The products from lipase-catalysed hydrolysis of bovine milkfat kill Helicobacter pylori in vitro

Free fatty acids and monoglycerides released from milkfat by partial pregastric lipase-catalysed hydrolysis are bactericidal towards Helicobacter pylori. Two milkfat preparations were investigated: a normal bovine milkfat, and a fractionated milkfat preparation, termed ModFat, enriched in triglycerides containing short- and medium-chain fatty acids. The released products were tested for bactericidal potency against H. pylori. The potencies of the respective preparations were consistent with expected potencies calculated from individual free fatty acid and monoglyceride concentrations and their lauric acid equivalence factors (Ki). ModFat products were more bactericidal, in accordance with release of free fatty acid types of high potency, and addition of the surfactant Tween 80 to the hydrolysed lipid increased potency eight times more than did addition of lecithin. Tween 80 micelles have smaller aggregation numbers, and the mixed micelles of Tween 80/free fatty acids would be more likely to expose the bacteria to higher apparent free fatty acid concentrations.     

A folding variant of alpha-lactalbumin with bactericidal activity against Streptococcus pneumoniae

This study describes an alpha-lactalbumin folding variant from human milk with bactericidal activity against antibiotic-resistant and -susceptible strains of Streptococcus pneumoniae. The active complex precipitated with the casein fraction at pH 4.6 and was purified from casein by a combination of anion exchange and gel chromatography. Unlike other casein components, the active complex was retained on the ion-exchange matrix and eluted only with high salt. The eluted fraction showed N-terminal and mass spectrometric identity with human milk alpha-lactalbumin, but native alpha-lactalbumin had no bactericidal effect. Spectroscopic analysis demonstrated that the active form of the molecule was in a different folding state, with secondary structure identical to alpha-lactalbumin from human milk whey, but fluctuating tertiary structure. Native alpha-lactalbumin could be converted to the active bactericidal form by ion-exchange chromatography in the presence of a cofactor from human milk casein, characterized as a C18:1 fatty acid. Analysis of the antibacterial spectrum showed selectivity for streptococci; Gram-negative and other Gram-positive bacteria were resistant. The folding variant of alpha-lactalbumin is a new example of naturally occurring molecules with antimicrobial activity.     

Interfacial reaction dynamics and acyl-enzyme mechanism for lipoprotein lipase-catalyzed hydrolysis of lipid p-nitrophenyl esters

The fatty acyl (lipid) p-nitrophenyl esters p-nitrophenyl caprylate, p-nitrophenyl laurate and p-nitrophenyl palmitate that are incorporated at a few mol % into mixed micelles with Triton X-100 are substrates for bovine milk lipoprotein lipase. When the concentration of components of the mixed micelles is approximately equal to or greater than the critical micelle concentration, time courses for lipoprotein lipase-catalyzed hydrolysis of the esters are described by the integrated form of the Michaelis-Menten equation. Least square fitting to the integrated equation therefore allows calculation of the interfacial kinetic parameters Km and Vmax from single runs. The computational methodology used to determine the interfacial kinetic parameters is described in this paper and is used to determine the intrinsic substrate fatty acyl specificity of lipoprotein lipase catalysis, which is reflected in the magnitude of kcat/Km and kcat. The results for interfacial lipoprotein lipase catalysis, along with previously determined kinetic parameters for the water-soluble esters p-nitrophenyl acetate and p-nitrophenyl butyrate, indicate that lipoprotein lipase has highest specificity for the substrates that have fatty acyl chains of intermediate length (i.e. p-nitrophenyl butyrate and p-nitrophenyl caprylate). The fatty acid products do not cause product inhibition during lipoprotein lipase-catalyzed hydrolysis of lipid p-nitrophenyl esters that are contained in Triton X-100 micelles. The effects of the nucleophiles hydroxylamine, hydrazine, and ethylenediamine on Km and Vmax for lipoprotein lipase catalyzed hydrolysis of p-nitrophenyl laurate are consistent with trapping of a lauryl-lipoprotein lipase intermediate. This mechanism is confirmed by analysis of the product lauryl hydroxamate when hydroxylamine is the nucleophile. Hence, lipoprotein lipase-catalyzed hydrolysis of lipid p-nitrophenyl esters that are contained in Triton X-100 micelles occurs via an interfacial acyl-lipoprotein lipase mechanism that is rate-limited by hydrolysis of the acyl-enzyme intermediate.     

