Publications

4510

A Gram-negative, non-motile, chemoheterotrophic, facultatively aerobic, short-rod-shaped bacterium, designated IMCC1097T, was isolated from coastal seawater (10 m depth) of the East Sea, Korea. The temperature, pH and NaCl ranges for growth were 15–30 °C, pH 5.0–10.0 and 1.5–10 % NaCl. The colonies of the strain were very small, having a mean diameter of 0.05 mm. 16S rRNA gene sequence data indicated that the strain was most closely related to genera within the class Gammaproteobacteria. Members of the most closely related genera showed less than 90 % sequence similarity and included Saccharospirillum (89.3 %), Oleiphilus (88.7 %), Reinekea (88.2 %), Alcanivorax (86.4–87.6 %) and Zooshikella (87.6 %), which represent five different families of the order Oceanospirillales. Phylogenetic analyses showed that this marine strain represented a distinct phylogenetic lineage in the order Oceanospirillales and could not be assigned to any of the defined families in the order. The predominant fatty acids were C16 : 1 ω7c and/or iso-C15 : 0 2-OH, C18 : 1 ω7c and C10 : 0 3-OH, and the DNA G+C content was 57.9 mol%. These chemotaxonomic properties, together with phenotypic characteristics, served to differentiate the strain from phylogenetically closely related genera. The very low sequence similarities (<90 %) and distant relationships between IMCC1097T and members of the order Oceanospirillales suggested that the strain merited classification within a novel genus within a novel family in the order. On the basis of taxonomic evidence collected in this study, a novel genus and species are proposed, Litoricola lipolytica gen. nov., sp. nov., within a new family Litoricolaceae fam. nov. Strain IMCC1097T (=KCCM 42360T =NBRC 102074T) is the type strain of Litoricola lipolytica.

Only five bacterial phyla with members capable of chlorophyll (Chl)–based phototrophy are presently known. Metagenomic data from the phototrophic microbial mats of alkaline siliceous hot springs in Yellowstone National Park revealed the existence of a distinctive bacteriochlorophyll (BChl)–synthesizing, phototrophic bacterium. A highly enriched culture of this bacterium grew photoheterotrophically, synthesized BChls a and c under oxic conditions, and had chlorosomes and type 1 reaction centers. “ Candidatus Chloracidobacterium thermophilum” is a BChl-producing member of the poorly characterized phylum Acidobacteria .

SUMMARY Phytoplasmas are plant‐pathogenic bacteria that are associated with numerous plant diseases. We have previously reported the complete genomic sequence of Candidatus Phytoplasma asteris, OY strain, OY‐M line, which causes mild symptoms. The phytoplasma genome lacks several important metabolic genes, implying that the consumption of metabolites by phytoplasmas in plants may cause disease symptoms. Here we show that the approximately 30‐kb region including the glycolytic genes was tandemly duplicated in the genome of OY‐W phytoplasma, which causes severe symptoms. Almost duplicated genes became pseudogenes by frameshift and stop‐codon mutations, probably because of their functional redundancy. However, five kinds of genes, including two glycolytic genes, remained full‐length ORFs, suggesting that it is advantageous for the phytoplasma to retain these genes in its lifestyle. In particular, 6‐phosphofructokinase is known as a rate‐limiting enzyme of glycolysis, implying that the different number of glycolytic genes between OY‐W and OY‐M may influence their respective glycolysis activities. We previously reported that the phytoplasma population of OY‐W was higher than that of OY‐M in their infected plants. Taking this result into account, the higher consumption of the carbon source may affect the growth rate of phytoplasmas and also may directly or indirectly cause more severe symptoms.

Phylogenetic analysis and phenotypic characterization were used to assign a multicellular magnetotactic prokaryote the name ‘Candidatus Magnetoglobus multicellularis’. ‘Candidatus Magnetoglobus multicellularis' lives in a large hypersaline coastal lagoon from Brazil and has properties that are unique among prokaryotes. It consists of a compact assembly or aggregate of flagellated bacterial cells, highly organized in a sphere, that swim in either helical or straight trajectories. The life cycle of ‘Candidatus Magnetoglobus multicellularis' is completely multicellular, in which one aggregate grows by enlarging the size of its cells and approximately doubling the volume of the whole organism. Cells then divide synchronously, maintaining the spherical arrangement; finally the cells separate into two identical aggregates. Phylogenetic 16S rRNA gene sequence analysis showed that ‘Candidatus Magnetoglobus multicellularis' is related to the dissimilatory sulfate-reducing bacteria within the Deltaproteobacteria and to other previously described, but not yet well characterized, multicellular magnetotactic prokaryotes.

Although Mycoplasma haemofelis and "Candidatus Mycoplasma haemominutum" infections have been reported in wild cats from United States, their presence among native and captive wild cats in Brazil is still unknown. A 12 year old healthy male lion (Panthera leo) from the Zoological Garden of Curitiba, Brazil was anesthetized for transportation and dental evaluation. A blood sample was obtained for a complete blood cell count (CBC) and PCR analysis. DNA was extracted and fragments of Mycoplasma haemofelis and "Candidatus Mycoplasma haemominutum" 16S ribosomal RNA gene were amplified in PCR assays. CBC results were within reference intervals. A weak band of 192 pb for "Candidatus Mycoplasma haemominutum" was observed, and no band was amplified from Mycoplasma haemofelis reaction. A weak PCR band associated with normal CBC results and without visible parasitemia or clinical signs may suggest a chronic subclinical infection with "Candidatus Mycoplasma haemominutum". The lack of clinical signs may also represent the low pathogenicity of this organism; however, it is noteworthy that immune suppression caused by management and/or corticoids treatment may induce parasitemia and anemia in this animal. This detection suggests further studies in captive wild cats in Brazilian Zoological Gardens.

ABSTRACT “ Candidatus Chlorothrix halophila” is a recently described halophilic, filamentous, anoxygenic photoautotroph (J. A. Klappenbach and B. K. Pierson, Arch. Microbiol. 181: 17-25, 2004) that was enriched from the hypersaline microbial mats at Guerrero Negro, Mexico. Analysis of the photosynthetic apparatus by negative staining, spectroscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the photosynthetic apparatus in this organism has similarities to the photosynthetic apparatus in both the Chloroflexi and Chlorobi phyla of green photosynthetic bacteria. The chlorosomes were found to be ellipsoidal and of various sizes, characteristics that are comparable to characteristics of chlorosomes in other species of green photosynthetic bacteria. The absorption spectrum of whole cells was dominated by the chlorosome bacteriochlorophyll c (BChl c ) peak at 759 nm, with fluorescence emission at 760 nm. A second fluorescence emission band was observed at 870 nm and was tentatively attributed to a membrane-bound antenna complex. Fluorescence emission spectra obtained at 77 K revealed another complex that fluoresced at 820 nm, which probably resulted from the chlorosome baseplate complex. All of these results suggest that BChl c is present in the chlorosomes of “ Ca . Chlorothrix halophila,” that BChl a is present in the baseplate, and that there is a membrane-bound antenna complex. Analysis of the proteins in the chlorosomes revealed an ∼6-kDa band, which was found to be related to the BChl c binding protein CsmA found in other green bacteria. Overall, the absorbance and fluorescence spectra of “ Ca . Chlorothrix halophila” revealed an interesting mixture of photosynthetic characteristics that seemed to have properties similar to properties of both phyla of green bacteria when they were compared to the photosynthetic characteristics of Chlorobium tepidum and Chloroflexus aurantiacus .