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Temperature dependent bacteriophages of a tropical bacterial pathogen.

Shan J, Korbsrisate S, Withatanung P, Adler NL, Clokie MR, Galyov EE - Front Microbiol (2014)

Bottom Line: Experiments on one phage in the related model B. thailandensis demonstrated that temperature defines the outcome of phage-bacteria interactions.Furthermore, when taken together with previous studies, our findings suggest that the phenomenon of temperature dependency in phages is widespread.Such phages are likely to have a profound effect on bacterial biology, and on our ability to culture and correctly enumerate viable bacteria.

View Article: PubMed Central - PubMed

Affiliation: Department of Infection, Immunity and Inflammation, University of Leicester Leicester, UK.

ABSTRACT
There is an increasing awareness of the multiple ways that bacteriophages (phages) influence bacterial evolution, population dynamics, physiology, and pathogenicity. By studying a novel group of phages infecting a soil borne pathogen, we revealed a paradigm shifting observation that the phages switch their lifestyle according to temperature. We sampled soil from an endemic area of the serious tropical pathogen Burkholderia pseudomallei, and established that podoviruses infecting the pathogen are frequently present in soil, and many of them are naturally occurring variants of a common virus type. Experiments on one phage in the related model B. thailandensis demonstrated that temperature defines the outcome of phage-bacteria interactions. At higher temperatures (37°C), the phage predominantly goes through a lytic cycle, but at lower temperatures (25°C), the phage remains temperate. This is the first report of a naturally occurring phage that follows a lytic or temperate lifestyle according to temperature. These observations fundamentally alter the accepted views on the abundance, population biology and virulence of B. pseudomallei. Furthermore, when taken together with previous studies, our findings suggest that the phenomenon of temperature dependency in phages is widespread. Such phages are likely to have a profound effect on bacterial biology, and on our ability to culture and correctly enumerate viable bacteria.

No MeSH data available.


Related in: MedlinePlus

Temperature-dependent lysogeny of B. thailandensis by ØBp-AMP1. (A)B. thailandensis E264 was grown to mid-log phase and split into four aliquots, two were then infected with ØBp-AMP1, and two non-infected cultures were used as a control. The cultures were incubated either at 25 or 37°C for 6 h and sampled hourly to estimate the bacterial density by measuring the OD at 600 nm. (B) Corresponding phage counts in the media were enumerated by counting the number of PFU. Data revealed that at 37°C, the phage lysed the host bacteria and produced phage progeny at titres of ∼1011 PFU/ml after 1 h of infection whereas at 25°C, most of the bacteria were not lysed and the infected bacteria produced phages at the significantly lower titre of ∼108 PFU/ml. Results for each data point are the mean of three biological replicates each performed in triplicate ±SD. (C)B. thailandensis E264 was grown to mid-log phase in liquid media and split into two aliquots. One aliquot was infected with ØBp-AMP1 at an MOI of 10 for 10 min and spread in serial dilutions onto two sets of LB agar plates. One set was then incubated at 25°C and the other at 37°C. Non-infected cultures were used as a control. At 25°C, infected and non-infected cultures yielded essentially the same number of colonies. However, at 37°C the mean of the infected culture was 2.17 × 106 (SD 2.47 × 106) CFU/ml compared to 7.33 × 107 (SD 2.52 × 107) for the infected culture at 25°C, 1.07 × 108 (SD 4.04 × 107) for the uninfected culture at 37°C and 8.33 × 107 (SD 1.53 × 107) uninfected culture at 25°C. Results plotted are these means from three biological replicates ±SD. (D) Stable lysogens of B. thailandensis E264 were selected and maintained on agar plates incubated at 25°C. The lysogen culture was then grown in liquid media at 25°C to mid-log phase. Approximately 106 bacteria were then mixed with 8 ml of melted 0.4% (w/v) agar precooled to 45°C, and plates were cast and incubated at either 25 or 37°C. A thick bacterial lawn was observed at 25°C, but substantial phage mediated lysis was observed at 37°C. Representative images from at least three independent experiments are shown.
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Figure 2: Temperature-dependent lysogeny of B. thailandensis by ØBp-AMP1. (A)B. thailandensis E264 was grown to mid-log phase and split into four aliquots, two were then infected with ØBp-AMP1, and two non-infected cultures were used as a control. The cultures were incubated either at 25 or 37°C for 6 h and sampled hourly to estimate the bacterial density by measuring the OD at 600 nm. (B) Corresponding phage counts in the media were enumerated by counting the number of PFU. Data revealed that at 37°C, the phage lysed the host bacteria and produced phage progeny at titres of ∼1011 PFU/ml after 1 h of infection whereas at 25°C, most of the bacteria were not lysed and the infected bacteria produced phages at the significantly lower titre of ∼108 PFU/ml. Results for each data point are the mean of three biological replicates each performed in triplicate ±SD. (C)B. thailandensis E264 was grown to mid-log phase in liquid media and split into two aliquots. One aliquot was infected with ØBp-AMP1 at an MOI of 10 for 10 min and spread in serial dilutions onto two sets of LB agar plates. One set was then incubated at 25°C and the other at 37°C. Non-infected cultures were used as a control. At 25°C, infected and non-infected cultures yielded essentially the same number of colonies. However, at 37°C the mean of the infected culture was 2.17 × 106 (SD 2.47 × 106) CFU/ml compared to 7.33 × 107 (SD 2.52 × 107) for the infected culture at 25°C, 1.07 × 108 (SD 4.04 × 107) for the uninfected culture at 37°C and 8.33 × 107 (SD 1.53 × 107) uninfected culture at 25°C. Results plotted are these means from three biological replicates ±SD. (D) Stable lysogens of B. thailandensis E264 were selected and maintained on agar plates incubated at 25°C. The lysogen culture was then grown in liquid media at 25°C to mid-log phase. Approximately 106 bacteria were then mixed with 8 ml of melted 0.4% (w/v) agar precooled to 45°C, and plates were cast and incubated at either 25 or 37°C. A thick bacterial lawn was observed at 25°C, but substantial phage mediated lysis was observed at 37°C. Representative images from at least three independent experiments are shown.

