Effects of low concentrations of fatty acids on Escherichia coli depend on the kind of culture medium and incubation temperature

Fatty acids play important, yet different roles in bacterial physiology, specifically their growth. On the one hand, these compounds may be used by bacteria to produce storage materials or serve as a carbon source. On the other hand, due to their influence on biolog-ical membranes, fatty acids have been reported to exhibit antimicrobial effects. It was in-dicated that the length of the fatty acid chain is crucial for specific effects on bacterial cells. However, the literature still contains reports of contradictory findings in studies on these molecules. Here, we present results showing to what degree short- and medium-chain fatty acids (butyric acid (butanoic acid, C4:0); caproic acid (hexanoic acid, C6:0); caprylic acid (octanoic acid, C8:0)), used at relatively low concentrations (in a range of g/mL, spe-cifically 0.25-16 g/mL, contrary to previously reported mg/mL which revealed inhibitory effects on bacterial growth) affect growth of Escherichia coli K-12 (MG1655 laboratory strain) depending on various conditions. In rich medium (LB) positive effects of all tested fatty acids on E. coli growth were observed, while temperature of incubation (growth at 25oC and 37oC was assessed) modulated these effects. In contrast, a slight but significant growth inhibition by fatty acids was observed in a minimal medium (M9) supplemented with glucose. Nonetheless, in minimal medium containing acetate, the effects of these compounds varied, being either positive or negative depending on their concentrations. No measurable bacterial growth was observed in the case of the presence of any tested fatty acids when primary carbon source (glucose or acetate) was removed from a minimal medium before addition of butyric acid, caproic acid or caprylic acid. These results indi-cated that effects of fatty acids on E. coli cells depend on growth conditions of bacterial cultures, and may suggest that previously reported discrepancies between results ob-tained by various groups might arise, at least partially, from using various cultivation procedures used for different experiments.

C6-C10-dicarboxylic acid C6-C10-omega-1-hydroxy monocarboxylic acids were measured in postmitochondrial (10,000 g) fractions of rat liver after incubation with hexanoic, octanoic, and decanoic acids. In livers both from fed and starved rats, the proportion of decanoic acid converted to sebacic acid was high (approximately 25%) with only minor accumulation of the intermediate 10-hydroxy decanoic acid (1-2%). The conversion of octanoic and hexanoic acids to suberic and adipic acids, respectively, was low (less than 1%). The intermediate 8-hydroxy octanoic and 6-hydroxy hexanoic acids were also accumulated in very small amounts (less than 1%). It was concluded that cytochrome-P-450-mediated omega-hydroxylation was of decisive importance for the production rate of the dicarboxylic acids. Analysis of kinetic parameters of human and rat liver microsomal omega- and omega-1-hydroxylation of hexanoic, octanoic, decanoic, and dodecanoic acids gave the following results: in rats, the apparent Km values for the omega-hydroxylation for dodecanoic and decanoic acids are low, ie., 171 and 3.1 mumole/liter, respectively, whereas they are high for octanoic and hexanoic acids (8211 and 8822 mumole/liter, respectively). In two different humans, the corresponding Km values for dodecanoic, decanoic, octanoic, and hexanoic acids are 3.6-186, 522-247, 4861-3892, and 6825-10400 mumole/liter, respectively. Based on these results, it is argued that adipic and suberic acids found in urine from rats and humans with acyl-CoA dehydrogenation deficiencies are not biosynthesized by direct omega-oxidation of hexanoic and octanoic acids, but most probably by means of beta-oxidation of sebacic and dodecanedioic acids, produced by direct omega-oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Low concentrations of fatty acids can inhibit calcium efflux from sarcoplasmic reticulum vesicles

Octanoic acid promotes branched-chain amino acid catabolisms via the inhibition of hepatic branched-chain alpha-keto acid dehydrogenase kinase in rats

Short- and medium-chain fatty acids exhibit antimicrobial activity for oral microorganisms

Antimicrobial and antitumoral activities of saturated fatty acid solutions

Fatty acid effects on calcium influx and efflux in sarcoplasmic reticulum vesicles from rabbit skeletal muscle

Aroma components of wines play an important role in the sensory quality of wines. In our paper we investigate the effect of commercially available yeast nutrients under different fermentation parameters. Caproic acid, caprylic acid, capric acid, and different fatty acid esters were used as markers of the alcoholic fermentation process. The optimal temperature for the fermentation of different white wines was at 15–16 °C, in the case of examined wines lower concentrations of fatty acids and fatty acid esters were found at this temperature. At 25–26 °C fermentation temperature very high concentrations of fatty acids and fatty acid esters were detected. Applying different nitrogen-containing wine additives we managed to achieve better aroma profiles for white wines even using musts of lower quality.

