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Fungal deterioration of frescoes was studied in situ on a selected Serbian church, and on a laboratory model, utilizing standard and newly implemented microscopy techniques. Scanning electron microscopy (SEM) with energy-dispersive X-ray confirmed the limestone components of the plaster. Pigments used were identified as carbon black, green earth, iron oxide, ocher, and an ocher/cinnabar mixture. In situ microscopy, applied via a portable microscope ShuttlePix P-400R, proved very useful for detection of invisible micro-impairments and hidden, symptomless, microbial growth. SEM and optical microscopy established that observed deterioration symptoms, predominantly discoloration and pulverization of painted layers, were due to bacterial filaments and fungal hyphal penetration, and formation of a wide range of fungal structures (i.e., melanized hyphae, chlamydospores, microcolonial clusters, Cladosporium-like conidia, and Chaetomium perithecia and ascospores). The all year-round monitoring of spontaneous and induced fungal colonization of a "mock painting" in controlled laboratory conditions confirmed the decisive role of humidity level (70.18±6.91% RH) in efficient colonization of painted surfaces, as well as demonstrated increased bioreceptivity of painted surfaces to fungal colonization when plant-based adhesives (ilinocopie, murdent), compared with organic adhesives of animal origin (bone glue, egg white), are used for pigment sizing.

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Significant percent of world cultural heritage artifacts is threatened by fungal infestation. Fungi can deteriorate different substrates via various physical and chemical mechanisms. Hyphal growth and penetration into the substrate can cause symptoms like discoloration, biopitting, cracking, exfoliation and patina formation. On the other hand, chemical mechanisms include acid secretion, release of extracellular enzymes, pigment production, oxidation/reduction reactions and secondary mycogenic minerals formation. These processes can lead to serious, both esthetic and structural, alterations which may be irreversible and could permanently impair artworks. Proper isolation and identification of autochthonous isolates, as well as employment of different microscopic techniques and in vitro biodegradation tests are pivotal in understanding complex biodeterioration mechanisms caused by microorganisms, including fungal deteriogens. Biodeterioration and biodegradation studies require multidisciplinary approach and close collaboration of microbiologists, chemists, geologists and different personnel responsible for the safeguarding of cultural heritage monuments and artifacts, especially restorers and conservators.

Pears are one of the oldest and the third most important fruit species grown in temperate regions. They are consumed because of their nutritional and health benefits, in fresh form or as various processed products. This paper resolves the etiology of the Penicillium-like mold symptoms on pear fruits in Serbia. Samples of pear fruits with blue mold and other Penicillium-like mold symptoms were collected in Serbia from 2016 to 2019, from four storages. The recovered isolates were identified and characterized using polyphasic approach. Morphological and physiological analyses were performed on three media and five temperatures, respectively. Four loci (internal transcribed spacer, beta-tubulin, calmodulin, and DNA-dependent RNA polymerase II second largest subunit) were used for sequencing, genetic identification and phylogenetic analyses. The results of the identification using conventional and molecular methods were in agreement and they revealed that the obtained isolates belong to five species: Penicillium crustosum, P. expansum, P. italicum, Talaromyces minioluteus and T. rugulosus. In a pathogenicity test, P. crustosum, P. expansum, T. minioluteus and T. rugulosus produced decay on artificially inoculated pear fruits, and P. italicum induced tissue-response lesions. The results of this study are the first reports of T. minioluteus and T. rugulosus as postharvest pear pathogens. Also, these are the first world records of T. minioluteus, T. rugulosus and P. italicum on fruits of European pear. Further, this is the first finding of P. crustosum, P. expansum, P. italicum, T. minioluteus and T. rugulosus on pear fruit in Serbia.

The mycobiome of the cave Church of Sts. Peter and Paul, housing the peculiar fresco painting of “The Bald-headed Jesus”, was analyzed via culture-dependent and -independent methods. Salt efflorescence, colored patinas, and biofilm, as well as biopitting, discolorations, and fruiting bodies of wood-decay fungi were observed on surfaces within the church. Microscopic analyses showed an abundance of fungal structures, i.e., conidiophores, conidia, chlamydospores, and ascospores. The estimated values of the contamination classified all surfaces as the “Danger zone”. A total of 24 fungi from 17 genera were determined as part of the culturable mycobiome, with a dominance of Ascomycota of genera Penicillium. Biodegradative profiles analyzed via plate assays demonstrated positive reactions for 16 isolates: most commonly acid production (8), followed by pigment production and ligninolytic activity (6), protein degradation (5), cellulolytic activity (3) and carbonate dissolution (2). Metabarcoding analysis showed a dominance of Ascomycota in all samples (79.9–99.7%), with high relative abundance documented for Hypoxylon fuscopurpureum on the iconostasis and unclassified Mycosphaerellaceae family within order Capnodiales on fresco and stone, as well as moderate relative abundance for unclassified Dothideomycetes, Botryolepraria lesdainii, Verrucaria sp. and Cladosporium sp. on stone walls. The used set of integrative methods pointed out species of genus Neodevriesia and H. fuscopurpureum as the main deteriogenic agents of fresco and iconostasis surfaces, respectively.