Microbial Fatty Acids Research Articles

Placental and fetal enrichment of microplastics from disposable paper cups: implications for metabolic and reproductive health during pregnancy

The disposable paper cups (DPCs) release millions of microplastics (MPs) when used for hot beverages. However, the tissue-specific deposition and toxic effects of MPs and associated toxins remain largely unexplored, especially at daily consumption levels. We administered MPs and associated toxins extracted from leading brand DPCs to pregnant mice, revealing dose-responsive harmful effects on fetal development and maternal physiology. MPs were detected in all 13 examined tissues, with preferred depositions in the fetus, placenta, kidney, spleen, lung, and heart, contributing to impaired phenotypes. Brain tissues had the smallest MPs (90.35 % < 10 µm). A dose-responsive shift in the cecal microbiome from Firmicutes to Bacteroidetes was observed, coupled with enhanced biosynthesis of microbial fatty acids. A moderate consumption of 3.3 cups daily was sufficient to alter the cecal microbiome, global metabolic functions, and immune health, as reflected by tissue-specific transcriptomic analyses in maternal blood, placenta, and mammary glands, leading to neurodegenerative and miscarriage risks. Gene-based benchmark dose framework analysis suggested a safe exposure limit of 2 to 4 cups/day in pregnant mice. Our results highlight tissue-specific accumulation and metabolic and reproductive toxicities in mice at DPC consumption levels presumed non-hazardous, with potential health implications for pregnant women and fetuses.

Analysis of the effects of β-mannanase on immune function and intestinal flora in broilers fed the low energy diet based on 16S rRNA sequencing and metagenomic sequencing

As an enzyme, β-mannanase (BM) can be widely used as feed additive to improve the growth performance of animals. This experiment aimed to determine the effect of the addition of BM to low-energy diet on the immune function and intestinal microflora of broiler chickens. In this study, 384 one-day-old Arbor Acres broilers were randomly divided into 3 groups (8 replicates per group): positive control (PC, received a corn-soybean meal basal diet), negative control (NC, received a low-energy diet with Metabolizable Energy (ME) reduced by 50 kcal/kg) and NC + BM group (NC birds + 100 mg/kg BM). All birds were raised for 42 d. The results showed that BM mitigated the damage of immune function in peripheral blood of broilers caused by the decrease of dietary energy level by increasing the Concanavalin A (Con A) index of stimulation (SI) and macrophages phagocytic activity in the peripheral blood of broilers at 42 d (P < 0.05). The analysis of cecum flora showed that the low-energy diet significantly reduced the observed_species index (P < 0.01), Chao1 index and ACE index (P < 0.05), which reduced the abundance and evenness of species in the cecum of broilers at 21 d. It also significantly reduced the relative abundance of Candidatus_Arthromitus and significantly increased the relative abundance of Pseudomonas in the cecum of broilers at 21 d, while also significantly increasing the relative abundance of Monoglobus at 42 d. BM significantly increased the relative abundance of Lachnospiraceae_UCG-001 and Lachnospiraceae_bacterium_615 in the cecum of broilers at 21 d. In addition, BM inhibited microbial Fatty acid degradation by decreasing the activity of glutaryl-CoA dehydrogenase. Collectively, BM could improve intestinal health by enhancing the immune function of broilers, promoting the proliferation of beneficial bacteria and reducing the number of harmful bacteria, regulating intestinal flora, thereby alleviating the adverse effects of lower dietary energy levels.

