Several halotolerant bacteria were isolated from dust allowed to settle passively on saline medium in Higashi-Hiroshima, Japan during Asia dust events in [2005][2006]. The primary identification, based on the sequence similarity of the 16S rRNA gene, revealed that these isolates were strains of Bacillus subtilis, B. licheniformis, Staphylococcus epidermidis, Gracillibacillus sp., and Halomonas venusta. A parallel investigation carried out on desert sand collected directly from sand dunes in Dunhuang, Gobi Desert, China resulted in the revivification of seven bacterial strains that were highly identical to the B. subtilis and B. licheniformis strains obtained in Higashi-Hiroshima (99.7 and 100% of 16S rDNA sequence similarity, respectively). A subsequent genetic analysis on the group of B. licheniformis isolates based on the universally house-keeping genes, gyrB and parE, revealed high sequence similarities in both genes among the strains of both locations (99.0-99.4%), which clustered them in a monophyletic line. Phenotype characterized by numerical taxonomy for 150 physiological tests confirmed the close relatedness between strains (similarity coefficient S SM = 96.0%). The remarkable agreement between phenotype and genotype of the bacterial isolates allows us to conclude that there may have been an aerosolized dispersion of a Gobi Desert B. licheniformis by dust storms to Japan. This study provides evidence of microbial transport by yellow dust events in NorthEast Asia.
The genus Halobacillus, with the type species Halobacillus halophilus, was established and described by Spring and co-workers in 1996 (Claus et al., 1983;Spring et al., 1996). So far, nine species of this genus have been identified (Amoozegar et al., 2003a, b;Yoon et al., 2003Yoon et al., , 2004Yoon et al., , 2005Liu et al., 2005). The increasing number of publications on bio-applications and other aspects of Halobacillus and the large number of 16S rRNA gene sequences deposited in databases for unidentified species reflect the wide distribution of these bacteria and their considerable scientific interest (Burja et al., 1999;Pinar et al., 2001;Yang et al., 2002; Rivadeneyra et al., 2004). In our investigations of the diversity of halophilic bacteria in various habitats over the last few years, we obtained strains IS-Hb4 T and IS-Hb7 T in an endemic population from a carbonate rock collected at a deep-sea methane seep at Kuroshima Knoll, south-western Japan. Living in the special environment of low temperature, high pressure and low oxygen availability, these bacteria possess several features that are different from those of described species that would be considered evidence of interesting adaptation.Samples from which the bacteria were isolated, carbonate rocks authentically formed in a methane seep of the Kuroshima Knoll, located at 642 m depth at 24 u 07.89 N 124 u 11.29 E (Fujikura et al., 2003;Inagaki et al., 2004), were collected with the remotely operated vehicle Dolphin 3K, operated by the Japan Agency for Marine Earth Science and Abbreviation: CZE, capillary zone electrophoresis.
A Gram-positive, endospore-forming, rod-shaped and moderately halophilic bacterium was isolated from a salt-crust sample collected from Gharsa salt lake (Chott el Gharsa), Tunisia. The newly isolated bacterium, designated SA-Vb1 Here we report the taxonomic description of a moderately halophilic, Gram-positive, rod-shaped bacterium, strain SA-Vb1 T , which represents a novel species of the genus Virgibacillus.Strain SA-Vb1T was originally isolated from a mixture of dry sediment and salt crusts collected directly from Chott el Gharsa. The sample was inoculated into ATCC medium 925 HP 101 [containing 1 % (w/v) peptone, 0.1 % yeast extract, 10 % NaCl, 0.43 % MgSO 4 . 7H 2 O, 0.2 % NaNO 3 , pH 7.2] and incubated at 30 u C. Pure cultures were Abbreviation: CZE, capillary zone electrophoresis.The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain SA-Vb1 T is AB197851.Fatty acid profiles of strain SA-Vb1 T and related type strains and detailed 16S rRNA gene sequence similarity and DNA-DNA hybridization results are available as supplementary material with the online version of this paper.
DNA base composition expressed as mol% of guanine plus cytosine (% GC) or GC content is a key parameter of bacterial taxonomy and genomic analyses. Direct chemical determination methods such as HPLC as well as indirect methods based on physical properties of deoxyribonucleic acid (DNA), melting point (T(m)), and buoyant density (B(d)) have been conventionally applied to determine the GC content. However, these methods require relatively large amounts of sample DNA, time, and labor. We have developed a protocol to determine the GC content by fine separation of nucleosides with CZE. Genomic DNAs with known GC content from 23 bacterial strains were determined by CE at the optimized conditions of 27 degrees C, 20 kV in 50 mM of NaHCO(3) (pH 9.0) and 70 mM SDS added. Nucleosides from <1 microg of DNA hydrolyzed with nuclease-P1 and bacterial alkaline phosphatase were separated in a 75 microm wide and 80 cm long silica capillary. The nucleoside peak areas were determined at 254 nm in less than 12 min. The CE-based determination of GC content requires only small amounts of DNA, and thus should be applicable to environmental genomics (metagenomics), as >90% of environmental micro-organisms are nonculturable and produce only small amounts of genomic DNA.
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