endocarditis in an addict,” Annals of Internal Medicine, vol. 80, no. 3, pp. 418–419, 1974.
View at: Publisher Site | Google Scholar
F. A. Drobniewski, “Bacillus cereus and related species,” Clinical Microbiology Reviews, vol. 6, no. 4, pp. 324–338, 1993.
View at: Google Scholar
C. From, R. Pukall, P. Schumann, V. Hormazábal, and P. E. Granum, “Toxin-producing ability among Bacillus spp. outside the Bacillus cereus group,” Applied and Environmental Microbiology, vol. 71, no. 3, pp. 1178–1183, 2005.
View at: Publisher Site | Google Scholar
P. B. Pedersen, M. E. Bjørnvad, M. D. Rasmussen, and J. N. Petersen, “Cytotoxic potential of industrial strains of Bacillus sp,” Regulatory Toxicology and Pharmacology, vol. 36, no. 2, pp. 155–161, 2002.
View at: Publisher Site | Google Scholar
M. S. Salkinoja-Salonen, R. Vuorio, M. A. Andersson et al., “Toxigenic strains of Bacillus licheniformis related to food poisoning,” Applied and Environmental Microbiology, vol. 65, no. 10, pp. 4637–4645, 1999.
View at: Google Scholar
M. C. Te Giffel, R. R. Beumer, S. Leijendekkers, and F. M. Rombouts, “Incidence of Bacillus cereus and Bacillus subtilis in foods in the Netherlands,” Food Microbiology, vol. 13, no. 1, pp. 53–58, 1996.
View at: Publisher Site | Google Scholar
C. P. Bailey and A. von Holy, “Bacillus spore contamination associated with commercial bread manufacture,” Food Microbiology, vol. 10, no. 4, pp. 287–294, 1993.
View at: Publisher Site | Google Scholar
I. B. Sorokulova, O. N. Reva, V. V. Smirnov, I. V. Pinchuk, S. V. Lapa, and M. C. Urdaci, “Genetic diversity and involvement in bread spoilage of Bacillus strains isolated from flour and ropy bread,” Letters in Applied Microbiology, vol. 37, no. 2, pp. 169–173, 2003.
View at: Publisher Site | Google Scholar
E. de Clerck, T. Vanhoutte, T. Hebb, J. Geerinck, J. Devos, and P. de Vos, “Isolation, characterization, and identification of bacterial contaminants in semifinal gelatin extracts,” Applied and Environmental Microbiology, vol. 70, no. 6, pp. 3664–3672, 2004.
View at: Publisher Site | Google Scholar
R. Moeller, G. Horneck, R. Facius, and E. Stackebrandt, “Role of pigmentation in protecting Bacillus sp. endospores against environmental UV radiation,” FEMS Microbiology Ecology, vol. 51, no. 2, pp. 231–236, 2005.
View at: Publisher Site | Google Scholar
C. Faille, F. Fontaine, and T. Bénézech, “Potential occurrence of adhering living Bacillus spores in milk product processing lines,” Journal of Applied Microbiology, vol. 90, no. 6, pp. 892–900, 2001.
View at: Publisher Site | Google Scholar
E. J. Vandamme, “Phage therapy and phage control: to be revisited urgently!!,” Journal of Chemical Technology and Biotechnology, vol. 89, no. 3, pp. 329–333, 2014.
View at: Publisher Site | Google Scholar
R. W. Hendrix, “Bacteriophages: evolution of the majority,” Theoretical Population Biology, vol. 61, no. 4, pp. 471–480, 2002.
View at: Publisher Site | Google Scholar
G. W. Hanlon, “Bacteriophages: an appraisal of their role in the treatment of bacterial infections,” International Journal of Antimicrobial Agents, vol. 30, no. 2, pp. 118–128, 2007.
View at: Publisher Site | Google Scholar
A. Sulakvelidze, Z. Alavidze, and J. G. Morris Jr., “Bacteriophage therapy,” Antimicrobial Agents and Chemotherapy, vol. 45, no. 3, pp. 649–659, 2001.
View at: Publisher Site | Google Scholar
R. Zink and M. J. Loessner, “Classification of virulent and temperate bacteriophages of Listeria spp. on the basis of morphology and protein analysis,” Applied and Environmental Microbiology, vol. 58, no. 1, pp. 296–302, 1992.
View at: Google Scholar
