Effects Of Long-chain Fatty Acids Research Articles

Dietary elaidic acid boosts tumoral antigen presentation and cancer immunity via ACSL5

Immunomodulatory effects of long-chain fatty acids (LCFAs) and their activating enzyme, acyl-coenzyme A (CoA) synthetase long-chain family (ACSL), in the tumor microenvironment remain largely unknown. Here, we find that ACSL5 functions as an immune-dependent tumor suppressor. ACSL5 expression sensitizes tumors to PD-1 blockade therapy invivo and the cytotoxicity mediated by CD8+ Tcells invitro via regulation of major histocompatibility complex class I (MHC-I)-mediated antigen presentation. Through screening potential substrates for ACSL5, we further identify that elaidic acid (EA), a trans LCFA that has long been considered harmful to human health, phenocopies to enhance MHC-I expression. EA supplementation can suppress tumor growth and sensitize PD-1 blockade therapy. Clinically, ACSL5 expression is positively associated with improved survival in patients with lung cancer, and plasma EA level is also predictive for immunotherapy efficiency. Our findings provide a foundation for enhancing immunotherapy through either targeting ACSL5 or metabolic reprogramming of antigen presentation via dietary EA supplementation.

Inhibitory effects of long chain fatty acids on anaerobic sludge treatment: Biomass adaptation and microbial community assessment

The study investigated the effects of long-chain fatty acids (LCFA) on anaerobic sludge treating lipid-rich wastewater. It involved batch experiments with three sludge samples: two acclimated to lipids and one non-acclimated. The experiments aimed to observe the degradation of LCFA, specifically oleate and palmitate, by dosing them at concentrations ranging from 50 to 600 mg/L. Measurements of the cumulative methane production and the LCFA concentration, quantified as fat, oil, and grease (FOG) were performed. To ensure the sludge was free from other biodegradable substrates, part of the samples was pre-incubated without feed. The tests were conducted with both pre-incubated and non-incubated inoculum sludge. The findings revealed that oleate was degraded more efficiently than palmitate across all sludge samples, with a greater conversion rate to methane. Sludge samples acclimated to lipids showed a superior capacity to degrade LCFA compared to non-acclimated ones. It was noted that at concentrations above 400 mg/L, the conversion of LCFAs to intermediate compounds was inhibited, although this did not affect the subsequent methane production. The study concludes with a recommendation for sludge adaptation strategies to boost the efficiency of anaerobic wastewater treatment systems dealing with lipid-rich waste. The presence of LCFA-degrading bacteria families like Kosmotogaceae, Petrotogaceae, and Synergistaceae in the acclimated sludge samples underscores the adaptation and potential for improved degradation performance.

Palmitic acid, but not other long-chain saturated fatty acids, increases S100B protein and TNF-α secretion by astrocytes

Obesity is a health problem that involves fat accumulation in adipose and other tissues and causes cell dysfunction. Long-chain saturated fatty acids can induce and propagate inflammation, which may also contribute to the brain alterations found in individuals with obesity. Fatty acids accumulate in astrocytes in situations of blood‒brain barrier disruption, such as inflammatory conditions. Furthermore, the increase in tumor necrosis factor-alpha (TNF-α) and S100 calcium-binding protein B (S100B) secretion is considered an essential component of the inflammatory response. We hypothesize that through their action on astrocytes, long-chain saturated fatty acids mediate some of the brain alterations observed in individuals with obesity. Here, we investigate the direct effect of long-chain fatty acids on astrocytes. Primary astrocyte cultures were incubated for 24 hours with myristic, palmitic, stearic, linoleic, or α-linolenic acids (25–100 µM). All saturated fatty acids tested led to an increase in TNF-α secretion, but only palmitic acid, one of the most common fatty acids, increased S100B secretion, indicating that S100B secretion is probably not caused in response to TNF-α release. Palmitic acid also caused nuclear migration of nuclear factor kappa B. Long-chain saturated fatty acids did not alter cell viability or redox status. In conclusion, long-chain saturated fatty acids can alter astrocytic homeostasis and may contribute to brain disorders associated with obesity, such as neuroinflammation.