Isolation, identification, and pathogenicity of Pseudomonas glycinae causing ginseng bacterial soft rot in China

By tissue separation method, tie-back experiment, and hypersensitive response test in potato, strain XJFL-1 was isolated and identified as the pathogen of ginseng bacterial soft rot in Liaoning Provence, China. The morphological characteristics of XJFL-1 were conformed to the Pseudomonads genus. Microbial fatty acid identification showed the principal cellular fatty acid traits of XLFJ-1 corresponded with Pseudomonas spp. API 50CH test results allowed the differentiation of strain XJFL-1 and MS586T from other closely related Pseudomonas species. The molecular identification, including 16S rRNA analysis and multilocus sequence typing (MLST) analysis, showed that XJFL-1 was in the same branch as P. glycinae MS586T.The genome of XJFL-1 was 6,296,473 bp, with an average guanine/cytosine (G + C) content of 60.72 %. Comparative genomics analysis using ANIb and GGDC algorithms indicated that the maximum value was observed between XJFL-1 and P. glycinae MS586T.The above morphological, cell morphology, and molecular biological identification results supported to identification of XJFL-1 as P. glycinae.This is the first report of P. glycinae as the plant pathogen causing ginseng bacterial root rot in China, which complements the biological significance of the species to a certain extent, enriches the pathogens of ginseng bacterial soft rot, and provides a theoretical basis for further investigation.

The stable carbon and hydrogen isotopic composition of microbial fatty acids traces microbial metabolism in soils and peats

The compound-specific stable carbon (δ13C) and hydrogen (δ2H) isotopic compositions of microbial fatty acids have been widely used to trace microbial metabolism across a range of mesophilic environments. However, few studies have combined the δ13C and δ2H values of microbial fatty acids. So far none have determined the δ2H of microbial phospholipid fatty acids (PLFAs) in soils or peats, even though these stable isotope combinations could provide new insights into soil microbial metabolism. Here, we measured the δ13C and δ2H values of microbial PLFAs in top soils from peatlands, meadows, and woodlands in the Dajiuhu basin, central China. We observed a significant (p < 0.05) positive correlation between the δ13C and δ2H of microbial PLFAs across the three habitats studied here, indicating that central metabolic pathways affect both carbon and hydrogen isotopic compositions of microbial PLFAs. Moreover, our stable isotope data consistently indicate a relatively conservative metabolic state, which is dominated by expected heterotrophic metabolism. The exception to these observations is PLFAs associated with methanotrophs, as these appear to have decoupled carbon and hydrogen isotopes, providing an additional tool for tracing methanotrophic signals. Our results suggest that the carbon and hydrogen dual isotopic composition of microbial PLFAs can not only provide cross-validation for microbial metabolism in natural environments, but as a combined tool can also provide new insights into the perturbation of soil microbial community metabolism.

Conformational Changes of Acyl Carrier Protein Switch the Chain Length Preference of Acyl-ACP Thioesterase ChFatB2.

Microbial fatty acids are synthesized by Type II fatty acid synthase and could be tailored by acyl-ACP thioesterase. With the prospects of medium-chain fatty-acid-derivative biofuels, the selectivity of thioesterase has been studied to control the fatty acid product chain length. Here, we report an alternative approach by manipulating the acyl carrier protein portion of acyl-ACP to switch the chain length propensity of the thioesterase. It was demonstrated that ChFatB2 from Cuphea hookeriana preferred C10-ACP to C8-ACP with ACP from E. coli, while converting preference to C8-ACP with ACP from Cuphea lanceolate. Circular dichroism (CD) results indicated that the C8-EcACP encountered a 34.4% α-helix increment compared to C10-EcACP, which resulted in an approximate binding affinity decrease in ChFatB2 compared to C10-EcACP. Similarly, the C10-ClACP2 suffered a 45% decrease in helix content compared to C8-ClACP2, and the conformational changes resulted in an 18% binding affinity decline with ChFatB2 compared with C10-ClACP2. In brief, the study demonstrates that the ACP portion of acyl-ACP contributes to the selectivity of acyl-ACP thioesterase, and the conformational changes of EcACP and ClACP2 switch the chain length preference of ChFatB2 between C8 and C10. The result provides fundamentals for the directed synthesis of medium-chain fatty acids based on regulating the conformational changes of ACPs.