(1) A non-sulfur purple bacterium, Rhodobacillus palustris, can utilize various fatty acids as substrates of respiration. The initial rate of respiration can be “saturated” by a very low concentrations of fatty acids, such as one several thousandsth of a mole/lit. The minimum “saturating” concentration of substrate becomes smaller as the length of carbon chain of fatty acids increases.(2) The initial rate of oxygen uptake, measured at the saturating concentration of substrate, increases with the increase of the carbon atom up to C7-C9 (Heptoic and pelargonic acids); with further increase of C, however, it decreases gradually until at C17-C18 (margalic and stearic acids) no positive O2-uptake occurs.(3) The rate of oxygen uptake caused by the addition of oxidizable fatty acids falls off abruptly to the value corresponding to endogeneous respiration when the fatty acids are used up. The amount of net oxygen uptake corresponding to the oxidation of fatty acid is directly proportional to the concentration of the acid initially added. The net oxygen uptake (in mole) per mole of fatty acid used, which is denoted by q, is the function of the number (n) of carbon atom in the acid molecule. In the case of normal fatty acids, except for acetic and propionic acid, the following linear relationship was found to hold approximately between q and n, q=0.5(n-2)This relation implies that for normal fatty acids longer than propionic acid, increase of one atom in the molecule entails increase of the net oxygen consumption by 1/2 O2. Propionic and isovaleric acids consumed 2-2.5 times as much oxygen as was predicted by this relation. On the other hand crotonic acid took up only half as much oxygen as did butyric acid.(4) The oxidation of fatty acids (tested with propionic, acetic, valeric, octanoic and isobutyric acids) seems to take place without liberation of carbon dioxide.(5) By the inhibition technique using cyanide and carbon monoxide, as well as by measuring the velocity of oxidation of para-phenylendiamine with and without butyric acid, it was shown that the oxidation of fatty acids by the organismis catalyzed by the function of cytochrome system.(6) Malonic acid, eyen in a concentration of M/100, does not exert any inhibitory action upon the oxidation of fatty acids, while monoiodoacetic acid causes about 50% inhibition in a concentration of M/10000.(7) Using Thunberg's technique it was shown that the dehydrogenase system of fatty acid oxidation cannot utilize redox-dyes such as Janus green, Nile blue, methylene blue, thionine, toluilene blue and 2, 6-dichlorophenol-indophenol, as hydrogen acceptor.

Morinda citrifolia (noni) which is locally known as mengkudu in Malaysia, is a small evergreen tree usually found growing in open coastal regions at sea level and in forest areas. It has been reported to have various therapeutic effects, including having anticancer activities, in clinical practices and laboratory animal models. However, consumers mostly avoid consuming mengkudu products due to mengkudu’s sensory properties such as a strong rancid-like odor that is released when the mengkudu fruit is fully ripe. Therefore, this study was conducted to determine the effectiveness of β-cyclodextrin in deodorizing the unpleasant odors in mengkudu juice which are mainly caused by medium chain fatty acids such as hexanoic acid, octanoic acid and decanoic acid. Initially, the optimal molar ratio for the encapsulation of hexanoic, octanoic and decanoic acid by β-cyclodextrin was constructed as a model system prior to the encapsulation of the juice. The formation of inclusion complex between all acids and β-cyclodextrin was verified by means of differential scanning calorimetry (DSC). Next, four dry weight ratios of mengkudu juice to β–cyclodextrin (1:0.5, 1:1, 1:1.5 and 1:2) were selected to determine the degree of the effectiveness of β-cyclodextrin in encapsulating unpleasant odors via gas chromatography-mass spectrometry (GC-MS). Based on the results, inclusion complex formation was confirmed by DSC through the disappearance of a melting point for pure acid, and shifting to a lower melting point from the pure β–cyclodextrin after the encapsulation process. Moreover, there were significant differences observed between hexanoic acid and octanoic acid content in the mengkudu juice before and after adding β-cyclodextrin (p<0.05). On the other hand, the results obtained from GC-MS and sensory evaluation had contributed to an optimum entrapment of fatty acids at the optimal dry weight ratio of 1:0.5 (dry weight of mengkudu: β-cyclodextrin). Hence, the ability of β-cyclodextrin as a masking agent has been proven to be able to reduce the odor-based fatty acids in mengkudu juice.