The effects of long-chain fatty acids supplemented to rations during the transition and early lactation periods on reproductive performance in Simmental cattle with low estrus signs

This study is based on the hypothesis that adding rumen bypass unsaturated fatty acids to rations during the transition and early lactation periods will reduce metabolic stress, milk fat synthesis, and milk fat concentration, increase the prevalence of estrus signs and fertilization rates and facilitate the implantation of the embryo. Thus, it was aimed to reveal the effects of calcium soap of long-chain fatty acids (CSFA) added to rations during the transition and early lactation periods in Simmental cattle with low estrus signs. Primiparous and multiparous Simmental cattle were used in the study. The animals were divided into two groups by random sampling, including 62 animals in the CSFA diet group and 44 animals in the basal ration (control; C) group. The modified Ovsynch protocol was used as the synchronization protocol. Pre-ovulatory follicle and uterine tension values were not significantly different between the CSFA and C groups (p>0.05). The rates of both the standing reflex and cervical mucus were greater in the CSFA group than in C (p<0.05). Conception rates on the 30th-35th and 60th-65th days were greater in the CSFA diet group than in C (p<0.05). Consequently, in this study, a positive correlation was identified between the appearance of estrus signs at the time of TAI application and conception outcomes. It was determined that supplementing 800 g/day CSFA to the rations of Simmental cattle with low rates of estrus signs in the transition and early lactation periods increased estrus signs and conception rates.

Insight into effects of long-chain fatty acids on propionic acid production in anaerobic fermentation: A case study of oleic acid and palmitic acid

This study revealed long-chain fatty acids(LCFAs) on propionic acid production by lipid anaerobic acidogenesis. Oleic acid and palmitic acid, the two most common LCFAs, were added into the acidogenic system to evaluate LCFAs type and concentration on the propionic acid production capacity. The results showed that when the concentration of oleic acid was 4 g/L, the content of volatile fatty acids(VFAs) was 1.3 times higher than that of the blank group(propionic acid was the main product, >70%). In contrast, palmitic acid and excess oleic acid inhibited propionic acid production(butyric acid was the main product). Propionic acid-producing bacteria were the dominant bacteria in an oleic acid production system. According to response surface analysis, the optimal concentration of oleic acid favoring for propionic acid production was 2.3 g/L and fermentation time was 7.4 days in this study. The results showed that a proper concentration of oleic acid has a promotion to propionic acid production. This study provides a theoretical basis for oleic acid to promote propionic acid production.

Long-chain fatty acids alter transcription of Helicobacter pylori virulence and regulatory genes.

Infection with Helicobacter pylori is one of the most important risk factors for developing gastric cancer (GC). The type IV secretion system (T4SS) encoded in the cag pathogenicity island is the main virulence factor of H. pylori associated with GC. Additionally, other virulence factors have been shown to play a role in the H. pylori virulence, such as vacuolizing cytotoxin (VacA), urease, flagella, and adhesins. Long-chain fatty acids (LCFAs) are signaling molecules that affect the transcription of virulence genes in several pathogenic bacteria such as Salmonella enterica, Vibrio cholerae, Pseudomonas aeruginosa and Mycobacterium tuberculosis. However, the effect of LCFAs on the transcription of H. pylori virulence and regulatory genes remains unknown. Here we analyzed whether the transcription of virulence genes that encode T4SS and cellular envelope components, flagellins, adhesins, toxins, urease, as well as the transcription of different regulatory genes of the H. pylori strain 26695, are altered by the presence of five distinct LCFAs: palmitic, stearic, oleic, linoleic, and linolenic acids. Palmitic and oleic acids up-regulated the transcription of most of the virulence genes tested, including cagL, cagM, flaB, sabA, mraY and vacA, as well as that of the genes encoding the transcriptional regulators NikR, Fur, CheY, ArsR, FlgR, HspR, HsrA, Hup, and CrdR. In contrast, the other LCFAs differentially affected the transcription of the virulence and regulatory genes assessed. Our data show that LCFAs can act as signaling molecules that control the transcription of the H. pylori virulome.

2-biofuels (H2 and CH4) production from anaerobic digestion of biscuits wastewater: Experimental study and techno-economic analysis

The up-flow anaerobic hybrid reactor (UAHR) was simultaneously employed for 2-biofuels (H2 and CH4) production from solely biscuits wastewater (BW) industry and a mixture of BW with domestic sewage (DS) at a mixing ratio of 3:1 respectively. The UAHR was fed with BW and operated at an organic loading rate (OLR) of 21.9 ± 1.7 gCOD/L/d., and hydraulic retention time (HRT) of 12.0 h. The module achieved volumetric hydrogen production rate (VHPR) and hydrogen yield (HY) of 0.95 ± 0.13 L/L reactor/d., and 118.6 ± 22.3 mL/gCODremoved respectively. A substantial deterioration in the H2 productivity was occurred after 94 days of continuous-feed operation, due to the inhibition effect of long-chain fatty acids (LCFAs). DS was integrated into the BW at mixing ratio of 3.0 (BW):1.0 (DS) where the UAHR was continuously operated at OLRs of 7.95 and 4.45 gCOD/L/d., achieving H2 and CH4 yields of 414.2 ± 38.1 and 318.5 ± 23.5 mL/gCOD removed, respectively. The payback periods for the production of biogas rich CH4 and H2 were 7.1 and 5.7 y respectively.

