Bacteriocins

Numerous bacteriocins are produced by lactic acid bacteria (Klaenhammer, 1988), but only a few bacteriocins have been found in propionibacteria (Lyon and Glatz, 1991, 1993 Giinstead and Barefoot, 1992). Recently, 14 dairy propionibacteria were screened for catalase-insentitive, protease-sensitive inhibition of Gram-positive and Gramnegative bacteria (Ratnam et al., 1998). Bacteriocin production was identified in 57% of these cultures. 

Jensenin G is produced by P. Jensenii 126, and is pH-tolerant (pH 2-11.0) and heat-stable, has a molecular weight of 4.5 kDa. It is active against propionibacteria, botulinal spores, lactobacilli, lactococci and Streptococcus thermophilus (Barefoot et al, 1995). 

Jensenin P is a bacteriocin produced by P. jensenii B1264- which inhibits closely related propionibacteria and lactic acid bacteria. It was shown that jensenin P is a new anionic bacteriocin (Ratnam et al., 1998). Jensenin P is stable at lOOT for 45 min, at pH 2 to 10 for 225 min, and in 0.1 to 0.3M NaCl (pH 10) for 225 min (Barefoot et al., 1995). The resistance of jensenins to the extremes of pH and high temperature, their wide inhibitory spectrum allows to consider them as useful natural preservatives in thermal food processing. P. jensenii strain DFl was found (Miesher et al., 1998) to markedly inhibit other P. jensenii strains and to suppress 15 out of 24 yeasts and 3 out of 4 molds tested. From the culture broth of P. jensenii DFl an inhibitory protein substance, named SMI, was isolated and partially purified (Miesher et al., 1998). Crude propionicin SMI was sensitive to proteolytic enzymes and stable to incubation at 30°C (more than 14 days), cold storage (more than 6 months at 4 C) and heat treatment (15 min, 100 C). 

Concerning the cutaneous propionibacteria, the data on their bacteriocins are scarce. Two bacteriocin-like substances were partially purified from a strain of P. acnes acnecin CN-8 and bacteriocin RTT108 (Fujimura and Nakamura, 1978). Acnecin was inhibitory to other strains of P. acnes, and bacteriocin RTT108 was active against both Gram-negative and Grampositive anaerobes. 

The first report of the production of a bacteriocin produced by lactic acid bacteria was made in 1928 [24]. The substance was determined as a polypeptide [25] and subsequently named nisin [26,27]. Since that time the bacteriocin field has expanded exponentially, and now bacteriocins produced by all genera of the lactic acid bacteria have been reported [1,21]. 

The majority of bacteriocins from lactic acid bacteria have been characterized according to the early definition of a proteinaceous inhibitor, estimation of their molecular mass, and determination of their inhibition spectrum [1,21]. Recent developments in the biochemical and molecular biological characterization of many of these compounds have elucidated their genetic organization, structures and mode of action. Despite their heterogeneity, bacteriocins produced by lactic acid bacteria were subdivided into three distinct classes based on these genetic and biochemical resemblances [28]. 

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Lactic acid-producing bacteria associated with fermented dairy products have been found to produce antibiotic-like compounds caUed bacteriocins. Concentrations of these natural antibiotics can be added to refrigerated foods in the form of an extract of the fermentation process to help prevent microbial spoilage. Other natural antibiotics are produced by Penicillium wqueforti the mold associated with Roquefort and blue cheese, and by Propionibacterium sp., which produce propionic acid and are associated with Swiss-type cheeses (3). 

Bacteriocin- Agent produced by certain bacteria that inhibits or kills closely related isolates and species. 

A number of additional methods have been proposed to target CH4 emissions such as the use of bacteriophages and bacteriocins (McAllister and Newbold, 2008), defaunation, and reductive acetogenesis (Martin et ah, 2010 McAllister and Newbold, 2008). Additional research is needed as well as animal trials for potential use on dairy farms. 

Hindre, T. Didelot, S. Le Pennec, J.-P Haras, D. Dufour, A. Vallee-Rehel, K. Bacteriocin detection from whole bacteria by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Appl. Environ. Microbiol. 2003, 69,1051-1058. 

Mahapatra, A.K., Muthukumarappan, K. and Julson, J.L. (2005) Applications of ozone, bacteriocins and irradiation in food processing a review . Criticul Reviems Food Science and Nutrition, 45, 447-461. 