A Review of Fatty Acid Biosynthesis Enzyme Inhibitors as Promising Antimicrobial Drugs.

Resistance to antimicrobial drugs is currently a serious threat to human health. Consequently, we are facing an urgent need for new antimicrobial drugs acting with original modes of action. The ubiquitous and widely conserved microbial fatty acid biosynthesis pathway, called FAS-II system, represents a potential target to tackle antimicrobial resistance. This pathway has been extensively studied, and eleven proteins have been described. FabI (or InhA, its homologue in mycobacteria) was considered as a prime target by many teams and is currently the only enzyme with commercial inhibitor drugs: triclosan and isoniazid. Furthermore, afabicin and CG400549, two promising compounds which also target FabI, are in clinical assays to treat Staphylococcus aureus. However, most of the other enzymes are still underexploited targets. This review, after presenting the FAS-II system and its enzymes in Escherichia coli, highlights the reported inhibitors of the system. Their biological activities, main interactions formed with their targets and structure-activity relationships are presented as far as possible.

Longitudinal multi-omics analyses of the gut-liver axis reveals metabolic dysregulation in hepatitis C infection and cirrhosis.

The gut and liver are connected via the portal vein, and this relationship, which includes the gut microbiome, is described as the gut-liver axis. Hepatitis C virus (HCV) can infect the liver and cause fibrosis with chronic infection. HCV has been associated with an altered gut microbiome; however, how these changes impact metabolism across the gut-liver axis and how this varies with disease severity and time is unclear. Here we used multi-omics analysis of portal and peripheral blood, faeces and liver tissue to characterize the gut-liver axis of patients with HCV across a fibrosis severity gradient before (n = 29) and 6 months after (n = 23) sustained virologic response, that is, no detection of the virus. Fatty acids were the major metabolites perturbed across the liver, portal vein and gut microbiome in HCV, especially in patients with cirrhosis. Decreased fatty acid degradation by hepatic peroxisomes and mitochondria was coupled with increased free fatty acid (FFA) influx to the liver via the portal vein. Metatranscriptomics indicated that Anaerostipes hadrus-mediated fatty acid synthesis influences portal FFAs. Both microbial fatty acid synthesis and portal FFAs were associated with enhanced hepatic fibrosis. Bacteroides vulgatus-mediated intestinal glycan breakdown was linked to portal glycan products, which in turn correlated with enhanced portal inflammation in HCV. Paired comparison of patient samples at both timepoints showed that hepatic metabolism, especially in peroxisomes, is persistently dysregulated in cirrhosis independently of the virus. Sustained virologic response was associated with a potential beneficial role for Methanobrevibacter smithii, which correlated with liver disease severity markers. These results develop our understanding of the gut-liver axis in HCV and non-HCV liver disease aetiologies and provide a foundation for future therapies.

Tailored designing of a diploid S. cerevisiae natural isolate for increased production of fatty acid ethyl ester

Developing microbial chassis for synthesizing value-added compounds is the most eco-friendly approach to minimize the impacts of overusing fossil fuels and other harsh chemicals. Recent research has focussed on harnessing microbial fatty acid metabolism to generate oleochemicals for use in industries as diverse as fuel production, cosmetics, lubricants and more. Considering the economic viability of generating “green biocatalysts”, we reconfigured the fatty acid biosynthesis pathway in an environmentally robust strain of Saccharomyces cerevisiae MTCC4796 to produce fatty acid ethyl ester (FAEE) with high yield and titer. We applied the push–pull-block strategy wherein a heterologous wax ester synthase (WS2) was initially integrated to establish a FAEE biosynthetic pathway (pull) with additional rewiring including overexpression of PDH-bypass pathway genes for increasing the supply of precursor fatty acyl-CoA (push) and single allele disruption of non-essential genes from competing pathways (block) to maximize the metabolic flux towards FAEE overproduction. Our final engineered strain NGYT carrying 11 genetic modifications produced 26 mg/L and 1 g/L of FAEE before and after glucose optimization respectively. This titer was further scaled-up to reach 5 g/L in fed-batch bioreactors, which, to our knowledge, is the highest reported FAEE titer achieved from Saccharomyces cerevisiae with glucose as carbon source. Additionally, the FAEE’s produced by NGYT strain showed a higher percentage of monounsaturated fatty acids, which are ideally suitable for biodiesel applications. Given the global emphasis on the development of cleaner fuels, the findings from this study expedite our progress towards industrial scale-FAEE production as a substitute to conventional diesel.

