School of Chemistry - Theses

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End date: 2019 × Start date: 2000 × Type: PhD thesis × Subject: biofilm × Subject: cultural heritage, cultural materials ×

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    Controlling the microbial deterioration of cultural materials: Investigations into potential free radical, nitric oxide-based treatments
    KYI, CAROLINE ( 2014)
    The biodeterioration of cultural heritage objects can cause adverse changes to the physical and chemical properties of cultural materials. This can lead to a reduction in the integrity of materials and changes to the aesthetic qualities of objects that can have a negative impact on their long-term preservation and may ultimately result in the loss/damage/alteration of unique objects of cultural significance. The biodeterioration of cultural heritage caused by microorganisms is a consequence of the successful establishment and activities communities of microorganism contained within the protective environment of a biofilm. Treatment methods aimed at reducing biofilm formation and enhancing biofilm dispersal can potentially reduce bacterial activity associated with bio-decay. The free-radical molecule nitric oxide (NO•) has been shown to possess both anti-biofilm properties. The approach to and design of investigations that underpin this thesis aimed to assess the potential and suitability of NO• as an intervention material in the treatment of cultural heritage objects. These investigations into NO• based treatments have examined the effects of NO• on biofilm formation, biofilm dispersal and cell motility in test populations that have included a model microorganism Pseudomonas. aeruginosa PAO1 as well as microorganisms representative of those found in association with cultural materials (CMO). The NO• based treatments studied include the nitric oxide donor (Z)- 1-[N-(2-aminoethyl)-N-(2 ammonioethyl) amino]diazen-1-ium- 1,2- diolate (DETA/NO•) and potassium nitrate (KNO3) as a source of nitrate in the bacterial generation of bioactivated NO•. These investigations demonstrate that treatment effects are concentration dependent; are evident at sub-lethal concentrations and are influenced by the duration of a NO• based treatment. Fluorescence based imaging techniques, using confocal laser scanning microscopy (CLSM), have been used to confirm the presence of bioactivated NO• in cells, as well as the properties of biofilms to which NO• based treatments have been administered. The results indicate that NO• based treatments have a dose dependant, non-toxic, anti-biofilm effect on the test populations studied.