Phylogeny of xerophilic aspergilli (subgenus Aspergillus) and taxonomic revision of section Restricti.

Aspergillus section Restricti together with sister section Aspergillus (formerly Eurotium) comprises xerophilic species, that are able to grow on substrates with low water activity and in extreme environments. We adressed the monophyly of both sections within subgenus Aspergillus and applied a multidisciplinary approach for definition of species boundaries in sect. Restricti. The monophyly of sections Aspergillus and Restricti was tested on a set of 102 isolates comprising all currently accepted species and was strongly supported by Maximum likelihood (ML) and Bayesian inferrence (BI) analysis based on ß-tubulin (benA), calmodulin (CaM) and RNA polymerase II second largest subunit (RPB2) loci. More than 300 strains belonging to sect. Restricti from various isolation sources and four continents were characterized by DNA sequencing, and 193 isolates were selected for phylogenetic analyses and phenotypic studies. Species delimitation methods based on multispecies coalescent model were employed on DNA sequences from four loci, i.e., ID region of rDNA (ITS + 28S), CaM, benA and RPB2, and supported recognition of 21 species, including 14 new. All these species were also strongly supported in ML and BI analyses. All recognised species can be reliably identified by all four examined genetic loci. Phenotype analysis was performed to support the delimitation of new species and includes colony characteristics on seven cultivation media incubated at several temperatures, growth on an osmotic gradient (six media with NaCl concentration from 0 to 25 %) and analysis of morphology including scanning electron microscopy. The micromorphology of conidial heads, vesicle dimensions, temperature profiles and growth parameters in osmotic gradient were useful criteria for species identification. The vast majority of species in sect. Restricti produce asperglaucide, asperphenamate or both in contrast to species in sect. Aspergillus. Mycophenolic acid was detected for the first time in at least six members of the section. The ascomata of A. halophilicus do not contain auroglaucin, epiheveadride or flavoglaucin which are common in sect. Aspergillus, but shares the echinulins with sect. Aspergillus.

Influence of Pythium oligandrum on the bacterial communities that colonize the nutrient solutions and the rhizosphere of tomato plants.

The influence exerted by the biocontrol oomycete Pythium oligandrum on the bacterial populations proliferating in the rhizosphere of tomato plants grown in a hydroponic system and in the circulating solutions is studied in the present experiment. Quantitative PCR and single-strand conformation polymorphism were used to investigate the genetic structure and dynamics of the bacterial communities colonizing the root systems and the various circulating solutions. Quantitative PCR assays showed that bacteria heavily colonized the rhizosphere of tomato plants with, however, no significant density changes throughout the cultural season (April-September). Single strand conformation polymorphism fingerprints revealed the occurrence of transient perturbations in the rhizospheric indigenous bacterial communities following P. oligandrum introduction in the root system of plants. This effect was, however, transient and did not persist until the end of the cropping season. Interestingly, the genetic structure of the bacterial microflora colonizing either the roots or the nutrient solutions evolved throughout the cropping season. This temporal evolution occurred whatever the presence and persistence of P. oligandrum in the rhizosphere. Evidence is also provided that bacterial microflora that colonize the root system are different from the ones colonizing the circulating solutions. The relationships between these 2 microflora (at the root and solution levels) are discussed.

Biodiversity of antifungal lactic acid bacteria isolated from raw milk samples from cow, ewe and goat over one-year period.

Antifungal lactic acid bacteria (ALAB) biodiversity was evaluated in raw milk from ewe, cow and goat over one year period. Lactic acid bacteria were enumerated using 8 semi-selective media, and systematically screened for their antifungal activity against 4 spoilage fungi commonly encountered in dairy products. Depending on the selective medium, between 0.05% (Elliker agar) and 5.5% (LAMVAB agar) screened colonies showed an antifungal activity. The great majority of these active colonies originated from cow (49%) and goat (43%) milks, whereas only 8% were isolated from ewe milk. Penicillium expansum was the most frequently inhibited fungus with 48.5% of colonies active against P. expansum among the 1235 isolated, followed by Mucor plumbeus with 30.6% of active colonies, Kluyveromyces lactis with only 12.1% of active colonies and Pichia anomala with 8.7% of active colonies. In the tested conditions, 94% of the sequenced active colonies belonged to Lactobacillus. Among them, targeted fungal species differed according to the Lactobacillus group, whose presence largely depended on year period and milk origin. The Lb. casei and Lb. reuteri groups, predominantly recovered in summer/fall, were overrepresented in the population targeting M. plumbeus, whereas isolates from the Lb. plantarum group, predominantly recovered in spring, were overrepresented in the population targeting K. lactis, the ones belonging to the Lb. buchneri group, predominantly recovered in spring, were overrepresented in the population targeting P. anomala. Raw milk, especially cow and goat milks from the summer/fall period appeared to be a productive reservoir for antifungal lactobacilli.

Characterization of Bacillus and Pseudomonas strains with suppressive traits isolated from tomato hydroponic-slow filtration unit.

