Dataset Information


Phages of non-dairy lactococci: isolation and characterization of ?L47, a phage infecting the grass isolate Lactococcus lactis ssp. cremoris DPC6860.

ABSTRACT: Lactococci isolated from non-dairy sources have been found to possess enhanced metabolic activity when compared to dairy strains. These capabilities may be harnessed through the use of these strains as starter or adjunct cultures to produce more diverse flavor profiles in cheese and other dairy products. To understand the interactions between these organisms and the phages that infect them, a number of phages were isolated against lactococcal strains of non-dairy origin. One such phage, ?L47, was isolated from a sewage sample using the grass isolate L. lactis ssp. cremoris DPC6860 as a host. Visualization of phage virions by transmission electron microscopy established that this phage belongs to the family Siphoviridae and possesses a long tail fiber, previously unseen in dairy lactococcal phages. Determination of the lytic spectrum revealed a broader than expected host range, with ?L47 capable of infecting 4 industrial dairy strains, including ML8, HP and 310, and 3 additional non-dairy isolates. Whole genome sequencing of ?L47 revealed a dsDNA genome of 128, 546 bp, making it the largest sequenced lactococcal phage to date. In total, 190 open reading frames (ORFs) were identified, and comparative analysis revealed that the predicted products of 117 of these ORFs shared greater than 50% amino acid identity with those of L. lactis phage ?949, a phage isolated from cheese whey. Despite their different ecological niches, the genomic content and organization of ?L47 and ?949 are quite similar, with both containing 4 gene clusters oriented in different transcriptional directions. Other features that distinguish ?L47 from ?949 and other lactococcal phages, in addition to the presence of the tail fiber and the genome length, include a low GC content (32.5%) and a high number of predicted tRNA genes (8). Comparative genome analysis supports the conclusion that ?L47 is a new member of the 949 lactococcal phage group which currently includes the dairy ?949.

PROVIDER: S-EPMC3888941 | BioStudies |

REPOSITORIES: biostudies

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