Nisin

Nisin belong to a group of polypeptide antibiotics (called bacteriocins) produced by Streptococcus lactis which have inhibitory properties directed toward other LAB (Radler, 1990a, 1990b). Yeasts, by comparison, are unaffected. The concentration needed for inhibition varied with species. Leu-conostoc oenos and Pediococcus sp. were controlled at relatively low treatment levels, whereas lactobacilli required much higher doses for inhibition (Radler, 1990a). 

Evaluation of the product during fermentation of several grape varieties suggests no differences in the sensory properties between treated and untreated lots (Radler, 1990b). Currently, nisin is not approved for use in winemaking. 

Nisin is a substance consisting of a mixture of at least two homeomeric peptides. Mattick and Hirsch (406) in 1947 obtained nisin from cultures of a strain of Streptococcus lactis, which exhibits remarkable antibiotic activity with respect to S. agalactiae. It is obtained in the following manner (64). 

Nisin appears to crystallise in the form of long needles, but it is not yet possible to tell whether these are true crystals or tactoids. 

Nisin is very soluble in acidified water, and at room temperature is stable in solution for weeks. It is resistant to ten minutes boiling, but is rapidly destroyed by boiling in alkaline or strongly acid media (22V HCl). The amino acids known to be present in nisin are alanine, valine, leucine and isoleucine. Cystine and aspartic acid may also be present (64). 

The D-glutamylpoly peptide of B. anthrads discovered by Kramar (359) was restudied by Tomcsik et al. (589) as a serologically specific proteinlike substance of encapsulated forms of this bacillus. However, it was Ivanovics et al. (100,313,315) who isolated this substance and showed that it was a peptide composed solely of D-glutamic acid. 

The D-glutamylpolypeptide (= DGP) is an extracellular substance characteristic of Gram-positive spore-forming bacteria belonging to the mesentericus group (310). This peptide, found only in the capsules of B. anthrads, is responsible for the specific dyeing of these capsules by the method of M Fadyean (251,397). Soluble forms of DGP are produced in the culture medium by certain nonencapsulated strains of B. mesentericus (313) and various strains of B. subtilis (88,200,321,336). 

This peptide is formed by several strains of Streptococcus lactis (Langfield-N-group). It contains a number of unusual amino acids, namely dehydroalanine, dehydro-P-methy 1-alanine, 

R = CH3 2-Amino crotonic acid (dehydro-a-amino butyric acid, Dhb ) 

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Fig. 9. Stmcture of nisin where Dha = dehydroalanine Dhb = dehydrobutyrine Abu = a-aminobutyric acid Ala-S-Ala = me50-lanthionine and Abu-S-Ala = t/ireo-methyllanthionine. The first amino acid residue (Ala or Abu) of the lanthionine or methyUanthionine is a D residue all other amino...

Nisin acts bactericidally primarily against gram-positive bacteria. It acts best at acid pH and is almost insoluble at physiological pH. Nisin and probably all lantibiotics appear to permeabilize the bacterial ceU membrane to release small molecules, resulting in an immediate coUapse of the membrane... 

Nisin [1414-45-5] M 3354.2. Polypeptide from 5. lactis. Crystd from EtOH. J 52 529 1952 synthesis by Fukase et al. Tetrahedron Lett 29 795 1988.]... 

Protected 3-methyl-D-cystein (257 Scheme 3.94), a structural unit of the peptide antibiotics nisin and subtilin, has been synthesized through the ring-opening of the aziridinecarbamide 254 with thiobenzoic acid (255) [143, 144]. The reaction took place overnight at room temperature and in methylene chloride to give 256 in greater than 95% yield. 

Notwithstanding the aforementioned difficulty in detecting specific target proteins other than the types normally observed in the taxonomic fingerprints from whole bacteria MALDI spectra (i.e., ribosomal proteins), some other target proteins and protein-like materials have been studied directly from whole cells. For example, Lantibiotics, antimicrobial peptides secreted by Gram-positive bacteria have been detected directly from whole bacteria by MALDI-TOF MS.51 The lantibiotics nisin and lacticin 481 were detected from whole cells and crude supernatants. Surprisingly, better results were reported from whole cells than the supernatants. In this study the presence of variants... 

