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La descomposicion de la hojarasca y la liberacion de nutrimentos depende de multiples factores como la identidad y caracteristicas de la hojarasca, las condiciones ambientales y los organismos involucrados, entre ellos la comunidad fungica. El objetivo fue determinar la relacion entre la hojarasca de Piscidia piscipula, Bursera simaruba y Cedrela odorata con la perdida de biomasa y la colonizacion fungica, bajo condiciones de laboratorio a corto plazo. Se establecieron tratamientos monoespeci cos y en las combinaciones posibles de las hojas de las especies arboreas mencionadas. Se aplico humedad a cada tratamiento y se analizo la perdida de biomasa de cada especie de hojarasca, asi como la identidad de las especies de hongos en cada tratamiento. Se diferenciaron 48 morfoespecies de hongos, con mayor numero de morfoespecies exclusivas para Cedrela odorata . La presencia de Cedrela odorata en las mezclas, incremento la riqueza de morfoespecies de hongos para las otras especies de arboles, mientras que la presencia de Bursera simaruba , disminuyo esta variable, posiblemente por su composicion quimica. A pesar del corto tiempo, se encontro perdida de biomasa signi cativa en las mezclas de hojas con Cedrela odorata mientras que en las mezclas con Piscidia piscipula y Bursera simaruba no se encontraron diferencias signi cativas. Tambien se observo que la perdida de biomasa y la riqueza de morfoespecies de hongos fue determinada por la identidad de la hojarasca, mas que por el numero de especies en las mezclas de hojas.

The establishment of microorganisms and particularly fungi on rock surfaces, which is favored by humid tropical climates, may accelerate the degradation of historical monuments and buildings and thereby cause the irreversible loss of rich cultural heritage. Therefore, it is urgent to search for new ways to preserve such buildings. The in vitro antifungal activity of calcium zinc hydroxide dihydrate [CaZn2(OH)6·2H2O] (CZ) synthesized via the sol–gel method has been previously reported for limestone. The present study reports for the first time, the minimum fungicidal concentration (MFC) of CZ obtained via mechanochemical processing, against diverse fungi involved in biodeterioration processes of limestone and dolostone. We found that CZ nanoparticles had a fungicidal effect on all evaluated fungi, at concentrations of 156–1250 μg/mL. The MFC depends on the number of cells in conidia and the presence of melanin in cell walls. For these reasons, Pestalotiopsis maculans and Curvularia lunata, which had more than four cells and melanin pigmentation, both required a greater CZ concentration (1250 μg/mL) for inhibition, compared with species from the genera Penicillium oxalicum and Aspergillus niger, which had one cell and were strongly inhibited. Thus, CZ nanoparticles are promising candidates for application in treatments to restore the cultural heritage.

A series of poly[2-(dimethylamino)ethyl methacrylate]s (PDMAEMAs) of different molar mass were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were subsequently treated with two different alkyl halides (1-iodobutane (BuI) and iodomethane (MeI)) to obtain a library of 21 PDMAEMAs with different degree of quaternization (DQ). This is the first report where the antifungal activity of these polymers is assessed for different fungi relevant in biomineralization and aesthetic biodeterioration of stone surfaces. The antifungal activity was assessed with the minimum inhibitory concentration (MIC), the minimum fungicidal concentration (MFC) and the mycelia growth inhibition in plate for the most promising materials. The obtained results demonstrated that all evaluated polymers possess certain level of antifungal activity against the evaluated fungi (even unquaternized PDMAEMAs). However, polymers of low molar mass (series III) revealed predominantly fungicidal activity at low values of MFC (from 2500 to 9.7 μg mL−1). Unexpectedly, the performed mycelia growth inhibition tests showed that the DQ has a less significant effect on the antifungal properties of the polymers than the polymer molar mass. Hence, the antifungal activity of these polymers may depend to a great extent on the physiological and morphological characteristics of the fungi, wherein the best antifungal activity was observed in III-M2, III-B1 and III-B2. It is worth mentioning that this detailed screening contributes to a better understanding of PDMAEMA-based composites that can be utilized in the development and optimization of low-cost and accessible antimicrobial protective coatings for petrous surfaces in cultural heritage monuments or modern buildings.

