Identification of Fungal Community Associated with Deterioration of Optical Observation Instruments of Museums in Northern Vietnam

Abstract

Fungi are the most harmful microorganisms responsible for the deterioration of nonmetallic materials such as glass, polymers, and composites. To date, biological aspects of glass deterioration have been poorly investigated. The present study aimed to evaluate the diversity of the fungal community colonizing eyepieces of binoculars collected from museums of the northern provinces of Vietnam and the biodeterioration effects on accurate glass reproductions. A total of 40 isolates belonging to 14 genera were identified based on internal transcribed spacer (ITS) sequencing, morphological features, and maximum likelihood analysis. The most abundant fungal genera included Aspergillus (43.8%) and Penicillium (31.3%). Among those detected, Byssochlamys, Curvularia, Phomopsis, Coprinellus, Perenniporia, Talaromyces, Pithomyces, Neopestalotiopsis, Trichoderma, Pleospora, and Humicola were found for the first time. Of the 40 strains tested, 8 strains showed great organic acid production, and the extent of mycelium covered from 33.6 to 46.24%. Specifically, the highest extracellular polymeric substance production was observed in Byssochlamys spectabilis BXMA1-2 (14.96 g/L), Aspergillus niger BXMA5-2 (12.17 g/L), and Aspergillus ochraceopetaliformis BMLC1-2 (9.89 g/L). Glass biodeterioration experiments revealed that the light transmission through the fungal-treated glasses was decreased by 30–42.2% as compared to the nontreated glass. In addition, the main alterations resulted from hyphal fingerprints and spots, leading to apparent damage and biocorrosion.

Genome-wide comparison deciphers lifestyle adaptation and glass biodeterioration property of Curvularia eragrostidis C52

“…C. eragrostidis C52 displayed a great expansion of certain gene families potentially involved in lifestyle adaptation and colonization. Given that airborne fungal spores have to germinate and develop into hyphae to colonize on glass surface 6 , C. eragrostidis C52 might successively undergo asexual and sexual stages. The sexual stage remains unknown, while the asexual stage of Curvularia species is reported to be crucial for causing disease to the hosts such as plant and human.…”

“…Organic acids were shown to be secreted by C. eragrostidis C52 at the aspect of phenotypic and genotypic levels. It is believed that fungal colonization on the glass through biofilm formation is linked to EPS production, which subsequently produces various organic acids to dissolve metal oxides such as Na 2 O, K 2 O, CaO, Al 2 O 3 , B 2 O, and ZnO 6 , 32 . Another nutrient source is the lipid layer that comprises long-chain hydrocarbons, fatty acids, and some alkaline metals such as Li, Na, K, Ca, Ba, Al, Zn, and Pb.…”

“…Of note, Curvularia spp. have been recovered from binocular eyepieces and air, indicating the widespread distribution of this genus in the natural environments 6 , 13 . Identification by morphology is not enough to delimit species within the genus, thus DNA barcodes and whole-genome sequencing are needed to allow accurate identification and comparison.…”

“…were the two predominant fungal genera isolated from historical glass windows, Portugal 5 . In our previous study, 40 fungal strains classified into 14 genera were recovered from optical observation instruments of museums in Vietnam where Aspergillus and Penicillium were the most abundant genera 6 . The biodeterioration ability of fungi on glass is identified by a combination of parameters, including organic acids, exopolysaccharides (EPSs), the interaction of carbohydrate-active enzymes, temperature, humidity, and so on.…”

Challenges in laser cleaning of cultural heritage stained glass

“…Exposure to human and environmental factors has subjected these important pieces of human history to damages [3]. The three main types of degradation that have continued to affect these valuable pieces are those of physical, chemical, and organic nature [4,5,6]. These degradation factors have led to glass abrasion, cracking, exfoliation of surface layers, corrosion, unwanted patina or crust formation, etc.…”