Influence of Fatty Acid Precursors, Including Food Preservatives, on the Growth and Fatty Acid Composition of Listeria monocytogenes at 37 and 10°C

Abstract

Listeria monocytogenes is a food-borne pathogen that grows at refrigeration temperatures and increases its content of anteiso-C 15:0 fatty acid, which is believed to be a homeoviscous adaptation to ensure membrane fluidity, at these temperatures. As a possible novel approach for control of the growth of the organism, the influences of various fatty acid precursors, including branched-chain amino acids and branched-and straightchain carboxylic acids, some of which are also well-established food preservatives, on the growth and fatty acid composition of the organism at 37°C and 10°C were studied in order to investigate whether the organism could be made to synthesize fatty acids that would result in impaired growth at low temperatures. The results indicate that the fatty acid composition of L. monocytogenes could be modulated by the feeding of branchedchain amino acid, C 4 , C 5 , and C 6 branched-chain carboxylic acid, and C 3 and C 4 straight-chain carboxylic acid fatty acid precursors, but the growth-inhibitory effects of several preservatives were independent of effects on fatty acid composition, which were minor in the case of preservatives metabolized via acetyl coenzyme A. The ability of a precursor to modify fatty acid composition was probably a reflection of the substrate specificities of the first enzyme, FabH, in the condensation of primers of fatty acid biosynthesis with malonyl acyl carrier protein.Listeriosis is a severe and life-threatening human infection encompassing meningoencephalitis, meningitis, focal infections in the immunocompromised, and stillbirths and neonatal sepsis due to infection of pregnant women (2). The disease is caused by the Gram-positive food-borne pathogen Listeria monocytogenes, which is responsible for common-source and sporadic disease involving a variety of different foods (27). Listeriosis has a high fatality rate (24). The U.S. Department of Agriculture has a zero tolerance policy for L. monocytogenes in ready-to-eat products, and high costs are associated with product recalls.L. monocytogenes has a remarkably low minimum growth temperature, e.g., Ϫ0.1°C (34), and thus the organism can multiply to dangerous levels when food is kept at refrigeration temperatures. We are interested in the molecular mechanisms of L. monocytogenes psychrotolerance, with a view to applying this knowledge to improve the control of the growth of the organism. Although the adaptations involved in low-temperature tolerance are global in scope, we have focused on changes in fatty acid composition that result in homeoviscous adjustments of membrane fluidity (31, 36). L. monocytogenes has a fatty acid composition that is dominated to an unusual extent (90% or more) by branched-chain fatty acids (BCFAs); the major fatty acids are anteiso-C 15:0 , anteiso-C 17:0 , and iso-C 15:0 . Numerous studies have shown that the major change in fatty acid composition when L. monocytogenes is grown at low temperatures is an increase in the content of anteiso-C 15:0 fatty acid to 65% or more of the total (1,12,23,...

Fatty Acids Regulate Stress Resistance and Virulence Factor Production for Listeria monocytogenes

“…Some Gram-negative bacteria such as Legionella species also contain high levels of BCFAs (13). When grown in rich brain heart infusion (BHI) medium at 37°C, L. monocytogenes membrane contains very high levels of BCFAs with approximately 81 to 86% anteiso-BCFAs and 13 to 18% isoBCFAs (28,30,62). Despite the similarity in their structures ( Fig.…”

Branched-Chain Fatty Acids Promote Listeria monocytogenes Intracellular Infection and Virulence

“…In this study, we aim to elucidate the contribution of anteiso-BCFA during L. monocytogenes intracellular infection by utilizing the previously characterized cld-2 transposon insertion mutant (1,11,15,26,27) and two independently transduced BKD-deficient mutants in which the cld-2 transposon insertion was transduced into a clean wild-type (WT) background. We show that anteiso-BCFA facilitate intracellular infection of L. monocytogenes by enhancing survival, growth, and phagosomal escape.…”

Using a different growth medium greatly improves distinction of Butyrivibrio fibrisolvens and Pseudobutyrivibrio xylanivorans strains by the cellular fatty acids and aldehydes profiles

“…Rosen and Hackette (1972) altered E. coli outer membrane to release more enzymes after osmotic shock in oleate-supplemented medium. Recently, Listeria monocytogenes impaired growth at refrigeration temperatures was achieved by growing cells in SCFA enriched medium (Julotok et al, 2010). Increased production of extracellular endoglucanase and exoglucanase, enzymes of cellulase complex, in fungus Neurospora crassa was succeeded also by adding oleic acid (Yazdi et al, 1990).…”