Phaseolus lunatus (lima bean) has been a model organism to understand direct and indirect defenses against herbivores. We investigated the identity and diversity of endophytic fungi associated with young, mature and old leaves of lima bean in its natural environment. We recovered 758 isolates that were identified and classified in 142 fungal species from 66 genera, with Curvularia , Fusarium , Phomopsis , Alternaria and Colletotrichum being the most abundant and diverse Ascomycota genera. Our data revealed that species richness and diversity increased with leaf age, this factor being also important for the structure of the endophytic community. The occurrence patterns of fungal species was highly heterogeneous among leaves, and only fourteen species were recovered from all three foliar ages investigated. In vitro dual assays between endophytes and the plant pathogen Colletotrichum lindemuthianum revealed that most endophytes tested can inhibit the growth of this pathogen, suggesting their potential as biocontrol agents.

The process of biodeterioration is one of the main problems affecting historical monuments and buildings. On rock surfaces, different types of microorganisms establish in the most adequate niches and accelerate degradation, leading to the irreversible loss of cultural heritage. Therefore, new ways to preserve cultural heritage must be urgently studied to prevent such damage. In this study, the broad-spectrum antimicrobial activity of calcium zinc hydroxide dehydrate [Ca(Zn(OH)3)2·2H2O] (CZ) and zinc oxide (ZnO) nanoparticles synthesized by the sol–gel method is examined against fungal and bacterial model organisms. The selected microbes were inhibited by both nanoparticles, yet CZ was the most effective, with a bactericidal activity of 1.25 to 5 mg/mL and a fungicidal activity of 0.625 mg/mL. Both nanoparticles caused structural damage to the evaluated fungal cells, resulting in morphological changes and affecting the germination of conidia. For the first time in the literature, the antibacterial activity and the mode of action of CZ are reported. In conclusion, CZ nanoparticles are shown to be potential candidates for the treatment of rock surfaces of built cultural heritage., We are grateful for the financial support of the National Council for Science and Technology (Consejo Nacional de Ciencia y Tecnología [CONACyT]) of the “Fronteras de la Ciencia 138” project. Additional thanks are extended to CONACyT for the doctoral scholarship granted to MSC 282192.

The evaluation of the antifungal activity of Mg(OH)2 and Ca(OH)2 nanoparticles (NPs), synthesized by sol–gel method and their mixtures at different concentrations, is reported. The antifungal activity of the hydroxide NPs was studied using Aspergillus niger and Penicillium oxalicum isolated from stone surfaces. These model organisms were selected due to their ability to grow on outdoor and indoor climates and their significant impact on human health. Moreover, the antifungal activity of Mg(OH)2 and Ca(OH)2 NPs dispersed in positively charged polymeric matrices based on partially quaternized poly(2-(dimethylamino ethyl) methacrylate) (pDMAEMA) was studied. With respect to the morphology, particle size, and textural properties of the NPs, the mixtures of Mg–Ca hydroxides revealed a uniform and smaller particle size, along with a greater surface area, as compared to pristine Ca(OH)2 NPs. However, the Ca(OH)2 and a mixture of Mg(OH)2 and Ca(OH)2 (10:90 weight ratio) NPs, showed an enhanced growth inhibition of A. niger and P. oxalicum, suggesting that the effect of particle size on the antifungal activity would not be a preponderating factor. In addition, improved antifungal properties against A. niger and P. oxalicum were detected in composite coatings based on hydroxide NPs dispersed in quaternized p(DMAEMA-co-METAI). The use of these systems might provide promising composite materials with potential antifungal properties for various applications., This study was financially supported by the National Council for Science and Technology (Consejo Nacional de Ciencia y Tecnología [CONACYT, Mexico]) of the “Fronteras de la Ciencia No. 138” project and by the Community of Madrid under the “Climortec”, BIA2014−53911-R, “Geomaterials 2” Programme (S2013/MIT_2914), and Multimat Challenge (S2013/MIT-2862). A.S.-F. would like to gratefully acknowledge the financial support of Santander Universidades through “Becas Iberoamérica Jóvenes Profesores e Investigadores, España 2015” scholarship program. C.G.-S., R.Y.-M., and U.S.S. thank CONACYT and the Deutscher Akademischer Austauschdienst (DAAD, Germany) for financial support within the framework of the funding program for international mobility PROALMEX 2015 (CONACyT project: 267752 and DAAD project: 57271725). C.G.-S. and U.S.S. also thank the Deutsche Forschungsgemeinschaft (DFG, Germany) for financial support for this research under the scheme of the grant SFB-1278 “PolyTarget” project B02.