Monoacylglycerol lipase activity in cardiac myocytes

Monoacylglycerol lipase activity in homogenates of isolated myocardial cells (myocytes) from rat hearts was recovered in both particulate and soluble subcellular fractions. The activity present in the microsomal (100,000 X g pellet) fraction was solubilized by treatment with Triton X-100 and combined with the 100,000 X g supernatant fraction; the properties of monoacylglycerol lipase were investigated with this soluble enzyme preparation. The Km for the hydrolysis of a 2-monoolein substrate was 16 microM. The rates of hydrolysis of 1-monoolein and 2-monoolein were identical, and 1-monoolein was a competitive inhibitor (Ki = 20 microM) of the hydrolysis of 2-monoolein. Monoacylglycerol lipase activity was regulated by product inhibition according to the following order of potency: fatty acyl CoA greater than free fatty acids greater than fatty acyl carnitine.     

Antimycobacterial activity of lecithin-cholesterol liposomes in the presence of phospholipase A2.

Tubercle bacilli were preincubated with lecithin-cholesterol liposomes to be subsequently exposed to phospholipase A2. After further incubation in the environment of acidic buffer, viable units in the final mixture were enumerated by inoculating the serial dilutions of an aliquot onto Kirchner agar medium containing horse serum in 5%. Another aliquot was used for lipid analyses to confirm hydrolysis of lecithin. In addition to this bactericidal type of experiments, bacteriostatic tests were also conducted with Kirchner semi-solid agar medium, into which liposome-treated bacilli were inoculated with the enzyme at a time. Various natural and synthetic lecithins different in constituent fatty acids were employed. The results indicated that toxic fatty acids released from lecithin acted to kill the bacilli or to inhibit their growth.     

Impact of Lipase, Bile Salts, and Polysaccharides on Properties and Digestibility of Tuna Oil Multilayer Emulsions Stabilized by Lecithin–Chitosan

The influence of lipase, bile salts, and polysaccharides (pectin and maltodextrin) on the properties and digestibility of lecithin/chitosan-stabilized tuna oil-in-water multilayer emulsions were studied when they were subjected to an in vitro digestion model. All emulsions became unstable to creaming after passing through the digestion model, as deduced from the formation of large visible brown clumps on the top of the emulsions. The release of free fatty acids and glucosamine from the emulsions suggested that lecithin/chitosan-coated droplets were degraded by lipase under simulated gastrointestinal conditions. The amount of free fatty acids released per unit amount of emulsion was higher when bile salt was included in the digestion model or anionic polysaccharide (pectin) was present in the emulsions. These results have important implications for the utilization of multilayered emulsions for the encapsulation, protection, and delivery of n-3 fatty acids and other bioactive lipids.     

A role for hormone-sensitive lipase in the selective mobilization of adipose tissue fatty acids.

The mobilization of fatty acids from rat and human fat cells is selective according to molecular structure, and notably carbon atom chain length. This study aimed at examining whether the release of individual fatty acids from triacylglycerols (TAG) by hormone-sensitive lipase (HSL) plays a role in the selectivity of fatty acid mobilization. Recombinant rat and human HSL were incubated with a lipid emulsion. The hydrolysis of 18 individual fatty acids, ranging in chain length from 12 to 24 carbon atoms and in unsaturation degree from 0 to 3 double bond(s), was measured by comparing the composition of non-esterified fatty acids (NEFA) to that of the original TAG. The relative hydrolysis (% in NEFA/% in TAG) differed between fatty acids, being about 5-fold and 3-fold higher for the most (18:1n-7) than for the least (24:0) readily released fatty acid by recombinant rat and human HSL, respectively. Relationships were found between the chain length of fatty acids and their relative hydrolysis. Among 12-24 carbon atom saturated fatty acids, the relative hydrolysis markedly decreased (by about 5- and 3-times for recombinant rat and human HSL, respectively) with increasing chain length. We conclude that fatty acids are selectively released from TAG by HSL according to carbon atom chain length. These data provide insight on the mechanism by which fatty acids are selectively mobilized from fat cells.     

