Diversity of Terrestrial Cyanobacteria Colonizing Selected Stone Monuments in Serbia

The presence of biofilms on stone monuments can lead to biodeterioration processes that significantly lower not only the aesthetic value of cultural heritage sites but also cause considerable physical and chemical damage to stone surfaces. In terrestrial environments, cyanobacteria have a significant role in biofilm formation on a variety of natural and artificial stone substrata, including granite, sandstone, limestone, lime mortar, etc. Studies on cyanobacterial diversity and estimation of biodeteriorative activity on stone cultural heritage objects can be very important for conservators and restorers, and cyanobacteria removal from stone monuments is currently a great challenge for conservation science. In that sense, the diversity of terrestrial cyanobacteria was investigated at six localities in Serbia. Samples for cyanobacterial analyses were taken from surface biofilms covering different substrata: granite and lime mortar (The Monument to the Unknown Hero), sandstone (Branko's Bridge, Eiffel's Lock) and carbonate rock (Medieval tombstones from Mramorje and Rastite, Gradac Monastery). A total of 18 cyanobacterial taxa were identified. The highest diversity was found on carbonate rock, followed by sandstone. Cyanobacteria were also recorded on an artificial substratum - lime mortar, while cyanobacteria were not found on granite. All detected cyanobacteria seriously impaired the structural and aesthetic integrity of the studied monuments via mechanical and chemical actions, so their presence must not be overlooked

Guidance on the use of microscopy in the detection of zoosporic parasites of phytoplankton in natural systems and algal biotechnology

The objective of this methodological paper is to outline a microscopy protocol for detecting and observing fungal zoosporic parasites of phytoplankton in natural environments, with potential applications in algal biotechnology to enhance the success and sustainability of algal cultivation endeavors. The fluorescent dual staining with wheat germ agglutinin (WGA) and Calcofluor White (CFW) showcased during the Training School "Identification and detection of zoosporic parasites" in Neuglobsow (Germany) from 16th till 18th of May 2023 and organized and funded by COST Action ParAqua (European Cooperation in Science and Technology) illustrated its ease of implementation and suitability for diverse natural and artificial systems

Antifungal activity of Nepeta rtanjensis essential oil

The chemical composition and antifungal activity of the essential oil of an endemic Serbian plant Nepeta rtanjensis Diklić & Milojević was studied. The essential oil was isolated from cultivated plants. Inhibition of mycelia growth of five micromycetes, two Alternaria species originally isolated from N. rtanjensis, Cladosporium cladosporoides, Trichoderma viride and Bipolaris spicifera, were tested using the agar dilution method. The essential oil of N. rtanjensis, the main component of which was 4aα,7α,7αβ-nepetalactone, showed strong antifungal activity against all the tested micromycetes. The minimum inhibitory concentration of N. rtanjensis essential oil ranged from 0.6 to 1.4 μg mL-1. The fungi most sensitive to the tested oil were Alternaria species, while Trichoderma viride was the most resistant

In vitro biodegradation potential of airborne Aspergilli and Penicillia

The study addresses in vitro degradation potential of airborne Aspergillus and Penicillium/Talarmyces species originating from cultural heritage conservation premises. A series of rapid, cost effective biodegradation assays were performed to assess production of extracellular pigments, acids, and enzymes. Most of the isolates have demonstrated positive growth in at least one of the preformed tests. Strongest overall degradation potential was demonstrated for Penicillium brevicompactum, P. glabrum, and Talaromyces sayulitensis while Aspergillus domesticus, A. penicillioides, A. pseudoglaucus, and A. ruber did not exhibit positive reaction in any of the employed assays. Majority of isolates exhibited proteolytic and cellulolytic activity while carbonate dissolution was observed for only five tested fungi. Highest alteration of pH value in liquid media was documented for T. sayulitensis while A. niger and P. expansum exhibited strongest acid production on CREA. Certain isolates, mostly Penicillium species, displayed production of extracellular pigments. The results imply that many of the tested fungi have significant biodegradation capacity, indicating their potential to inflict structural and esthetic alterations on cultural heritage objects

N-channel polysilicon thin film transistors as gamma-ray detectors

N-type thin film transistors (TFTs) fabricated with fluorinated and hydrogenated polysilicon were exposed to gamma radiation to a cumulative dose up to 1200 Gy(Si). During irradiation, the gate electrode was biased with a positive voltage up to 4.8 V. The effect of irradiation on the electrical characteristics of the devices was monitored after the irradiation steps and in a prolonged period after irradiation. The main monitoring parameter was the threshold voltage which was found to have linear dependence on irradiation dose. This, together with obtained low fading, suggests that thin transistors have potential as radiation dosimeters