Impact of Oil Sources on In Vitro Fermentation, Microbes, Greenhouse Gas, and Fatty Acid Profile in the Rumen

This study estimated the effects of oil sources on fermentation characteristics, greenhouse gas, microbial diversity, and biohydrogenation of fatty acids in the rumen. In vitro ruminal incubation was performed with 7 mg of oil source, 15 mL rumen buffer, and 150 mg of synthetic diet at 39 °C for 0, 3, 6, 12, and 24 h. Oil sources consisted of corn oil (CO; linoleic acid (C18:2n-6)), linseed oil (LSO; linolenic acid (C18:3n-3)), or Ca-salts (protected C18:2n-6). The ruminal gas was collected for CH4 and CO2 analysis. Incubated rumen buffer was sub-sampled for the analysis of microbial quantification, fermentation characteristics, and fatty acid profiles. The results showed that Ca-salt increased acetate (p = 0.013), while CO increased propionate (p = 0.007). Fibrobacter succinogenes, Ruminococcus flavefaciens, and R. albus increased (p &lt; 0.05) with Ca-salt after 12 h of incubation, while Streptococcus bovis increased (p &lt; 0.05) by LSO. The CO and Ca-salt resulted in the highest C18:2n-6 (p = 0.002), while LSO resulted in the highest C18:3n-3 (p = 0.001). The Ca-salt had the lowest C18:0 (p = 0.002), but the highest C18:1cis-9 (p = 0.004). In conclusion, Ca-salt supplementation resisted biohydrogenation to some extent, decreased methanogenic archaea and protozoa, and exerted less toxic effects on fibrolytic bacteria.

Characterization and Molecular Mechanism of a Novel Cytochrome b5 Reductase with NAD(P)H Specificity from Mortierella alpina.

The electron-transfer capabilities of cytochrome b5 reductase (Cyt b5R) and NADPH supply have been shown to be critical factors in microbial fatty acid synthesis. Unfortunately, Cyt b5R substrate specificity is limited to the coenzyme NADH. In this study, we discovered that a novel Cyt b5R from Mortierella alpina (MaCytb5RII) displays affinity for NADPH and NADH. The enzymatic characteristics of high-purity MaCytb5RII were determined with the Km,NADPH and Km,NADH being 0.42 and 0.07 mM, respectively. MaCytb5RII shows high specific activity at 4 °C and pH 9.0. We anchored the residues that interacted with the coenzymes using the homology models of MaCytb5Rs docking NAD(P)H and FAD. The enzyme activity analysis of the purified mutants MaCytb5RII[S230N], MaCytb5RII[Y242F], and MaCytb5RII[S272A] revealed that Ser230 is essential for MaCytb5RII to have dual NAD(P)H dependence, whereas Tyr242 influences MaCytb5RII's NADPH affinity and Ala272 greatly decreases MaCytb5RII's NADH affinity.