Antecedentes y Objetivos: La colonización de los sustratos líticos por comunidades fúngicas está determinada por las propiedades del sustrato (bioreceptividad) y las condiciones climáticas y microclimáticas. Sin embargo, los efectos del tiempo de exposición de la superficie de la roca calcárea al ambiente sobre la composición de las comunidades fúngicas no se ha investigado. En este estudio, analizamos la composición y estructura de las comunidades fúngicas inmersas en biopelículas asociadas a roca calcárea, en paredes de edificaciones modernas construidas a diferentes tiempos en un ambiente subtropical en Campeche, México.Métodos: Se consideró una cronosecuencia de paredes construidas a uno, cinco y 10 años. Sobre cada pared, se rasparon tres superficies de 3 × 3 cm para cada biopelícula. Los hongos se aislaron por la técnica de lavado y filtración de partículas, posteriormente se inocularon en dos medios de cultivo contrastantes (un medio oligotrófico y uno copiotrófico). Los hongos se identificaron de acuerdo a sus características macro y microscópicas.Resultados clave: Encontramos 73 géneros y 202 especies de 844 aislados. Los resultados mostraron que las comunidades fúngicas son diferentes en las tres biopelículas. En la biopelícula de desarrollo intermedio encontramos un alto número de aislados, pero tanto la riqueza como la diversidad fueron bajas. En contraste, en la biopelícula avanzada, los valores de riqueza de especies y diversidad fueron altos, y las especies abundantes fueron Hyphomycete 1, Myrothecium roridum y Pestalotiopsis maculans. Las especies dominantes en la biopelícula intermedia fueron Curvularia lunata, Curvularia pallescens, Fusarium oxysporum y Fusarium redolens, y en la biopelícula joven fueron Cladosporium cladosporioides, Curvularia clavata, Paraconiothyrium sp. y Phoma eupyrena.Conclusiones: Nuestros resultados sugieren que la composición de la comunidad fúngica en cada biopelícula cambia de acuerdo al tiempo de exposición de la roca calcárea al ambiente. Además, como parte de la composición de la comunidad fúngica, encontramos un conjunto de especies poco comunes que podrían ser autóctonas en la roca calcárea.

The antifungal and photocatalytic activity of mixed compounds of double hydroxide (CaZn2(OH)6•2H2O) with portlandite (Ca(OH)2) synthesized via sol-gel were evaluated. The compound was tested by in vitro assay to determine its antifungal activity using the agar diffusion and broth microdilution assays, applied to the fungal models: Aspergillus niger and Penicillium oxalicum. Also, these compounds were characterized by X-ray diffraction, infrared spectroscopy, dispersion light scattering, and its morphological structure was identified by HR-SEM and TEM-SAED which shows agglomerated particles formed by nanoparticle sizes between 100-500 nm, which are correlated whit hydrodynamic radio around 155 nm. Additionally, in the relation of microbiological assays, the outstanding minimum inhibitory concentration of unmixed calcium zincate hydroxide dihydrate (CZ) correspond to 156 μg/mL, however, when is mixed with 10% of Ca(OH)2 diminishes up to 78 μg/mL, indistinctively of the evaluated fungus. Likewise, a photocatalytic degradation test was carried out with methylene blue dye as a model organic pollutant, reaching an efficiency of ∼92%. Our results suggest that low concentrations of Ca(OH)2 improve the antifungal activity of CZ, without altering the solution stability, the photocatalytic and chemical properties of the compounds. Therefore, the compatibility with the limestone of both materials can be proposed as an excellent product to avoid fungal biodeterioration.

Microbial biofilms frequently cause the esthetic and biological deterioration of stone monuments. Chichén Itzá, designated as a UNESCO World Heritage Site and as one of the seven new wonders of the world, is one Maya archeological site affected by biofilms. In the present study, we analyzed the biofilms at three different building complexes of Chichén Itzá: the Lower Temple of the Jaguars, the Temple of the Warriors, and Tzompantli. Samples of biofilms and detached rocks were taken from walls with abundant white-, green-, black-, and orange-colored biofilms. The morphology of rock fragments and dust was analyzed by electron and optical microscopy and was structurally characterized by X-ray diffraction. An HCl treatment (5% v/v) was subsequently applied to eliminate carbonates. The morphological analysis evidenced the presence of cyanobacteria, algae, and lichens. Some algae formed small nodules on orange- or black-colored rocks. Lichens were associated with a distinct mineral content on the inner surface of rocks versus on the outer surface. The presence of calcium oxalates such as weddellite (C2CaO4·2H2O) and whewellite (C2CaO4·H2O) and other minerals, including quartz and feldspars, was confirmed by X-ray diffraction. The lichens collected from the Lower Temple of the Jaguars and Tzompantli were therefore confirmed to disintegrate rock surfaces through biomineralization and the formation of oxalate crystals. At sites with greater solar radiation, a higher quantity of weddellite and a lower quantity of whewellite were observed. In conclusion, the establishment of microorganisms on the stone surfaces of Chichén Itzá causes esthetic damage and also leads to the biomineralization of these rock surfaces.

