Transcriptional analysis of bacteriocin production by malt isolateLactobacillus sakei5

Abstract

Malt isolate Lactobacillus sakei 5 produces three bacteriocins, sakacin P, sakacin T and sakacin X. The structural and regulatory genes for sakacin T and sakacin X are part of the sakacin TX locus, which consists of two adjacent, but divergently oriented gene clusters. Primer extension transcriptional analysis pointed to the existence of three distinct promoters within the sakacin TX locus, indicating that the three-component regulatory system in this locus is atypical in the sense that it is divided into a pheromone-specifying operon and an operon containing the genes for the histidine protein kinase and response regulator. Quantitative real-time PCR analyses showed that a transient increase in the expression of these two regulatory operons precedes transcription of the bacteriocin genes and appearance of bacteriocins in the culture medium. The identified promoters of the sakacin TX locus contain putative regulatory sequences (direct repeats) at corresponding positions in front of their -10 regions, which are likely to play a role in gene regulation.

Lactobacillus plantarum and Pediococcus pentosaceus Starter Cultures as a Tool for Microflora Management in Malting and for Enhancement of Malt Processability

“…Furthermore, a combined culture of L. plantarum E76 and P. pentosaceus E390 effectively suppressed the growth of clostridia during the storage of brewers spent grain (). Several investigations have been conducted to study the antimicrobial properties of LAB isolates from barley and malt and their potential against microbial contaminants in malting ( 32 , − . The antagonistic action of LAB is based both on competition for nutrients and space and on the production of various antimicrobial compounds such as organic acids, hydrogen peroxide, bacteriocins, and low molecular weight antimicrobial compounds ().…”

Gene Cluster Responsible for Secretion of and Immunity to Multiple Bacteriocins, the NKR-5-3 Enterocins

“…In fact, Perez et al have demonstrated that the enterocin production of strain NKR-5-3 is influenced by some culture conditions and that at least 2 nM Ent53D triggers the production of enterocins, except for Ent53B (33). Additionally, Vaughan et al have identified the respective promoters of sakT ␣ , stxT, and stxP in the sakacin TX gene cluster and shown that the transcription of genes located downstream of these promoters is enhanced by IP-TX, an inducing peptide (47). These results imply that biosynthetic genes such as enkT in the Ent53ACDZ gene cluster, as well as bacteriocin structure genes, are controlled by the TCS.…”

“…Previous reports have shown that bacteriocin production is enhanced by the interaction between an inducing peptide and a specific HK as a signal and by an RR via phosphorylation bound to particular DNA sequences upstream of some promoters. In addition, some studies have indicated that an inducing peptide regulates some promoters in a biosynthetic gene cluster (44,47). Therefore, the TCS consisting of Ent53D, EnkR, and EnkK may potentially control many genes in the Ent53ACDZ gene cluster.…”