Author(s): Turova TP, Nazina TN, Mikhalova EM, Rodionova TA, Ekimov AN,
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Abstract Screening of alkane hydroxylase genes (alkB) was performed in the thermophilic aerobic bacteria of the genus Geobacillus. Total DNA was extracted from the biomass of 11 strains grown on the mixture of saturated C10-C20 hydrocarbons, PCR amplification of fragments of alkB genes was performed with degenerate oligonucleotide primers, PCR products were cloned and sequenced. For the first time in the genome of thermophilic bacteria the presence of a set of alkB gene homologues was revealed. The strains each contain three to six homologues among which only two are universal for all of the strains. Comparative phylogenetic analysis of the nucleotide sequences and the inferred amino acid sequences showed close relatedness of six of the revealed variants of geobacilli sequences to the alkB4, alkB3, and alkB2 genes that had previously been revealed by other authors in Rhodococcus erythropolis strains NRRL B-16531 and Q15. The rest two variants of alkB sequences were unique. Analysis of the GC composition of all the Geobacillus alkB homologues revealed closer proximity to the rhodococcal chromosomal DNA than to the chromosomal DNA of geobacilli. This may be an indication of the introduction of the alkB genes into the Geobacillus genome by interspecies horizontal transfer; and rhodococci or other representatives of the Actinobacteria phylum were probably the donors of these genes. Analysis of the codon usage in fragments of alkB genes confirms the suggestion that the pool of these genes is common to the majority of Gram-positive and certain Gram-negative bacteria. Formation of a set of several alkB homologues in a genome of a particular microorganism may result from free gene exchange within this pool.
This article was published in Mol Biol (Mosk)
and referenced in Journal of Petroleum & Environmental Biotechnology