The Role of Long-Chain Fatty Acids in Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a complicated disease involving multiple pathogenic factors. The complex relationships between long-chain fatty acids (LCFAs) and the morbidity of IBD drive numerous studies to unravel the underlying mechanisms. A better understanding of the role of LCFAs in IBD will substitute or boost the current IBD therapies, thereby obtaining mucosal healing. In this review, we focused on the roles of LCFAs on the important links of inflammatory regulation in IBD, including in the pathogen recognition phase and in the inflammatory resolving phase, and the effects of LCFAs on immune cells in IBD.

Long-Chain Fatty Acid Receptors Mediate Relaxation of the Porcine Lower Esophageal Sphincter.

Long-chain fatty acids activate the free fatty acid receptor 1 (FFA1) and FFA4. In the gastrointestinal system, FFA1 and FFA4 have been found in the pancreas and intestine. Fatty food and decreased lower esophageal sphincter (LES) motility are associated with gastroesophageal reflux disease. The effect of long-chain fatty acids on the esophageal motility is unknown. The purpose of this study is to investigate the effects of long-chain fatty acids on the porcine LES motility ex vivo using isometric transducers. In endothelin 1-precontracted porcine LES strips, the FFA1 selective agonists, fasiglifam, TUG424, and GW9508, caused marked relaxations in a concentration-dependent manner. The relative efficacies to elicit relaxation were GW9508 > TUG424 > fasiglifam in both clasp and sling strips. In contrast, the FFA4 specific agonists, TUG891 and GSK137647, produced mild relaxations. In addition, the endogenous FFA1 agonist DHA caused a mild relaxation whereas GW1100, an FFA1 antagonist, inhibited GW9508 induced relaxation of the porcine LES clasp and sling muscle. Both real-time PCR and immunohistochemistry revealed that FFA1 and FFA4 were expressed in the porcine LES. Real-time PCR analysis showed that the FFA4 expression was much lower than FFA1. Taken together, long-chain fatty acid receptor agonists elicit relaxation of the porcine LES. FFA1 might influence LES motility.

Effects of unsaturation of long-chain fatty acids on rumen protozoal engulfment and microbial protein recycling in protozoa in vitro

The present study investigated the effects of long-chain fatty acids with different degrees of unsaturation on rumen protozoal engulfment and microbial protein recycling by protozoa in vitro. The seven experimental treatments included stearic acid (C18:0, Group A), oleic acid (C18:1, n-9, Group B), linoleic acid (C18:2, n-6, Group C), α-linoleic acid (C18:3, n-3, Group D), arachidonic acid (C20:4, n-6, Group E), eicosapentaenoic acid (C20:5, n-3, Group F) and calcium palmitate (C16:0, control group, G), each being included at 3% (w/w) in the total culture substrate containing starch, xylan, araban, glucan, mannan, cellulose, pectin, lignin, urea and casein. Three goats fitted with rumen cannula were used to provide rumen fluid. The incubation medium was collected for the measurement of engulfing rate of bacteria by protozoa and microbial biomass after 24 h of in vitro incubation. The results showed that the bacterial density of Group D (5.75 × 109 cells/mL) was significantly higher than that of Groups A, B, E, F and G (P &amp;lt; 0.05), but that of the control (Group G) as well as those of Groups A and B were lower than those of Groups D and C (P &amp;lt; 0.05). Similarly, the bacterial protein was the highest in Group D and the lowest in Group G. The number of bacteria engulfed by protozoa per millilitre were the highest in the Control group G (847 × 105 cells/(mL.h)) and the lowest in Group D (392 × 105 cells/(mL.h)). The recycling rate of bacterial cells was lowest in Group D (0.68%) and the recycling time of bacterial cells was the longest (147 h). The quantity of protein recycled was lowest in Group D and highest in Group G, which derived from the number of bacterial cells engulfed. Therefore, it was concluded that the effects of long-chain fatty acids on rumen microbial protein recycling and microbial protein synthesis mainly relate to their degree of unsaturation, with α-linoleic acid possessing a better ability to suppress bacterial-cell (by protozoa) and reduce protein yield.