Mentions: To probe the impact of temperature on phage-host dynamics, liquid bacterial cultures were infected with phage ØBp-AMP1 (Gatedee et al., 2011) and incubated at either 25°C or 37°C with non-infected cultures used as a control. At 37°C, the phage caused rapid bacterial lysis, whereas when incubated at 25°C, both the phage-infected and non-infected bacteria grew steadily (Figures 2A,B). Adsorption assays showed that there were no difference in terms of binding efficiency as ∼90% of all of the phages bound to bacterial cells within 45 min at both a temperature of 25°C and at 37°C. Furthermore, experiments using the virucide FAS confirmed that the phage can still inject DNA into host cells at both temperatures. This suggests that the phage infection cycle is temperature dependent, with a higher temperature permissive for lytic infection and the lower temperature for lysogenic infection.


Temperature dependent bacteriophages of a tropical bacterial pathogen.

Shan J, Korbsrisate S, Withatanung P, Adler NL, Clokie MR, Galyov EE - Front Microbiol (2014)

Temperature-dependent lysogeny of B. thailandensis by ØBp-AMP1. (A)B. thailandensis E264 was grown to mid-log phase and split into four aliquots, two were then infected with ØBp-AMP1, and two non-infected cultures were used as a control. The cultures were incubated either at 25 or 37°C for 6 h and sampled hourly to estimate the bacterial density by measuring the OD at 600 nm. (B) Corresponding phage counts in the media were enumerated by counting the number of PFU. Data revealed that at 37°C, the phage lysed the host bacteria and produced phage progeny at titres of ∼1011 PFU/ml after 1 h of infection whereas at 25°C, most of the bacteria were not lysed and the infected bacteria produced phages at the significantly lower titre of ∼108 PFU/ml. Results for each data point are the mean of three biological replicates each performed in triplicate ±SD. (C)B. thailandensis E264 was grown to mid-log phase in liquid media and split into two aliquots. One aliquot was infected with ØBp-AMP1 at an MOI of 10 for 10 min and spread in serial dilutions onto two sets of LB agar plates. One set was then incubated at 25°C and the other at 37°C. Non-infected cultures were used as a control. At 25°C, infected and non-infected cultures yielded essentially the same number of colonies. However, at 37°C the mean of the infected culture was 2.17 × 106 (SD 2.47 × 106) CFU/ml compared to 7.33 × 107 (SD 2.52 × 107) for the infected culture at 25°C, 1.07 × 108 (SD 4.04 × 107) for the uninfected culture at 37°C and 8.33 × 107 (SD 1.53 × 107) uninfected culture at 25°C. Results plotted are these means from three biological replicates ±SD. (D) Stable lysogens of B. thailandensis E264 were selected and maintained on agar plates incubated at 25°C. The lysogen culture was then grown in liquid media at 25°C to mid-log phase. Approximately 106 bacteria were then mixed with 8 ml of melted 0.4% (w/v) agar precooled to 45°C, and plates were cast and incubated at either 25 or 37°C. A thick bacterial lawn was observed at 25°C, but substantial phage mediated lysis was observed at 37°C. Representative images from at least three independent experiments are shown.
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Related In: Results  -  Collection