Effects of traditional field retting of hemp on soil organic carbon and the soil microbial community

AbstractRetting is a process used with bast fiber crops such as industrial hemp (Cannabis sativaL.) to expedite the separation of fibers from the woody core of the stalk. Field retting involves partial decomposition of stalks on the soil surface and is facilitated by soil microorganisms. Effects of field retting on soil C have not been studied, and little information is available on how field retting affects the soil microbial community. We conducted an experiment to investigate effects of field retting on total organic soil C (TOC), permanganate oxidizable soil C (POXC), and relative abundance of microbial fatty acid methyl ester biomarkers (FAMEs). Four treatments were imposed: (a) no retting (NR), (b) low‐density retting (LDR) (2,500 kg stalks ha–1), (c) high‐density retting (HDR) (5,000 kg stalks ha–1), and (d) control (CON). The NR, LDR, and HDR treatments were conducted on plots where hemp was grown, whereas the CON treatment excluded production and retting. Plots under HDR treatment generally had greater TOC and POXC than plots where no retting occurred. Analysis of FAMEs indicated that soil microbial communities were grouped according to retting treatments. Greater fungal abundance and higher fungi to bacteria ratios were associated with soils where retting occurred. Compared with retting methods where harvested stalks are immediately removed from the field, field retting may mitigate soil C losses associated with harvest and may be a useful component of maintaining soil health when used in concert with management practices that build soil C.

A6 MECHANISMS UNDERLYING GUT DYSFUNCTION FOLLOWING C. DIFFICILE INFECTION AND IMPLICATIONS FOR TREATMENT

BackgroundRecent evidence suggests an increasing prevalence of gut dysfunction following C. difficile infection (CDI). The accompanying prolonged antibiotic (AB) exposure likely contributes to chronic gut dysfunction and our ability to induce gut dysfunction in germ free (GF) mice colonized with microbiota from a patient with severe slow transit post CDI (PCDI) supports this notion (10.1093/jcag/gwz047.117). Furthermore, we were able to restore gut function following fecal microbial transfer from healthy murine donors. Our studies have implicated a role for macrophages in the destruction of the Interstitial Cell of Cajal (ICC) network underlying slow colonic transit in the humanized mouse model. These findings prompted us to evaluate microbiota-directed therapy in normalising gut function in this model.Aims 1)To investigate whether dietary psyllium rescues the development of slow colonic transit (SCT) through modulating host function via microbiota mediated immune mechanisms; and 2)To evaluate the mechanisms underlying the beneficial effects of psylliumMethodsGF mice were colonized with either microbiota from the PCDI patient or healthy control (HC) for 3 weeks following which PCDI mice were treated with either a control diet or a 15% psyllium diet (PSY). Colonic motility was assessed before and after the diet intervention using the bead expulsion test. Stool samples were collected for microbial profiling, and short and branched-chain fatty acids (SCFA/BCFA) analysis. Colonic muscle layers encompassing myenteric plexus (MP) were collected for gene expression analysis and to evaluate activated macrophages and ICC degeneration using immunohistochemistry.ResultsMicrobiota from a PCDI patient induced a SCT phenotype in GF mice (n=13) as compared to mice colonized with HC microbiota (p=0.0002). Psyllium rescued this SCT phenotype in mice (PCDI(n=7) vs.PSY(n=6):p=0.0014). The psyllium-induced rescue was accompanied by normalization of the ICC network and morphological alterations in infiltrating macrophages. This was supported by changes in immune-related gene expression in the MP including CD11b, NOS, Myd88, Mapk1 and NF-κB. Additionally, bacterial composition was different between PCDI and PSY group (p=0.003). SCFAs like acetic and propionic acid were increased, while BCFA like isobutyric and isovaleric acid were decreased following PSY treatment. These alterations in SCFA/BCFA were supported by fluctuations in specific bacteria like Butyricimonas, Phascolarctobacterium and Allistipes.ConclusionsOur results provide evidence that chronic gut dysfunction following CDI and AB exposure is microbiota-driven. Furthermore, microbiota-directed therapy using psyllium could serve as a novel therapeutic strategy to normalize gut function via microbiota-mediated restoration of immune homeostasis in these patients.Funding AgenciesW. Garfield Weston Foundation