Enzymatic surface hydrolysis of poly(ethylene terephthalate) and bis(benzoyloxyethyl) terephthalate by lipase and cutinase in the presence of surface active molecules

A lipase from Thermomyces lanuginosus and cutinases from Thermobifida fusca and Fusarium solani hydrolysed poly(ethylene terephthalate) (PET) fabrics and films and bis(benzoyloxyethyl) terephthalate (3PET) endo-wise as shown by MALDI-Tof-MS, LC–UVD/MS, cationic dyeing and XPS analysis. Due to interfacial activation of the lipase in the presence of Triton X-100, a seven-fold increase of hydrolysis products released from 3PET was measured. In the presence of the plasticizer N,N-diethyl-2-phenylacetamide (DEPA), increased hydrolysis rates of semi-crystalline PET films and fabrics were measured both for lipase and cutinase. The formation of novel polar groups resulted in enhanced dye ability with additional increase in colour depth by 130% and 300% for cutinase and lipase, respectively, in the presence of plasticizer.     

Stereospecific synthesis and enzyme studies of CDP-diacylglycerols

The fatty acid specificity of two enzymes that metabolize CDPdiacylglycerol, CDPdiacylglycerol hydrolase (EC 3.6.1.26) and CDPdiacylglycerol: inositol phosphatidyltransferase (EC 2.7.8.11), has been examined in guinea pig brain. Mixed CDPdiacylglycerols were stereospecifically synthesized by the following sequence: (i) hydrolysis of a homodiacyl lecithin to 1-acyl lysoPC by action of snake venom phospholipase A2, (ii) reacylation with the anhydride of the desired second fatty acid and dimethylaminopyridine, (iii) hydrolysis of the resultant heterodiacyl lecithin to phosphatidate with cabbage phospholipase D, and (iv) reaction of phosphatidate with CMPmorpholidate to give CDPdiacylglycerol. CDPdiacylglycerol: inositol phosphatidyltransferase showed the following rates of conversion of 40-microM suspensions of CDPdiacylglycerol in 0.15% Triton X-100 to phosphatidylinositol relative to the 1-stearoyl-2-oleoyl derivative (100%): dipalmitoyl, 70%; distearoyl, 38%; diarachidonoyl, 9%; 1-arachidonoyl-2-stearoyl, 6%; 1-stearoyl-2-arachidonoyl, 4%. These results indicate that the composition of isolated phosphatidylinositol and related lipids is not explained by the fatty acid specificity of the biosynthetic enzymes and supports the intervention of a deacylation-reacylation sequence. The rates of hydrolysis of the synthetic CDPdiacylglycerols at 76 microM, in 0.3% Triton X-100, by the CDPdiacylglycerol hydrolase relative to the 1-stearoyl-2-oleoyl derivative (100%) were: dipalmitoyl, 70%; distearoyl, 32%; 1-arachidonoyl-2-stearoyl, 30%; 1-stearoyl-2-arachidonoyl, 28%; diarachidonoyl, 22%. Inhibition of this enzyme by AMP was shown to be non-competitive, with a Ki of 40 microM. The lysosomal localization of the mammalian hydrolase was confirmed.     

Effect of beta-lactoglobulin on the activity of pregastric lipase. A possible role for this protein in ruminant milk.

The interaction of bovine beta-lactoglobulin with palmitic and oleic acids has been studied by a partition equilibrium method. Bovine beta-lactoglobulin displays only one high affinity binding site for fatty acids whose association constants for palmitic and oleic acids are 4.2 x 10(6) and 2.3 x 10(6) M-1, respectively. However, other binding sites with low affinity are also present. The existence of one high affinity binding site is in accordance with the amount of fatty acids naturally bound to beta-lactoglobulin isolated from milk. The effect of beta-lactoglobulin on ruminant pregastric lipases from a pharyngeal extract has been assayed. The activity of pharyngeal lipase on a triglyceride emulsion is increased about 200%, 250% and 190% in the presence of 10 mg/ml, 20 mg/ml and 40 mg/ml of beta-lactoglobulin, respectively, the last concentration representing that found physiologically in colostrum. Albumin, another ligand-binding protein, increases the activity of this enzyme to a lesser extent and high levels tend to inhibit enzyme action. These results indicate that beta-lactoglobulin could participate in the digestion of milk lipids during the neonatal period by enhancing the activity of pregastric lipase through removal of the fatty acids that inhibit this enzyme.     

A stable, radioactive substrate emulsion for assay of lipoprotein lipase.