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Figure 2: Temperature-dependent lysogeny of B. thailandensis by ØBp-AMP1. (A)B. thailandensis E264 was grown to mid-log phase and split into four aliquots, two were then infected with ØBp-AMP1, and two non-infected cultures were used as a control. The cultures were incubated either at 25 or 37°C for 6 h and sampled hourly to estimate the bacterial density by measuring the OD at 600 nm. (B) Corresponding phage counts in the media were enumerated by counting the number of PFU. Data revealed that at 37°C, the phage lysed the host bacteria and produced phage progeny at titres of ∼1011 PFU/ml after 1 h of infection whereas at 25°C, most of the bacteria were not lysed and the infected bacteria produced phages at the significantly lower titre of ∼108 PFU/ml. Results for each data point are the mean of three biological replicates each performed in triplicate ±SD. (C)B. thailandensis E264 was grown to mid-log phase in liquid media and split into two aliquots. One aliquot was infected with ØBp-AMP1 at an MOI of 10 for 10 min and spread in serial dilutions onto two sets of LB agar plates. One set was then incubated at 25°C and the other at 37°C. Non-infected cultures were used as a control. At 25°C, infected and non-infected cultures yielded essentially the same number of colonies. However, at 37°C the mean of the infected culture was 2.17 × 106 (SD 2.47 × 106) CFU/ml compared to 7.33 × 107 (SD 2.52 × 107) for the infected culture at 25°C, 1.07 × 108 (SD 4.04 × 107) for the uninfected culture at 37°C and 8.33 × 107 (SD 1.53 × 107) uninfected culture at 25°C. Results plotted are these means from three biological replicates ±SD. (D) Stable lysogens of B. thailandensis E264 were selected and maintained on agar plates incubated at 25°C. The lysogen culture was then grown in liquid media at 25°C to mid-log phase. Approximately 106 bacteria were then mixed with 8 ml of melted 0.4% (w/v) agar precooled to 45°C, and plates were cast and incubated at either 25 or 37°C. A thick bacterial lawn was observed at 25°C, but substantial phage mediated lysis was observed at 37°C. Representative images from at least three independent experiments are shown.
Mentions: To probe the impact of temperature on phage-host dynamics, liquid bacterial cultures were infected with phage ØBp-AMP1 (Gatedee et al., 2011) and incubated at either 25°C or 37°C with non-infected cultures used as a control. At 37°C, the phage caused rapid bacterial lysis, whereas when incubated at 25°C, both the phage-infected and non-infected bacteria grew steadily (Figures 2A,B). Adsorption assays showed that there were no difference in terms of binding efficiency as ∼90% of all of the phages bound to bacterial cells within 45 min at both a temperature of 25°C and at 37°C. Furthermore, experiments using the virucide FAS confirmed that the phage can still inject DNA into host cells at both temperatures. This suggests that the phage infection cycle is temperature dependent, with a higher temperature permissive for lytic infection and the lower temperature for lysogenic infection.

Bottom Line: Experiments on one phage in the related model B. thailandensis demonstrated that temperature defines the outcome of phage-bacteria interactions.Furthermore, when taken together with previous studies, our findings suggest that the phenomenon of temperature dependency in phages is widespread.Such phages are likely to have a profound effect on bacterial biology, and on our ability to culture and correctly enumerate viable bacteria.

View Article: PubMed Central - PubMed

Affiliation: Department of Infection, Immunity and Inflammation, University of Leicester Leicester, UK.

ABSTRACT
There is an increasing awareness of the multiple ways that bacteriophages (phages) influence bacterial evolution, population dynamics, physiology, and pathogenicity. By studying a novel group of phages infecting a soil borne pathogen, we revealed a paradigm shifting observation that the phages switch their lifestyle according to temperature. We sampled soil from an endemic area of the serious tropical pathogen Burkholderia pseudomallei, and established that podoviruses infecting the pathogen are frequently present in soil, and many of them are naturally occurring variants of a common virus type. Experiments on one phage in the related model B. thailandensis demonstrated that temperature defines the outcome of phage-bacteria interactions. At higher temperatures (37°C), the phage predominantly goes through a lytic cycle, but at lower temperatures (25°C), the phage remains temperate. This is the first report of a naturally occurring phage that follows a lytic or temperate lifestyle according to temperature. These observations fundamentally alter the accepted views on the abundance, population biology and virulence of B. pseudomallei. Furthermore, when taken together with previous studies, our findings suggest that the phenomenon of temperature dependency in phages is widespread. Such phages are likely to have a profound effect on bacterial biology, and on our ability to culture and correctly enumerate viable bacteria.

No MeSH data available.


Related in: MedlinePlus