Mediterranean ecosystems have not been consistently investigated as natural habitats for microbes in general, and fungi in particular. Here we present the results of a survey of epiphytic mycobiota (filamentous fungi and yeasts) on the phylloplane of selected plants in the Arrábida Natural Park, an ecosystem of Mediterranean characteristics in Portugal, using conventional culture-dependent isolation methods. Leaves from the species Acer monspessulanum and Quercus faginea (deciduous trees) and Cistus albidus, Pistacia lentiscus, and Osyris quadripartita (evergreen shrubs) were collected twice a year for two consecutive years, at two distinct locations of Serra da Arrábida: the more humid northern slope and the drier southern slope. A total of 1029 strains of filamentous fungi and 540 strains of yeasts were isolated, which represented at least 36 and 46 distinct species, respectively. Total counts were higher on the plants from the northern slope and there was a general increase from spring to autumn, notably on the deciduous trees for the yeasts. Plant species that had higher numbers of leaf colonists (A. monspessulanum, C. albidus, and Q. faginea) also yielded a wider range of species. Among the filamentous fungi there was a predominance of species of ascomycetous affinity, whereas basidiomycetous species dominated among yeast isolates. Some of the taxa recovered were common to other phylloplane studies (e.g., ubiquitous molds and yeasts such as Cladosporium spp. and Cryptococcus spp., respectively), but less common species were also found, some of which appeared to represent undescribed taxa. Interestingly, a few species seemed to be associated with a particular plant, notably in the case of the evergreen shrub C. albidus. However, for a considerable number of fungi and yeasts the same taxon was recovered throughout the year from more than one plant and at both sites, suggesting that such species might be genuine phylloplane inhabitants (or at least of aerial plant surfaces) even though they appeared not to display host specificity.
a b s t r a c tWe investigated whether an intact extraradical mycelium (ERM) is more effective than other forms of propagule from indigenous arbuscular mycorrhizal fungi (AMF) in providing protection against stress to a host plant. The response of wheat (Triticum aestivum L.) to Mn toxicity was studied in a two-phase greenhouse experiment. In Phase 1, four Mn tolerant species from the natural vegetation, ranging from strongly mycotrophic to non-or weakly mycotrophic, were grown to develop different amounts of ERM. Wheat was then planted (Phase 2) with the ERM fragmented by sieving (Disturbed Treatment) or kept intact with no prior soil disturbance (Undisturbed Treatment). The growth of wheat was doubled by earlier and faster mycorrhizal colonization (AC) in the presence of an intact ERM at planting. There was a positive correlation between plant growth and the reduction of Mn and enhancement of P and S uptake into shoots. However, the growth of plants in undisturbed soil was significantly affected by the ERM developer species, which was not explained by differences in AC. Colonization starting from an intact ERM greatly enhanced the potential of AMF for protection against Mn toxicity. However, the degree of protection depended on the plant previously grown to develop the ERM, suggesting that there may be functional diversity within the ERM developed by mycotrophic plants of the natural vegetation.
As functional diversity influences the benefits conferred on host plants by arbuscular mycorrhizal fungi (AMF) and large scale commercial inoculation is currently impracticable, strategies are required to manage communities of indigenous AMF associated with different hosts within agricultural cropping systems. In a non-sterilized soil, using 454 pyrosequencing of the LSU-D2 rDNA gene, host plant AMF diversity was assessed following successions of different plant species, grown with or without prior soil disturbance. Diversity present in the
Objectives. The aim of this study was to determine whether irrigation with sodium hypochlorite, chlorhexidine, and ozone gas, alone or in combination, were effective against Enterococcus faecalis and Candida albicans; these are microorganisms frequently isolated from teeth with periapical lesions resistant to endodontic treatment. Material and Methods. 220 single root teeth, recently extracted, were inoculated with Candida albicans and Enterococcus faecalis. The formulations tested were sodium hypochlorite at 1, 3, and 5% chlorhexidine at 0.2% and 2% and ozone gas applied for different periods of time. The combination of sodium hypochlorite at 5% and chlorhexidine at 2%, with gaseous ozone, were also assessed. For the most active treatments the mechanism of action was assessed through flow cytometry. Results. Sodium hypochlorite, chlorhexidine, and gaseous ozone alone were ineffective in completely eliminating the microorganisms. The association of chlorhexidine at 2% followed by ozone gas for 24 seconds promoted the complete elimination of Candida albicans and Enterococcus faecalis. Flow cytometry shows that ozone and chlorhexidine act differently, which could explain its synergic activity. Conclusions. This new disinfection protocol, combining irrigation with chlorhexidine at 2% and ozone gas for 24 seconds, may be advantageous when treating infected root canals.
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