Enhancement of nisin production in milk by conjugal transfer of the protease‐lactose plasmid pLP712 to the wild strain Lactococcus lactis UQ2 |
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| Authors: | MARÍA D GARCÍA‐PARRA ANA B CAMPELO BLANCA E GARCÍA‐ALMENDÁREZ CARLOS REGALADO ANA RODRÍGUEZ BEATRIZ MARTÍNEZ |
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| Affiliation: | 1. DIPA, PROPAC, Facultad de Química, Universidad Autónoma de Querétaro, C.U., Cerro de las Campanas s/n Col. Las Campanas, Querétaro, 76010 Qro., México;2. Department of Technology and Biotechnology of Dairy Products, Instituto de Productos Lácteos de Asturias (IPLA‐CSIC), Apdo. 85. 33300‐Villaviciosa, Asturias, Spain |
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| Abstract: | Lactococcus lactis UQ2 is a wild nisin A producer isolated from a Mexican cheese that grows poorly in milk. Conjugal matings with L. lactis NCDO712 to transfer the Lac+ Prt+ plasmid pLP712 and selection with nisin and lactose yielded L. lactis NCDO712 NisA+. Naturally rifampicin resistant L. lactis UQ2Rif was isolated to provide an additional selective marker. The identity of a transconjugant L. lactis UQ2Rif Lac+ was confirmed by RAPD‐PCR fingerprinting, nisA PCR amplification, nisin production, presence of pLP712 and phospho‐β‐galactosidase activity. This strain performed well in milk and synthesised 200 IU/mL nisin, 40 times more than the original strain. |
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| Keywords: | Dairy starter Nisin Lactococcus lactis pLP712 Conjugation |
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