The degradation of stone cultural heritage represents an irreversible loss of rich cultural heritage, and seeking ways to preserve it is urgent. Among different degradation processes, the loss of stone cohesion and biodeterioration are two of the most common issues that affect stone substrates. To solve this, the introduction of nanotechnology in the cultural heritage preservation field has represented a great revolution. The reason is that a particle size reduction of materials to the nanoscale highly increases their effectiveness as stone treatments. Thereby, different nanomaterials have been developed and applied as consolidating products and protective coatings in stone artworks. Due to the increased compatibility of inorganic nanoparticles (NPs) with a large part of the built and sculptural heritage, this chapter accentuates the use of inorganic NPs for the consolidation and antifungal protection of stone heritage. Special focus is given to the factors that can influence the success of the treatment.

Avocado (Persea americana) and papaya (Carica papaya) are tropical fruits with high international demand. However, these commercially important crops are affected by the fungusColletotrichum gloeosporioides, which causes anthracnose and results in significant economic losses. The antifungal activity of metal oxide nanomaterials (zinc oxide (ZnO), magnesium oxide (MgO), and ZnO:MgO and ZnO:Mg(OH)2composites) prepared under different conditions of synthesis was evaluated against strains ofC. gloeosporioidesobtained from papaya and avocado. All nanoparticles (NPs) at the tested concentrations significantly inhibited the germination of conidia and caused structural damage to the fungal cells. According to the radial growth test, the fungal strain obtained from avocado was more susceptible to the NPs than the strain obtained from papaya. The effect of the tested NPs on the fungal strains confirmed that these NPs could be used as strong antifungal agents againstC.gloeosporioidesto control anthracnose in tropical fruits.

More recently, the biological colonization of stone heritage and consequently its biodeterioration has become the focus of numerous studies. Among all microorganisms, fungi are considered to be one of the most important colonizers and biodegraders on stone materials. This is why the development of new antifungal materials requires immediate action. ZnMgO nanoparticles (NPs) have several exciting applications in different areas, highlighting as an efficient antimicrobial agent for medical application. In this research, the application of Zn-doped MgO (Mg1–xZnxO, x = 0.096) NPs obtained by sol–gel method as antifungal coatings on dolomitic and calcitic stones has been explored as a means to develop effective protective coatings for stone heritage. Moreover, the photocatalytic and antifungal activity of Mg1–xZnxO NPs were comparatively studied with single ZnO and MgO NPs. Thus, compared to the MgO and ZnO nanomaterials, the Mg1–xZnxO NPs exhibited an enhanced photocatalytic activity. After UV irradiation for 60 min, 87% methylene blue was degraded over Zn-doped MgO NPs, whereas only 58% and 38% of MB was degraded over ZnO and MgO NPs, respectively. These nanoparticles also displayed a better antifungal activity than that of single pure MgO or ZnO NPs, inhibiting the growth of fungi Aspergillus niger, Penicillium oxalicum, Paraconiothyrium sp., and Pestalotiopsis maculans, which are especially active in the bioweathering of stone. The improved photocatalytic and antifungal properties detected in the Mg1–xZnxO NPs was attributed to the formation of crystal defects by the incorporation of Zn into MgO. The application of the MgO- and Zn-doped MgO NPs as protective coatings on calcareous stones showed important antifungal properties, inhibiting successfully the epilithic and endolithic colonization of A. niger and P. oxalicum in both lithotypes, and indicating a greater antifungal effectiveness on Zn-doped MgO NPs. The use of Zn-doped MgO NPs may thus represent a highly efficient antifungal protection for calcareous stone heritage., This research has been financially supported under projects FOMIX-Yuc 2008–108160, CONACYT LAB-2009-01-123913, 188345, Fronteras de la Ciencia No. 138, by the Community of Madrid under the Geomaterials 2 Programme (S2013/MIT_2914), Climortec, BIA2014–53911-R and MAT2013-47460-C5-5-P, and the Autonomous Region Program of Madrid, MULTIMAT CHALLENGE (S2013/MIT-2862). A.S.-F. would like to gratefully acknowledge the financial support of Santander Universidades through “Becas Iberoamérica Jóvenes Profesores e Investigadores, España 2015” scholarship program.