Dose- and type-dependent effects of long-chain fatty acids on adipogenesis and lipogenesis of bovine adipocytes

Differentiation and lipid metabolism of adipocytes have a great influence on milk performance, health, and feed efficiency of dairy cows. The effects of dietary long-chain fatty acids (FA) on adipogenesis and lipogenesis of dairy cows are often confounded by other nutritional and physiological factors in vivo. Therefore, this study used an in vitro approach to study the effect of dose and type of long-chain FA on adipogenesis and lipogenesis of bovine adipocytes. Stromal vascular cells were isolated from adipose tissue of dairy cows and induced into mature adipocytes in the presence of various long-chain FA including myristic, palmitic, stearic, oleic, or linoleic acid. When concentrations of myristic, palmitic, and oleic acids in adipogenic mediums were 150 and 200 μM, the induced mature adipocytes had greater lipid content compared with other concentrations of FA. In addition, mature adipocytes induced at 100 μM stearic acid and 300 μM linoleic acid had the greatest content of lipid than at other concentrations. High concentrations of saturated FA were more toxic for cells than the same concentration of unsaturated FA during the induction. When commitment stage was solely treated with FA, the number of differentiated mature adipocytes was greater for oleic and linoleic acids than other FA. When the maturation stage was treated with FA, the number of mature adipocytes was not affected, but the lipid content in adipocytes was affected and ranked oleic > linoleic > myristic > stearic > palmitic. In summary, this study showed that adipogenesis and lipogenesis of bovine adipocytes were differentially affected by long-chain FA, with unsaturated FA more effective than saturated FA.

Palmitate inhibits arthritis by inducing t-bet and gata-3 mRNA degradation in iNKT cells via IRE1\u03b1-dependent decay

Long chain fatty acids (LCFAs) exert pro-inflammatory effects in vivo. However, little is known regarding the effect of LCFAs on invariant (i) NKT cell functions. Here, we report an inhibitory effect of saturated LCFAs on transcription factors in iNKT cells. Among the saturated LCFAs, palmitic acid (PA) specifically inhibited IL-4 and IFN-γ production and reduced gata-3 and t-bet transcript levels in iNKT cells during TCR-mediated activation. In iNKT cells, PA was localized and induced dilation in the endoplasmic reticulum and increased the mRNA levels of downstream molecules of IRE1α RNase. Moreover, PA increased the degradation rates of gata-3 and t-bet mRNA, which was restored by IRE1α inhibition or transfection with mutant gata-3 or t-bet, indicating that gata-3 and t-bet are cleaved via regulated IRE1α-dependent decay (RIDD). A PA-rich diet and PA injection suppressed IL-4 and IFN-γ production by iNKT cells in C57BL/6, but not Jα18 knockout mice, which was restored by injection of STF083010, an IRE1α-specific inhibitor. Furthermore, a PA-rich diet and PA injection attenuated arthritis in an iNKT cell-dependent manner. Taken together, our experiments demonstrate that a saturated LCFA induced RIDD-mediated t-bet and gata-3 mRNA degradation in iNKT cells, thereby suppressing arthritis.

MiR-149 Compromises the Reactions of Liver Cells to Fatty Acid via its Polymorphism and Increases Non-Alcoholic Fatty Liver Disease (NAFLD) Risk by Targeting Methylene Tetrahydrofolate Reductase (MTHFR).

BackgroundNon-alcoholic fatty liver disease (NAFLD) is a worldwide health problem, and microRNA (miRNA) has been reported to be involved in NAFLD. The objective of our study was to explore the effect of polymorphism in miR-149 on the pathogenesis of NAFLD.Material/MethodsReal-time PCR was performed to explore the effect of long-chain fatty acid (FFA) on the level of miR-149 and methylene tetrahydrofolate reductase (MTHFR). Then in-silicon analysis and luciferase assay were investigated to verify MTHFR was the target gene of miR-149. Finally, Western-blot analysis and real-time PCR were performed to confirm the control of MTHFR by miR-149.ResultsIn this study, we found that miR-149 was apparently upregulated in hepatocytes genotyped as TT treated with FFA; and MTHFR in hepatocytes genotyped as TT treated with FFA was evidently downregulated compared to control. Whereas, FFA had no obvious effect on MTHFR level in hepatocytes genotyped as CC. We searched an online miRNA database and found that miR-149 was a regulator of MTHFR expression, which was confirmed by luciferase assay. In hepatocytes genotyped as TT and treated with or without FFA, miR-149 mimic dose-dependently decreased the level of MTHFR, and miR-149 inhibitor dose-dependently increased the level of MTHFR. And in hepatocytes genotyped as CC treated with or without FFA exhibited a similar inhibition effect of miR-149 on expression of MTHFR.ConclusionsThe data suggested that the polymorphism in miR-149 played an important role in the development of NAFLD via altering the expression of miR-149 as well as its target, MTHFR.