C. E. D. Rees, C. E. R. Dodd, S. S. Allen, and I. Laskin, “Phage for rapid detection and control of bacterial pathogens in food,” in Advances in Applied Microbiology, pp. 159–186, Academic Press, New York, NY, USA, 2006.
View at: Google Scholar
M. Skurnik, M. Pajunen, and S. Kiljunen, “Biotechnological challenges of phage therapy,” Biotechnology Letters, vol. 29, no. 7, pp. 995–1003, 2007.
View at: Publisher Site | Google Scholar
N. K. Petty, T. J. Evans, P. C. Fineran, and G. P. C. Salmond, “Biotechnological exploitation of bacteriophage research,” Trends in Biotechnology, vol. 25, no. 1, pp. 7–15, 2007.
View at: Publisher Site | Google Scholar
H. W. Ackermann, D. Tremblay, and S. Moineau, “Long-term bacteriophage preservation,” WFCC Newsletter, vol. 38, pp. 35–40, 2004.
View at: Google Scholar
E. Jończyk, M. Kłak, R. Miedzybrodzki, and A. Górski, “The influence of external factors on bacteriophages—review,” Folia Microbiologica, vol. 56, no. 3, pp. 191–200, 2011.
View at: Publisher Site | Google Scholar
H.-W. Ackermann, R. R. Azizbekyan, R. L. Bernier et al., “Phage typing of Bacillus subtilis and B. thuringiensis,” Research in Microbiology, vol. 146, no. 8, pp. 643–657, 1995.
View at: Publisher Site | Google Scholar
Y. Inatsu, K. Kimura, and Y. Itoh, “Characterization of Bacillus subtilis strains isolated from fermented soybean foods in Southeast Asia: comparison with B. subtilis (natto) starter strains,” Japan Agricultural Research Quarterly, vol. 36, no. 3, pp. 169–175, 2002.
View at: Google Scholar
K. Kimura and Y. Itoh, “Characterization of poly-γ-glutamate hydrolase encoded by a bacteriophage genome: possible role in phage infection of bacillus subtilis encapsulated with poly-γ-glutamate,” Applied and Environmental Microbiology, vol. 69, no. 5, pp. 2491–2497, 2003.
View at: Publisher Site | Google Scholar
K. Xu and M. A. Strauch, “Identification, sequence, and expression of the gene encoding $γ$ -glutamyltranspeptidase in Bacillus subtilis,” Journal of Bacteriology, vol. 178, no. 14, pp. 4319–4322, 1996.
View at: Google Scholar
S. Yao, X. Gao, N. Fuchsbauer, W. Hillen, J. Vater, and J. Wang, “Cloning, sequencing, and characterization of the genetic region relevant to biosynthesis of the lipopeptides iturin A and surfactin in Bacillus subtilis,” Current Microbiology, vol. 47, no. 4, pp. 0272–0277, 2003.
View at: Publisher Site | Google Scholar
L. K. Nakamura, “Taxonomic relationship of black-pigmented Bacillus subtilis strains and a proposal for Bacillus atrophaeus sp. nov,” International Journal of Systematic Bacteriology, vol. 39, no. 3, pp. 295–300, 1989.
View at: Publisher Site | Google Scholar
M. Adams, Bacteriophages, Interscience, New York, NY, USA, 1959.
H. Yang, L. Liang, S. Lin, and S. Jia, “Isolation and characterization of a virulent bacteriophage AB1 of Acinetobacter baumannii,” BMC Microbiology, vol. 10, no. 1, p. 131, 2010.
View at: Publisher Site | Google Scholar
R. Gallet, Y. Shao, and I.-N. Wang, “High adsorption rate is detrimental to bacteriophage fitness in a biofilm-like environment,” BMC Evolutionary Biology, vol. 9, no. 1, article 241, 2009.
View at: Publisher Site | Google Scholar
C. Roncero, A. Darzins, and M. J. Casadaban, “Pseudomonas aeruginosa transposable bacteriophages D3112 and B3 require pili and surface growth for adsorption,” Journal of Bacteriology, vol. 172, no. 4, pp. 1899–1904, 1990.
View at: Google Scholar
M. Pajunen, S. Kiljunen, and M. Skurnik, “Bacteriophage φYeO3-12, specific for Yersinia enterocolitica serotype O:3, is related to coliphages T3 and T7,” Journal of Bacteriology, vol. 182, no. 18, pp. 5114–5120, 2000.
