Population Structure of Pathogenic Bacteria
Population Structure of Pathogenic Bacteria
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DOI：
10.1016/b978-0-12-799942-5.00003-2
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发表时间：
2017-01-01
期刊：
影响因子：
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通讯作者：
Robinson, D. A.
中科院分区：
文献类型：
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作者：
Andam, C. P.;Challagundla, L.;Robinson, D. A.
There is no universally accepted definition for a bacterial population. This deficiency might be viewed as a consequence of the longstanding, and sometimes contentious, discussion on the nature of species in the bacterial world. 1e6 At present, existing bacterial species labels are more often a reflection of practical necessity and arbitrary thresholds, many of which are rooted in historical methods of phenotypic characterization and without reference to any ecological or evolutionary theory. This is particularly noticeable for many bacterial pathogens that were named after the disease they cause (eg, Burkholderia pseudomallei and Burkholderia mallei, Neisseria meningitidis, andNeisseria gonorrhoeae). 7 Resolution of the species “dilemma” is therefore essential as it has practical application to human and veterinary health, agriculture, and biosafety, but the species concept also embraces more fundamental biological questions that remain unanswered today: What are the characteristics shared between all members of a species? What is the unit of selection in bacterial evolution? How does the standard taxonomic demarcation of species reflect ecology and niche boundaries? A frequently used method to classify bacterial isolates is multilocus sequence typing (MLST), which involves the sequencing of single-copy housekeeping gene fragments (usually seven) and using the allelic mismatches between isolates to define strains or clones. 8 This method has proven to be a popular and effective tool in microbiology, particularly in identifying clinically important lineages of pathogenic bacteria. 9 Its utility in pathogen research is largely due to its use of multiple loci, which provides greater taxonomic resolution while allowing detection of the distorting effects of recombination between strains. It is important to note that MLST genes are also not immune to recombination, which can lead to taxonomic ambiguities within and even between species. The concept of “fuzzy species” has therefore been used to describe strains containing sequences typical of more than one species and thus do not form clear and distinct sequence clusters. 10, 11
