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Open Access Research article

Differentiation of regions with atypical oligonucleotide composition in bacterial genomes

Oleg N Reva12* and Burkhard Tümmler1

Author Affiliations

1 Klinische Forschergruppe, OE6711, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany

2 Danylo Zabolotny Institute of Microbiology and Virology of the National Academy of Science of Ukraine, Dep. of Antibiotics, 154 Zabolotnogo Str., D03680, Kyiv GSP, Ukraine

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BMC Bioinformatics 2005, 6:251  doi:10.1186/1471-2105-6-251

Published: 14 October 2005



Complete sequencing of bacterial genomes has become a common technique of present day microbiology. Thereafter, data mining in the complete sequence is an essential step. New in silico methods are needed that rapidly identify the major features of genome organization and facilitate the prediction of the functional class of ORFs. We tested the usefulness of local oligonucleotide usage (OU) patterns to recognize and differentiate types of atypical oligonucleotide composition in DNA sequences of bacterial genomes.


A total of 163 bacterial genomes of eubacteria and archaea published in the NCBI database were analyzed. Local OU patterns exhibit substantial intrachromosomal variation in bacteria. Loci with alternative OU patterns were parts of horizontally acquired gene islands or ancient regions such as genes for ribosomal proteins and RNAs. OU statistical parameters, such as local pattern deviation (D), pattern skew (PS) and OU variance (OUV) enabled the detection and visualization of gene islands of different functional classes.


A set of approaches has been designed for the statistical analysis of nucleotide sequences of bacterial genomes. These methods are useful for the visualization and differentiation of regions with atypical oligonucleotide composition prior to or accompanying gene annotation.