Horsfall, Louise

Wallace, Stephen

Ahmed, Dina

2024-05-06T12:17:13Z

2024-05-06T12:17:13Z

2024-05-06

The growing interest in nanoparticles as potent anti-microbial agents, particularly in industries like the marine sector, holds significant importance. Bio-fouling and corrosion prevention and control remain a big challenge to the marine environment from an environmental and economic point of view. The global cost associated with corrosion is £1.8 trillion annually. Effective biocidal anti-fouling agents are strictly regulated, and their use can be withdrawn if the environmental impacts are severe. Traditional chemical and physical synthesis methods, entailing high energy consumption and the use of toxic reagents, pose significant drawbacks. In contrast, harnessing biological approaches for nanoparticle (NP) synthesis holds the potential to circumvent these issues. Nonetheless, the intricacies of the biological synthesis mechanism remain a subject of ongoing investigation. A comprehensive understanding of this synthesis process offers a pathway to upscaling bio-based production methods while presenting opportunities for addressing the pressing challenges in corrosion control and environmental sustainability in the marine sector. This project aims to synthesise metallic nanoparticles for use in anti-corrosion and anti-fouling agents. Nanoparticles (NP) have a strong anti-microbial activity that holds promise as an effective tool for combating bio-fouling. Bacteria are one route to a more green synthesis of NP in contrast to current chemical methods. By harnessing genetic engineering techniques, bacteria can be modified to express genes encoding proteins responsible for producing metallic NP and resistance to metal ions used in the production methods. This study used Morganella psychrotolerans as a host organism to enhance the biological synthesis of Ag and CuNP and tailor their properties. This was accomplished by genetically modifying Morganella psychrotolerans strain to express selected proteins, that overexpression of these genes with the inducible promoter led to significantly higher rates of AgNP synthesis, resulting in smaller-sized NP with diverse shapes than the control group. To look at the application of these nanoparticles in an environmental context, Mussels were used as a bioindicator species to assess the toxicity of various xenobiotics; additionally, Desulfovibrio alaskensis, which is associated with bio-fouling and corrosion in marine structures, was also targetted. The study aimed to compare the toxicity profiles of these biogenic nanoparticles to a reference nanoparticle sample, NM300 AgNP. Results showed that NM300 exhibited a higher toxicity level than the biogenic NP, indicating the biogenic nanoparticles synthesised in this study hold significant potential as anti-fouling agents that could be employed in various applications, such as marine coating including the transporter adenosine triphosphatase (P-Type ATPase), SilE, and glutathione reductase. The study compared the yields of AgNP under constitutive protein expression with those under an inducible promoter. The results demonstrate

https://hdl.handle.net/1842/41743

http://dx.doi.org/10.7488/era/4466

en

The University of Edinburgh

nanoparticles

Morganella psychrotolerans

bio-fouling

nanoparticle production

corrosion

AgNP synthesis

Biosynthesis of metallic nanoparticles for use in anti-corrosion and anti-fouling agents

The biosynthesis of metallic nanoparticles for use in anti-corrosion and anti-fouling agents

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy