Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 37
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Sci Total Environ ; 654: 1379-1388, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30527887

RESUMO

Machu Picchu Inca sanctuary (Cusco Region, Peru) was constructed on a granitic plateau, better known as Vilcabamba batholith. One of the most important carved granitic rocks from this archaeological site is the Sacred Rock, used by Inca citizens for religious rituals. Due to the location and climatic conditions, different rocks from this archaeological site are affected by biocolonizations. Concretely, the Sacred Rock shows flaking and delamination problems. In this work, a non-destructive multi analytical methodology has been applied to determine the possible role of the biodeteriogens, forming the biological patina on the Sacred Rock, in the previously mentioned conservation problems. Before characterizing the biological patina, a mineralogical characterization of the granitic substrate was conducted using X-ray Diffraction, Raman microscopy (RM) and micro energy dispersive X-ray fluorescence spectrometry. For the identification of the main biodeteriogens in the biofilm, Phase Contrast Microscopy was used. RM also allowed to determine the distribution (imaging) and the penetration (depth profiling) of the biogenic pigments present in the biopatina. Thanks to this study, it was possible to asses that some colonizers are growing on inner areas of the rock, reinforcing their possible assistance in the delamination. Moreover, the in-depth distribution of a wide variety of carotenoids in the patinas allowed to approach the penetration ability of the main biodeteriogens and the diffusion of these biogenic pigments to the inner areas of the rocky substrate.


Assuntos
Biofilmes/crescimento & desenvolvimento , Cianobactérias/fisiologia , Líquens/fisiologia , Microalgas/fisiologia , Arqueologia , Cianobactérias/isolamento & purificação , Líquens/isolamento & purificação , Microalgas/isolamento & purificação , Microscopia Óptica não Linear , Peru , Pigmentos Biológicos/classificação , Dióxido de Silício , Espectrometria por Raios X , Análise Espectral Raman , Difração de Raios X
2.
ISME J ; 12(4): 1032-1046, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29445133

RESUMO

Biological soil crusts (biocrusts) cover about 12% of the Earth's land masses, thereby providing ecosystem services and affecting biogeochemical fluxes on a global scale. They comprise photoautotrophic cyanobacteria, algae, lichens and mosses, which grow together with heterotrophic microorganisms, forming a model system to study facilitative interactions and assembly principles in natural communities. Biocrusts can be classified into cyanobacteria-, lichen-, and bryophyte-dominated types, which reflect stages of ecological succession. In this study, we examined whether these categories include a shift in heterotrophic communities and whether this may be linked to altered physiological properties. We analyzed the microbial community composition by means of qPCR and high-throughput amplicon sequencing and utilized flux measurements to investigate their physiological properties. Our results revealed that once 16S and 18S rRNA gene copy numbers increase, fungi become more predominant and alpha diversity increases with progressing succession. Bacterial communities differed significantly between biocrust types with a shift from more generalized to specialized organisms along succession. CO2 gas exchange measurements revealed large respiration rates of late successional crusts being significantly higher than those of initial biocrusts, and different successional stages showed distinct NO and HONO emission patterns. Thus, our study suggests that the photoautotrophic organisms facilitate specific microbial communities, which themselves strongly influence the overall physiological properties of biocrusts and hence local to global nutrient cycles.


Assuntos
Microbiologia do Solo , Processos Autotróficos , Bactérias/genética , Bactérias/isolamento & purificação , Biodiversidade , Briófitas , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Ecossistema , Fungos/genética , Fungos/isolamento & purificação , Processos Heterotróficos , Líquens/isolamento & purificação , Solo/química
3.
Molecules ; 22(5)2017 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-28513562

RESUMO

Microscopic and molecular studies suggest that lichen symbioses contain a plethora of associated fungi. These are potential producers of novel bioactive compounds, but strains isolated on standard media usually represent only a minor subset of these fungi. By using various in vitro growth conditions we are able to modulate and extend the fraction of culturable lichen-associated fungi. We observed that the presence of iron, glucose, magnesium and potassium in growth media is essential for the successful isolation of members from different taxonomic groups. According to sequence data, most isolates besides the lichen mycobionts belong to the classes Dothideomycetes and Eurotiomycetes. With our approach we can further explore the hidden fungal diversity in lichens to assist in the search of novel compounds.


Assuntos
Biodiversidade , Meios de Cultura/química , Líquens/crescimento & desenvolvimento , Líquens/isolamento & purificação , DNA Fúngico/análise , Glucose/farmacologia , Ferro/farmacologia , Líquens/classificação , Magnésio/farmacologia , Filogenia , Potássio/farmacologia , Análise de Sequência de DNA , Simbiose
4.
Extremophiles ; 20(4): 461-70, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27240672

RESUMO

Endolichenic fungi within 17 lichen species in the area near Ny-Ålesund (Svalbard, High Arctic) were studied by a culture-based method. The 247 fungal isolates were obtained from 2712 lichen thallus segments. The colonization rate of endolichenic fungi ranged from 1.6 to 26.5 %, respectively. These isolates were identified to 40 fungal taxa, including 35 Ascomycota (10 orders), 4 Basidiomycota (3 orders), and 1 unidentified fungus. Thelebolales was the most abundant order, while Sordariales were the most diverse order. The common fungal taxa shared by more than 3 lichen species were Thelebolus microsporus (93 isolates), Coniochaeta hoffmannii (7 isolates), Sarocladium kiliense (33 isolates), Coniochaeta sp. 1 (5 isolates), Coniochaeta sp. 4 (28 isolates), and Coniochaeta sp. 2 (5 isolates). Low Sorenson's similarity coefficients were observed among different lichen species, indicating that host-related factor may shape the endolichenic fungal communities in this region. In addition, no endolichenic fungal taxa were previously found in the Antarctica and Austrian Alps, suggesting endolichenic fungal communities in this region might be also shaped by the Arctic climate. The results demonstrate the existence of specific cultured endolichenic fungal species, which may be suitable objects for further study of their possible functional roles in the lichen thalli.


Assuntos
Líquens/classificação , Microbiota , Regiões Antárticas , Líquens/genética , Líquens/isolamento & purificação
5.
Sci Rep ; 5: 15839, 2015 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-26514347

RESUMO

Cultivable Actinobacteria are the largest source of microbially derived bioactive molecules. The high demand for novel antibiotics highlights the need for exploring novel sources of these bacteria. Microbial symbioses with sessile macro-organisms, known to contain bioactive compounds likely of bacterial origin, represent an interesting and underexplored source of Actinobacteria. We studied the diversity and potential for bioactive-metabolite production of Actinobacteria associated with two marine lichens (Lichina confinis and L. pygmaea; from intertidal and subtidal zones) and one littoral lichen (Roccella fuciformis; from supratidal zone) from the Brittany coast (France), as well as the terrestrial lichen Collema auriforme (from a riparian zone, Austria). A total of 247 bacterial strains were isolated using two selective media. Isolates were identified and clustered into 101 OTUs (98% identity) including 51 actinobacterial OTUs. The actinobacterial families observed were: Brevibacteriaceae, Cellulomonadaceae, Gordoniaceae, Micrococcaceae, Mycobacteriaceae, Nocardioidaceae, Promicromonosporaceae, Pseudonocardiaceae, Sanguibacteraceae and Streptomycetaceae. Interestingly, the diversity was most influenced by the selective media rather than lichen species or the level of lichen thallus association. The potential for bioactive-metabolite biosynthesis of the isolates was confirmed by screening genes coding for polyketide synthases types I and II. These results show that littoral lichens are a source of diverse potentially bioactive Actinobacteria.


Assuntos
Actinobacteria/genética , Líquens/genética , Actinobacteria/classificação , Actinobacteria/isolamento & purificação , Biodiversidade , Análise por Conglomerados , Líquens/classificação , Líquens/isolamento & purificação , Filogenia , Policetídeo Sintases/genética , Policetídeo Sintases/metabolismo , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Análise de Sequência de DNA , Microbiologia do Solo
6.
Mycologia ; 107(6): 1120-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26354803

RESUMO

Parmotrema perforatum and its relatives form a morphologically distinctive group of species, most of which are common and endemic to eastern North America. Species delimitation in this ecologically important group was the subject of extensive inquiry before the advent of molecular systematics and computationally intensive niche modeling. As part of a large-scale lichen biodiversity inventory of the Mid-Atlantic Coastal Plain, we used ITS sequence data to examine the utility of characters (morphological, chemical, reproductive, ecological) in circumscribing four species in this group (P. hypoleucinum, P. hypotropum, P. perforatum, P. subrigidum). We found that P. hypoleucinum and P. subrigidum as currently circumscribed are monophyletic and the latter comprises two chemotypes differing in the presence or absence of norstictic acid in addition to alectoronic acid. The sequences of P. hypotropum and P. perforatum, which are chemically identical species and differ only in reproductive mode, were intermixed in a single, well-supported clade. The two chemotypes of P. subrigidum are partially allopatric and their sequences are >99% identical. Nonetheless, niche modeling suggests they occupy significantly different ecological niches. These results provide a new perspective on much-debated questions on species circumscription in lichens and suggest new avenues for genetic, ecological and systematic research.


Assuntos
Ácidos/metabolismo , Ascomicetos/isolamento & purificação , Líquens/isolamento & purificação , Ácidos/análise , Ascomicetos/classificação , Ascomicetos/genética , Ascomicetos/metabolismo , Líquens/classificação , Líquens/genética , Líquens/metabolismo , Dados de Sequência Molecular , Filogenia , Estados Unidos
8.
Int. microbiol ; 16(4): 243-252, dic. 2013. ilus
Artigo em Inglês | IBECS | ID: ibc-125455

RESUMO

Decreasing quality of forest habitats is among the major factors leading to a loss of epiphytic lichen diversity. However, there is little information about how this factor influences the diversity of terricolous lichens, which do not grow over living trees and could be less susceptible to such disturbances. In this work we describe the genetic diversity of Peltigeraterricolous cyanolichens and their cyanobiont (Nostoc) from three habitats at the Karukinka Natural Park (Tierra del Fuego, southern Chile), which represent different conservation states: native mature-forest (low disturbance intensity), native young forest (medium disturbance intensity) and grassland (high disturbance intensity). In both forest contexts, a higher diversity and a higher number of unique OTUs (operational taxonomic units) were found. In contrast, in the grassland, the diversity was lower and the Peltigera species were mostly cosmopolitan. The presence of unique OTUs and the higher diversity of lichens in native forest areas highlight the importance of their preservation, indicating that decreasing forest quality also has a negative impact on terricolous lichens diversity (AU)


No disponible


Assuntos
Humanos , Variação Genética , Árvores/parasitologia , Líquens/isolamento & purificação , Líquens/genética , Nostoc/isolamento & purificação
9.
Prikl Biokhim Mikrobiol ; 49(3): 322-8, 2013.
Artigo em Russo | MEDLINE | ID: mdl-23882952

RESUMO

An enzyme immunoassay for usnic acid in lichens was developed, the sensitivity of which was 0.1 microg/g of air-dried material (0.00001%). Polyclonal rabbit antibodies against bovine serum albumin conjugated to (+)-usnic acid under the conditions of formaldehyde condensation made it possible to determine the analyzed substance in solutions at concentrations from 1 ng/mL when it interacts with an immobilized gelatin conjugate homologous in the binding mode. Usnic acid in 2-26600 microg/g (0.0002-2.6%) amounts was found in all 236 studied samples of lichens belonging to 53 species and 8 families.


Assuntos
Benzofuranos/isolamento & purificação , Líquens/isolamento & purificação , Anticorpos , Antígenos/imunologia , Benzofuranos/imunologia , Técnicas Imunoenzimáticas , Líquens/classificação , Líquens/imunologia
10.
FEMS Microbiol Ecol ; 83(2): 310-23, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22906221

RESUMO

The epiphytic lichen Ramalina farinacea is distributed throughout the northern hemisphere in which the same two algal Trebouxia species (provisionally named TR1 and TR9) coexist in every thallus. Ramalina farinacea symbionts were characterized based on the two fungal nuclear loci (nrITS and rpb2) along with the primary and secondary structures of nrITS from each Trebouxia species in the Iberian Peninsula and Canary Islands. The results indicated a noticeable genetic differentiation between mycobionts from these two geographic areas and also suggested concerted changes in the three partners of a lichen symbiosis toward two clearly distinguishable 'holobiont' lineages. Modeling of ITS2 RNA secondary structures suggested their temperature sensitivity in TR1 but not in TR9, which was consistent with the observed superior physiological performance of TR9 phycobionts under relatively high temperatures. Both TR1 and TR9 phycobionts have been also found in a variety of taxonomically distinct lichens with a preferably Mediterranean distribution, being TR1 much more widespread than TR9. Our observations support a model in which ecological diversification and speciation of lichen symbionts in different habitats could include a transient phase consisting of associations with more than one photobiont in individual thalli. Such diversification is likely to be promoted by different physiological backgrounds.


Assuntos
Ascomicetos/genética , Clorófitas/genética , Líquens/genética , Simbiose/genética , Ascomicetos/classificação , Ascomicetos/isolamento & purificação , Clorófitas/classificação , Europa (Continente) , Variação Genética , Genótipo , Líquens/classificação , Líquens/isolamento & purificação , Conformação de Ácido Nucleico , Filogenia , RNA Ribossômico/química , Espanha
11.
J Toxicol Environ Health A ; 75(22-23): 1392-403, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23095157

RESUMO

Throughout the world, epidemiological studies were established to examine the relationship between air pollution and mortality rates and adverse respiratory health effects. However, despite the years of discussion the correlation between adverse health effects and atmospheric pollution remains controversial, partly because these studies are frequently restricted to small and well-monitored areas. Monitoring air pollution is complex due to the large spatial and temporal variations of pollution phenomena, the high costs of recording instruments, and the low sampling density of a purely instrumental approach. Therefore, together with the traditional instrumental monitoring, bioindication techniques allow for the mapping of pollution effects over wide areas with a high sampling density. In this study, instrumental and biomonitoring techniques were integrated to support an epidemiological study that will be developed in an industrial area located in Gijon in the coastal of central Asturias, Spain. Three main objectives were proposed to (i) analyze temporal patterns of PM10 concentrations in order to apportion emissions sources, (ii) investigate spatial patterns of lichen conductivity to identify the impact of the studied industrial area in air quality, and (iii) establish relationships amongst lichen conductivity with some site-specific characteristics. Samples of the epiphytic lichen Parmelia sulcata were transplanted in a grid of 18 by 20 km with an industrial area in the center. Lichens were exposed for a 5-mo period starting in April 2010. After exposure, lichen samples were soaked in 18-MΩ water aimed at determination of water electrical conductivity and, consequently, lichen vitality and cell damage. A marked decreasing gradient of lichens conductivity relative to distance from the emitting sources was observed. Transplants from a sampling site proximal to the industrial area reached values 10-fold higher than levels far from it. This finding showed that lichens reacted physiologically in the polluted industrial area as evidenced by increased conductivity correlated to contamination level. The integration of temporal PM10 measurements and analysis of wind direction corroborated the importance of this industrialized region for air quality measurements and identified the relevance of traffic for the urban area.


Assuntos
Poluição do Ar , Monitoramento Ambiental/métodos , Resíduos Industriais/análise , Indústrias , Material Particulado/análise , Poluição do Ar/efeitos adversos , Poluição do Ar/legislação & jurisprudência , Altitude , Ascomicetos/química , Ascomicetos/efeitos dos fármacos , Ascomicetos/crescimento & desenvolvimento , Ascomicetos/isolamento & purificação , Permeabilidade da Membrana Celular/efeitos dos fármacos , Condutividade Elétrica , Monitoramento Ambiental/instrumentação , Monitoramento Epidemiológico , Europa (Continente) , Guias como Assunto , Humanos , Resíduos Industriais/efeitos adversos , Líquens/química , Líquens/efeitos dos fármacos , Líquens/crescimento & desenvolvimento , Líquens/isolamento & purificação , Material Particulado/administração & dosagem , Material Particulado/toxicidade , Estações do Ano , Espanha , Integração de Sistemas , Emissões de Veículos/toxicidade , Vento , Organização Mundial da Saúde
12.
Mycologia ; 104(2): 362-70, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22223171

RESUMO

Lichens produce unique polyketide secondary metabolites including depsides, depsidones, dibenzofurans and depsones. The biosynthesis of these compounds is governed by polyketide synthase (PKS), but the mechanism via which they are produced has remained unclear until now. We reported the 6-methylsalicylic acid synthase (6-MSAS) type of PKS gene, which is a member of the fungal-reducing PKSs. A cultured mycobiont of Cladonia metacorallifera was employed in the isolation and characterization of a polyketide synthase gene (CmPKS1). The complete sequence information for CmPKS1 was acquired via the screening of a Fosmid genomic library with a 456 bp fragment corresponding to part of the acyl transferase (AT) domain as a probe. CmPKS1 contains ß-ketoacyl synthase (KS), AT, dehydratase (DH), ketoreductase (KR) and phosphopantetheine attachment site (PP) domains.: The domain organization of CmPKS1 (KS-AT-DH-KR-PP) is a typical 6-MSAS-type PKS, and the results of phylogenetic analysis showed that CmPKS1 grouped with other fungal-reducing PKSs. Quantitative real time PCR analyses showed that CmPKS1 was expressed preferentially in the early growth stage of the axenically cultured mycobiont. Furthermore CmPKS1 expression was found to be dependent on the carbon sources and concentrations in the medium.


Assuntos
Ascomicetos/enzimologia , Líquens/enzimologia , Policetídeo Sintases/genética , Policetídeos/metabolismo , Aciltransferases/genética , Sequência de Aminoácidos , Ascomicetos/classificação , Ascomicetos/genética , Ascomicetos/isolamento & purificação , Sequência de Bases , Southern Blotting , Proteínas Fúngicas/genética , Regulação Enzimológica da Expressão Gênica , Biblioteca Genômica , Líquens/classificação , Líquens/genética , Líquens/isolamento & purificação , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Oxirredução , Filogenia , Policetídeo Sintases/metabolismo , Estrutura Terciária de Proteína , Reação em Cadeia da Polimerase em Tempo Real , Análise de Sequência de DNA
13.
Microb Ecol ; 62(2): 299-313, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21359558

RESUMO

This study examines the microbial colonization of three fronts of an abandoned dolostone quarry (Redueña, Madrid, Spain) exposed to atmospheric conditions for different time periods since Roman times to the present. Through scanning electron microscopy in backscattered electron mode (SEM-BSE), endolithic colonization was predominantly detected in the most recently exposed front, while in the longer exposed quarry fronts, epilithic forms of growth were most often observed. These observations were confirmed by denaturing gradient gel electrophoresis (DGGE) analysis. Based on the distribution pattern of microbial colonization in the different quarry fronts, we then established a sequence of colonization events that took place over this long time frame. Bioalteration processes related to this sequential colonization were also identified. Characterizing these sequential processes can be useful for interpreting biodeterioration processes in historic dolostone monuments, especially those affecting constructions in the area of the Redueña stone quarry. In a second experimental stage, different biocide treatments were tested on this quarry rock to find the best way to avoid the microbial colonization effects identified. Through combined SEM-BSE/DGGE analysis, the efficacy of several biocides against the microorganisms inhabiting the dolostones was assessed after 4 and 16 months treatment. In general, all treatments were effective at reducing around 80% of the lichen cover, although effects on endolithic lithobiontic communities were dependent on how well the rock surface had been mechanically cleaned prior to treatment and gradually disappeared over time.


Assuntos
Biotransformação , Carbonato de Cálcio/química , Materiais de Construção/microbiologia , Desinfetantes/farmacologia , Líquens/crescimento & desenvolvimento , Magnésio/química , Biota , Colorimetria , DNA Fúngico/genética , DNA Espaçador Ribossômico/genética , Eletroforese em Gel de Gradiente Desnaturante , Genes de RNAr , Líquens/efeitos dos fármacos , Líquens/isolamento & purificação , Microscopia Eletrônica de Varredura , Porosidade , Espanha
14.
Environ Pollut ; 158(3): 812-9, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19880227

RESUMO

We investigated lichen diversity in temperate oak forests using standardized protocols. Forty-eight sites were sampled in the Czech Republic, Slovakia and Hungary. The effects of natural environmental predictors and human influences on lichen diversity (lichen diversity value, species richness) were analysed by means of correlation tests. We found that lichen diversity responded differently to environmental predictors between two regions with different human impact. In the industrial region, air pollution was the strongest factor. In the agricultural to highly forested regions, lichen diversity was strongly influenced by forest age and forest fragmentation. We found that several natural factors can in some cases obscure the effect of human influences. Thus, factors of natural gradient must be considered (both statistically and interpretively) when studying human impact on lichen diversity.


Assuntos
Biodiversidade , Monitoramento Ambiental , Líquens/isolamento & purificação , Quercus , Ecossistema , Europa (Continente) , Humanos , Líquens/classificação , Líquens/fisiologia , Árvores
15.
Mycol Res ; 113(Pt 10): 1216-27, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19683572

RESUMO

Sterile cultured isolates of lichen-forming aposymbionts have not yet been used to investigate lichen-rock interactions under controlled conditions. In this study mycobionts and photobiont of the endolithic lichens Bagliettoa baldensis and Bagliettoa marmorea were isolated and inoculated with coupons of one limestone and four marbles commonly employed in the Cultural Heritage framework. After one year of incubation, microscopic observations of polished cross-sections were performed to verify if the typical colonization patterns observed in the field may be reproduced in vitro and to evaluate the receptivity of the five lithotypes to endolithic lichens. The mycobionts of the two species developed both on the surface of and within all the lithotypes, showing different penetration pathways which depend on mineralogical and structural features and highlight different receptivity. By contrast, algae inoculated with the coupons did not penetrate them. Observations suggest that the hyphal penetration along intrinsic discontinuities of rocks is a relatively fast phenomenon when these organisms are generally considered as slow-growing. Samples from limestone outcrops and abandoned marble quarries, colonized by the same species or other representatives of Verrucariaceae, showed penetration pathways intriguingly similar to those reproduced in vitro and highlighted that lichen-driven erosion processes only increase the availability of hyphal passageways after a long-term colonization. These results show that in vitro incubation of sterile cultured lichen-forming ascomycetes with rock coupons is a practicable experimental system to investigate the lichen-rock interactions under controlled conditions and, together with analysis in situ, may support decisions on conservative treatments of historical and cultural significant stone substrata.


Assuntos
Ascomicetos/isolamento & purificação , Carbonato de Cálcio/química , Sedimentos Geológicos/microbiologia , Líquens/isolamento & purificação , Simbiose , Ascomicetos/fisiologia , Líquens/fisiologia
16.
Microb Ecol ; 58(2): 394-407, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19479305

RESUMO

In temperate regions, biological soil crusts (BSCs: complex communities of cyanobacteria, eukaryotic algae, bryophytes, and lichens) are not well investigated regarding community structure and diversity. Furthermore, studies on succession are rare. For that reason, the community assembly of crusts representing two successional stages (initial, 5 years old; and stable, >20 years old) were analyzed in an inland sand ecosystem in Germany in a plot-based approach (2 x 18 plots, each 20 x 20 cm). Two different methods were used to record the cyanobacteria and eukaryotic algae in these communities comprehensively: determination directly out of the soil and enrichment culture techniques. Additionally, lichens, bryophytes, and phanerogams were determined. We examine four hypotheses: (1) A combination of direct determination and enrichment culture technique is necessary to detect cyanobacteria and eukaryotic algae comprehensively. In total, 45 species of cyanobacteria and eukaryotic algae were detected in the study area with both techniques, including 26 eukaryotic algae and 19 cyanobacteria species. With both determination techniques, 22 identical taxa were detected (11 eukaryotic algae and 11 cyanobacteria). Thirteen taxa were only found by direct determination, and ten taxa were only found in enrichment cultures. Hence, the hypothesis is supported. Additionally, five lichen species (three genera), five bryophyte species (five genera), and 24 vascular plant species occurred. (2) There is a clear difference between the floristic structure of initial and stable crusts. The different successional stages are clearly separated by detrended correspondence analysis, showing a distinct structure of the community assembly in each stage. In the initial crusts, Klebsormidium flaccidum, Klebsormidium cf. klebsii, and Stichococcus bacillaris were important indicator species, whereas the stable crusts are especially characterized by Tortella inclinata. (3) The biodiversity of BSC taxa and vascular plant species increases from initial to stable BSCs. There are significantly higher genera and species numbers of cyanobacteria and eukaryotic algae in initial BSCs. Stable BSCs are characterized by significantly higher species numbers of bryophytes and vascular plant species. The results show that, in the investigated temperate region, the often-assumed increase of biodiversity in the course of succession is clearly taxa-dependent. Both successional stages of BSCs are diversity "hot spots" with about 29 species of all taxa per 20 x 20 cm plot. (4) Nitrogen and chlorophyll a concentrations increase in the course of succession. The chlorophyll a content of the crusts (cyanobacteria, eukaryotic algae, bryophyte protonemata) is highly variable across the studied samples, with no significant differences between initial and stable BSCs; nor were ecologically significant differences in soil nutrient contents observed. According to our results, we cannot confirm this hypothesis; the age difference between our two stages is probably not big enough to show such an increase.


Assuntos
Ecossistema , Dióxido de Silício/análise , Microbiologia do Solo , Biomassa , Clorofila/análise , Clorofila A , Cianobactérias/classificação , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Eucariotos/classificação , Eucariotos/genética , Eucariotos/isolamento & purificação , Alemanha , Líquens/classificação , Líquens/genética , Líquens/isolamento & purificação , Fatores de Tempo
17.
Microb Ecol ; 57(2): 229-47, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18850242

RESUMO

Biological soil crusts (BSCs) are found in all dryland regions of the world, including the polar regions. They are also known to occur in the southern African region. Although there were a number of case studies on BSCs from that region, we did not know if they are a normal part of the vegetation cover or just a phenomenon that occasionally occurs here and there. In order to investigate diversity, distribution patterns, and the driving factors of both, we followed a random sampling system of observatories along a transect, stretching from the Namibian-Angolan border down south to the Cape Peninsula, covering seven different major biomes. Biological soil crusts were found to occur in six out of seven biomes. Despite the fact that soil-dwelling algae occurred in the Fynbos biome, crust formation was not observed for hitherto unknown reasons. Seven BSC types were distinguished on the basis of morphology and taxonomic composition: three of them were cyanobacteria-dominated, one with additional chlorolichens, two with bryophytes, one hypolithic type restricted to quartz gravel pavements, and the unique lichen fields of the Namib Desert. Besides 29 green algal species in 21 genera, one heterokont alga, 12 cyanolichens, 14 chlorolichens, two genera of liverworts, and three genera of mosses, these crusts are positioned among the most diverse BSCs worldwide mainly because of the unusual high cyanobacterial species richness comprising 58 species in 21 genera. They contribute considerably to the biodiversity of arid and semi-arid bioregions. Taxonomic diversity of cyanobacteria was significantly higher in the winter rain zone than in the summer rain zone (54 versus 32 species). The soil photosynthetic biomass (chlorophylla/m2), the carbon content of the soil and the number of BSC types were significantly higher in the winter rain zone (U27, 29=215.0, p=0.004 [chla]; U21, 21=135.0, p=0.031 [C]; U27, 29=261.5, p=0.028 [BSC types]; excluding the fog-dominated Namib biome). The winter rain zone is characterized by a lower precipitation amount, but a higher rain frequency with the number of rainy days more evenly distributed over the year. The dry period is significantly shorter per year in the winter rain zone (U8, 9=5.0, p=0.003). We conclude that rain frequency and duration of dry periods rather than the precipitation amount is the main factor for BSC growth and succession. Nitrogen content of the soils along the transect was generally very low and correlated with soil carbon content. There was a weak trend that an increasing proportion of silt and clay (<0.63 mm) in the soil is associated with higher values of BSC chlorophyll content (Pearson correlation coefficient=0.314, p=0.237). Furthermore, we found a significant positive correlation between silt and clay and the number of BSC types (Pearson correlation coefficient=0.519, p=0.039), suggesting that fine grain-size promotes BSC succession and their biomass content. Lichens and bryophytes occurred in BSCs with lower disturbance frequencies (e.g. trampling) only. Crust thickness and chlorophyll content increased significantly from crusts of the early successional type to the late successional crust types. From our results, we conclude that BSCs are a normal and frequent element of the vegetation in arid and semi-arid southwestern Africa, and that rain frequency and duration of dry periods rather than the precipitation amount are the key factors for the development, differentiation and composition of BSCs.


Assuntos
Biodiversidade , Chuva , Microbiologia do Solo , Biomassa , Carbono/análise , Clorofila/análise , Clima , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Líquens/genética , Líquens/isolamento & purificação , Namíbia , Nitrogênio/análise , RNA Bacteriano/análise , RNA Ribossômico 16S/análise , Estações do Ano
18.
Mycol Res ; 112(Pt 1): 50-6, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18207379

RESUMO

The phylogenetic positions of the always-sterile microfilamentous lichens Cystocoleus ebeneus and Racodium rupestre were studied in a phylogenetic framework using sequence data of 5' nuSSU, nuLSU, and mtSSU rDNA. The analysis reveals that both genera are ascomycetes and belong to Dothideomycetidae: they are not close to lichenized members within the subclass, but rather belong to Capnodiales. The macroscopically scarcely distinguishable C. ebeneus and R. rupestre do not form a monophyletic group. The well-supported clade of R. rupestre is basal to the one in which C. ebeneus is close to Mycosphaerellaceae. This study provides another example of ascomycetes with very different life-styles and ecologies being closely related.


Assuntos
Ascomicetos/classificação , Ascomicetos/isolamento & purificação , Líquens/classificação , Líquens/isolamento & purificação , Micoses/microbiologia , Doenças das Plantas/microbiologia , Ascomicetos/genética , Ascomicetos/fisiologia , Áustria , DNA Fúngico/genética , DNA Mitocondrial/genética , DNA Ribossômico , Humanos , Itália , Líquens/genética , Líquens/fisiologia , Dados de Sequência Molecular , Filogenia , Plantas , RNA Ribossômico/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Reino Unido
19.
Pak J Biol Sci ; 11(18): 2201-8, 2008 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-19137828

RESUMO

A contribution to the lichen flora of Turkey is performed. A total of 171 lichen taxa (including 2 subspecies and 2 varieties) and 1 lichenicolous fungus are determined from 14 localities in Antalya, Cankiri, Konya and Nevsehir provinces of Turkey. Caloplaca scrobiculata H. Magn. is new to Turkey. Besides Caloplaca scrobiculata H. Magn. and Xanthoria sorediata (Vain.) Poelt were found for the second time in Asia. Carbonea vitellinaria (Nyl.) Hertel was found to grow on Candelariella vitellina (Hoffm.) Müll. Arg. while Muellerella pymaea (Körb.) D. Hawksw. var. athallina (Müll. Arg.) Triebel (lichenicolous fungus) on Tephromela atra (Huds.) Hafellner as parasitic. All lichen taxa found in Cankiri are new to this province (92 intraspecific taxa), while 39 new to Nevsehir, 8 new to Konya and 5 new to Antalya provinces. For every each taxon, the habitat pattern and distribution data are presented.


Assuntos
Líquens/isolamento & purificação , Líquens/classificação , Líquens/microbiologia , Especificidade da Espécie , Turquia
20.
J Microbiol ; 43(3): 228-36, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15995639

RESUMO

Fifty-six species in 36 genera of macrolichens are reported from the Zhongdian area, northwest Yunnan, China during the lichenological expedition for highland macrolichen survey in June, 2004. More than 60% of these species have not been reported in South Korea. All of the 182 collected specimens are deposited in the Korean Lichen Research Institute (KoLRI) at Sunchon National University in Korea, and some of them are duplicated in the lichen herbarium, Crytogamic Herbarium, Kunming Institute of Botany, Academia Sinica (KUN-L) in China. This is the first report on the macrolichen flora in the visited areas.


Assuntos
Altitude , Líquens/classificação , Líquens/isolamento & purificação , China , DNA Espaçador Ribossômico/análise , Ecossistema , Líquens/genética , Dados de Sequência Molecular , RNA Ribossômico 5,8S , Análise de Sequência de DNA
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...