Correction to: Microbiome and nitrate removal processes by microorganisms on the ancient Preah Vihear temple of Cambodia revealed by metagenomics and N-15 isotope analyses

n/

Black Fungi on Stone-Built Heritage: Current Knowledge and Future Outlook

Black fungi are considered as one of the main group of microorganisms responsible for the biodeterioration of stone cultural heritage artifacts. In this paper, we provide a critical analysis and review of more than 30 years of studies on black fungi isolated from stone-built heritage from 1990 to date. More than 109 papers concerning the fungal biodeterioration activity of stone were analysed. The main findings were a check list of the black fungal taxa involved in the biodeterioration of stone-built heritage, with a particular reference to meristematic black fungi, the main biodeterioration pattern attributed to them, and the methods of study including the new molecular advances. A particular focus was to discuss the current approaches to control black fungi from stone-built heritage and future perspectives. Black fungi are notoriously hard to remove or mitigate, so new methods of study and of control are needed, but it is also important to combine classical methods with new approaches to improve current knowledge to implement future conservation strategies

Whole Genome Sequencing and Comparative Genome Analysis of the Halotolerant Deep Sea Black Yeast Hortaea werneckii

Hortaea werneckii, an extreme halotolerant black yeast in the order of Capnodiales, was recently isolated from different stations and depths in the Mediterranean Sea, where it was shown to be the dominant fungal species. In order to explore the genome characteristics of these Mediterranean isolates, we carried out a de-novo sequencing of the genome of one strain isolated at a depth of 3400 m (MC873) and a re-sequencing of one strain taken from a depth of 2500 m (MC848), whose genome was previously sequenced but was highly fragmented. A comparative phylogenomic analysis with other published H. werneckii genomes was also carried out to investigate the evolution of the strains from the deep sea in this environment. A high level of genome completeness was obtained for both genomes, for which genome duplication and an extensive level of heterozygosity (~4.6%) were observed, supporting the recent hypothesis that a genome duplication caused by intraspecific hybridization occurred in most H. werneckii strains. Phylogenetic analyses showed environmental and/or geographical specificity, suggesting a possible evolutionary adaptation of marine H. werneckii strains to the deep sea environment. We release high-quality genome assemblies from marine H. werneckii strains, which provides additional data for further genomics analysis, including niche adaptation, fitness and evolution studies

Surface Active Ionic Liquids Based Coatings as Subaerial Anti-Biofilms for Stone Built Cultural Heritage

New surface active ionic liquids (SAILs), based on cholinium cations and dodecylbenzenesulfonate as anion, have been synthesized and their potential application as antimicrobial colonization agents on cultural heritage (CH)stone materials investigated. The biocidal activity and antifouling capabilities were, preliminarily, evaluated by a screening on pure Gram (+) and Gram (−) bacteria strain cultures, yeasts, hyphomycetes and single-celled algae. Tests on stone materials (marble and tufa) vs. a stabilized community, constituted by a mixture of microbial strains, revealed that some SAILs display both antimicrobial and preventive antibiofilm action against new colonization. Analogous tests have been performed on the cholinium@halide precursors

Description of Kribbella italica sp. nov., isolated from a Roman catacomb

A novel actinobacterium, strain BC637T, was isolated from a biodeteriogenic biofilm sample collected in 2009 in the Saint Callixstus Roman catacomb. The strain was found to belong to the genus Kribbella by analysis of the 16S rRNA gene. Phylogenetic analysis using the 16S rRNA gene and the gyrB, rpoB, relA, recA and atpD concatenated gene sequences showed that strain BC637T was most closely related to the type strains of Kribbella lupini and Kribbella endophytica . DNA–DNA hybridization experiments confirmed that strain BC637T is a genomic species that is distinct from its closest phylogenetic relatives, K. endophytica DSM 23718T (63 % DNA relatedness) and K. lupini LU14T (63 % DNA relatedness). Physiological comparisons showed that strain BC637T is phenotypically distinct from the type strains of K. endophytica and K. lupini . Thus, strain BC637T represents the type strain of a novel species, for which the name Kribella italica sp. nov. is proposed ( = DSM 28967T = NRRL B-59155T)