Bacillus and Pseudomonas spp. are known to be involved in plant pathogenic fungi elimination during the slow filtration process used in tomato soilless cultures. We isolated 6-8 strains of both Bacillus and Pseudomonas from the top, middle, and bottom sections of filters and identified them after 16S rDNA sequencing. Four Pseudomonas strains were identified as Pseudomonas fulva, 5 as Pseudomonas plecoglossicida, and 12 as Pseudomonas putida. The use of specific oligonucleotide polymerase chain reaction primer sets designed from gyrB gene sequences additionally permitted the identification of 17 Bacillus cereus and 3 Bacillus thuringiensis strains. Ribotyping with EcoRI pointed out an important polymorphism within Bacillus and Pseudomonas strains. Molecular characterization did not reveal a correlation between the location of isolates within the filter (top, middle, or bottom) and bacterial identification or riboclusters. Functional aspects assessed by community-level physiological profiling showed marked phenotypic differences between Pseudomonas communities isolated from the top and bottom filter layers; differences were lower between Bacillus communities of different layers and far less noticeable between mixed communities of Bacillus and Pseudomonas. These strains were tested for several suppressive activities. Conversely to most Bacillus, the majority of Pseudomonas strains were auxin producers and promoted the growth of tomato plantlet roots. On the other hand, only Bacillus strains displayed antagonistic activities by inhibiting the growth of pathogenic fungi frequently detected in soilless cultures. Siderophores were produced by nearly all bacteria, but at higher amounts by Pseudomonas than Bacillus strains. The biocontrol agent potentiality of certain strains to optimize the slow filtration process and to promote the suppressive potential of nutrient solution is discussed.

Indigenous bacteria with antagonistic and plant-growth-promoting activities improve slow-filtration efficiency in soilless cultivation.

In tomato soilless culture, slow filtration allows one to control the development of diseases caused by pathogenic microorganisms. During the disinfecting process, microbial elimination is ensured by mechanical and biological factors. In this study, system efficacy was enhanced further to a biological activation of filter by inoculating the pozzolana grains contained in the filtering unit with 5 selected bacteria. Three strains identified as Pseudomonas putida and 2 as Bacillus cereus came from a filter whose high efficiency to eliminate pathogens has been proven over years. These 5 bacteria displayed either a plant growth promoting activity (P. putida strains) or antagonistic properties (B. cereus strains). Over the first months following their introduction in the filter, the bacterial colonisation of pozzolana grains was particularly high as compared to the one observed in the control filter. Conversely to Bacillus spp. populations, Pseudomonas spp. ones remained abundant throughout the whole cultural season. The biological activation of filter unit very significantly enhanced fungal elimination with respect to the one displayed by the control filter. Indeed, the 6-month period needed by the control filter to reach its best efficacy against Fusarium oxysporum was shortened for the bacteria-amended filter; in addition, a high efficacy filtration was got as soon as the first month. Fast colonization of pozzolana grains by selected bacteria and their subsequent interaction with F. oxysporum are likely responsible for filter efficiency. Our results suggest that Pseudomonas spp. act by competition for nutrients, and Bacillus spp. by antibiosis and (or) direct parasitism. Elimination of other fungal pathogens, i.e., Pythium spp., seems to differ from that of Fusarium since both filters demonstrated a high efficacy at the experiment start. Pythium spp. elimination appears to mainly rely on physical factors. It is worth noting that a certain percentage of the 5 pozzolana-inoculated bacteria failed to colonise the filter unit and were, thus, driven to the plants by the nutrient solution. Their contribution to the establishment of a beneficial microbial community in the rhizosphere is discussed.

[Spontaneous bilateral chylothorax revealing disseminated tuberculosis complicated by massive pulmonary embolism]. / Chylothorax spontané bilatéral révélateur d'une tuberculose disséminée, compliquée d'une embolie pulmonaire massive.

We report a case of bilateral chylothorax revealing diffuse tuberculosis. The clinical presentation was complicated by the apparition of a massive acute pulmonary embolism and an acute respiratory distress syndrome. Mycobacterium tuberculosis was isolated from the cultures of the bronchi aspiration of the bronchoscopic examination. With antituberculous chemotherapy, the course of the chylothorax was satisfactory.

Mycobacterium kansasii infection in a Paris suburb: comparison of disease presentation and outcome according to human immunodeficiency virus status. Groupe dEtude Des Mycobactéries de la Seine-Saint-Denis.

SETTING: Department of Seine-Saint-Denis, France. OBJECTIVE: To compare the presentation and outcome of Mycobacterium kansasii infections according to human immunodeficiency virus (HIV) status. DESIGN: Retrospective analysis of all the medical charts of adults meeting the diagnostic criteria of the American Thoracic Society for M. kansasii infection between 1991 and 1995. RESULTS: Between 1991 and 1995, 35 cases (23 HIV-[6%] and 12 HIV+ [34%]) were found, giving an annual incidence of 0.5/100000. The following particularities were common to both groups: 1) frequency and prominence of respiratory and general symptoms, 2) rarity of clinically apparent extra-thoracic involvement, 3) bacteriological confirmation mostly obtained with respiratory tract specimens, 4) favourable bacteriological outcome, and 5) low mortality attributable to the mycobacterial infection. The most striking differences concerned chest radiography: HIV- patients had apical cavitated and nodular lesions, while HIV+ patients exhibited a variety of other patterns, including alveolar infiltrates, miliary lesions and/or thoracic lymphadenopathy. CONCLUSION: Apart from pulmonary radiographic differences, presentation and short-term outcome of M. kansasii infections were similar in HIV+ and HIV-patients.