Betaine and carnitine uptake systems in Listeria monocytogenes affect growth and survival in foods and during infection

Abstract

Aims: To establish the relative importance of the osmo-and cryoprotective compounds glycine betaine and carnitine, and their transporters, for listerial growth and survival, in foods and during infection. Methods and Results: A set of Listeria monocytogenes mutants with single, double and triple mutations in the genes encoding the principal betaine and carnitine uptake systems (gbu, betL and opuC, respectively) was used to determine the specific contribution of each transporter to listerial growth and survival. Food models were chosen to represent high-risk foods of plant and animal origin i.e. coleslaw and frankfurters, which have previously been linked to major human outbreaks of listeriosis. BALB/c mice were used as an in vivo model of infection. Interestingly, while betaine appeared to confer most protection in foods, the hierarchy of transporter importance differs depending on the food type: Gbu>BetL>OpuC for coleslaw, as opposed to Gbu>OpuC>BetL in frankfurters. By contrast in the animal model, OpuC and thus carnitine, appears to play the dominant role, with the remaining systems contributing little to the infection process. Conclusions: This study demonstrates that the individual contribution of each system appears dependent on the immediate environment. In foods Gbu appears to play the dominant role, while during infection OpuC is most important. Significance and Impact of the Study: It is envisaged that this information may ultimately facilitate the design of effective control measures specifically targeting this pathogen in foods and during infection.

Transcriptional Regulation and PosttranslationalActivity of the Betaine Transporter BetL in Listeriamonocytogenes Are Controlled by EnvironmentalSalinity

“…The immediate response of preexisting BetL protein to relatively low salt concentrations (1 to 2% NaCl) suggests that this secondary betaine uptake system represents one of the primary respondents to rapid changes in medium salinity, whereas during prolonged exposure, it is the Gbu system that is most important. Thus, in addition to being tailored for optimal effects in diverse environmental niches (29), each system appears to prevail in a distinct time frame and salinity range within the overall salt stress response.…”

“…The ability of the organism to survive, and indeed thrive, at elevated osmolarities and reduced temperatures is attributed mainly to the accumulation of osmo-and cryoprotective compounds termed osmolytes, or compatible solutes (13,27). Indeed, recent evidence suggests that osmolyte uptake in L. monocytogenes is linked not only to the ability of the organism to grow and survive in foods but also to the ability of the organism to cause infection (26,29). The preferred compatible solute for the majority of bacteria, and the most effective osmolyte in L. monocytogenes, is the trimethyl ammonium compound glycine betaine.…”

“…The principal transporters include the multicomponent, ATP-dependent GbuABC system (12) and the ionmotive-force-dependent secondary transporter BetL (24). Each system exhibits distinct substrate specificities and kinetic parameters and thus is presumably optimized for maximal effects in diverse ecological niches (29).…”

Improving gastric transit, gastrointestinal persistence and therapeutic efficacy of the probiotic strain Bifidobacterium breve UCC2003

“…However, while genomic analysis has identified a number of stress adaptation systems employed by B. breve UCC2003 (Ventura et al, 2004a(Ventura et al, , 2005a(Ventura et al, , b, c, d, e, 2006, the genome appears devoid of obvious compatible solute-uptake systems. Found in numerous prokaryotic and eukaryotic species, compatible solute accumulation has been shown to protect a variety of cell types under a range of stressful conditions by maintaining cytoplasmic protein and membrane integrity (Abee & Wouters, 1999;Sleator et al, 2000Sleator et al, , 2001bSleator et al, , 2003a.…”

Antimicrobial susceptibility and serotype distribution of Listeria monocytogenes isolates obtained from raw milk cheese samples sold in Nigde

“…As a facultative intracelluler pathogen, L. monocytogenes is remarkably tolerant to external stress such as extreme pH, low temperature and osmolarity, oxidative stress, carbon starvation etc… (23). A large variety of foods, particularly milk, cheeses and ready-to eat products have been implicated as vehicles of listeriosis (15).…”