Development of Eco-Friendly Hydrophobic and Fouling-Release Coatings for Blue-Growth Environmental Applications: Synthesis, Mechanical Characterization and Biological Activity

The need to ensure adequate antifouling protection of the hull in the naval sector led to the development of real painting cycles, which involve the spreading of three layers of polymeric material on the hull surface exposed to the marine environment, specifically defined as primer, tie coat and final topcoat. It is already well known that coatings based on suitable silanes provide an efficient and non-toxic approach for the hydrophobic and antifouling/fouling release treatment of surfaces. In the present work, functional hydrophobic hybrid silica-based coatings (topcoats) were developed by using sol-gel technology and deposited on surfaces with the “doctor blade” method. In particular, those organic silanes, featuring opportune functional groups such as long (either fluorinated) alkyl chains, have a notable influence on surface wettability as showed in this study. Furthermore, the hydrophobic behavior of this functionalized coating was improved by introducing an intermediate commercial tie-coat layer between the primer and the topcoat, in order to decrease the wettability (i.e., decreasing the surface energy with a matching increase in the contact angle, CA) and to therefore make such coatings ideal for the design and development of fouling release paints. The hereby synthesized coatings were characterized by optical microscopy, contact angle analysis and a mechanical pull-off test to measure the adhesive power of the coating against a metal substrate typically used in the nautical sector. Analysis to evaluate the bacterial adhesion and the formation of microbial biofilm were related in laboratory and simulation (microcosm) scales, and assessed by SEM analysis

Silver-Doped TiO2-PDMS Nanocomposite as a Possible Coating for the Preservation of Serena Stone: Searching for Optimal Application Conditions

The main objective of this research is to determine the optimal application conditions of a newly synthesized multifunctional coating containing Ag-doped TiO2 nanoparticles when used as a possible protective agent for sandstone. Firstly, Ag-TiO2 nanoparticles with anatase structure, spherical shape and controllable sizes were prepared using the sol–gel method and characterized. The biocidal activity of Ag-doped TiO2 NPs was studied by comparing its performance to pure TiO2 NPs against two representative Gram-positive and Gram-negative bacterial strains, under both visible irradiation and in the dark; then, the antimicrobial efficiency of two different concentrations of Ag-TiO2 nanoparticles (0.1–1 mol%) was evaluated against two phototrophic strains commonly isolated from deteriorated surfaces. Results showed that the photoactivation and photokilling activity of TiO2 were highly improved by doping with Ag. Next, prepared nanopowders were dispersed in a binder with different powder/PDMS ratios: (0.1, 0.2, 0.5 and 1% w/v TiO2) and then applied in different amounts (2, 3 and 6 g/m2) on Serena stone specimens. Results revealed that the application of 2 g/m2 nanocomposite at powder/binder ratios equal to 1% w/v TiO2 provided a fine hydrophobic character for the stone material with acceptable chromatic variations

Silver-Doped TiO₂-PDMS Nanocomposite as a Possible Coating for the Preservation of Serena Stone: Searching for Optimal Application Conditions

The main objective of this research is to determine the optimal application conditions of a newly synthesized multifunctional coating containing Ag-doped TiO2 nanoparticles when used as a possible protective agent for sandstone. Firstly, Ag-TiO2 nanoparticles with anatase structure, spherical shape and controllable sizes were prepared using the sol–gel method and characterized. The biocidal activity of Ag-doped TiO2 NPs was studied by comparing its performance to pure TiO2 NPs against two representative Gram-positive and Gram-negative bacterial strains, under both visible irradiation and in the dark; then, the antimicrobial efficiency of two different concentrations of Ag-TiO2 nanoparticles (0.1–1 mol%) was evaluated against two phototrophic strains commonly isolated from deteriorated surfaces. Results showed that the photoactivation and photokilling activity of TiO2 were highly improved by doping with Ag. Next, prepared nanopowders were dispersed in a binder with different powder/PDMS ratios: (0.1, 0.2, 0.5 and 1% w/v TiO2) and then applied in different amounts (2, 3 and 6 g/m2) on Serena stone specimens. Results revealed that the application of 2 g/m2 nanocomposite at powder/binder ratios equal to 1% w/v TiO2 provided a fine hydrophobic character for the stone material with acceptable chromatic variations