Impact of surface structure and feed gas composition on Bacillus subtilis endospore inactivation during direct plasma treatment

Hertwig, Christian; Steins, Veronika; Reineke, Kai; Rademacher, Antje; Klocke, Michael; Rauh, Cornelia; Schlüter, Oliver

doi:10.3389/fmicb.2015.00774

Cited by 38 publications

(30 citation statements)

References 34 publications

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“…While on polypropylene granules, 10 min of treatment yielded spore reductions by about 5 log 10 , the maximum spore inactivation on wheat grains was 3 log 10 units after 60 min of treatment (Butscher et al ). Hertwig et al () reported about a significantly lower sporicidal ( B. subtilis ) action of CAP on peppercorns compared to flat glass or spherical glass beads. This was explained by the more complex surface structure of peppercorns which is characterized by cracks, grooves and pits, which might cause shadow effects for the different generated components of the plasma (Hertwig et al ).…”

Section: Discussionmentioning

confidence: 99%

“…The sporicidal action of different CAP systems has been demonstrated with different setups (Boudam et al 2006;Bourke et al 2017;Hertwig et al 2018). It is well accepted that the highest sporicidal effect can be achieved when spores are directly exposed to the plasma discharge (Moisan et al 2014).…”

Section: Discussionmentioning

confidence: 99%

“…et al 2016). Hertwig et al (2015) reported about a significantly lower sporicidal (B. subtilis) action of CAP on peppercorns compared to flat glass or spherical glass beads. This was explained by the more complex surface structure of peppercorns which is characterized by cracks, grooves and pits, which might cause shadow effects for the different generated components of the plasma (Hertwig et al 2015).…”

Section: Impact Of the Surface Topography On The Sporicidal Effect Ofmentioning

confidence: 99%

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Inactivation of bacterial endospores on surfaces by plasma processed air

Krämer

Hasse

Guist

et al. 2020

Journal of Applied Microbiology

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Aims In case of biological hazards and pandemics, personal protective equipment of rescue forces is currently manually decontaminated with harmful disinfectants, primarily peracetic acid. To overcome current drawbacks regarding supply, handling and disposal of chemicals, the use of plasma processed air (PPA) represents a promising alternative for surface decontamination on site. In this study, the sporicidal efficiency of a portable plasma system, designed for field applications, was evaluated. Methods and Results The developed plasma device is based on a dielectric barrier discharge (DBD) and operated with ambient air as process gas. PPA from the plasma nozzle was flushed into a treatment chamber (volume: 300 l) and bacterial endospores (Bacillus subtilis and Bacillus atrophaeus) dried on different surfaces were treated under variable conditions. Reductions in spores by more than 4 log10 were found within 3 min of PPA exposure. However, the presence of endospores in agglomerates or in an organic matrix as well as the complexity of the respective surface microstructure negatively affected the inactivation efficiency. When endospores were embedded in a dried protein matrix, mechanical wiping with swabs during exposure to PPA increased the inactivation effect significantly. Gaseous ozone alone did not provide a sporicidal effect. Significant spore inactivation was only obtained when water vapour was injected into the PPA stream. Conclusion The results show that endospores dried on surfaces can be reduced by several orders of magnitude within few minutes in a treatment chamber which is flushed with PPA from of a DBD plasma nozzle. Significance and Impact of the Study Plasma processed air generated on site by DBD plasma nozzles could be a suitable alternative for the disinfection of various surfaces in closed rooms.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Impact Of the Surface Topography On The Sporicidal Effect Ofmentioning

confidence: 99%

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Inactivation of bacterial endospores on surfaces by plasma processed air

Krämer

Hasse

Guist

et al. 2020

Journal of Applied Microbiology

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“…NTP technology is considered efficient and economically viable as a result of its relatively low operating cost and energy consumption, with actual or potential applications with respect to inactivating microorganisms on foods such as almonds, fresh produce, food processing equipment and food handling environments, as well as in heat‐sensitive packaging materials, pharmaceuticals and medical devices . Because of its efficiency and ease for implementation, non‐thermal atmospheric pressure plasma, with different configurations and discharge gases, has been the focus of recent studies investigating the inactivation of spores …”

Section: Introductionmentioning

confidence: 99%

An investigation of inactivation mechanisms of Bacillus amyloliquefaciens spores in non‐thermal plasma of ambient air

Huang

Doona

et al. 2018

J Sci Food Agric

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Progressive erosion of spore surface by NTP-AA with ensuing or concomitant biochemical damage, which includes the alteration of structural proteins, internal lipids and the loss of dipicolinic acid content from the spore core, represent the main mechanisms of inactivation, and there is evidence that reactive NTP-AA species could penetrate the cortex and reach the core of spores to cause damage. © 2018 Society of Chemical Industry.

