Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA.
Appl Environ Microbiol. 2013 Nov;79(22):6903-10. doi: 10.1128/AEM.01777-13. Epub 2013 Aug 30.
Many strains of Bifidobacterium animalis subsp. lactis are considered health-promoting probiotic microorganisms and are commonly formulated into fermented dairy foods. Analyses of previously sequenced genomes of B. animalis subsp. lactis have revealed little genetic diversity, suggesting that it is a monomorphic subspecies. However, during a multilocus sequence typing survey of Bifidobacterium, it was revealed that B. animalis subsp. lactis ATCC 27673 gave a profile distinct from that of the other strains of the subspecies. As part of an ongoing study designed to understand the genetic diversity of this subspecies, the genome of this strain was sequenced and compared to other sequenced genomes of B. animalis subsp. lactis and B. animalis subsp. animalis. The complete genome of ATCC 27673 was 1,963,012 bp, contained 1,616 genes and 4 rRNA operons, and had a G+C content of 61.55%. Comparative analyses revealed that the genome of ATCC 27673 contained six distinct genomic islands encoding 83 open reading frames not found in other strains of the same subspecies. In four islands, either phage or mobile genetic elements were identified. In island 6, a novel clustered regularly interspaced short palindromic repeat (CRISPR) locus which contained 81 unique spacers was identified. This type I-E CRISPR-cas system differs from the type I-C systems previously identified in this subspecies, representing the first identification of a different system in B. animalis subsp. lactis. This study revealed that ATCC 27673 is a strain of B. animalis subsp. lactis with novel genetic content and suggests that the lack of genetic variability observed is likely due to the repeated sequencing of a limited number of widely distributed commercial strains.
许多双歧杆菌动物亚种。乳杆菌被认为是有益健康的益生菌微生物，通常被制成发酵乳制品。对双歧杆菌动物亚种。乳杆菌先前测序的基因组分析显示遗传多样性很小，表明它是一个单态亚种。然而，在双歧杆菌的多位点序列分型调查中，发现双歧杆菌动物亚种。乳杆菌 ATCC 27673 的图谱与该亚种的其他菌株明显不同。作为正在进行的研究的一部分，旨在了解该亚种的遗传多样性，对该菌株的基因组进行了测序，并与其他双歧杆菌动物亚种。乳杆菌和双歧杆菌动物亚种。ATCC 27673 的完整基因组为 1,963,012 bp，包含 1,616 个基因和 4 个 rRNA 操纵子，GC 含量为 61.55%。比较分析表明，ATCC 27673 的基因组包含 6 个独特的基因组岛，编码 83 个开放阅读框，在同一亚种的其他菌株中未发现。在四个岛屿中，鉴定出噬菌体或移动遗传元件。在第 6 个岛屿中，发现了一个新的簇状规则间隔短回文重复（CRISPR）基因座，其中包含 81 个独特的间隔子。这种 I-E 型 CRISPR-cas 系统与该亚种先前鉴定的 I-C 系统不同，代表了在双歧杆菌动物亚种中首次鉴定出不同的系统。乳杆菌。这项研究表明，ATCC 27673 是双歧杆菌动物亚种。乳杆菌具有新的遗传特征，并表明观察到的遗传可变性缺乏可能是由于对广泛分布的商业菌株进行了有限数量的重复测序。
