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A new apparatus to induce lysis of planktonic microbial cells by shock compression, cavitation and spray

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ABSTRACT

Experiments were conducted on an aqueous growth medium containing cultures of Escherichia coli (E. coli) XL1-Blue, to investigate, in a single experiment, the effect of two types of dynamic mechanical loading on cellular integrity. A bespoke shock tube was used to subject separate portions of a planktonic bacterial culture to two different loading sequences: (i) shock compression followed by cavitation, and (ii) shock compression followed by spray. The apparatus allows the generation of an adjustable loading shock wave of magnitude up to 300 MPa in a sterile laboratory environment. Cultures of E. coli were tested with this apparatus and the spread-plate technique was used to measure the survivability after mechanical loading. The loading sequence (ii) gave higher mortality than (i), suggesting that the bacteria are more vulnerable to shear deformation and cavitation than to hydrostatic compression. We present the results of preliminary experiments and suggestions for further experimental work; we discuss the potential applications of this technique to sterilize large volumes of fluid samples.

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Sequence of high-speed photographs recorded with a transparent water shock tube shows evidence of cavitation in the water upon bursting of a thin brass diaphragm. The number shown in each frame indicates the time elapsed from triggering of the high-speed camera. (a) T = 8.380 ms; deformation of the diaphragm begins. (b) T = 8.451 ms; onset of failure, emergence and expansion of a cavitation zone. (c) T = 8.629 ms; ejection of water and collapse of the cavitated region. (d) T = 9.410 ms; further collapse of the cavitation zone.
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RSOS160939F3: Sequence of high-speed photographs recorded with a transparent water shock tube shows evidence of cavitation in the water upon bursting of a thin brass diaphragm. The number shown in each frame indicates the time elapsed from triggering of the high-speed camera. (a) T = 8.380 ms; deformation of the diaphragm begins. (b) T = 8.451 ms; onset of failure, emergence and expansion of a cavitation zone. (c) T = 8.629 ms; ejection of water and collapse of the cavitated region. (d) T = 9.410 ms; further collapse of the cavitation zone.

Mentions: A high-speed camera (Vision Research v. 7.1) was employed to record the response of the fluid subsequent to bursting of the diaphragm (figure 3). Owing to sterility requirements, this test was carried out with filtered water rather than bacterial broth; however, speed of sound and density of water are similar to those of the bacterial broth (see §2.4) and therefore the fluid–structure interaction processes observed in these tests are representative of those active in the case of studies using bacterial broth.


A new apparatus to induce lysis of planktonic microbial cells by shock compression, cavitation and spray
Sequence of high-speed photographs recorded with a transparent water shock tube shows evidence of cavitation in the water upon bursting of a thin brass diaphragm. The number shown in each frame indicates the time elapsed from triggering of the high-speed camera. (a) T = 8.380 ms; deformation of the diaphragm begins. (b) T = 8.451 ms; onset of failure, emergence and expansion of a cavitation zone. (c) T = 8.629 ms; ejection of water and collapse of the cavitated region. (d) T = 9.410 ms; further collapse of the cavitation zone.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383840&req=5

RSOS160939F3: Sequence of high-speed photographs recorded with a transparent water shock tube shows evidence of cavitation in the water upon bursting of a thin brass diaphragm. The number shown in each frame indicates the time elapsed from triggering of the high-speed camera. (a) T = 8.380 ms; deformation of the diaphragm begins. (b) T = 8.451 ms; onset of failure, emergence and expansion of a cavitation zone. (c) T = 8.629 ms; ejection of water and collapse of the cavitated region. (d) T = 9.410 ms; further collapse of the cavitation zone.
Mentions: A high-speed camera (Vision Research v. 7.1) was employed to record the response of the fluid subsequent to bursting of the diaphragm (figure 3). Owing to sterility requirements, this test was carried out with filtered water rather than bacterial broth; however, speed of sound and density of water are similar to those of the bacterial broth (see §2.4) and therefore the fluid–structure interaction processes observed in these tests are representative of those active in the case of studies using bacterial broth.

View Article: PubMed Central - PubMed

ABSTRACT

Experiments were conducted on an aqueous growth medium containing cultures of Escherichia coli (E. coli) XL1-Blue, to investigate, in a single experiment, the effect of two types of dynamic mechanical loading on cellular integrity. A bespoke shock tube was used to subject separate portions of a planktonic bacterial culture to two different loading sequences: (i) shock compression followed by cavitation, and (ii) shock compression followed by spray. The apparatus allows the generation of an adjustable loading shock wave of magnitude up to 300 MPa in a sterile laboratory environment. Cultures of E. coli were tested with this apparatus and the spread-plate technique was used to measure the survivability after mechanical loading. The loading sequence (ii) gave higher mortality than (i), suggesting that the bacteria are more vulnerable to shear deformation and cavitation than to hydrostatic compression. We present the results of preliminary experiments and suggestions for further experimental work; we discuss the potential applications of this technique to sterilize large volumes of fluid samples.

No MeSH data available.


Related in: MedlinePlus