Erratum to "Inhibitory Effect of Long-Chain Fatty Acids on Biogas Production and the Protective Effect of Membrane Bioreactor".

[This corrects the article DOI: 10.1155/2016/7263974.].

Acyl CoA synthetase-1 links facilitated long chain fatty acid uptake to intracellular metabolic trafficking differently in hearts of male versus female mice

RationaleAcyl CoA synthetase-1 (ACSL1) is localized at intracellular membranes, notably the mitochondrial membrane. ACSL1 and female sex are suggested to indirectly facilitate lipid availability to the heart and other organs. However, such mechanisms in intact, functioning myocardium remain unexplored, and roles of ACSL1 and sex in the uptake and trafficking of fats are poorly understood. ObjectiveTo determine the potential for ACSL1 and sex-dependent differences in metabolic trapping and trafficking effects of long-chain fatty acids (LCFA) within cardiomyocytes of intact hearts. Methods and results13C NMR of intact, beating mouse hearts, supplied 13C palmitate, revealed 44% faster trans-sarcolemmal uptake of LCFA in male hearts overexpressing ACSL1 (MHC-ACSL1) than in non-transgenic (NTG) males (p<0.05). Acyl CoA content was elevated by ACSL1 overexpression, 404% in males and 164% in female, relative to NTG. Despite similar ACSL1 content, NTG females displayed faster LCFA uptake kinetics compared to NTG males, which was reversed by ovariectomy. NTG female LCFA uptake rates were similar to those in ACSL1 males and ACSL1 females. ACSL1 and female sex hormones both accelerated LCFA uptake without affecting triglyceride content or turnover. ACSL1 hearts contained elevated ceramide, particularly C22 ceramide in both sexes and specifically, C24 in males. ACSL1 also induced lower content of fatty acid transporter-6 (FATP6) indicating cooperative regulation with ACSL1. Surprisingly, ACSL1 overexpression did not increase mitochondrial oxidation of exogenous palmitate, which actually dropped in female ACSL1 hearts. ConclusionsACSL1-mediated metabolic trapping of exogenous LCFA accelerates LCFA uptake rates, albeit to a lesser extent in females, which distinctly affects LCFA trafficking to acyl intermediates but not triglyceride storage or mitochondrial oxidation and is affected by female sex hormones.

Inhibitory Effect of Long-Chain Fatty Acids on Biogas Production and the Protective Effect of Membrane Bioreactor.

Anaerobic digestion of lipid-containing wastes for biogas production is often hampered by the inhibitory effect of long-chain fatty acids (LCFAs). In this study, the inhibitory effects of LCFAs (palmitic, stearic, and oleic acid) on biogas production as well as the protective effect of a membrane bioreactor (MBR) against LCFAs were examined in thermophilic batch digesters. The results showed that palmitic and oleic acid with concentrations of 3.0 and 4.5 g/L resulted in >50% inhibition on the biogas production, while stearic acid had an even stronger inhibitory effect. The encased cells in the MBR system were able to perform better in the presence of LCFAs. This system exhibited a significantly lower percentage of inhibition than the free cell system, not reaching over 50% at any LCFA concentration tested.

Long-chain unsaturated fatty acids reduce the transcriptional activity of the rat follicle-stimulating hormone β-subunit gene.

