Implementation of ATP Biolumenescence Method in the Study of the Fungal Deterioration of Textile Artefacts

Milica Ljaljević Grbić, Nikola Unković, Miloš Stupar, Jelena Vukojević, *Tatjana Nedeljković University of Belgrade, Faculty of Biology, Institute of Botany and Botanical Garden “Jevremovac”, Takovska 43, 11 000 Belgrade, Serbia E-mail: *Central Institute for Conservation, Terazije 26, 1111 000 Belgrade, Serbia Implementation of ATP Biolumenescence Method in the Study of the Fungal Deterioration of Textile Artefacts Abstract Two silk artefacts from museum collections in Serbia, a silk icon from Petar Lubarda Legacy and a scroll made with traditional japanese techniques were analyzed for fungal presence. Fungi isolated from both the silk artefacts belonged to the genera Aspergillus, Chaetomium, Penicillium and Rhizopus. Actively growing colonies of Aspergillus and Penicillium species had caused chromatic alterations on the silk icon and their metabolic activity was demonstrated by high relative light unit values. In this research, measurement of the total microbial activity using the ATP bioluminescence method was used for the first time on silk artefacts and on textile in general. Scaning electron microscopy analysis of the scroll indicated that hyphae of Chaetomium globosum are capable of the mechanical deterioration of silk, as shown by the presence of cracks and gaps in silk fibres. This appears to be the first report of silk fibre degradation caused by C. globosum. Key words: ATP, biodeterioration, silk fibres, Chaetomium globosum, microfungi, SEM. Abbreviations ATP - adenosine-5’-triphosphate CzA - Czapek-Dox agar MEA - malt extract agar PDA - potato dextrose agar RLU - relative light units n Introduction Nowadays the biodeterioration of textile artefacts in museum collections is a significant problem. Among all natural fibres, of both plant and animal origin, silk is the most resistant to the process of biodeterioration [1]. Silks are fibrous proteins spun into fibres by various insects and spiders [2]. The main producers of commercial silk are lepidopters: domestic silkworm, Bombyx mori L. and other silkworms of the Bombycidae family [3]. Due to its remarkable properties and availability, the silk produced by silkworms has been used in textile manufacture in the Orient for at least 4000 years and in Western countries after its introduction to Europe around the 4th century AD [4]. Many historically important textile artefacts (tapestry, icons, garments, rugs…) are made of raw silk, which is composed of highly crystalline polypeptide fibres, fibroin, linked to one another by a gum-like protein, sericin [1]. Fibroin is composed mostly of amino-acids with short chain alanine, serine and glycine folded into antiparallel β-sheets as repeated motifs [4]. This amino acid composition results in a very stable β-pleated crystal structure, which essentially makes fibroin totally insoluble in aqueous solvents and very resistant to enzymatic hydrolysis [5]. Nowadays commercial silk production usually involves sericin removal by degumming 132 [4]. Although fungi are the most active microorganisms in textile biodeterioration [6], they are not frequently associated with the deterioration of silk fibres. Micromycetes can induce damage if silk contains a high degree of sericin and is stored under warm and humid conditions [7]. As a result of biodeterioration, most silk textiles and artefacts lose their mechanical strength and became more or less brittle [8]. Hence it is very important to detect the presence of living microorganisms and identify causative agents of textile artefact biodeterioration. In this research we applied the modern ATP bioluminiscence method along with traditional culture-based and microscopical analyses to deteriorated silk artefacts. The main goal was the implementation of the ATP bioluminiscence method in the study of biodeteriorated textile artefacts and comparison of results obtained, with identified microfungi documented by traditional methods. n Experimental Description of silk artefacts examined Two silk artefacts under conservation were chosen for this study. Figure 1.a shows a rectangular silk icon (23.5 × 30 cm) embroidered with metal and silk thread on a linen “canvas” lined with silk. In the central medallion a monk (Benedectine order) is depicted reading a prayer. The icon was found in one of the rooms of the house of the eminent Serbian painter Petar Lubarda. The front and back of the object were covered with dust, cobwebs and rubble (remains of a fallen wall and ceilings). The back of the linen support was completely covered with glue, the thick layer of which acted as a consolidant. There was some smaller mechanical damage on the upper part of the icon, probably a result of rodent activity and some small holes from insects. The velvety surface of the silk was worn out and thinned, and on several spots the warp and weft were torn and missing. Chromatic alterations and visible mould growth are marked in Figure 1.a with a circle. Due to major damage it is difficult to determine the age of the icon without further laboratory analysis. Given the iconography of the medieval monk in prayer and age of materials and fibres used, it can be concluded that the object originates from the 19th century. The appearance of the silk scroll examined is given in Figure 1.b. The scroll was a painting made using traditional Japanese techniques in the form of a scroll with a narrow wooden slat on its top and bottom. The dimensions of the scroll were 178 × 46.5 cm. There were 14 representations painted on the central (vertical) silk panel, with two frames of silk of different colours and designs. The object was made with a combination of textiles and paper, joined with glue. Due to moisture, in some parts the adhesion of the glue had been lost (especially on the front of the artefact), which had led to the detachment of the silk from the paper support and formed stains from capillary water rising. There were deformations and traces of folding, probably as a result of inadequate storing. Large discolored areas of brown spots are marked on the scroll with a circle in Figure 1.b. There is no information on the age of the scroll, but it is assumed to originate from the 19th century. Ljaljević Grbić M, Unković N, Stupar M, Vukojević J, NedeljkovićI T. Implementation of ATP Biolumenescence Method in the Study of the Fungal Deterioration of Textile Artefacts. FIBRES & TEXTILES in Eastern Europe 2014; 22, 6(108): 132-136. In situ measurement of the total microbial activity using the ATP bioluminescence method Living cells present on the sampled areas of the deteriorated silk artefacts were collected using a swab device - Lightning MVP (BioControl Systems). Sampling was carried out by dragging and rotating the ATP swab tip whilst applying firm pressure to break through any microbial growth present on the silk surface. Afterwards activation was carried out by dipping the swab into the kit provided, luciferin/luciferase reagent. Upon activation, the swabs were proc (...truncated)