Katarzyna Pietrzak

Influence of silver nanoparticles on metabolism and toxicity of moulds.

The unique antimicrobial features of silver nanoparticles (AgNPs) are commonly applied in innumerable products. The lack of published studies on the mechanisms of AgNPs action on fungi resulted in identification of the aim of this study, which was: the determination of the influence of AgNPs on the mould cytotoxicity for swine kidney cells (MTT test) and the production of selected mycotoxins, organic acids, extracellular enzymes by moulds. The conducted study had shown that silver nanoparticles can change the metabolism and toxicity of moulds. AgNPs decrease the mycotoxin production of Aspergillus sp. (81-96%) and reduce mould cytotoxicity (50-75%). AgNPs influence the organic acid production of A. niger and P. chrysogenum by decreasing their concentration (especially of the oxalic and citric acid). Also, a change in the extracellular enzyme profile of A. niger and P. chrysogenum was observed, however, the total enzymatic activity was increased.

Antimicrobial properties of silver nanoparticles misting on cotton fabrics

The purpose of this research was to investigate whether silver nanoparticles (AgNPs) misting could be an effective disinfection and protection method for cotton fabric. The study showed that the disinfection resulted in the reduction of microorganism number by 32–100%, depending on the strain. Fabric humidity of not less than 84% ensures high effectiveness of the process. It was proved that vegetative cells are more susceptible to nanoparticles than spores. The antimicrobial protection of cotton fabric results in the 33–93% reduction of microorganism number. The application of AgNPs does not influence significantly the optical and mechanical parameters of cotton fabric, even after accelerated light ageing. The AgNPs misting is safe for personnel. The AgNPs misting can be considered as an alternative for currently used disinfection methods of ancient textiles.

Silver nanoparticles: a mechanism of action on moulds

Silver nanoparticles (AgNPs) are widely used in all branches of industry. However, their mechanisms of action towards moulds have not been studied yet. Thus we conducted this study in which we have used laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF-MS) analysis to determine metabolomic changes, and microscopic analysis (transmission electron microscopy, fluorescent microscopy) to observe changes in mould cells. The AgNP treatment caused the downregulation of 162 (15 ppm) and 284 (62 ppm), and 19 (15 ppm) and 29 (62 ppm) metabolites of Aspergillus niger and Penicillium chrysogenum, respectively. All influenced features were below m/z 600 (mass-to-charge ratio). We have observed silver ions and their clusters (Ag, Ag2, and Ag3) accumulated in the mould mycelium. As well as, mono-silver ion adducts with nucleotide derivatives (Coenzyme A), amino acids (phenylglycine), peptides (LeuSerAlaLeuGlu) and lipids (fatty acids, diacylglycerophosphoglycerols, monoglicerides and glycerophospholipids). The ultrastructure analysis revealed many sever alterations due to the action of AgNPs, such us shortening and condensation of hyphae, ultrastructural reorganisation, cell plasmolysis, increased vacuolisation, numerous membranous structures, collapsed cytoplasm, accumulation of lipid material, condensed mitochondria, disintegration of organelles, nuclear deformation, condensation and fragmentation of chromatin, creation of apoptotic bodies, as well as a new inside cell wall in P. chrysogenum.

Historical textiles – a review of microbial deterioration analysis and disinfection methods

All historical textile materials, due to their chemical composition (cellulose, protein), under conditions of high humidity are potentially exposed to microbial degradation. Numerous examples of microbial deterioration of archaeological textile materials demonstrate the need for the use of modern analytical methods for examination of diversity of organisms inhabiting them, as well as an analysis of their behavior. It is recommended that objects with a high degree of microbiological contamination are disinfected before being incorporated to a collection. Today, due to the progress in research on the effects of disinfection on historical material, risks to health and the environment, new methods of disinfection are still being developed. The presented literature review describes the testing methods of microbial deterioration of historical textile materials, including the latest methods for assessing biodiversity (called Next Generation Sequencing) and properties of historical textiles (chemical, microscopic, mechanical). It is particularly suitable for conservators and scientists who are interested in biodeterioration, disinfection technology, and maintenance problems of this type. Characteristics of test methods and disinfection include their application to historical objects, description, advantages, and disadvantages, as well as directions for future studies that aim to even better protect cultural heritage using the latest scientific and technical innovations.

Antimicrobial properties of silver nanoparticles against biofilm formation by Pseudomonas aeruginosa on archaeological textiles

The aims of this work were to: (i) microscopically analyse the pre- and post-Columbian archaeological textiles using Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDX); (ii) microbiologically analyse the archaeological textiles (from the Southern Andean Area, La Plata Museum); (iii) determine the ability of Pseudomonas sp. isolates from archaeological textiles to biofilm formation by SEM; (iv) assess the anti-biofilm properties of AgNPs protecting cotton against Pseudomonas sp. Results showed the presence of bacteria with proteolytic and lipolytic activities on archaeological textiles, including Clostridium sp. and Pseudomonas aeruginosa. Two nucleotide sequences of 16S ribosomal RNA gene of P. aeruginosa strains were deposited in GeneBank NCBI database with accession numbers: KP842564 (strain 1) and KP842565 (strain 2). Those strains exhibited different morphological and growth characteristics: strain 1 with ability to form biofilms on archaeological textiles was rod-shaped, produced bluish-green pigment, and smaller than strain 2; and strain 2 was pleomorphic and produced brown pigment. The use of silver nanoparticles (90 ppm, φ 10–80 nm) allowed to protecting textiles against P. aeruginosa growth by 63%–97%, depending on the strain and exposition time.

Influence of the silver nanoparticles on microbial community in different environments.

The aim of this study was to assess the influence of silver nanoparticles (AgNPs) on the number and diversity of microbial community in different environments (soil extract, water, sewage), and to determine whether the environment inhibits or accelerates the influence of AgNPs on moulds. AgNPs (45 ppm) present in the environment decreased bacterial (91%) and fungal (33-85%) numbers, and eliminated some strains, e.g., Alternaria alternata and Cryptococcus laurentii. Based on the biomass growth of Aspergillus niger and Penicillium chrysogenum in a medium with AgNPs and the environmental samples, it was noticed that environment can enhance (soil extract) or inhibit (sewage) antifungal activity of AgNPs.