Now showing 1 - 3 of 3
  • Publication
    Effects of cold plasma on wheat grain microbiome and antimicrobial efficacy against challenge pathogens and their resistance
    The safety and quality of cereal grain supplies are adversely impacted by microbiological contamination, with novel interventions required to maximise whole grains safety and stability. The microbiological contaminants of wheat grains and the efficacy of Atmospheric Cold Plasma (ACP) for potential to control these risks were investigated. The evaluations were performed using a contained reactor dielectric barrier discharge (DBD) system; samples were treated for 0–20 min using direct and indirect plasma exposure. Amplicon-based metagenomic analysis using bacterial 16S rRNA gene and fungal 18S rRNA gene with internal transcribed spacer (ITS) region was performed to characterize the change in microbial community composition in response to ACP treatment. The antimicrobial efficacy of ACP against a range of bacterial and fungal contaminants of wheat, was assessed to include individual isolates from grains as challenge pathogens. ACP influenced wheat microbiome composition, with a higher microbial diversity as well as abundance found on the untreated control grain samples. Culture and genomic approaches revealed different trends for mycoflora detection and control. A challenge study demonstrated that using direct mode of plasma exposure with 20 min of treatment significantly reduced the concentration of all pathogens. Overall, reduction levels for B. atrophaeus vegetative cells were higher than for all fungal species tested, whereas B. atrophaeus spores were the most resistant to ACP among all microorganisms tested. Of note, repeating sub-lethal plasma treatment did not induce resistance to ACP in either B. atrophaeus or A. flavus spores. ACP process control could be tailored to address diverse microbiological risks for grain stability and safety.
      60Scopus© Citations 13
  • Publication
    Efficacy of Cold Plasma for Direct Deposition of Antibiotics as a Novel Approach for Localized Delivery and Retention of Effect
    Antimicrobial coating of medical devices has emerged as a potentially effective tool to prevent or ameliorate device-related infections. In this study the plasma deposition process for direct deposition of pharmaceutical drugs on to a range of surfaces and the retention of structure function relationship and antimicrobial efficacy against mono-species biofilms were investigated. Two selected sample antibiotics—ampicillin and gentamicin, were deposited onto two types of surfaces—polystyrene microtiter plates and stainless steel coupons. The antimicrobial efficacy of the antibiotic-coated surfaces was tested against challenge populations of both planktonic and sessile Escherichia coli and Pseudomonas aeruginosa, with responses monitored for up to 14 days. The plasma deposition process bonded the antibiotic to the surfaces, with localized retention of antibiotic activity. The antibiotics deposited on the test surfaces retained a good efficacy against planktonic cells, and importantly prevented biofilm formation of attached cells for up to 96 h. The antibiotic rapidly eluted from the surface of antibiotic-coated surfaces to the surrounding medium, with retention of effect in this surrounding milieu for up to 2 weeks. Control experiments established that there was no independent antimicrobial or growth promoting effect of the plasma deposition process, where there was no antibiotic in the helium plasma assisted delivery stream. Apart from the flexibility offered through deposition on material surfaces, there was no additive or destructive effect associated with the helium assisted plasma deposition process on the antibiotic. The plasma assisted process was a viable mean of coating clinically relevant materials and developing innovative functional materials with retention of antibiotic activity, without employing a linker or plasma modified polymer, thus minimizing bio-compatibility issues for medical device materials. This offers potential to prevent or control instrumented or non-permanent device associated infection localized to the surgical or implant site.
      48Scopus© Citations 5
  • Publication
    Assessing the Biological Safety of Atmospheric Cold Plasma Treated Wheat Using Cell and Insect Models
    Atmospheric cold plasma (ACP) is under investigation for an extensive range of biocontrol applications in food biosystems. However, the development of a novel intervention technology requires a thorough evaluation of the potential for negative effects and the implications for the human and animal food chains' safety. The evaluations were performed using a contained, high-voltage, dielectric barrier discharge plasma system. The cytotoxicity of two types of food models-a liquid model (wheat model medium (WMM)) vs. a solid model (wheat grain extract (WGE)) was compared in vitro using the mammalian cell line CHO-K1. The residual toxicity of ACP treatment of grains for food purposes was assessed using the invertebrate model Tribolium castaneum, by feeding the beetles with flour produced from ACP-treated wheat grains. The cytotoxic effects and changes in the chemistry of the ACP-treated samples were more pronounced in samples treated in a liquid form as opposed to actual wheat grains. The feeding trial using T. castaneum demonstrated no negative impacts on the survivability or weight profiles of insects. Investigations into the interactions of plasma-generated species with secondary metabolites in the food matrices are necessary to ensure the safety of plasma for food applications.
      49Scopus© Citations 6