Open Access Research article

Differential efficiency in exogenous DNA acquisition among closely related Salmonella strains: implications in bacterial speciation

Hong-Xia Bao1238, Le Tang1238, Lu Yu123, Xu-Yao Wang123, Yang Li123, Xia Deng123, Yong-Guo Li4, Ang Li5, Da-Ling Zhu26, Randal N Johnston7, Gui-Rong Liu123*, Ye Feng1239* and Shu-Lin Liu12348*

Author Affiliations

1 Genomics Research Center (one of The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin 150081, China

2 Department of Biopharmaceutical Sciences, Harbin Medical University, Harbin, China

3 HMU-UCFM Centre for Infection and Genomics, Harbin Medical University, Harbin, China

4 Department of Infectious Diseases of First Affiliated Hospital, Harbin Medical University, Harbin, China

5 Department of Biostatistics, Harbin Medical University, Harbin, China

6 College of Pharmacy of Daqing Campus, Harbin Medical University, Harbin, China

7 Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Canada

8 Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Canada

9 Institute for Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China

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BMC Microbiology 2014, 14:157  doi:10.1186/1471-2180-14-157

Published: 14 June 2014

Abstract

Background

Acquisition of exogenous genetic material is a key event in bacterial speciation. It seems reasonable to assume that recombination of the incoming DNA into genome would be more efficient with higher levels of relatedness between the DNA donor and recipient. If so, bacterial speciation would be a smooth process, leading to a continuous spectrum of genomic divergence of bacteria, which, however, is not the case as shown by recent findings. The goal of this study was todetermine if DNA transfer efficiency is correlated with the levels of sequence identity.

Results

To compare the relative efficiency of exogenous DNA acquisition among closely related bacteria, we carried out phage-mediated transduction and plasmid-mediated transformation in representative Salmonella strains with different levels of relatedness. We found that the efficiency was remarkably variable even among genetically almost identical bacteria. Although there was a general tendency that more closely related DNA donor-recipient pairs had higher transduction efficiency, transformation efficiency exhibited over a thousand times difference among the closely related Salmonella strains.

Conclusion

DNA acquisition efficiency is greatly variable among bacteria that have as high as over 99% identical genetic background, suggesting that bacterial speciation involves highly complex processes affected not only by whether beneficial exogenous DNA may exist in the environment but also the “readiness” of the bacteria to accept it.

Keywords:
Bacterial speciation; Homologous recombination; Salmonella; Transduction; Transformation