Variations in the Membrane Fatty Acid Composition of Resistant or Susceptible Leuconostoc or Weissella Strains in the Presence or Absence of Mesenterocin 52A and Mesenterocin 52B Produced by Leuconostoc mesenteroides subsp. mesenteroides FR52

Abstract

Mesenterocins 52A (Mes52A) and 52B (Mes52B) are antimicrobial peptides produced by Leuconostoc mesenteroides subsp. mesenteroides FR 52. Mes52A is a class IIa bacteriocin of lactic acid bacteria with a broad spectrum of activity. Mes52B is an atypical class II bacteriocin with a narrow spectrum of activity. Four Leuconostoc and Weissella wild-type strains were selected for their susceptibility or insensitivity to these mesenterocins. Four strains resistant to Mes52A or Mes52B were generated from the three susceptible wild-type strains by increasing bacteriocin concentrations in culture media. These resistant strains were at least 30 times more resistant than the wild-type strains. No cross-resistance to Mes52A and Mes52B was observed in these strains. No significant differences in membrane fatty acid composition were observed among the three susceptible wild-type strains and the four resistant strains cultured in MRS broth. Thus, the mesenterocin resistance is unlikely to be due to changes in membrane fatty acid composition. When cultured with Mes52A or Mes52B, the membranes of insensitive and resistant strains contained more saturated fatty acids (1 to 10% more) and less unsaturated fatty acids (3 to 6% less), resulting in a more rigid membrane. Thus, the presence of mesenterocin in the culture media of insensitive or resistant strains induced a significant increase in saturated fatty acid contents and a decrease in unsaturated fatty acid contents. Weissella paramesenteroides DSM 20288BR, resistant to Mes52B, responded atypically, probably due to the production of an inhibitor.Some lactic acid bacteria, defined to be generally recognized as safe, produce bacteriocins that are industrially interesting antimicrobial substances. These small peptides have inhibitory activity against related bacterial species. In 1993, Klaenhammer (14) proposed a classification of lactic acid bacterial bacteriocins based on their modes of action and their structures. In this classification, class II bacteriocins are small, heat-stable, nonlanthionine peptides consisting of 30 to 60 amino acids (Ͻ10 kDa). Subclass IIa contains peptides with the consensus sequence YGNGV near the N terminus that are active against Listeria strains.The lethal activity of bacteriocins involves three steps (peptide binding, [ii] peptide insertion and association, and [iii] pore formation) leading to intracellular compound efflux (1,7,8,19). To investigate this mechanism of action, resistant strains were generated from susceptible wild-type strains by two methods: (i) culture of the wild-type strain in the presence of a large amount of bacteriocin (4, 18) and (ii) culture in media with increasing bacteriocin concentrations (11,16,28). Some induced resistance provides cross-resistance to other bacteriocins (4, 21). Some authors have therefore concluded that resistance to a class IIa bacteriocin protects against the lethal activities of other bacteriocins of this class (6,22,27). The resistance mechanism seems to be complex. In 1998, Crandall and Montville ...

Membranes of five-fold alamethicin-resistantStaphylococcus aureus, Enterococcus faecalis andBacillus cereus show decreased interactions with alamethicin due to changes in membrane fluidity and surface charge

“…They observed saturated (C12:0, C14:0, C16:0, C18:0, C19:0) and unsaturated fatty acids (C16:1and C18:1) as major composition of membrane fatty acids in mundticin KS sensitive and resistant mutants of E. faecium and also reported significant reduction in unsaturated fatty acids and increase in saturated fatty acids in the muditicin KS resistant mutants than in wild type strains of E. faecium. Decrease in membrane fluidity has also been reported in L. monocytogenes against nisin (Mazotta and Montville, 1997; Li et al, 2002) and in Leuconostoc or Weisella strains against mesentericin 52A and 52B (Limonet et al, 2002). There were significant increase in saturated fatty acids (10% more) and reduction in unsaturated fatty acids (6% less) of mesentericin 52A and 52B resistant mutants of Leuconostoc species making their membrane more rigid when compared to wild type strains.…”

Characterization of Enterococcus faecium mutants resistant to mundticin KS, a class IIa bacteriocin

“…Recently, resistance to class IIa bacteriocins has been reported. For example, Limonet et al (2002) reported variations in fatty acid composition of mutants of Leuconostoc and Weissela strains resistant to the class IIa bacteriocin mesenterocin 52A (Mes 52A). They showed that resistant strains contained more saturated fatty acids when cultured with Mes 52A.…”

“…Recently, Limonet et al (2002) reported variations in fatty acid composition of mutants of Leuconostoc and Weissela strains resistant to mesenterocin 52A (Mes 52A). We have also found differences in fatty acid (Table 1) and phospholipid contents (Table 2).…”

Substantiation in Enterococcus faecalis of Dose-Dependent Resistance and Cross-Resistance to Pore-Forming Antimicrobial Peptides by Use of a Polydiacetylene-Based Colorimetric Assay

“…This increased fluidity of the bacterial cell membrane did not allow alamethicin to form stable pores in the phospholipid bilayer. A decrease in membrane fluidity has been reported in L. monocytogenes against nisin (11) and in Leuconostoc and Weisela strains against mesentericin 52A and 52B (12). The decrease in the total BCFA of Alm r variants led to increased membrane rigidity, as their main role in bacteria is to increase fluidity.…”