The types of Nisin

Nisin exists in six types: A, B, C, D, E, and Z, among which types A and Z have been the most extensively and deeply studied. The differences and activity comparisons between them are as follows:

Structural Differences

The overall molecular structures of Nisin A and Nisin Z are similar: both consist of 34 amino acids, contain rare amino acids such as lanthionine and dehydroalanine, and form five internal cyclic structures via thioether bonds. Their only difference lies in the type of amino acid at the 27th position in the sequence: Nisin A has histidine (His) at position 27, while Nisin Z has asparagine (Asn) at the same position.

Differences in Properties and Activity

Solubility: This subtle structural difference results in better solubility of Nisin Z compared to Nisin A. Under the same conditions, Nisin Z dissolves more readily in water or other solvents, making it easier to disperse uniformly in matrices such as food during practical applications, thereby exerting its effects more effectively.

Antimicrobial activity: Generally, Nisin Z exhibits stronger antimicrobial activity than Nisin A. At the same concentration, Nisin Z shows more significant inhibitory effects against various Gram-positive bacteria, including Lactobacillus, Clostridium botulinum, Staphylococcus, and Listeria. However, some studies have found exceptions for specific bacterial strains. For example, in inhibiting Clostridium species, the minimum inhibitory concentration (MIC) of Nisin A is 0.8 μg/mL, much lower than that of Nisin Z, indicating that Nisin A is more effective in this specific scenario. Nevertheless, from the overall body of research, it is a common observation that Nisin Z generally has superior antimicrobial activity relative to Nisin A.

These differences between Nisin A and Nisin Z allow for their selective use based on specific needs and scenarios in practical applications. Further in-depth research on them will also help explore their application potential in fields such as food preservation.