View at: Publisher Site | Google Scholar
J. Sambrook and D. W. Russell, Molecular Cloning, Cold Spring Harbor Laboratory, New York, NY, USA, 2001.
E. Lingohr, S. Frost, and R. P. Johnson, “Determination of bacteriophage genome size by pulsed-field gel electrophoresis,” Methods in Molecular Biology, vol. 502, pp. 19–25, 2009.
View at: Publisher Site | Google Scholar
P. García, B. Martínez, J. M. Obeso, and A. Rodríguez, “Bacteriophages and their application in food safety,” Letters in Applied Microbiology, vol. 47, no. 6, pp. 479–485, 2008.
View at: Publisher Site | Google Scholar
S. Hagens and M. J. Loessner, “Bacteriophage for biocontrol of foodborne pathogens: calculations and considerations,” Current Pharmaceutical Biotechnology, vol. 11, no. 1, pp. 58–68, 2010.
View at: Publisher Site | Google Scholar
W. Kuit, N. P. Minton, A. M. López-Contreras, and G. Eggink, “Disruption of the acetate kinase (ack) gene of Clostridium acetobutylicum results in delayed acetate production,” Applied Microbiology and Biotechnology, vol. 94, no. 3, pp. 729–741, 2012.
View at: Publisher Site | Google Scholar
A. Gálvez, H. Abriouel, R. L. López, and N. B. Omar, “Bacteriocin-based strategies for food biopreservation,” International Journal of Food Microbiology, vol. 120, no. 1-2, pp. 51–70, 2007.
View at: Publisher Site | Google Scholar
H.-W. Ackermann, “Phage classification and characterization,” Methods in Molecular Biology, vol. 501, pp. 127–140, 2009.
View at: Publisher Site | Google Scholar
H. W. Ackermann, “Bacteriophage observations and evolution,” Research in Microbiology, vol. 154, no. 4, pp. 245–251, 2003.
View at: Publisher Site | Google Scholar
H.-W. Ackermann, “5500 Phages examined in the electron microscope,” Archives of Virology, vol. 152, no. 2, pp. 227–243, 2007.
View at: Publisher Site | Google Scholar
R. Lavigne, P. Darius, E. J. Summer et al., “Classification of myoviridae bacteriophages using protein sequence similarity,” BMC Microbiology, vol. 9, article 224, 2009.
View at: Publisher Site | Google Scholar
J. Klumpp, R. Lavigne, M. J. Loessner, and H.-W. Ackermann, “The SPO1-related bacteriophages,” Archives of Virology, vol. 155, no. 10, pp. 1547–1561, 2010.
View at: Publisher Site | Google Scholar
C. M. Fauquet, M. A. Mayo, J. Maniloff, U. Desselberger, and A. Ball, VIII Report of the International Committe on the Taxonomy of Viruses—Virus Taxonomy Classification and Nomenclature, Elsevier/Academic Press, London, UK, 2005.
M. R. Olson, R. P. Axler, and R. E. Hicks, “Effects of freezing and storage temperature on MS2 viability,” Journal of Virological Methods, vol. 122, no. 2, pp. 147–152, 2004.
View at: Publisher Site | Google Scholar
J. Lasobras, M. Muniesa, J. Frías, F. Lucena, and J. Jofre, “Relationship between the morphology of bacteriophages and their persistence in the environment,” Water Science and Technology, vol. 35, no. 11-12, pp. 129–132, 1997.
View at: Publisher Site | Google Scholar
S. Palefski, H. E. Hemphill, P. E. Kolenbrander, and H. R. Whiteley, “Dominance relationships in mixedly infected Bacillus subtilis,” Journal of Virology, vol. 9, no. 4, pp. 594–601, 1972.
View at: Google Scholar
A. Sampath and C. R. Stewart, “Roles of genes 44, 50, and 51 in regulating gene expression and host takeover during infection of Bacillus subtilis by bacteriophage SPO1,” Journal of Bacteriology, vol. 186, no. 6, pp. 1785–1792, 2004.
View at: Publisher Site | Google Scholar

Copyright

Copyright © 2015 Anna Krasowska et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

9659

Downloads

2582

Citations