Kihyun Lee

INTRODUCING EZTAXON-E: A PROKARYOTIC 16S RRNA GENE SEQUENCE DATABASE WITH PHYLOTYPES THAT REPRESENT UNCULTURED SPECIES

Despite recent advances in commercially optimized identification systems, bacterial identification remains a challenging task in many routine microbiological laboratories, especially in situations where taxonomically novel isolates are involved. The 16S rRNA gene has been used extensively for this task when coupled with a well-curated database, such as EzTaxon, containing sequences of type strains of prokaryotic species with validly published names. Although the EzTaxon database has been widely used for routine identification of prokaryotic isolates, sequences from uncultured prokaryotes have not been considered. Here, the next generation database, named EzTaxon-e, is formally introduced. This new database covers not only species within the formal nomenclatural system but also phylotypes that may represent species in nature. In addition to an identification function based on Basic Local Alignment Search Tool (blast) searches and pairwise global sequence alignments, a new objective method of assessing the degree of completeness in sequencing is proposed. All sequences that are held in the EzTaxon-e database have been subjected to phylogenetic analysis and this has resulted in a complete hierarchical classification system. It is concluded that the EzTaxon-e database provides a useful taxonomic backbone for the identification of cultured and uncultured prokaryotes and offers a valuable means of communication among microbiologists who routinely encounter taxonomically novel isolates. The database and its analytical functions can be found at http://eztaxon-e.ezbiocloud.net/.

EzEditor: a versatile sequence alignment editor for both rRNA- and protein-coding genes.

EzEditor is a Java-based molecular sequence editor allowing manipulation of both DNA and protein sequence alignments for phylogenetic analysis. It has multiple features optimized to connect initial computer-generated multiple alignment and subsequent phylogenetic analysis by providing manual editing with reference to biological information specific to the genes under consideration. It provides various functionalities for editing rRNA alignments using secondary structure information. In addition, it supports simultaneous editing of both DNA sequences and their translated protein sequences for protein-coding genes. EzEditor is, to our knowledge, the first sequence editing software designed for both rRNA- and protein-coding genes with the visualization of biologically relevant information and should be useful in molecular phylogenetic studies. EzEditor is based on Java, can be run on all major computer operating systems and is freely available from http://sw.ezbiocloud.net/ezeditor/.

Flavobacterium limnosediminis sp. nov., isolated from sediment of a freshwater lake.

A Gram-stain-negative, rod-shaped, pale yellow, aerobic bacterial strain, JC2902(T), was isolated from a sediment sample of Ungok Lake in Gochang, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain JC2902(T) belongs to the genus Flavobacterium and forms a distinct phyletic line within a clade containing four recognized species of the genus Flavobacterium. The genomic relatedness between strain JC2902(T) and closely related strains was calculated using average nucleotide identity values of whole genome sequences, which indicated that the new isolate represents a novel genomic species. Through comparison of chemotaxonomic and other phenotypic characteristics between strain JC2902(T) and the type strains of the four phylogenetically related species, a number of characteristics differentiated strain JC2902(T) from the previously described type strains. Differential characteristics of strain JC2902(T) include fatty acid profiles, cellular motility, inability to grow on Luria-Bertani and tripticase soy agar media, and absence of N-acetyl-β-glucosaminidase and flexirubin-type pigments. Based on data from this polyphasic taxonomic study, strain JC2902(T) is considered to represent a novel species of the genus Flavobacterium, for which the name Flavobacterium limnosediminis sp. nov. is proposed. The type strain is JC2902(T) ( = KACC 16937(T) = JCM 18661(T)).

Burkholderia megalochromosomata sp. nov., isolated from grassland soil

A Gram-stain negative, rod-shaped, non-spore-forming, obligate aerobic bacterial strain, JC2949(T), was isolated from grassland soil in Gwanak Mountain, Seoul, Republic of Korea. Phylogenetic analysis, based on 16S rRNA sequences, indicated that strain JC2949(T) belongs to the genus Burkholderia, showing highest sequence similarities with Burkholderia grimmiae R27(T) (98.8 %), Burkholderia cordobensis LMG 27620(T) (98.6 %), Burkholderia jiangsuensis MP-1T(T) (98.6 %), Burkholderia zhejiangensis OP-1(T) (98.5 %), Burkholderia humi LMG 22934(T) (97.5 %), Burkholderia terrestris LMG 22937(T) (97.3 %), Burkholderia telluris LMG 22936(T) (97.2 %) and Burkholderia glathei ATCC 29195(T) (97.0 %). The major fatty acids of strain JC2949(T) were C18 : 1ω7c, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. Its predominant polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and an unknown amino phospholipid. The dominant isoprenoid quinone was ubiquinone Q-8. The pairwise average nucleotide identity values between strain JC2949(T) and the genomes of 30 other species of the genus Burkholderia ranged from 73.4-90.4 %, indicating that the isolate is a novel genomic species within this genus. Based on phenotypic and chemotaxonomic comparisons, it is clear that strain JC2949(T) represents a novel species of the genus Burkholderia. We propose the name for this novel species to be Burkholderia megalochromosomata sp. nov. The type strain is JC2949(T) ( = KACC 17925(T) = JCM 19905(T)).

Draft Genome Sequence of Escherichia coli AI27, a Porcine Isolate Belonging to Phylogenetic Group B1

Escherichia coli AI27 is a putatively commensal strain isolated from feces of a pig. Here we report the draft genome sequence of E. coli AI27. This is the first porcine strain in the phylogenetic group B1 whose genome sequence has been determined.

Repair Crew Scheduling Considering Variable Disaster Aspects

Human beings have suffered from disasters continuously, therefore, the post-disaster efforts to reduce additional damages have been widely conducted. In this study, we focused on the repair crew scheduling to set a plan for repairing destroyed roads. Rural areas were considered because of limited link members of supply chain networks, and rural isolation caused by road destruction is the main concern of this study. To reflect the intrinsic nature of a disaster in the short-term, additional damages and variable damage rates were considered. The repair crew scheduling problem considering variable disaster aspects was proposed to minimize total damages caused by isolation. A small-scale experiment was conducted and the result showed that our model can be used to effectively reduce further damages compared to previous research.