A method is described for the assay of lipoprotein lipase, using a stable, radioactive substrate emulsion. Fatty acid-labeled trioleoylglycerol was emulsified by homogenization in glycerol with lecithin as detergent. This anhydrous emulsion was stable for at least six weeks. Substrate solutions for enzyme assay were prepared by diluting the emulsion with buffer containing serum and albumin. The fatty acid produced on hydrolysis was isolated in a one-step liquid-liquid partition system. Incubations with extracts of acetone powders from adipose tissue displayed characteristics of lipoprotein lipase activity, i.e., serum dependence and inhibition by NaCl and protamine. The method is rapid (less than 1 hour), sensitive and reproducible, and suitable for routine use.     

Antimicrobial mechanism of action of surfactant lipid preparations in enteric Gram-negative bacilli

Two surfactant lipid preparations (SLPs) were investigated to determine their mechanism of antimicrobial action. 8N8, a water-in-oil emulsion, and W60C, a liposome, both have bactericidal activity against Gram-positive bacteria and non-enteric Gram-negative bacteria. Additionally, W60C is bactericidal for enteric Gram-negative bacilli when suspended in deionized water. Zeta potential measurements suggested that the resistance of Gram-negative bacilli to 8N8 might be caused by ionic repulsion. Addition of 50 micromol 1(-1) ethylene diamine tetra acetic acid in 100 mmol 1(-1) Tris buffer to either SLPs yielded efficient bactericidal activity against Gram-negative bacilli. This appeared to be due to disruption of the outer membrane and the chelation of divalent cations, as the addition of excess calcium inhibited the antimicrobial effect. Electron microscopy studies documented that 8N8 disrupts the bacterial cell wall, lysing the bacteria, while W60C fuses and internalizes within the cell, causing damage without immediate cell lysis. Understanding the mechanisms of action of these biocidal formulations will help to produce improved formulations with broader spectra of activity.     

Fatty acid specificity of hormone-sensitive lipase. Implication in the selective hydrolysis of triacylglycerols.

The selective mobilization of fatty acids from white fat cells depends on their molecular structure, in particular the degree of unsaturation. The present study was designed to examine if the release of fatty acids by hormone-sensitive lipase (HSL) in vitro i) is influenced by the amount of unsaturation, ii) depends on the temperature, and iii) could explain the selective pattern of fatty acid mobilization and notably the preferential mobilization of certain highly unsaturated fatty acids. Recombinant rat and human HSL were incubated with a lipid emulsion. The hydrolysis of 35 individual fatty acids, ranging in chain length from 12 to 24 carbon atoms and in unsaturation from 0 to 6 double bonds was measured. Fatty acid composition of in vitro released NEFA was compared with that of fat cell triacylglycerols (TAG), the ratio % NEFA/% TAG being defined as the relative hydrolysis. The relative hydrolysis of individual fatty acids differed widely, ranging from 0.44 (24:1n-9) to 1.49 (18:1n-7) with rat HSL, and from 0.38 (24:1n-9) to 1.67 (18:1n-7) with human HSL. No major difference was observed between rat and human HSL. The relative release was dependent on the number of double bonds according to chain length. The amount of fatty acid released by recombinant rat HSL was decreased but remained robust at 4 degrees C compared with 37 degrees C, and the relative hydrolysis of some individual fatty acids was affected. The relative hydrolysis of fatty acids moderately, weakly, and highly mobilized by adipose tissue in vivo was similar and close to unity in vitro. We conclude that i) the release of fatty acids by HSL is only slightly affected by their degree of unsaturation, ii) the ability of HSL to efficiently and selectively release fatty acids at low temperature could reflect a cold adaptability for poikilotherms or hibernators when endogenous lipids are needed, and iii) the selectivity of fatty acid hydrolysis by HSL does not fully account for the selective pattern of fatty acid mobilization, but could contribute to explain the preferential mobilization of some highly unsaturated fatty acids compared with others.     

