Bacteriocins of gram-positive bacteria.

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

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.

Transformation of Lactobacillus strains used in meat and vegetable fermentations

Transformation of Lactobacillus by electroporation.

Sakacin A is an antilisterial bacteriocin produced by Lactobacillus sake Lb706. In order to identify genes involved in sakacin A production and immunity, the plasmid fraction of L. sake Lb706 was shotgun cloned directly into a sakacin A-nonproducing and -sensitive variant, L. sake Lb706-B, by using the broad-host-range vector pVS2. Two clones that produced sakacin A and were immune to the bacteriocin were obtained. A DNA fragment of approximately 1.8 kb, derived from a 60-kb plasmid of strain Lb706 and present in the inserts of both clones, was necessary for restoration of sakacin A production and immunity in strain Lb706-B. The sequence of the 1.8-kb fragment from one of the clones was determined. It contained one large open reading frame, designated sakB, potentially encoding a protein of 430 amino acid residues. Hybridization and nucleotide sequence analyses revealed that the cloned sakB complemented a mutated copy of sakB present in strain Lb706-B. The sakB gene mapped 1.6 kb from the previously cloned structural gene for sakacin A (sakA) on the 60-kb plasmid. The putative SakB protein shared 22% amino acid sequence identity (51% similarity if conservative changes are considered) to AgrB, the deduced amino acid sequence of the Staphylococcus aureus gene agrB. The polycistronic agr (accessory gene regulator) locus is involved in the regulation of exoprotein synthesis in S. aureus. Similar to the AgrB protein, SakB had some features in common with a family of transmembrane histidine protein kinases, involved in various adaptive response systems of bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning and nucleotide sequence of a gene from Lactobacillus sake Lb706 necessary for sakacin A production and immunity.

Lactobacillus plantarum ATCC 8014 was transformed with pTV1 by electroporation using a modification of a procedure described for Escherichia coli. The plasmid pTV1 which contains the pE194 replicon from Staphylococcus aureus and transposon Tn917 from Streptococcus faecalis was shown to replicate as a high copy number plasmid in L. plantarum, and the two encoded antibiotic resistance traits were expressed. Tn917 transposed with a high frequency into plasmid DNA of L. plantarum as shown by restriction enzyme analysis and Southern hybridization studies. There are no previous reports on transposition in the lactobacilli. This system may prove to be an important tool in further work on the genetics of these organisms.

Thea Aukrust

Papers

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

Transformation of Lactobacillus strains used in meat and vegetable fermentations

Transformation of Lactobacillus by electroporation.

Cloning and nucleotide sequence of a gene from Lactobacillus sake Lb706 necessary for sakacin A production and immunity.

Transformation of Lactobacillus plantarum with the plasmid pTV1 by electroporation