Moreno Edgardo, Cloeckaert Axel, Moriyón Ignacio
Tropical Disease Research Program, Veterinary School, National University, Apartado 304-3000, Heredia, Costa Rica.
Vet Microbiol. 2002 Dec 20;90(1-4):209-27. doi: 10.1016/s0378-1135(02)00210-9.
The genus Brucella contains alpha-Proteobacteria adapted to intracellular life within cells of a variety of mammals. Controversy has arisen concerning Brucella internal taxonomy, and it has been proposed that the DNA-DNA hybridization-based genomospecies concept be applied to the genus. According to this view, only one species, Brucella melitensis, should be recognized, and the classical species should be considered as biovars (B. melitensis biovar melitensis; B. melitensis biovar abortus; etc.). However, a critical reappraisal of the species concept, a review of the population structure of bacteria and the analysis of Brucella genetic diversity by methods other than DNA-DNA hybridization show that there are no scientific grounds to apply the genomospecies concept to this genus. On the other hand, an enlarged biological species concept allows the definition of Brucella species that are consistent with molecular analyses and support the taxonomical standing of most classical species. Both the host range as a long-recognized biological criterion and the presence of species-specific markers in outer membrane protein genes and in other genes show that B. melitensis, B. abortus, B. ovis, B. canis and B. neotomae are not mere pathovars (or nomenspecies) but biologically meaningful species. The status of B. suis is, however, less clear. These approaches should be useful to define species for the marine mammal Brucella isolates, as illustrated by the grouping of the isolates from pinnipeds or from cetaceans by omp2 gene analysis. It is shown that a correct Brucella species definition is important to understand the evolution of the genus.
布鲁氏菌属包含适应于在多种哺乳动物细胞内进行胞内生活的α-变形菌。关于布鲁氏菌的内部分类学已经出现了争议，有人提议将基于DNA-DNA杂交的基因组种概念应用于该属。按照这种观点，只应承认一个种，即羊种布鲁氏菌，而经典的种应被视为生物变种（羊种布鲁氏菌生物变种羊种；羊种布鲁氏菌生物变种流产种等）。然而，对种概念的严格重新评估、对细菌种群结构的综述以及通过DNA-DNA杂交以外的方法对布鲁氏菌遗传多样性的分析表明，没有科学依据将基因组种概念应用于该属。另一方面，一个扩大的生物学种概念允许定义与分子分析一致的布鲁氏菌种，并支持大多数经典种的分类地位。作为一个长期公认的生物学标准的宿主范围以及外膜蛋白基因和其他基因中物种特异性标记的存在表明，羊种布鲁氏菌、流产种布鲁氏菌、绵羊种布鲁氏菌、犬种布鲁氏菌和新墨西哥州布鲁氏菌不仅仅是致病变种（或命名种），而是具有生物学意义的种。然而，猪种布鲁氏菌的地位不太明确。这些方法对于定义海洋哺乳动物布鲁氏菌分离株的种应该是有用的，如通过omp2基因分析对来自鳍足类动物或鲸类动物的分离株进行分组所示。结果表明，正确定义布鲁氏菌种对于理解该属的进化很重要。
