A New Extremotolerant Ecotype of the Fungus Pseudotaeniolina globosa Isolated from Djoser Pyramid, Memphis Necropolis, Egypt

Abstract

Most of the rock-inhabiting fungi are meristematic and melanized microorganisms often associated with monument biodeterioration. In previous microbial profiling of the Egyptian Djoser pyramid, a Pseudotaeniolina globosa isolate was found. The current study aimed to characterize the P. globosa isolated from the Djoser pyramid compared with an Italian isolate at morphological, physiological, and molecular levels. Experiments were carried out to test temperature, salinity, and pH preferences, as well as stress tolerance to UV radiation and high temperature, in addition to a multi-locus genotyping using ITS, nrSSU or 18S, nrLSU or 28S, BT2, and RPB2 markers. Morphological and molecular data confirmed the con-specificity of the two isolates. However, the Egyptian isolate showed a wider range of growth at different environmental conditions being much more tolerant to a wider range of temperature (4–37 °C) and pH values (3.0–9.0 pH) than the Italian (10–30 °C, 4.0–6.0 pH), and more tolerant to extreme salinity levels (5 M NaCl), compared to the lowest in the Italian isolate (0.2 M NaCl). Besides, the Egyptian isolate was more tolerant to high temperature than the Italian isolate since it was able to survive after exposure to up to 85 °C for 5 min, and was not affected for up to 9 h of UV exposure, while the Italian one could not regrow after the same treatments. The Pseudotaeniolina globosa species was attributed to the family Teratosphaeriaceae of the order Capnodiales, class Dothideomycetes. Our results demonstrated that the Egyptian isolate could be considered an ecotype well adapted to harsh and extreme environments. Its potential bio-deteriorating effect on such an important cultural heritage requires special attention to design and conservation plans and solutions to limit its presence and extension in the studied pyramid and surrounding archaeological sites.

Expanding the Microcolonial Black Fungi Aeminiaceae Family: Saxispiralis lemnorum gen. et sp. nov. (Mycosphaerellales), Isolated from Deteriorated Limestone in the Lemos Pantheon, Portugal

“…Among halotolerant fungi, Hortaea werneckii is currently considered the most halotolerant fungus known to date, as it can tolerate a wide range of NaCl concentrations from 0% to 32%, with an optimal growth range of 6% to 14% NaCl [ 17 , 94 ]. Additionally, a recently discovered new ecotype of Pseudotaeniolina globosa [ 85 ] has also demonstrated the ability to grow at up to 30% NaCl, placing Saxispiralis lemnorum alongside these notable “kings” of salinity. The fungus’ capacity to develop in diverse NaCl concentrations assumes particular significance when considering its original isolation from a sample collected in an environment characterized by pronounced salt damage.…”

“…Tolerance to UV, high temperature, and cold stress was assessed following the methodology adapted from Rizk et al [ 85 ] and Trovão et al [ 57 ]. Inoculation was conducted in the same manner as previously described for each tested condition.…”

Culturable and unculturable potential heterotrophic microbiological threats to the oldest pyramids of the Memphis necropolis, Egypt

“…Compared with fungal culture-dependent isolation, seven common genera were observed at both pyramidal sites. The most remarkable isolated fungal species was a black meristematic fungus, Pseudotaeniolina globosa De Leo, Urzì & De Hoog, which was an extremotolerant ecotype adapted to harsh and arid conditions and was attributed to the family Teratosphaeriacea, order Capnodiales ( Rizk et al, 2021 ). Meristematic growth is infrequent in the fungal kingdom and can be interpreted as a specific response to external stress ( Isola et al, 2016 ).…”

Black yeasts in hypersaline conditions

“…It is commonly isolated from exposed surfaces such as desert rocks, outdoor statues, leathery plant foliage and hypersaline coastal ponds. It is highly halo- and thermotolerant and grows optimally at 1.5% NaCl and up to 30% NaCl (w/v) and at a broad range of temperatures from 4 to 37 °C (Ortiz et al 2014 ; Rizk et al 2021 ).…”