Biodeterioration of Mayan buildings at uxmal and tulum,Mexico

Uxmal and Tulum are two important Mayan sites in the Yucatan peninsula. The buildings are mainly composed of limestone and grey/black discoloration is seen on exposed walls and copious greenish biofilms on inner walls. The principal microorganisms detected on interior walls at both Uxmal and Tulum were cyanobacteria; heterotrophic bacteria and filamentous fungi were also present. A dark‐pigmented mitosporic fungus and Bacillus cereus, both isolated from Uxmal, were shown to be acidogenic in laboratory cultures. Cyanobacteria belonging to rock‐degrading genera Synechocystis and Gloeocapsa were identified at both sites. Surface analysis previously showed that calcium ions were present in the biofilms on buildings at Uxmal and Tulum, suggesting the deposition of biosolubilized stone. Apart from their potential to degrade the substrate, the coccoid cyanobacteria supply organic nutrients for bacteria and fungi, which can produce organic acids, further increasing stone degradation.     

Diversity of phototrophic components in biofilms from Piperno historical stoneworks

We investigated phototrophic microorganisms dwelling on stone walls made of Piperno, a volcanic rock frequently used as construction material in historical buildings in Naples, Italy. Biofilms from three historical buildings in the center of the city and from a natural Piperno quarry located in a suburban area were examined. Light and electron microscopy, and molecular biology techniques allowed the identification of 17 species belonging to Cyanobacteria, Rhodophyta, Bacillariophyta, and Chlorophyta. Cyanobacteria were the dominant components in all the biofilms. No significant differences in microbial composition were observed for biofilms collected in autumn and spring, with minor exceptions for the quarry samples, where environmental conditions were relatively more stable than in the city. Results are discussed in comparison with information on microbial communities dwelling on other kinds of substrata commonly used in historical buildings in the Neapolitan area.     

Analysis of Salt-Containing Biofilms on Limestone Buildings of the Mayan Culture at Edzna,Mexico

Biofilms on the salted ceiling of a limestone tunnel at the Mayan site of Edzna, Mexico, were characterised using SEM, EDS, chemical analysis, light microscopy, culture and pigment analysis. Major superficial biomass was pigmented, scytonemin-rich Subsection II cyanobacteria. Main endolithic phototrophs were Subsection I and II cyanobacteria and the alga Nanochlorum. Bacteria and actinomycetes of the Geodermatophilus, nocardioform, and streptomycete groups were present at all levels. Salt crystals, mainly sulfates, were found throughout the stone. Microbial ion transport, metabolite production, chelation, and water retention caused degradation and salt deposits. Exfoliation is the major erosion process.     

Characterization of cyanobacteria isolated from biofilms on stone monuments at Santiniketan,India

Cyanobacterial biofilms occurring on the exterior of three stone monuments at Santiniketan, India were analyzed. Species of Scytonema and Tolypothrix were the major components of these biofilms. Identification was obtained by morphometric procedures and 16S rRNA gene sequencing. Biofilms cultured for prolonged periods revealed the presence of several other cyanobacteria belonging to 14 different genera. Cyanobacteria on stone in the tropical environment of India formed a distinct cluster that was quite different from that of cyanobacteria reported for a similar substratum in temperate regions. Absorption spectra of the organisms from Santiniketan showed a high quantity of scytonemin, mycosporine-like amino acids, and carotenoids. All of the organisms survived in a desiccated state and rapidly revived after wetting. The organisms were heterocystous and nitrogenase activity was reactivated within 24?h of wetting by which time heterocysts in their filaments had also appeared.     

Biodeterioration of Mayan archaeological sites in the Yucatan Peninsula, Mexico

Many of the monuments of the Mayan civilization are suffering deterioration caused by environmental factors (high temperatures and relative humidities), increasing contamination from natural and anthropogenic sources, and by the action of micro- and macro-biological communities. Archaeological sites and historical monuments in the Mayan area were constructed with different limestones which offer different resistances to degradation by the various types of contamination. Two different sampling sites were chosen at the archaeological site of Uxmal in the Yucatan Peninsula, Mexico. Heterotrophic bacteria, cyanobacteria and different fungi were isolated and classified taxonomically. The other archaeological site chosen for this study was the fortress of Tulum, located at the side of the Caribbean Sea and exposed to chloride of marine spray and sand erosion. In this case, heterotrophic aerobic and anaerobic bacteria, cyanobacteria and fungi were isolated from the four sampling areas selected. In both archaeological sites crust deposits were observed by using light microscopy, SEM and ESEM. Surface analyses were made by means of EDAX and electron microprobe. Possible mechanisms of stone decay, based on the type of microorganisms isolated, the physico-chemical characteristics of the constructional materials and environmental factors are discussed.     

Wild Meat Use and Traditional Hunting Practices in a Rural Mayan Community of the Yucatan Peninsula,Mexico

Overexploitation of Neotropical ecosystems for wild meat constitutes a threat to biodiversity and might seriously affect local people who depend on wild animals as a primary food resource. To assess this problem at the local level, social use of wild animals was evaluated in a Mayan community of the Yucatan Peninsula. Over 8 months, peasant-hunters carried out a total of 175 hunting trips, gathering 253 animals of 12 species (mammals, birds and reptiles). Most preys (95%) were taken in 4 months (January–April) during the dry season and the main target species were white-tailed deer and iguana (jointly representing 59% of preys). During an 11-week period, total per capita wild meat consumption (182 kg; n = 14 families) was three times greater in nuclear than in extended families. The observed wild fauna use is a reflection of traditional knowledge and represents an important subsistence strategy for the local people.     

The ATP-bioluminescence method for a rapid evaluation of the microbial activity in the stone materials of monuments

The examination of the state of conservation of works of art in stone includes the assessment of the presence of microbiological agents on the surface of the decayed monuments. These microorganisms can accelerate, via their metabolic activity, the decay process of the stone surface. At present this assessment is made with the traditional techniques for the microbiological examination of the soil, provides results only after a delay of 30 days. A bioluminescent ATP assay should provide rapid quantitation of actively growing organisms on the surface of a stone monument, and the applicability of this technique was verified on some samples of sandstone (Pietraforte) collected from a historic building (the Strozzi Palace) in Florence. These samples were evaluated for the amount of the ATP and the total number of microorganisms. The results obtained suggest that the bioluminescent assay could be suitable for detecting and quantitating the presence of microorganisms in a sample of stone.     

Phosphate regime structures species composition in cultured phototrophic biofilms

1. The effect of phosphate on species composition in biofilms was studied under three different phosphate regimes (0.5, 5 and 50 μm ) in two different multi species communities: one composed of the four diatom species Melosira varians, Nitzschia perminuta, Navicula trivialis and Achnanthes lanceolata and one containing these diatom species plus the two cyanobacterial species Leptolyngbya foveolarum and Cylindrospermum stagnale. 2. Algal growth in monocultures and mixtures was measured as chlorophyll a and PAM fluorimetry was applied to document density and physiological condition of the two main groups of photosynthetic organisms in mixed cultures. 3. In phosphate‐replete communities, a single species dominated the community (N. perminuta in the diatom mixture and L. foveolarum in the all species mixture), while in the phosphate‐deprived communities several species persisted, in spite of severe phosphate limitation. 4. We conclude that high supply of phosphate enables the species L. foveolarum, and to a lesser extent N. perminuta, to overgrow biofilm consortia, facilitated by their filamentous growth form, motility or the excretion of inhibitors. The persistence of several species under a low phosphate regime is explained by a less intense interspecific interaction in low‐density biofilms. This clarifies field observations published previously.     

Adhesion to and degradation of marble by a micrococcus strain isolated from it

A Micrococcus strain occurring frequently and isolated multiple times from stones was studied for its ability to adhere to substrates and to produce exopolysaccharides or extracellular polymeric substances, one of the essential prerequisites for biofilm formation. Measurements of the biodeterioration activity of this strain in terms of (i) pH drop, (ii) organic acid production, and (iii) weight loss of marble slabs demonstrated the highly aggressive biodeteriorating potential of the strain in question.     

Importance of subaerial biofilms and airborne microflora in the deterioration of stonework: a molecular study

The study characterized the sessile microbial communities on mortar and stone in Milan University's Richini's Courtyard and investigated the relationship between airborne and surface-associated microbial communities. Active colonization was found in three locations: green and black patinas were present on mortar and black spots on stone. Confocal laser scanning microscopy, scanning electron microscopy and culture-independent molecular methods revealed that the biofilm causing deterioration was dominated by green algae and black fungi. The mortar used for restoration contained acrylic and siloxane resins that could be used by microorganisms as carbon and energy sources thereby causing proliferation of the biofilm. Epifluorescence microscopy and culture-based methods highlighted a variety of airborne microflora. Bacterial and fungal counts were quantitatively similar to those reported in other investigations of urban areas, the exception being fungi during summer (1–2 orders of magnitude higher). For the first time in the cultural heritage field, culture-independent molecular methods were used to resolve the structure of airborne communities near discoloured surfaces, and to investigate the relationship between such communities and surface-associated biofilms.     

Chlorophyll f distribution and dynamics in cyanobacterial beachrock biofilms

Chlorophyll (Chl) f, the most far‐red (720–740 nm) absorbing Chl species, was discovered in cyanobacterial isolates from stromatolites and subsequently in other habitats as well. However, the spatial distribution and temporal dynamics of Chl f in a natural habitat have so far not been documented. Here, we report the presence of Chl f in cyanobacterial beachrock biofilms. Hyperspectral imaging on cross‐sections of beachrock from Heron Island (Great Barrier Reef, Australia), showed a strong and widely distributed signature of Chl f absorption in an endolithic layer below the dense cyanobacterial surface biofilm that could be localized to aggregates of Chroococcidiopsis‐like unicellular cyanobacteria packed within a thick common sheath. High‐pressure liquid chromatography‐based pigment analyses showed in situ ratios of Chl f to Chl a of 5% in brown‐pigmented zones of the beachrock, with lower ratios of ~0.5% in the black‐ and pink‐pigmented biofilm zones. Enrichment experiments with black beachrock biofilm showed stimulated synthesis of Chl f and Chl d when grown under near‐infrared radiation (NIR; 740 nm), with a Chl f to Chl a ratio increasing 4‐fold to 2%, whereas the Chl d to Chl a ratio went from 0% to 0.8%. Enrichments grown under white light (400–700 nm) produced no detectable amounts of either Chl d or Chl f. Beachrock cyanobacteria thus exhibited characteristics of far‐red light photoacclimation, enabling Chl f ‐containing cyanobacteria to thrive in optical niches deprived of visible light when sufficient NIR is prevalent.     

Heterogeneity of biofilms in rotating annular reactors: Occurrence, structure, and consequences

A rotating annular reactor (Roto Torque) was used for qualitative and quantitative studied on biofilm heterogeneity. In contrast to the classic image of biofilms as smooth, homogeneous layers of biomass on a substratum, studies using various pure and mixed cultures consistently revealed more-dimensional structures that resembled dunes and ridges, among others. These heterogeneities were categorized and their underlying causes analyzed. Contrary to expectations, motility of the microorganisms not a decisive factor in determining biofilm homogeneity. Small Variations in substratum geometry homogeneity. Small variations in substratum geometry and flow patterns were clearly reflected in the biofilm pattern. Nonhomogeneous flow and shear patterns in the reactor, together with inadequate mixing resulted in significant, position-dependent differences in surface growth. It was therefore not possible to take representative samples of the attached biomass. Like many other types of reactors, the Roto Torque reactor is valuable for qualitative and morphological biofilm experiments but less suitable for quantitative physiological and kinetics studies using attached microorganisms. (c) 1994 John Wiley & Sons, Inc.     

Biodeterioration of ornamental marble statues in the Boboli Gardens (Florence, Italy)

The colonisation of ornamental marble statues in theBoboli Gardens of Florence (Italy) by photosyntheticmicro-organisms was investigated. The greenmicroalga Coccomyxa was the first colonizer ofnewly restored marble surfaces, appearing one yearafter the periodic cleaning and restoration of thestatues. Two years after restoration this alga gaverise to very thin green biofilms, with densitiesreaching about 3 × 10² cells cm^-2. Later,the biofilms were enriched by cyanobacterial forms,which became dominant. In about six years, aphotosynthetic microbial community, amounting to about3 × 10⁴ cells cm^-2, and structurally similarto that occurring on the unrestored statues wasdeveloped. This epilithic community showed amarked biodiversity; the main representative formsincluded Chroococcidiopsis, Leptolyngbya,Pleurocapsa, Coccomyxa and Apatococcus.Coccomyxa initiated the colonisation of themarble surfaces, favoured in this process by itsfacultative oligotrophic capacity and high cellsurface hydrophobicity, combined with tolerance ofhigh light intensity. The other investigated isolatedstrains did not show this set of features. Thesecretion of polysaccharidic substances and cellsurface hydrophobicity enhancing the capacity toadhere, favoured permanent colonisation of thecyanobacterial population. Indeed, the majority of thecyanobacterial strains (90%), were shown to besurrounded by exopolysaccharidic envelops, whichcontributed to the formation of stable microbialbiofilms, and possessed variable cell surfacehydrophobicity.     

甘肃小陇山麻沿林区土壤纤毛虫群落特征

2006年7月和2007年11月,用活体观察和固定染色方法对小陇山麻沿林区土壤纤毛虫群落特征进行了研究.研究中共鉴定到土壤纤毛虫91种,其中包括8个未定名种.林区土壤纤毛虫群落结构复杂,计有3纲11目28科42属91种,下毛目为优势类群,肾形目和前口目为次优势类群,侧口目、缘毛目和寡毛目为偶见类群,膨胀肾形虫(Colpoda inflata)、长篮环虫(Cyrtolophosis elongata)、大口薄咽虫(Leptopharynx eurystoma)和长圆膜袋虫(Cyclidium oblongum)为优势种.林区各样点之间的土壤纤毛虫群落相似性为极不相似到中等不相似.结果表明,小陇山麻沿林区土壤纤毛虫群落物种丰富,特有和稀有物种繁多;林区各样点之间的小生境不同,土壤纤毛虫群落结构出现较大的差异.从林区生态环境的复杂性和独特性方面讨论了保护区土壤纤毛虫群落的特点.     

Characteristics and role of the exocellular polysaccharides produced by five cyanobacteria isolated from phototrophic biofilms growing on stone monuments

Three coccoid and two filamentous cyanobacterial strains were isolated from phototrophic biofilms exposed to intense solar radiation on lithic surfaces of the Parasurameswar Temple and Khandagiri caves, located in Orissa State, India. Based on to their morphological features, the three coccoid strains were assigned to the genera Gloeocapsosis and Gloeocapsa, while the two filamentous strains were assigned to the genera Leptolyngbya and Plectonema. Eleven to 12 neutral and acidic sugars were detected in the slime secreted by the five strains. The secretions showed a high affinity for bivalent metal cations, suggesting their ability to actively contribute to weakening the mineral substrata. The secretion of protective pigments in the polysaccharide layers, namely mycosporine amino acid-like substances (MAAs) and scytonemins, under exposure to UV radiation showed how the acclimation response contributes to the persistence of cyanobacteria on exposed lithoid surfaces in tropical areas.     

Effect of photosynthesis on pH variation in cyanobacterial biofilms from Roman catacombs

Cyanobacterial biofilms present on stone surfaces inRoman hypogea were studied with the aim of assessingtheir deteriogenic activity on the colonisedsubstrata. In order to achieve this, non-destructivemethods were developed and applied to measure pHvariation induced via photosynthesis and respirationin representative cyanobacteria from Roman catacombs.Amperometric and potentiometric microsensors were alsoused on Scytonema biofilms in culture in orderto measure photosynthesis and assess pH decreases andincreases during dark–light periods. Measurementsof pH showed that, starting with values slightly belowneutral, the pH in Scytonema biofilms increasedby 0.24–0.77 units in the transition from dark to1000 mol photon m^-2 s^-1 irradiance.Comparison of photosynthesis and pH curves recordedsimultaneously on the same artificial biofilm showeda maximum increase in pH value at irradiances higherthan those saturating photosynthesis. Alkalinisationof the substrate during illumination occurred to asufficient extent to induce precipitation of mineralcompounds, especially on calcareous substrates such asthose present in Roman hypogea.     

Ethnomedical Syndromes and Treatment-Seeking Behavior among Mayan Refugees in Chiapas,Mexico

This survey investigated the prevalence of ethnomedical syndromes and examined treatments and treatment-seeking in Mayan Guatemalans living in United Nations High Commissioner for Refugee (UNHCR) camps in Chiapas, Mexico. Methods included a rapid ethnographic assessment to refine survey methods and inform the cross-sectional survey, which also examined mental health outcomes; 183 households were approached for interview, representing an estimated 1,546 residents in five refugee camps and 93% of all households. One adult per household (N = 170) was interviewed regarding his or her health; an additional 9 adults in three surveyed households participated and were included in this analysis; of the 179 participants, 95 primary child-care providers also answered a children’s health questionnaire for their children. Results indicated that ethnomedical syndromes were common in this sample, with 59% of adults and 48.4% of children having experienced susto (fright condition) and 34.1% of adults reporting ataques de nervios (nervous attacks); both conditions were significantly associated with symptoms consistent with posttraumatic stress disorder, anxiety and depression and are mental health conditions recognized by the American Psychiatric Association. Combining healthcare provider and indigenous treatments such as physician prescribed medication (65%), medicinal plants (65.7%), and limpias (spiritual cleansings) (40.6%) was reported. Most participants (86%) sought routine medical treatment from UNHCR trained health promoters in their camp. Assessing ethnomedical health is important for informing mental health programs among this population.     

Survey of the black howler monkey,<Emphasis Type="Italic">Alouatta pigra</Emphasis>, population at the Mayan site of Palenque,Chiapas, Mexico

A survey of the population of the black howler monkey (Alouatta pigra) present at the Mayan site of Palenque was conducted during 2000. A total of 911 man/hours, spread over 112 days were spent surveying the 600 ha area of pristine forest at the site for howler troops. We detected the presence of 136 individuals of which 131 were members of 20 troops, the rest were 3 solitary adult males and 2 adult males travelling as a pair. Ecological density was estimated at 23 individuals/km². Mean troop size was 7.0 individuals and it ranged from 2–12 individuals; 60% of the troops were multimale. All sighting of howler monkeys were in evergreen rain forest and 75% were in trees ≥20 m in height. The reported densities and mean troop size are higher than those reported for the species in Guatemala and in central Quintana Roo, Mexico. The vegetation of the forest contains tree species reported to be used by species ofAlouatta in the Moraceae, Sapotaceae, Leguminosae, and Lauraceae plant families. Protection of a large perimeter area (ca 1700 ha) around the archeological site by the Mexican government ensures the conservation of the forest and of the black howler monkey population present at the site.     

Processes Forming Daily Lamination in a Microbe-Rich Travertine Under Low Flow Condition at the Nagano-yu Hot Spring,Southwestern Japan

A daily rhythm of microbial processes, in terms of sub-mm order lamination, was identified for a microbe-rich aragonite travertine formed at a low-flow site of the Nagano-yu Hot Spring in Southwestern Japan. Continuous observation and sampling clearly showed that the lamination consisted of diurnal microbe-rich layers (M-layers) and nocturnal crystalline layers (C-layers). The M-layers originated from biofilm formed by growth and upward migration of filamentous cyanobacteria related to Microcoleus sp., which can rapidly glide and secrete extracellular polymeric substances (EPS). During the daytime, cyanobacterial biofilm development inhibited aragonite precipitation on the travertine surface due to the calcium-binding ability of EPS. After sunset, aragonite precipitation started on the surface where aerobic heterotrophic bacteria decomposed EPS, which induced precipitation of micritic crystals. This early stage of C-layer formation was followed by abiotic precipitation of fan-shaped aragonite aggregates. Despite their major role in lamina formation, the cyanobacteria were readily degraded within 6–10 days after embedding, and the remaining open spaces in the M-layers were sparsely filled with crystal clots. These lamina-forming processes were different from those observed in a high-flow site where the travertine has a dense texture of aragonite crystals. The microbial travertine at Nagano-yu is similar to some Precambrian stromatolites in terms of in situ mineral precipitation, regular sub-mm order lamination, and arrangement of filamentous microbes; therefore, the lamination of these stromatolites possibly occur with a daily rhythm. The microbial processes demonstrated in this study may revise the interpretation of ancient stromatolite formation.     

Population of the black howler monkey (Alouatta pigra) in a fragmented landscape in Palenque,Chiapas, Mexico

Little is known about the population characteristics of Alouatta pigra under conditions of forest fragmentation-information that is important to understanding its tolerance to habitat loss. In this work we present data on forest loss and on troop size, age, and sex composition for a population of black howler monkeys existing in the fragmented landscape surrounding the Mayan site of Palenque, Chiapas, Mexico. Two aerial photos (1:70,000) of the study area (261 km(2)) taken in 1984 and 2001 were examined to assess forest loss. Between June and December 2001 and January and March 2002 we surveyed 44 forest fragments for the presence of howler monkeys. Examination of aerial photos showed that 33% of the forest present in 1984 had disappeared by 2001, and detected an increment in the number of forest fragments present in the landscape. We discovered a total of 115 howler monkeys living in 22 of the 44 forest fragments studied, of which 107 were members of 18 troops. The rest were solitary males or small groups of males living in isolated forest fragments. Troop size ranged from two to 15 individuals (mean 5.9+3.0 ind). 31% and 15% of individuals in the troops were juveniles and infants, respectively, suggesting continued reproductive activity. Howler monkey troops in the forest fragments were on average smaller (5.9+/-3.0 ind) than troops in the nearby protected forest of the Mayan site (7.0+/-2.8 ind). The mean density of howlers in the forest fragments was 119+/-82.9 ind/km(2). The establishment of corridors is suggested as a possible conservation scenario for the fragmented howler population investigated, and as a conservation measure to connect this population with the howler population found in the protected forest of the Mayan site.