School of Microbiology, University College Cork, T12 YT20 Cork, Ireland.
School of Microbiology, University College Cork, T12 YT20 Cork, Ireland; APC Microbiome Institute, University College Cork, T12 YT20 Cork, Ireland.
Int J Food Microbiol. 2018 May 2;272:29-40. doi: 10.1016/j.ijfoodmicro.2018.02.024. Epub 2018 Mar 1.
Lactococcus lactis is a lactic acid bacterium that is intensively and globally exploited in commercial dairy food fermentations. Though the presence of prophages in lactococcal genomes is widely reported, only limited studies pertaining to the stability of prophages in lactococcal genomes have been performed. The current study reports on the complete genome exploration of thirty lactococcal strains for the presence of potentially intact prophages, so as to assess their genomic diversity and the associated risk or benefit of harbouring such prophages. Genomic predictions partnered with mitomycin C inductions and flow cytometric analysis of the induced cell lysates confirmed that only four strains consistently produced intact phage particles, thus indicating a relatively low risk associated with prophage induction in the fermentation setting. Our analysis revealed the widespread presence of putative phage-resistance systems encoded by lactococcal prophages, thus highlighting the potential benefits for host fitness. Many of the identified lactococcal prophages belong to the so-called P335 phage group, while a large group of phage remnants bear similarity to members of the 936 phage group. The P335 phage group was recently shown to encompass four distinct genetic lineages. Our study identified an additional lineage, thus expanding the diversity of this industrially significant phage group.
乳球菌是一种乳酸细菌，在商业乳制品发酵中被广泛且深入地开发利用。尽管乳球菌基因组中存在前噬菌体已被广泛报道，但仅对乳球菌基因组中前噬菌体的稳定性进行了有限的研究。本研究报告了对三十株乳球菌菌株进行完整基因组探测，以确定其潜在完整前噬菌体的存在，从而评估其基因组多样性以及携带这些前噬菌体的相关风险或益处。基因组预测与丝裂霉素 C 诱导以及诱导细胞裂解物的流式细胞术分析相结合，证实只有四种菌株始终产生完整的噬菌体颗粒，这表明在发酵环境中诱导前噬菌体的风险相对较低。我们的分析揭示了乳球菌前噬菌体编码的广泛存在的噬菌体抗性系统，从而突出了宿主适应性的潜在益处。许多鉴定出的乳球菌前噬菌体属于所谓的 P335 噬菌体群，而大量噬菌体残余物与 936 噬菌体群的成员具有相似性。最近研究表明，P335 噬菌体群包含四个不同的遗传谱系。我们的研究确定了另一个谱系，从而扩展了这一具有重要工业意义的噬菌体群的多样性。
