Article Abstract:
Proteolytic activity in Lactococcus lactis Wg2 requires the expression of prtP, which encodes a serine proteinase, and prtM, which is involved in the processing of the proteinase. The transcriptional start and termination signals for these genes were determined. The localization of these sequences allowed for further characterization. The results showed that the Wg2 promoter is not as strong as previously isolated promoters. The proteolytic activity of the bacterium was increased by orienting the two prt genes in tandem, and replacing the native promoter with a stronger one.
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Article Abstract:
A rapid and efficient purification method for small, hydrophobic, cationic bacteriocins, Lactococcin B and Pediocin PA-1 involves ethanol precipitation, preparative isoelectric focussing and ultrafiltration. The method has an edge over other purification protocols as it reproducibly leads to pure bacteriocin preparations and high final yields of 30-40%. Minimal loss of activity occurs during isoelectric focusing, and all activity remains unaltered after ultrafiltration.
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Article Abstract:
Polymerase chain reaction analysis and southern hybridization to study lactococcin production and secretion in Lactococcus lactis IL1403, a plasmid-free strain that does not produce bacteriocin. Results suggest that the strains of L. lactis are capable of carrying a bacteriocin secretion and maturation mechanism without producing bacteriocin. This mechanism is found in the genes of the chromosomes of L. lactis.
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