The effectiveness of bacteriocins is often a function of environmental factors such as pH, temperature, food composition, structure, and food microflora (De Vuyst and Leroy 2007). A novel bacteriocin-like substance produced by Bacillus licheniformis P40 inhibits the activity of the soft rot bacterium Envinia carotovora. This compound caused a bactericidal effect on the pathogen cells at a 30 p.g/mL concentration (Cladera-Olivera and others 2006). 

Cladera-Olivera F, Caron GR, Motta AS, Souto AA and Brandelli A. 2006. Bacteriocin-like substance inhibits potato soft rot caused by Erwinia carotovora. Can J Microbiol 52(6) 533-539. 

De Vuyst L and Leroy F. 2007. Bacteriocins from lactic acid bacteria production, purification, and food applications. J Mol Microbiol Biotechnol 13 194-199. 

Galvez A, Abriouel H, Lopez RL and Ben Omar N. 2007. Bacteriocin-based strategies for food biopreservative. Int J Food Microbiol 120(l-2) 51-70. 

Bacteriological sulfur, 23 577-578 Bacteriophages, 3 135 12 474 in fermentation, 11 46 Bacteriorhodopsin, 20 826, 840 photochromic material, 6 603 Bacteriosins, 12 76. See also Bacteriocins Bacteriostatic water, 18 714 Bacterium lactis, 11 7 Baculovirus expression system, 5 346 Baddeleyite, 21 489 26 623-624 colorants for ceramics, 7 346t Badische Anilin und Soda Fabrik (BASF) terpenoid manufacture process, 24 481 Baeyer-Villiger oxidation reactions, 14 592 chiral recognition by enzymes, 3 675 microbial, 16 401 Baffled shellside flow, 13 262 Baffles, in stirred tank geometries,... 

The detailed structure of the small bacteriocin (isolated from the culture broth of the Gram-negative bacterium Rhizobium leguminosarum) as N-[(3R)-hydroxy-7-ns-tetradecenoyl]-L-HSL 14 was elucidated largely by the 1-D and 2-D and 13C spectroscopy. The absolute configuration of both asymmetric carbon atoms in the molecule was determined by the use of chiral solvating agents (S)-(+)- and (R)-(-)-2,2,2-trifhioro-l-(9-anthryl)ethanol [11]. 

Figure 6 Sequence alignment of lantibiotic and nonlantibiotic bacteriocin prepeptides. The residues in red indicate those positions that are fully conserved within that class, and those in blue are highly conserved. For the nonlantibiotic bacteriocins, only the leader sequences are shown. The site of proteolysis is indicated by the arrow. For cytolysin, the additional six residues removed by CylA are indicated in green.

Peptide Pheromone Dependent Signaling Systems in Bacteriocin Production 305... 

The Signaling Pathway of Plantaricin Cl 1 System and Other Class II Bacteriocins 307... 

The regulation of bacteriocin synthesis by PPs goes back to mid-1990s when it was shown that the Class II bacteriocins (nonmodified heat-stable bacteriocins) as well as Class I bacteriocins most often referred to as lantibiotics (post-translatory modified containing most frequently lanthionine, methyl-lanthionine, dehydrated serine, and threonine) were regulated by small ribosomally synthesized peptides either resembling a peptide... 

Table 1 Peptide pheromones (PPs) involved in regulation of Class I involved in different bacteriocin systems...

Bacteriocin Peptide pheromone Length of amino acid residues Reference(s) Producer... 

Since the initial discovery of quorum sensing regulation of bacteriocin synthesis in LAB, numerous systems have been described both among Class I and Class II bacteriocins. An overview of the best-characterized PPs of the various three-component systems among Class II bacteriocins is presented in Tables 1 and 2. It should be emphasized that not all Class II bacteriocins are regulated through such a quorum sensing system and several bacteriocins seem to be constitutively produced. 

In the first part of this review, the regulation of plantaricin expression in L. plantarum will be used as the model to describe the signaling system of bacteriocin biosynthesis and where relevant, it will be extended to other similar systems to emphasize differences between the various systems. 

In the plantaricin system, five operons are coordinately controlled by the plantaricin A signaling system. In addition to the regulatory operon, two operons encode bacteriocin precursors and immunity proteins, one operon encodes the transport system of the bacteriocins and the PP itself, and the last operon contains four genes of unknown function (it could be a bacteriocin encoding operon but no activity has been found so far). The key operon encoding the three-component signaling pathway (composed of a PP, an HPK, and two RRs) will be discussed below. 

The existence of specific binding sites for RR was also experimentally demonstrated in sakacin P production in Lactobacillus sake LTH673 that involves at least four regulated operons. The promoters controlling bacteriocin operons were shown to be strictly regulated, and their activity increased more than 1000-fold upon activation by a PP. 

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