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“…are typically reduced 4 to 6 logs by several minutes of treatment by different types of plasma systems (15)(16)(17)(18)(19)(20)(21)(22). The mechanisms of spore killing by plasma are complex (18), as UV photons, charged particles, electric fields, and reactive oxygen species (ROS) (e.g., ozone, atomic oxygen, and hydroxyl radicals if water is present) are all involved in spore killing (16,17).…”

mentioning

confidence: 99%

Use of Raman Spectroscopy and Phase-Contrast Microscopy To Characterize Cold Atmospheric Plasma Inactivation of Individual Bacterial Spores

Wang

Doona

Setlow

et al. 2016

Appl Environ Microbiol

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Raman spectroscopy and phase-contrast microscopy were used to examine calcium dipicolinate (CaDPA) levels and rates of nutrient and nonnutrient germination of multiple individual Bacillus subtilis spores treated with cold atmospheric plasma (CAP). Major results for this work include the following: (i) >5 logs of spores deposited on glass surfaces were inactivated by CAP treatment for 3 min, while deposited spores placed inside an impermeable plastic bag were inactivated only ϳ2 logs in 30 min; (ii) >80% of the spores treated for 1 to 3 min with CAP were nonculturable and retained CaDPA in their core, while >95% of spores treated with CAP for 5 to 10 min lost all CaDPA; (iii) Raman measurements of individual CAP-treated spores without CaDPA showed differences from spores that germinated with L-valine in terms of nucleic acids, lipids, and proteins; and (iv) 1 to 2 min of CAP treatment killed 99% of spores, but these spores still germinated with nutrients or exogenous CaDPA, albeit more slowly and to a lesser extent than untreated spores, while spores CAP treated for >3 min that retained CaDPA did not germinate via nutrients or CaDPA. However, even after 1 to 3 min of CAP treatment, spores germinated normally with dodecylamine. These results suggest that exposure to the present CAP configuration severely damages a spore's inner membrane and key germination proteins, such that the treated spores either lose CaDPA or can neither initiate nor complete germination with nutrients or CaDPA. Analysis of the various CAP components indicated that UV photons contributed minimally to spore inactivation, while charged particles and reactive oxygen species contributed significantly. IMPORTANCEMuch research has shown that cold atmospheric plasma (CAP) is a promising tool for the inactivation of spores in the medical and food industries. However, knowledge about the effects of plasma treatment on spore properties is limited, especially at the single-cell level. In this study, Raman spectroscopy and phase-contrast microscopy were used to analyze CaDPA levels and kinetics of nutrient-and non-nutrient-germinant-induced germination of multiple individual spores of Bacillus subtilis that were treated by a planar CAP device. The roles of different plasma species involved in spore inactivation were also investigated. The knowledge obtained in this study will aid in understanding the mechanism(s) of spore inactivation by CAP and potentially facilitate the development of more effective and efficient plasma sterilization techniques in various applications.A mong low-temperature and nontoxic methods for microorganism inactivation, the application of cold atmospheric plasma (CAP) created by electrical discharge in a gas has attracted significant interest (1-5). CAP is a weakly ionized gas with a roughly zero net electrical charge and usually operates under atmospheric conditions below 40°C, with variations depending on the type of feed gas and the equipment configuration (6). Compared to conventional sterilization methods, such as w...

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Impact of surface structure and feed gas composition on Bacillus subtilis endospore inactivation during direct plasma treatment

Cited by 38 publications

References 34 publications

Inactivation of bacterial endospores on surfaces by plasma processed air

Inactivation of bacterial endospores on surfaces by plasma processed air

An investigation of inactivation mechanisms of Bacillus amyloliquefaciens spores in non‐thermal plasma of ambient air

Use of Raman Spectroscopy and Phase-Contrast Microscopy To Characterize Cold Atmospheric Plasma Inactivation of Individual Bacterial Spores

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