Hydrolysis of long-chain, n-3 fatty acid enriched chylomicrons by cardiac lipoprotein lipase

The hydrolysis of chylomicrons enriched in long-chain n-3 fatty acids by cardiac lipoprotein lipase was studied. In 60 min, 24.8% of the triacylglycerol fatty acids were released as free fatty acids. The fatty acids were hydrolyzed at different rates. DHA (docosahexaenoic acid, 22:6n-3) and EPA (eicosapentaenoic acid, 20:5n-3) were released at rates significantly less than average. Stearic acid (18:0), 20:1n-9, and alpha-linolenic acid (18:3n-3) were released significantly faster than average. There was no relationship between the rate of release of a fatty acid and the number of carbons or the number of double bonds. Lipoprotein lipase selectively hydrolyzes the fatty acids of chylomicron triacylglycerols. This selectively will result in remnants that are relatively depleted in 18:0, 20:1, and 18:3 and relatively enriched in 20:5 and 22:6.     

Characterization of mono-, di- and triacylglycerol lipase activities in the isolated rat heart

The lipolytic activities of heart tissue towards full and partial acylglycerols were characterized. Tissue lysosomal, acid lipase activity (pH 4.8) was inhibited by high salt, protamine sulfate, NaF, MgATP, Triton X-100, serum and the esterase-inhibitor diethylparanitrophenyl phosphate. The tissue neutral triacylglycerol lipase activity (pH 7.4) was recovered predominantly in the microsomal and soluble fractions and exhibited essentially identical properties towards activators (serum, apolipoprotein C-II) and reagents (NaCl, Triton X-100, NaF, MgATP and diethylparanitrophenyl phosphate) relative to vascular lipoprotein lipase, except for protamine sulfate which increased the serum-stimulated neutral triacylglycerol lipase activity. Triacylglycerol hydrolysis at acid pH was incomplete, whereas at neutral pH full hydrolysis occurred. Myocardial mono- and diacylglycerol lipase activities, with pH optima of 8.0 and 7.4, respectively, were recovered in the microsomal fraction. They differed immunologically from neutral lipase and lipoprotein lipase and did not bind to heparin-Sepharose 4B. They were kinetically different, partially inhibited by NaCl and differentially affected by protamine sulfate. NaF, Triton X-100 and diethylparanitrophenyl phosphate. Our data suggest that endogenous hydrolytic activity against full and partial acylglycerols is mediated by separate enzymes.     

Effect of phosphatidylcholine and free fatty acids on the activity of pancreatic lipase-colipase

Mixed micelles of bile salt and phospholipids inhibit the lipase-colipase-catalysed hydrolysis of triacylglycerols. Free fatty acids can reverse this inhibition and reactivate lipase-colipase. This reactivation is either due to the formation of a high-affinity complex between lipase and colipase induced by free fatty acids and/or to a change of the quality of the interface. Lauric acid, oleic acid and linoleic acid are the most potent reactivators, while short-chain free fatty acids have no effect and long-chain, saturated free fatty acids inhibit the lipase-colipase activity further. The physiological relevance of these results is evident as the glyceride emulsion reaching the duodenum already contains free fatty acids due to the activity of lingual lipase in the stomach.     

Comparative Study of Surface-Active Properties and Antimicrobial Activities of Disaccharide Monoesters

The objective of this research was to determine the effect of sugar or fatty acid in sugar ester compounds on the surface-active properties and antimicrobial activities of these compounds. Disaccharides of medium-chain fatty acid monoesters were synthesized through transesterifications by immobilized lipase (Lipozyme TLIM) to yield nine monoesters for subsequent study. Their antimicrobial activities were investigated using three pathogenic microorganisms: Staphylococcus aureus, Escherichia coli O157:H7 and Candida albicans. Their surface-active properties including air–water surface tension, critical micelle concentration, and foaming and emulsion power and stability were also studied. The results showed that all of the tested monoesters were more effective against Staphylococcus aureus (Gram-positive bacterium) than against Escherichia coli O157:H7 (Gram-negative bacterium). The results demonstrated that the carbon chain length was the most important factor influencing the surface properties, whereas degree of esterification and hydrophilic groups showed little effect.     