The assembly of fungal communities on stone materials is mainly influenced by the differential bioreceptivity of such materials and environmental conditions. However, little is known about the role of fungal interactions in the colonization and establishment of fungal species. We analyzed the effects of intra- and interspecific interactions between 11 species of fungi in oligotrophic and copiotrophic media and on limestone coupons. In a previous study, these species were the most frequently isolated in the epilithic biofilms of limestone walls exposed to a subtropical climate. In the culture media, we found a greater frequency of intra- and interspecific inhibitory effects in the oligotrophic medium than in the copiotrophic medium. On the limestone coupons, all fungi were able to establish; however, the colonization success rate varied significantly. Cladosporium cladosporioides had a less extensive colonization in isolation (control) than in dual interactions (coexistence) with other species. Phoma eupyrena exhibited the highest colonization success rate and competitive dominance among all tested species. X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses revealed that Pestalotiopsis maculans and Paraconiothyrium sp. produced calcium oxalate crystals during their growth on coupon surfaces, both in isolation and in dual interactions. Our results demonstrate that interactions between abundant fungal species influence the fungal colonization on substrates, the biomineralization and the fungal community assemblage growing in limestone biofilms.

The antifungal properties of protective coatings based on Ca[Zn(OH)3]2·2H2O have been evaluated both on glass slides and on three different limestone materials, which have regional significance as the most commonly used building and restoration materials in the region, including for historic Mayan monuments and artifacts. The protective coatings were found to have excellent antifungal properties, inhibiting the growth of Penicillium oxalicum and Aspergillus niger, both in the dark and under illumination. Experiments were carried out at a laboratory test site under simulated photoperiod conditions, consisting of 24-h cycles of 12 h in the dark and 12 h under illumination: 21 days after inoculation and exposure to photoperiod conditions, no fungal growth was observed for any type of limestone, for both fungi. X-ray diffraction illustrated that the formation of calcium oxalate in the weddellite structure is an indicator of the fungal activity. Close inspection of samples with scanning electron microscopy (SEM) revealed that for all limestone substrates without protective coating, fungal growth was observed as well as fungal penetration into the limestone material. SEM images also show that the Ca[Zn(OH)3]2·2H2O coating is well-adhered to all substrates, without the presence of significant cracks in the coating. For the three limestone substrates with the protective coating, no fungal growth was observed, illustrating the excellent antifungal properties of the calcium zinc hydroxide dihydrate material.

Little is known about the dynamics of succession of fungi on limestone exposed in subtropical environments. In this study, the colonization of experimental blocks of compact and porous limestone by a fungal community derived from natural biofilms occurring on Structure X from the archaeological site of Becan (Mexico), was studied using a cultivation-dependent approach after short-term (9 m) exposure in order to provide a preliminary insight of the colonization process under seminatural conditions. Microbial growth seen as the change of colour of stone surfaces to black/dark green was more abundant on the porous limestone. There was a fairly clear difference in microbial colonization between the onset of the experiment and the 6th month for both limestone types, but no significant increase in the colonization of coupons occurred between months 6 and 9. This could be related to the low rainfall expected for this period, corresponding to the dry season. A total of 977 isolates were obtained. From these, 138 sterile fungi were unidentified, 380 could only be assigned to the order Sphaeropsidales; the remaining isolates (459) were grouped into 27 genera and 99 different species. Nearly all detected fungal species belonged to the Ascomycota (90 %). Rare taxa (species represented by one to three isolates) included the recently described genus Elasticomyces, several species of genera Hyalodendron, Monodyctis, Papulospora, Curvularia, and Septoria. Other taxa were Minimedusa and Gliomastix luzulae, which have not been previously described for stone environments. Abundant fungi included several species of the common genera Cladosporium, Alternaria, and Taeniolella typical for a range of habitats. Succession of populations was observed for certain taxa, this shift in the composition of fungal communities was more evident in porous limestone. After 6 m of exposure, species of the genera Scolecobasidium, Hyalodendron, and Taeniolella were predominant, while after 9 m, the predominant species belonged to the genera Curvularia and Alternaria, particularly on porous stone. These results suggest that Curvularia and Alternaria replaced other fungi, due to a higher tolerance towards low levels of available water during the dry season. Higher levels of water within the porous stone, keep longer periods of microbial activity, minimizing the impact of desiccation. This study contributes to understand the diversity of fungal communities in stone surfaces in subtropical settings and the dynamics of colonization on limestone.