No abstract

A plasmid-linked antimicrobial peptide, named coagulin, produced by Bacillus coagulans I 4 has recently been reported (B. Hyronimus, C. Le Marrec and M. C. Urdaci, J. Appl. Microbiol. 85:42-50, 1998). In the present study, the complete, unambiguous primary amino acid sequence of the peptide was obtained by a combination of both N-terminal sequencing of purified peptide and the complete sequence deduced from the structural gene harbored by plasmid I 4 . Data revealed that this peptide of 44 residues has an amino acid sequence similar to that described for pediocins AcH and PA-1, produced by different Pediococcus acidilactici strains and 100% identical. Coagulin and pediocin differed only by a single amino acid at their C terminus. Analysis of the genetic determinants revealed the presence, on the pI 4 DNA, of the entire 3.5-kb operon of four genes described for pediocin AcH and PA-1 production. No extended homology was observed between pSMB74 from P. acidilactici and pI 4 when analyzing the regions upstream and downstream of the operon. An oppositely oriented gene immediately dowstream of the bacteriocin operon specifies a 474-amino-acid protein which shows homology to Mob-Pre (plasmid recombination enzyme) proteins encoded by several small plasmids extracted from grampositive bacteria. This is the first report of a pediocin-like peptide appearing naturally in a non-lactic acid bacterium genus.Bacteriocins are ribosomally synthesized antimicrobial polypeptides that are usually inhibitory only to strains closely related to the producing bacteria. These antimicrobial compounds are thought to provide the producer strain with a selective advantage over other strains. Bacteriocins produced by gram-positive bacteria are often membrane-permeabilizing cationic peptides with fewer than 60 amino acid residues (25,29). In recent decades, the major advances in this field have been made in the lactic acid bacterium (LAB) family, due to the eminent economic importance of these microorganisms. Hence, the great structural diversity of LAB bacteriocins in combination with the fact that many bacteriocin producing LAB are present in a variety of naturally fermented food and feed products has led to a great interest in the potential of these bacteria as biopreservatives that could, at least partially, replace chemical preservatives (50). The bacteriocins of LAB have been divided into four distinct classes by biochemical and genetic means (28,29). Bacteriocins of class I and II are by far the most studied because they are both the most abundant ones and the most prominent for industrial application (41). Class I bacteriocins called lantibiotics contain modified amino acid residues, lanthionine and methyllanthionine, which are formed posttranslationally (10). Class II consists of bacteriocins that lack modified residues. The pediocin-like bacteriocins constitute a large subgroup within class II: they are all small, heat-stable, membrane-active peptides that have a YGN GVXC consensus motif and are also characterized by their strong inh...

A protease‐sensitive antibacterial substance produced by Bacillus coagulans I4 strain, isolated from cattle faeces, was classified as a bacteriocin‐like inhibitory substance and named coagulin. The inhibitory spectrum included B. coagulans and unrelated bacteria such as Enterococcus, Leuconostoc, Oenococcus, Listeria and Pediococcus. Coagulin was stable at 60 °C for 90 min, at a pH ranging from 4 to 8 and appeared to be unaffected by α‐amylase, lipase or organic solvents (10% v/v). Coagulin exhibited a bactericidal and a bacteriolytic mode of action against indicator cells. The apparent molecular mass was estimated to be about 3–4 kDa by SDS‐PAGE. The B. coagulans I4 strain harbours a plasmid, pI4, approximately 14 kb in size. Novobiocin curing experiments yielded two derivatives that no longer produced the bacteriocin‐like inhibitory substance. Plasmid content of these two derivatives showed that one had lost pI4,whereas the second harboured a deleted form of this plasmid, thus suggesting a plasmid location for the genes for coagulin production.

Since 2018, when a process hygiene criterion for Campylobacter in broilers at the slaughterhouse was implemented across Europe, efforts to reduce Campylobacter at farm level have increased. Despite numerous studies aiming to reduce Campylobacter colonization in broilers, no efficient control strategy has been identified so far. The present work assessed first the efficacy of a commercial litter treatment to reduce Campylobacter colonization in broilers during two in-vivo trials and second, its impact on cecal microbiota. The treatment does not affect broiler growth and no effect on Campylobacter counts was observed during the in-vivo trials. Nevertheless, cecal microbiota were affected by the treatment. Alpha and beta diversity were significantly different for the control and litter-treated groups on day 35. In addition, several taxa were identified as significantly associated with the different experimental groups. Further work is needed to find a suitable control measure combining different strategies in order to reduce Campylobacter.