Mierau, I. and Kleerebezem, M. (2005) 10 years of the nisin-controlled gene expression system (NICE) in Lactococcus lactis. Applied Microbiology and Biotechnology, 68 (6), 705—717. 

Recent results indicate that not only topogenic signals and membrane composition contribute to the proper topology of a membrane protein. The antimicrobial peptide nisin, produced by Lactococcus lactis, kills Gram-positive bacteria via pore formation, thus leading to the permeabilisation of the membrane. Nisin depends on the cell-wall precursor Lipid II, which functions as a docking molecule to support a perpendicular stable transmembrane orientation [43]. 

Annex III lays down the conditions of use for permitted preservatives and antioxidants, with lists of foods and maximum levels in each case. Part A lists the sorbates, benzoates and p-hydroxybenzoates, E 200-E 219 part B lists sulphur dioxide and the sulphites, E 220-E 228 part C lists other preservatives with their uses, including nisin, dimethyl dicarbonate and substances allowed for surface treatment of certain fruits, E 249 potassium nitrite, E 250 sodium nitrite, E 251 sodium nitrate and E 252 potassium nitrate, E 280-E 283 propionic acid and the propionates part D lists the antioxidants E 320 butylated hydroxyanisole (BHA), E 321 butylated hydroxytoluene (BHT), E 310 propyl gallate, E 311 octyl gallate, E 312 dodecyl gallate, E 315 eiythorbic acid and E 316 sodium erythorbate. 

Potential therapeutic applications of host defense peptides also include the lantibiotic nisin. Indeed, nisin has had an impressive history as a food preservative with FDA approval in 1988 for use in pasteurized, processed cheese spreads. The attractiveness of nisin as a potential therapeutic is also enhanced due to its relative resistance to proteases and broad spectrum Gram-positive antimicrobial activity including multidrug-resistant strains. Biosynexus Inc. has licensed the use of nisin for human clinical applications and Immucell Corp. has licensed the use of Mast Out, an antimastitic nisin-containing product, to Pfizer Animal Health." Indeed, nisin formulations have been used as an active agent in the topical therapies Mast Out and Wipe-Out for bovine mastitis, an inflammatory disorder of the udder that is the most persistent disease in dairy cows." ... 

Figure 4 The biosynthesis of nisin A as a representative example of the posttranslational maturation process of lantibiotics. Following ribosomal synthesis, NisB dehydrates serine and threonine residues in the structural region of the prepeptide NisA. NisC subsequently catalyzes intramolecular addition of cysteine residues onto the dehydro amino acids in a stereo- and regioselective manner. Subsequent transport of the final product across the cell membrane by NisT and proteolytic cleavage of the leader sequence by NisP produces the mature lantibiotic. For the sequence of the leader peptide, see Figure 6. Adapted with permission from J. M. Willey W. A. van der Donk, Annu. Rev. Microbiol. 2007, 61, 477-501.

Figure 5 The structural region of the NisA prepeptide is modified by a putative muitienzyme compiex consisting of the dehydratase NisB, the cyclase NisC, and the transporter NisT. After export, the leader peptide is removed by NisP, which is anchored to the cell wall. Mature nisin activates the two-component response regulatory system NisRK, and phosphorylated NisR serves as a positive regulator of nisA and the biosynthetic and immunity operons expressing NisABTC and NisFEG,...

Figure 7 Sequence requirements of the leader peptides of nisin, mutacin II, lacticin 481, and lacticin 3147 as determined by site-directed mutagenesis. For nisin and mutacin II, mutants that still resulted in full processing of the prepeptides are shown in green, whereas mutants that resulted in abolished lantibiotic production are shown in orange. For lacticin 481, the mutants shown in green were good substrates in vitro for either the bifunctional synthetase LctM or the protease domain of LctT, whereas the mutants in orange were poor substrates. Conserved residues in the leader peptides of subgroups of lantibiotics are indicated in blue and red as described in Figure 6.

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