Lactic acid bacteria produce a variety of bacteriocins that have recently come under detailed investigation. The biochemical and genetic characteristics of these antimicrobial proteins are reviewed and common elements are discussed between the different classes of bacteriocins produced by these Gram-positive bacteria.

Genetics of bacteriocins produced by lactic acid bacteria

A large number of new bacteriocins in lactic acid bacteria (LAB) has been characterized in recent years. Most of the new bacteriocins belong to the class II bacteriocins which are small (30–100 amino acids) heat-stable and commonly not post-translationally modified. While most bacteriocin producers synthesize only one bacteriocin, it has been shown that several LAB produce multiple bacteriocins (2–3 bacteriocins).

Biosynthesis of bacteriocins in lactic acid bacteria

http://wpage.unina.it/giamauri/Materiale_vario/Preservation_fermentation.pdf

Preservation and fermentation: past, present and future.

Biological preservation of foods with reference to protective cultures, bacteriocins and food-grade enzymes

The lantibiotics are a group of ribosomally synthesised, post-translationally modified peptides containing unusual amino acids, such as dehydrated and lanthionine residues. This group of bacteriocins has attracted much attention in recent years due to the success of the well characterised lantibiotic, nisin, as a food preservative. Numerous other lantibiotics have since been identified and can be divided into two groups on the basis of their structures, designated type-A and type-B. To date, many of these lantibiotics have undergone extensive characterisation resulting in an advanced understanding of them at both the structural and mechanistic level. This review outlines some of the more recent developments in the biochemistry, genetics and mechanism of action of these peptides.

Lantibiotics: structure, biosynthesis and mode of action

SUMMARY: Sakacin A, a bacteriocin produced by Lactobacillus sake Lb706 and which inhibits the growth of Listeria monocytogenes, was purified to homogeneity by ammonium sulphate precipitation and ion-exchange, hydrophobic-interaction and reversed-phase chromatography. The complete amino acid sequence of sakacin A was determined by Edman degradation. The bacteriocin consisted of 41 amino acid residues and had a calculated M
r of 4308.7, which is in good agreement with the value determined by mass spectrometry. The structural gene encoding sakacin A (sakA) was cloned and sequenced. The gene encoded a primary translation product of 59 amino acid residues which was cleaved between amino acids 18 and 19 to yield the active sakacin A. Sakacin A shared some sequence similarities with other bacteriocins.

Purification and amino acid sequence of sakacin A, a bacteriocin from Lactobacillus sake Lb706.

Lactobacillus plantarum is a highly versatile lactic acid bacterium found in various ecological niches, such as fermented vegetable, meat, and dairy products and the gastrointestinal tract We sequenced the genome of L plantarum NC8, a naturally plasmid-free strain, which has been used as a model strain in many laboratories worldwide

https://journals.asm.org/doi/pdf/10.1128/JB.00141-12

Genome Sequence of the Naturally Plasmid-Free Lactobacillus plantarum Strain NC8 (CCUG 61730)

The purpose of this study was to explore the microbiota of Norwegian fermented fish (rakfisk), a traditional product popular in the Norwegian market. Brine samples, collected from six producers during two subsequent years, were used. The producers applied different salt concentrations (between 3.8% and 7.2% NaCl), ripening temperatures (between 3.5 and 7.5 °C), fish species (trout or char), and fish upbringing (wild trout, on-shore farmed trout or char, and off-shore farmed char). The microbiota in the brine during the ripening process was mainly characterized by DNA-based, culture-independent methods. In total, 1710 samples were processed and of these 1342 were used for the final analysis. The microbiota was dominated by Gammaproteobacteria and Bacilli with the largest variance between samples associated with the genera Psychrobacter and Lactobacillus. The variance in the material was mainly determined by the origin of the samples, i.e., the different producers. The microbiota from the individual producers was to a large extent reproducible from one year to the next and appeared to be determined by the relatively small differences in the salinity and the ripening temperature. This is the first study exploring the microbiota in rakfisk brine and it provides insights into environmental factors affecting the rakfisk ecosystems.

https://www.mdpi.com/2304-8158/8/2/72/pdf

Exploring the Brine Microbiota of a Traditional Norwegian Fermented Fish Product (Rakfisk) from Six Different Producers during Two Consecutive Seasonal Productions

SUMMARY: In Bacillus subtilis the α, β, γ and δ components comprise 80–90% of the total acid-soluble spore proteins (ASSPs). Sequence analysis demonstrates that α and β share 32 of their first 36 amino acids and are closely related to the A and C ASSPs of Bacillus megaterium spores, confirming the results of analysis of their cloned genes. Despite the difference in apparent size of γ and δ, they have identical N-terminal sequences (37 residues). Unless γ and δ derive from very recently duplicated genes, it appears that γ is derived from δ, either in vivo or during isolation. Although the sequenced regions of γ and δ have no homology to α and β, outside of the previously recognized pentapeptide recognition sequence for the spore endopeptidase, they share 10 and 15 residue peptides flanking this sequence with ASSP B of B. megaterium, but in reverse order. At least two groups of ASSPs have, therefore, been conserved between B. subtilis and B. megaterium: the multigene ACαβ family and the Bγ(δ) group. Sequence conservation in each group implies selection for functions in addition-to storage. Both the α and β components of B. subtilis ASSPs and their mRNAs are located in the forespore compartment of cells at t
5·5 of sporulation, the time of most rapid ASSP synthesis. The sizes of these transcripts (250–350 bp) and their ability to direct the in vitro synthesis of ASSPs of mature size, indicate that genes for these ASSPs are monocistronic, consistent with dispersed map location. Synthesis of ASSPs is, therefore, coordinately controlled by selective transcription in the forespore.

Hans Blom

Papers

Purification and amino acid sequence of sakacin A, a bacteriocin from Lactobacillus sake Lb706.

Genome Sequence of the Naturally Plasmid-Free Lactobacillus plantarum Strain NC8 (CCUG 61730)

Exploring the Brine Microbiota of a Traditional Norwegian Fermented Fish Product (Rakfisk) from Six Different Producers during Two Consecutive Seasonal Productions

The major acid-soluble proteins of Bacillus subtilis spores: partial amino acid sequence and forespore location of their mRNAs.

Plasmid-Free Lactobacillus plantarum Genome Sequence of the Naturally