Properties of Nisin Z and distribution of its gene, nisZ, in Lactococcus lactis

Article Abstract:

A comparison of the relevant physicochemical and biological properties of two naturally occuring nisin variants, nisin A and nisin Z, is discussed. Gene level analysis of a large quantity of Lactococcus lactis strains were conducted by polymerase chain reaction amplification of the nis gene and the subsequent sequence analysis of the amplified DNA in order to study the distribution of nisins A and Z producers. Results indicate that nisinZ gene is widely distributed in naturally occuring nisin producing L. lactis strains.

Antibiotics, Genetic aspects, Polymerase chain reaction

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Metabolic engineering of Lactococcus lactis: influence of the overproduction of alpha-acetolactate synthase in strains deficient in lactate dehydrogenase as a function of culture conditions

Article Abstract:

An overproduction of alpha-acetolactate synthase in Lactococcus (L.) lactis, coupled with optimum pH and aeration for fermentation, results in an 85% increase in the conversion of lactose to acetoin. The enzyme overproduction leads to butanediol formation which is 40% of the converted pyruvate in a dehydrogenase-deficient strain of L. lactis under anaerobic conditions. The enzyme overproduction is the result of the overexpression of the als gene.

Physiological aspects, Gene expression, Enzyme kinetics

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Improvement of solubility and stability of the antimicrobial peptide nisin by protein engineering

Article Abstract:

The antimicrobial peptide nisin was modified to increase its solubility and stability. The solubility of nisins A and Z was greater at low ionic strength and low pH. The addition of lysyl residues to nisin Z increased its solubility at neutral pH without significantly affecting its antimicrobial activity. Replacing dehydroalanine on nisin Z with dehydrobutyrine resulted in increased resistance to acid-catalyzed degradation.

Peptides, Protein engineering, Structural stability

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