Electrical discharges in water induce spores’ DNA damage

Abstract

Bacterial spores are one of the most resilient life forms on earth and are involved in many human diseases, such as infectious diarrhea, fatal paralytic illnesses and respiratory infections. Here, we investigated the mechanisms involved in the death of Bacillus pumilus spores after exposure to electric arcs in water. Cutting-edge microscopies at the nanoscale did not reveal any structural disorganization of spores exposed to electric arcs. This result suggested the absence of physical destruction by a propagating shock wave or an exposure to an electric field. However, Pulsed-Field Gel Electrophoresis (PFGE) revealed genomic DNA damage induced by UV radiation and Reactive Oxygen Species (ROS). UV induced single-strand DNA breaks and thymine dimers while ROS were mainly involved in base excision. Our findings revealed a correlation between DNA damage and the treatment of spores with electrical discharges.

Mechanism of E. coli Inactivation by Direct-in-liquid Electrical Discharge Plasma in Low Conductivity Solutions

“…According to Lamarche et al . 56 , no structural disorganization under transmission electron microscopy (TEM) is observed with spores treated by underwater electric arcs that in practice generate much stronger shockwaves than underwater streamer discharges. Nevertheless, if low power discharges in low conductivity solutions such as those used in this study produce shockwaves of measurable intensity, the influence of shockwaves on electroporation should not be ignored.…”

Low temperature plasmas and electrosprays

“…Recently, great attention has been paid to the investigation of plasma-liquid interactions, especially in atmospheric pressure plasma discharges over water or aqueous solution surfaces, as summarized by the latest large review and roadmap paper (Bruggeman et al 2016). This research is mainly motivated by new emerging applications of plasma discharges in biomedicine: starting from bio-decontamination and sterilization, through various medical therapies in dentistry, dermatology and cancer treatments, to applications in water cleaning, food production and agriculture (Laroussi et Fundamental investigations of electro-and plasma-chemical processes due to electrical discharges used for organic contaminants neutralization, spores destruction or bacteria killing at the air-water or other gas-liquid interfaces have been carried out by many authors (Sun et al 1997, Šunka et al 1999, Andre et al 2001, Mezei et al 2005, Sugama et al 2006, Baerdemaeker et al 2007, Liu et al 2007, 2008, Shmelev 2008, Shmelev et al 2009, Kanazawa et al 2009, Machala et al 2009, Locke and Shih 2011, Pongrac and Machala 2011, Shirai et al 2011a, 2011b, Pyrgiotakis et al 2012, Elsawah et al 2013, Kovalova et al 2013, 2016, Machala et al 2013, Kim et al 2014, Di Natale et al 2018, Hong et al 2018, Lamarche et al 2018. These processes were typically studied in low or medium power glow-corona, spark, streamer or arc discharges discharges.…”