Differences in Susceptibility of Listeria monocytogenes Strains to Sakacin P, Sakacin A, Pediocin PA-1, and Nisin

The purpose of this study was to characterize the variation in biochemical composition of 89 strains of Listeria monocytogenes with different susceptibilities towards sakacin P, using Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. The strains were also analyzed using amplified fragment length polymorphism (AFLP) analysis. Based on their susceptibilities to sakacin P, the 89 strains have previously been divided into two groups. Using the FTIR spectra and AFLP data, the strains were basically differentiated into the same two groups. Analyses of the FTIR and Raman spectra revealed that the strains in the two groups contained differences in the compositions of carbohydrates and fatty acids. The relevance of the variation in the composition of carbohydrates with respect to the variation in the susceptibility towards sakacin P for the L. monocytogenes strains is discussed.The food-borne pathogenic bacterium Listeria monocytogenes represents a major concern with respect to food safety, especially because the bacterium is able to grow in refrigerated ready-to-eat products with an extended shelf life, a consumer product type with increasing popularity (25). Bacteriocins are antibacterial peptides produced by certain bacteria-for example, lactic acid bacteria (LAB)-in order to kill or inhibit the growth of other closely related bacteria (4). LAB have been used for the production and preservation of food for a long time, and since both the bacteria and their bacteriocins have been consumed for centuries, they are generally regarded as safe to eat. Thus, it has been suggested that the growth of L. monocytogenes in food might be limited by the addition of bacteriocins and/or bacteriocin-producing LAB (16). This suggestion has been supported by the results of several studies (8, 9). Katla et al. (10) investigated 200 strains of L. monocytogenes isolated from food or food-processing facilities for their susceptibilities towards four bacteriocins produced by LAB, among them sakacin P, which is a class IIa bacteriocin (15). The results showed that the different strains had different susceptibilities to the various bacteriocins. The reason for this variation is unknown, but if bacteriocins and/or bacteriocinproducing LAB are to be used as protective cultures against L. monocytogenes, it is important to understand the basis for this variation in order to certify the effects of these protective agents. A previous investigation of L. monocytogenes strains that were resistant to class IIa bacteriocins suggested that the resistance was coupled to several changes in the cell surfaces of the bacteria (26).Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy are chemical analytical methods that have also been used to collect information about whole bacterial cells (14). The outputs from these methods are FTIR and Raman spectra that contain signals from the organic functional groups in the sample. Since the bands in FTIR spectra are due to polar functional groups while the bands in Raman spectra ar...

supporting

confidence: 60%

contrasting

confidence: 54%

See 1 more Smart Citation

Fourier Transform Infrared and Raman Spectroscopy for Characterization of Listeria monocytogenes Strains

Oust

Møretrø²,

Naterstad³

et al. 2006

“…That some strains contradicted this correlation is not totally unexpected, as the strains being compared are not isogenic, and thus another factor(s) contributing to nisin tolerance may vary, e.g., membrane charge or fluidity. While natural variation in nisin tolerance within a species has previously been reported (9,16,22), to our knowledge, gadD1 is the first genetic locus that has been linked to this phenomenon. Given this link, it is noteworthy that strains which possess gadD1 are more frequently isolated from foods than those lacking the gene (23).…”

Section: Resultsmentioning

confidence: 99%

Glutamate Decarboxylase-Mediated Nisin Resistance in Listeria monocytogenes

Begley

Cotter

Hill

et al. 2010

Analysis of a complete set of glutamate decarboxylase (gad) mutants of Listeria monocytogenes strain LO28 (⌬gadD1, ⌬gadDT1, ⌬gadD2, ⌬gadT2, and ⌬gadD3 mutants) revealed that the ⌬gadD1 mutant is impaired in its ability to tolerate exposure to both sublethal and lethal levels of the lantibiotic nisin. gadD1 is strain variable and is found only in approximately 50% of L. monocytogenes strains. Growth and survival experiments revealed that possession of gadD1 correlates with a higher degree of tolerance to nisin. Significantly, a similar finding using a gadB mutant of L. lactis IL1403 implies that this may be a general phenomenon in Grampositive bacteria. Our findings thus suggest that the specific inhibition of GAD activity or a reduction in the levels of free glutamate may prevent the growth of otherwise resistant GAD ؉ bacteria in foods where low pH and/or nisin is used as a preservative.

“…Bacteriocins belonging to class IIa are promising alternative antimicrobials since they are more stable over a broader range of heating regimens and pH conditions. In addition, these bacteriocins exhibit stronger antimicrobial activity against the genus Listeria than nisin (17) but have a narrower antimicrobial spectrum.…”

mentioning

confidence: 99%

Characterization of Mundticin L, a Class IIa Anti- Listeria Bacteriocin from Enterococcus mundtii CUGF08

Feng

Guron

Churey

et al. 2009

Enterococcus mundtii CUGF08, a lactic acid bacterium isolated from alfalfa sprouts, was found to produce mundticin L, a new class IIa bacteriocin that has a high level of inhibitory activity against the genus Listeria. The plasmid-associated operons containing genes for the mundticin L precursor, the ATP binding cassette (ABC) transporter, and immunity were cloned and sequenced. The fifth residue of the conservative consensus sequence YGNGX in the mature bacteriocin is leucine instead of valine in the sequences of the homologous molecules mundticin KS (ATO6) and enterocin CRL35. The primary structures of the ABC transporter and the immunity protein are homologous but unique.Bacteriocins are ribosomally synthesized proteinaceous compounds that inhibit closely related bacteria (19). Due to consumer concerns with chemical and irradiation preservation methods and due to the rising demand for minimally processed food products, alternative methods for shelf life extension and enhanced safety are needed. Bacteriocins are considered "natural" antimicrobials since many bacteriocins are produced by food grade lactic acid bacteria, which are generally recognized as safe. Bacteriocins can be divided into three main classes: the class I lanthionine-containing lantibiotics, exemplified by nisin; the class II non-lanthionine-containing bacteriocins; and the class III heat-labile, large proteins (6). Class III bacteriocins have limited application due to their thermal instability and cytolytic activity against eukaryotic cells. Class II can be further divided into class IIa containing pediocin-like bacteriocins, class IIb containing two-peptide bacteriocins, and class IIc containing other bacteriocins (8). Class IIa bacteriocins have been extensively studied since pediocin PA-1 was first discovered (12) and characterized (20). Currently, only nisin in class I has been approved by the FDA as a natural food additive. Bacteriocins belonging to class IIa are promising alternative antimicrobials since they are more stable over a broader range of heating regimens and pH conditions. In addition, these bacteriocins exhibit stronger antimicrobial activity against the genus Listeria than nisin (17) but have a narrower antimicrobial spectrum.The potential applications of class IIa bacteriocins in both meat and plant-based foods as a means to provide protection against potential food-borne pathogens and extend shelf life continue to expand. In an attempt to use biological methods for controlling food-borne pathogens on fresh sprouts, a number of food grade lactic acid bacteria were isolated from the indigenous microbiota on alfalfa sprouts. Some of these isolates were found to be bacteriocinogenic. This study describes a new class IIa bacteriocin, mundticin L produced by Enterococcus mundtii CUGF08 isolated from alfalfa sprouts.Bacteriology. The mundticin L producer E. mundtii CUGF08 was obtained from alfalfa sprouts. The genus and species were determined by BLAST homology analysis (http://blast.ncbi.nlm .nih.gov/blast.cgi) of the 16S rRNA...