Here, we assessed the effects of long-chain fatty acids (LCFAs) and the LCFA receptor agonist GW9508 on the transcription of the gonadotropin subunit genes Cga, Lhb and Fshb because LCFA receptor GPR120 was observed in mouse gonadotropes in our recent study. A transcription assay using LβT2 cells demonstrated that LCFAs, oleic acid, α-linolenic acid, docosahexaenoic acid and palmitate, repressed the expression of Cga, Lhb, and Fshb at concentrations between 50 and 100 µM. On the other hand, treatment with 10 µM unsaturated LCFAs, oleic acid, α-linolenic acid and docosahexaenoic acid, repressed only Fshb expression, while the same dose of a saturated LCFA, palmitate, had no effect on the expression of gonadotropin subunit genes. Furthermore, GW9508 did not affect promoter activity. Next, we examined deletion mutants of the upstream region of Fshb and found that the upstream regulatory region (-2824 to -2343 bp) of Fshb was responsible for the notable repression by 10 µM unsaturated LCFAs. Our results suggest that the upstream region of Fshb is susceptible to unsaturated LCFAs. In addition, unsaturated LCFAs play a role in repressing Fshb expression through the distal -2824 to -2343 bp region, which might be independent of the LCFA receptor GPR120 pathway.

Saturated and Unsaturated Fatty Acids Differently Modulate Colonic Goblet Cells In Vitro and in Rat Pups1–3

Background: High-fat diets induce intestinal barrier alterations and promote intestinal diseases. Little is known about the effects of long-chain fatty acids (LCFAs) on mucin 2 (MUC2) production by goblet cells, which are crucial for intestinal protection.Objective: We investigated the effects of LCFAs on the differentiation of colonic goblet cells, MUC2 expression, and colonic barrier function.Methods: Upon reaching confluence, human colonic mucus-secreting HT29-MTX cells were stimulated (21 d) with a saturated LCFA (palmitic or stearic acid), a monounsaturated LCFA (oleic acid), or a polyunsaturated LCFA (linoleic, γ-linolenic, α-linolenic, or eicosapentaenoic acid). In addition, rat pups underwent oral administration of oil (palm, rapeseed, or sunflower oil) or water (10 μL/g body weight, postnatal days 10–15). Subsequently, colon goblet cells were studied by Western blotting, reverse transcriptase–quantitative polymerase chain reaction, and immunohistochemistry and colonic transmucosal electrical resistance was measured by using Ussing chambers.Results: In vitro, palmitic acid enhanced MUC2 production (140% of control) and hepatocyte nuclear factor 4α expression, whereas oleic, linoleic, γ-linolenic, α-linolenic, and eicosapentaenoic acids reduced MUC2 expression (at least −50% of control). All unsaturated LCFAs decreased the expression of human atonal homolog 1, a transcription factor controlling goblet cell differentiation (at least −31% vs. control). In vivo, rats fed palm oil had higher palmitic acid concentrations (3-fold) in their colonic contents and increased mucus granule surfaces in their goblet cells (>2-fold) than did all other groups. Palm oil also increased colonic transmucosal electrical resistance (245% of control), yet had no effect on occludin and zonula occludens-1 expression. In contrast, sunflower and rapeseed oils decreased goblet cell number when compared with control (at least −10%) and palm oil (at least −14%) groups.Conclusions: Palm oil in rat pups and palmitic acid in HT29-MTX cells increase the production of MUC2 and strengthen the intestinal barrier. In contrast, unsaturated LCFAs decrease MUC2 expression. These data should be taken into account in the context of preventive or therapeutic nutritional programs.

Assessment of crude glycerol for Enhanced Biological Phosphorus Removal: Stability and role of long chain fatty acids

Enhanced Biological Phosphorus Removal (EBPR) of urban wastewaters is usually limited by the available carbon source required by Polyphosphate Accumulating Organisms (PAO). External carbon sources as volatile fatty acids (VFA) or other pure organic compounds have been tested at lab scale demonstrating its ability to enhance PAO activity, but the application of this strategy at full-scale WWTPs is not cost-effective. The utilization of industrial by-products with some of these organic compounds provides lower cost, but it has the possible drawback of having inhibitory or toxic compounds to PAO. This study is focused on the utilization of crude glycerol, the industrial by-product generated in the biodiesel production, as a possible carbon source to enhance EBPR in carbon-limited urban wastewaters. Crude glycerol has non-negligible content of other organic compounds as methanol, salts, VFA and long chain fatty acids (LCFA). VFA and methanol have been demonstrated to enhance PAO activity, but there is no previous study about the effect of LCFA on PAO. This work presents the operation of an EBPR SBR system using crude glycerol as sole carbon source, studying also its long-term stability. The effect of LCFA is evaluated at short and long-term operation, demonstrating for the first time EBPR activity with LCFA as sole carbon source and its long-term failure due to the increased hydrophobicity of the sludge.

Effects of long-chain fatty acids on in vitro rumen microbial population, dry matter degradability and methane production

Effects of long-chain fatty acids on in vitro rumen microbial population, dry matter degradability and methane production