Molecular Characterization of a Lactococcal Plasmid Reducing the Growth Rate of Host Cells
| Autor: | Masaru Nomura, Takashi Okamoto, Sadahiro Ohmomo, Miho Kobayashi, Yasuhito Fujita |
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| Rok vydání: | 2003 |
| Předmět: | |
| Zdroj: | Japan Agricultural Research Quarterly: JARQ. 37:53-57 |
| ISSN: | 2185-8896 0021-3551 |
| DOI: | 10.6090/jarq.37.53 |
| Popis: | Lactococcus Lactis subsp. lactis biovar. diacetylactis DRC1 carries more than 6 plasmids, including a 7.4 kb cryptic plasmid, which was designated as pDR1-1. The pDR1-1 plasmid was found to significantly affect the maximum specific growth rate (μ m a x ) of the host cells because of its limiting effect on growth. To investigate the properties of the limiting effect, the entire nucleotide sequence of pDR1-1 was determined. It consisted of 7412 bp, and 6 open reading frames (ORFs) were identified. The first ORF showed a high degree of similarity to a family of replication genes (rep) that are commonly found in lactococcal strains. The rep gene in pDR1-1was followed by a second ORF of unknown function. Directly downstream of the second ORF, a third ORF was found, that showed homology to the S subunit from type 1 restriction/modification systems. No significant similarity to the contents of the database was found for the other ORFs. PCR analysis was carried out in order to detect pDR1-1 in the other L lactis strains. The μ m a x of the pDR1-1-positive strain was the same as that of DRC1. These results suggest that the load of pDR1-1 (or pDR1-1-like plasmid) is a major factor influencing the μ m a x of DRC1 because of its limiting effect on growth, an effect which is much more pronounced than that produced by the overall load of other coexisting plasmids. |
| Databáze: | OpenAIRE |
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