内陆土壤冷适应细菌的筛选分类与细胞膜脂肪酸的适冷机制

嗜冷菌及耐冷菌是冷适应酶及生物活性物质的重要资源。本研究从内陆土壤筛得33株冷适应细菌,包括6株革兰氏阳性菌与27株革兰氏阴性菌。通过细胞膜脂肪酸分析表明,革兰氏阳性菌的膜脂肪酸主要为分支脂肪酸,推测分支结构是阳性菌膜脂的主要适冷机制。革兰氏阴性菌呈现了不饱和、分支、短链等多样的膜脂适冷调节方式。根据脂肪酸组分的多样性,选择并鉴定了17株嗜冷及耐冷菌分布在11个属中,细胞膜脂肪酸组成的变化规律与细菌16SrRNA的进化分布高度一致。研究还表明同为不饱和脂肪酸为主的革兰氏阴性菌呈现了不同的适冷机理。相关研究不仅阐述了冷适应细菌的细胞膜脂肪酸的适应机制,而且为相关适冷酶源的开发利用提供了宝贵的资源。     

Hydrolysis of lipid mixtures by rat hepatic lipase

The hydrolysis of phospholipid mixtures by purified rat hepatic lipase, also known as hepatic triglyceride lipase, was studied in a Triton X-100/lipid mixed micellar system. Column chromatography of the mixed micelles showed elution of Triton X-100 and binary lipid mixtures of phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine as a single peak. This indicated that the mixed micelles were homogenous and contained all components in the designated molar ratios. The molar ratio of Triton X-100 to lipid was kept constant at 4 to 1. Labeling one lipid with 3H and the other lipid with 14C enabled us to determine the hydrolysis of both components of these binary lipid mixed micelles. We found that the hydrolysis of phosphatidylcholine was activated by the inclusion of small amounts of phosphatidic acid (2.5-fold), phosphatidylethanolamine (1.5-fold) or phosphatidylserine (1.4-fold). The maximal activation of phosphatidylcholine hydrolysis was observed when 5 mol% of phosphatidylethanolamine, 7.5 mol% phosphatidic acid or 5 mol% phosphatidylserine was added to Triton X-100 mixed micelles. The hydrolysis of phosphatidic acid was activated 30%, and that of phosphatidylserine was inhibited 30% when the molar proportion of phosphatidylcholine was less than 50 mol%. The hydrolysis of phosphatidylethanolamine was slightly activated when the mol% of phosphatidylcholine was below 5. The hydrolysis of phosphatidylserine was inhibited by phosphatidylethanolamine when the mol% of the latter was 50 or less whereas phosphatidylethanolamine hydrolysis was not affected by phosphatidylserine. Under the conditions used sphingomyelin and cholesterol did not have a significant effect on the hydrolysis of the phospholipids studied. In agreement with our previous study (Kucera et al. (1988) J. Biol. Chem. 263, 1920-1928) these studies show that the phospholipid polar head group is an important factor which influences the action of hepatic lipase and that the interfacial properties of the substrate play a role in the expression of the activity of this enzyme. The molar ratios of phosphatidic acid, phosphatidylethanolamine and phosphatidylserine which activated phosphatidylcholine hydrolysis correspond closely to the molar ratios of these lipids found in the surface lipid film of lipoproteins e.g., high density lipoproteins.(ABSTRACT TRUNCATED AT 400 WORDS)     

Trophosome of the Deep-Sea Tubeworm Riftia pachyptila Inhibits Bacterial Growth

The giant tubeworm Riftia pachyptila lives in symbiosis with the chemoautotrophic gammaproteobacterium Cand. Endoriftia persephone. Symbionts are released back into the environment upon host death in high-pressure experiments, while microbial fouling is not involved in trophosome degradation. Therefore, we examined the antimicrobial effect of the tubeworm’s trophosome and skin. The growth of all four tested Gram-positive, but only of one of the tested Gram-negative bacterial strains was inhibited by freshly fixed and degrading trophosome (incubated up to ten days at either warm or cold temperature), while no effect on Saccharomyces cerevisiae was observed. The skin did not show antimicrobial effects. A liquid chromatography-mass spectrometric analysis of the ethanol supernatant of fixed trophosomes lead to the tentative identification of the phospholipids 1-palmitoleyl-2-lyso-phosphatidylethanolamine, 2-palmitoleyl-1-lyso-phosphatidylethanolamine and the free fatty acids palmitoleic, palmitic and oleic acid, which are known to have an antimicrobial effect. As a result of tissue autolysis, the abundance of the free fatty acids increased with longer incubation time of trophosome samples. This correlated with an increasing growth inhibition of Bacillus subtilis and Listeria welshimeri, but not of the other bacterial strains. Therefore, the free fatty acids produced upon host degradation could be the cause of inhibition of at least these two bacterial strains.