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Clostridium phoceensis sp. nov., strain GD3T (= CSUR P1929 = DSM 100334) is the type strain of C. phoceensis sp. nov., a new species within the genus Clostridium. This strain was isolated from the gut microbiota of a 28-year-old healthy French man. C. phoceensis is a Gram-negative, spore-forming, nonmotile, strictly anaerobic bacterium. We describe its complete genome sequence and annotation, together with its phenotypic characteristics.

Polymorphism of the internal transcribed spacers (ITS) of the ribosomal DNA inScutellospora castanea(Glomales, Zygomycota) and its organization among spores were evaluated. Polymerase chain reaction (PCR) amplification with ITS1/ITS4 primers yielded several fragments of different lengths, even from single spores. Fragments produced from multisporal DNA were cloned and grouped into 6 ITS types by PCR-RFLP and sequence analysis. Five type-specific primers were designed. Spores were then analyzed by PCR and amplification profiles revealed that they were qualitatively different one from another due to the presence or absence of some ITS types. Intrasporal segregation of ITS variant length types was also shown, by PCR experiments, utilizing diluted fractions of nuclear suspensions from single spores. The results demonstrate the mainly multikaryotic condition of the spores ofS. castanea.

The nuclear DNA content of 11 species of Glomales was evaluated by flow cytometry after DAPI staining relative to Gigaspora margarita, which was used as internal standard. The nuclear DNA content of this species was calibrated by propidium iodide staining relative to chicken red blood cells. A correction was applied when the difference in AT content of the DNA was significant between a sample and the standard. A single unimodal peak of fluorescence was observed for nuclei from the quiescent spores of the 11 fungal species studied. It was considered that this peak corresponded to the amount of DNA in the genome of each species. Important interspecific variations in DNA content per nucleus (1- to 8-fold) were observed among four species of the genus Scutellospora.Key words: nucleus, DNA content, flow cytometry, spore, Glomales.

Glomales (Zygomycetes) are obligate fungal symbionts of roots of land plants and form arbuscular mycorrhiza. Sporal DNA of 10 isolates belonging to nine species was purified and the base composition was determined by RP-HPLC. Base composition fell in a narrow range between 30 and 35% G + C. A high amount of methylated cytosine (mC) accounting for 2-4% of the total nucleotides was found in all taxa. The DNA melting profile was defined for Scutellospora castanea. It corresponded to 32% G + C, and the shape of the denaturation curve suggested a heterogeneity in the GC content within the fungal genome. Knowledge of GC contents and variations between taxa are essential for evaluating nuclear DNA content using fluorimetric methods, and high proportions of mC/C + mC in the genomes of glomalean fungi could reflect the existence of repeated DNA families. Results are discussed in relation to data for other fungi and eukaryotes.

A highly repeated DNA sequence from the genome of an arbuscular mycorrhizal fungus has been isolated and characterized. This 1,202-bp sequence (SC1) represents about 0.24% of the Scutellospora castanea genome, estimated to be 1 pg by flow cytometry. The sequence was shown to be a Scutellospora-specific probe in Southern blots and dot blot hybridizations. After complete sequencing of SC1, PCR primers were generated and used to amplify a 907-bp fragment from spores of S. castanea or from colonized Allium porrum roots. No amplification products were obtained with DNA from either spores or mycorrhizal root of other species of arbuscular mycorrhizal fungi. These primers were sufficiently specific for unequivocal detection of S. castanea in planta.