Biodeterioration of limestone: role of bacterial biofilms and possible intervention strategies

Skipper, Philip (2018) Biodeterioration of limestone: role of bacterial biofilms and possible intervention strategies. PhD thesis, University of Lincoln.

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Biodeterioration of limestone: role of bacterial biofilms and possible intervention strategies
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Item Type:Thesis (PhD)
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Abstract

Limestone built heritage is at risk from the effects of biofilms, a microbial community
encapsulated in a matrix of sugars, protein and extracellular DNA. Although biofilm research has
been carried out in Mediterranean regions, few studies cover temperate Northern Europe
climates, or the UK. This study concentrates on bacterial colonisation of Lincoln limestone, a
highly vulnerable building material, and identifies the species, their role in biodeterioration and
the efficacy of biocides against them.
As part of this study the core species which comprise the bacterial component of the limestone
microbiome have been characterised for the first time; this has allowed the identification of noncore species which are significantly associated with damaged and undamaged surfaces.
Four mechanisms of biodeterioration have been identified, one previously unidentified, and
isolated species have been characterised as to whether they are biodeteriorative and the
mechanisms of biodeterioration that they employ. Two species, Curtobacterium flaccumfaciens
and Solibacillus silvestris, have been characterised as producing biofilm matrix which actively
causes biomechanical damage to the oolitic limestone structure as opposed to the passive
enhancement of physical weathering which has been previously associated with biofilm matrix.
Species capable of biodeterioration have also been shown to be present on both damaged and
undamaged surfaces, something which has not been previously investigated.
Environmental sampling, species identification and characterisation of species for
biodeterioration have all combined to identify markers of biodeterioration, ie both physical
markers and biomarkers. Specifically, a surface pH of 5.5 or lower and the presence of B.
licheniformis is indicative of biodeterioration with a proportionally higher level of M. luteus when
comparing damaged and undamaged stone.
Finally this study brings the literature on conservation methods up to date by testing biocides
which are in current usage, as many biocides in the literature are discontinued. This study is also
the first in the field to show their efficacy against biofilm encapsulated bacteria and their
propensity for chemically disrupting the biofilm matrix.

Divisions:College of Science > School of Life Sciences
ID Code:37655
Deposited On:04 Oct 2019 14:59

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