Quantitative analyses of fatty acids from five triacylglycerol products, coconut oil, palm kernel oil, palm oil, lard and cocoa butter, were carried out using two analytical methods: matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and gas chromatography (GC), in an effort to validate the application of MALDI-TOFMS in quantitative fatty acid analysis. For the GC analysis, transmethylated products were used, whereas, for the MALDI-TOF analysis, saponified products were used. Under MALDI-TOF conditions, the acids were detected as sodiated sodium carboxylates [RCOONa + Na](+) consistent with the mode of ionization that was previously reported. Thus, the MALDI-TOF mass spectrum of saponified coconut oil showed the presence of sodiated sodium salts of caprylic acid (7.5 +/- 0.67, m/z 189), capric acid (6.9 +/- 0.83, m/z 217), lauric acid (47.8 +/- 0.67, m/z 245), myristic acid (20.4 +/- 0.51, m/z 273), palmitic acid (9.8 +/- 0.47, m/z 301), linoleic acid (0.9 +/- 0.07, m/z 325), oleic acid (4.8 +/- 0.42, m/z 327) and stearic acid (2.0 +/- 0.13, m/z 329). Saponified palm kernel oil had a fatty acid profile that included caprylic acid (3.5 +/- 0.59), capric acid (4.7 +/- 0.82), lauric acid (58.6 +/- 2.3), myristic acid (20.9 +/- 1.5), palmitic acid (7.2 +/- 1.1), oleic acid (3.8 +/- 0.62) and stearic acid (1.2 +/- 0.15). Saponified palm oil gave myristic acid (0.83 +/- 0.18), palmitic acid (55.8 +/- 1.7), linoleic acid (4.2 +/- 0.51), oleic acid (34.5 +/- 1.5), stearic acid (3.8 +/- 0.26) and arachidic acid (0.80 +/- 0.22). Saponified lard showed the presence of myristic acid (1.5 +/- 0.24), palmitic acid (28.9 +/- 1.3), linoleic acid (13.7 +/- 0.67), oleic acid (38.7 +/- 1.4), stearic acid (12.8 +/- 0.64) and arachidic acid (2.4 +/- 0.35). Finally, for saponified cocoa butter, the fatty acid distribution was: palmitic acid (32.3 +/- 1.0), linoleic acid (2.6 +/- 0.35), oleic acid (34.9 +/- 1.7) and stearic acid (30.3 +/- 1.6). Quantitative gas chromatographic analysis of the corresponding methyl esters from these triacylglycerol products yielded data that were mostly in agreement with the MALDI-TOFMS data. The MALDI-TOF experiment, however, proved to be superior to the GC experiment, particularly with regard to baseline resolution of unsaturated acids. Furthermore, the ability of MALDI-TOFMS to detect low concentrations of fatty acids rendered it more sensitive than the GC methodology.

At low Ca2+ concentrations the pore of the inner mitochondrial membrane can open in substates with lower permeability (Hunter, D. R., and Haworth, R. A. (1979) Arch. Biochem. Biophys., 195, 468-477). Recently, we showed that Ca2+ loading of mitochondria augments the cyclosporin A-dependent decrease in transmembrane potential (DeltaPsi) across the inner mitochondrial membrane caused by 10 micro M myristic acid but does not affect the stimulation of respiration by this fatty acid. We have proposed that in our experiments the pore opened in a substate with lower permeability rather than in the "classic" state (Bodrova, M. E., et al. (2000) IUBMB Life, 50, 189-194). Here we show that under conditions lowering the probability of "classic pore" opening in Ca2+-loaded mitochondria myristic acid induces the cyclosporin A-sensitive DeltaPsi decrease and mitochondrial swelling more effectively than uncoupler SF6847 does, though their protonophoric activities are equal. In the absence of P(i) and presence of succinate and rotenone (with or without glutamate) cyclosporin A either reversed or only stopped DeltaPsi decrease induced by 5 micro M myristic acid and 5 micro M Ca2+. In the last case nigericin, when added after cyclosporin A, reversed the DeltaPsi decrease, and the following addition of EGTA produced only a weak (if any) DeltaPsi increase. In P(i)-containing medium (in the presence of glutamate and malate) cyclosporin A reversed the DeltaPsi decrease. These data show that the cyclosporin A-sensitive decrease in DeltaPsi by low concentrations of fatty acids and Ca2+ cannot be explained by specific uncoupling effect of fatty acid. We propose that: 1) low concentrations of Ca2+ and fatty acid induce the pore opening in a substate with a selective cation permeability, and the cyclosporin A-sensitive DeltaPsi decrease results from a conversion of DeltaPsi to pH gradient due to the electrogenic cation transport in mitochondria; 2) the ADP/ATP-antiporter is involved in this process; 3) higher efficiency of fatty acid compared to SF6847 in the Ca2+-dependent pore opening seems to be due to its interaction with the nucleotide-binding site of the ADP/ATP-antiporter and higher affinity of fatty acids to cations.

Effects of various non-esterified fatty acids on the particle size redistribution of high density lipoproteins induced by the human cholesteryl ester transfer protein

Fatty Acid Synthesis by Elongases in Trypanosomes

Influence of long-chain free fatty acids on the binding of warfarin to bovine serum albumin