Does a high dietary intake of resistant starch affect glycaemic control and alter the gut microbiome in women with gestational diabetes? A randomised control trial protocol

BackgroundGestational Diabetes Mellitus (GDM) is prevalent with lasting health implications for the mother and offspring. Medical nutrition therapy is the foundation of GDM management yet achieving optimal glycaemic control often requires treatment with medications, like insulin. New dietary strategies to improve GDM management and outcomes are required.Gut dysbiosis is a feature of GDM pregnancies, therefore, dietary manipulation of the gut microbiota may offer a new avenue for management. Resistant starch is a fermentable dietary fibre known to alter the gut microbiota and enhance production of short-chain fatty acids. Evidence suggests that short-chain fatty acids improve glycaemia via multiple mechanisms, however, this has not been evaluated in GDM.MethodsAn open-label, parallel-group design study will investigate whether a high dietary resistant starch intake or resistant starch supplement improves glycaemic control and changes the gut microbiome compared with standard dietary advice in women with newly diagnosed GDM. Ninety women will be randomised to one of three groups - standard dietary treatment for GDM (Control), a high resistant starch diet or a high resistant starch diet plus a 16 g resistant starch supplement. Measurements taken at Baseline (24 to 30-weeks’ gestation), Day 10 and Day 56 (approximately 36 weeks’ gestation) will include fasting plasma glucose levels, microbial composition and short-chain fatty acid concentrations in stool, 3-day dietary intake records and bowel symptoms questionnaires. One-week post-natal data collection will include microbial composition and short-chain fatty acid concentrations of maternal and neonatal stools, microbial composition of breastmilk, birthweight, maternal and neonatal outcomes. Mixed model analysis of variance will assess change in glycaemia and permutation-based multivariate analysis of variance will assess changes in microbial composition within and between intervention groups. Distance-based linear modelling will identify correlation between change in stool microbiota, short-chain fatty acids and measures of glycaemia.DiscussionTo improve outcomes for GDM dyads, evaluation of a high dietary intake of resistant starch to improve glycaemia through the gut microbiome needs to be established. This will expand the dietary interventions available to manage GDM without medication.Trial registrationAustralian New Zealand Clinical Trial Registry, ACTRN12620000968976p. Registered 28 September 2020

Overview of the Cellular Stress Responses Involved in Fatty Acid Overproduction in E. coli.

Research on microbial fatty acid metabolism started in the late 1960s, and till date, various developments have aided in elucidating the fatty acid metabolism in great depth. Over the years, synthesis of microbial fatty acid has drawn industrial attention due to its diverse applications. However, fatty acid overproduction imparts various stresses on its metabolic pathways causing a bottleneck to further increase the fatty acid yields. Numerous strategies to increase fatty acid titres in Escherichia coli by pathway modulation have already been published, but the stress generated during fatty acid overproduction is relatively less studied. Stresses like pH, osmolarity and oxidative stress, not only lower fatty acid titres, but also alter the cell membrane composition, protein expression and membrane fluidity. This review discusses an overview of fatty acid synthesis pathway and presents a panoramic view of various stresses caused due to fatty acid overproduction in E. coli. It also addresses how certain stresses like high temperature and nitrogen limitation can boost fatty acid production. This review paper also highlights the interconnections that exist between these stresses.

The effects of ozone treatments on the agro-physiological parameters of tomato plants and the soil microbial community

Ozone has been applied in many processes (drinking water disinfection and wastewater treatment, among others) based on its high degree of effectiveness as a wide-spectrum disinfectant and its potential for the degradation of pollutants and pesticides. Nevertheless, the effects of irrigation with ozonated water on the soil microbial community and plant physiology and productivity at the field scale are largely unknown. Here, we assessed the impact of irrigation with ozonated water on the microbial community of a Mediterranean soil and on Solanum lycopersicum L. agro-physiology and productivity in a greenhouse experiment. For this purpose, we evaluated: i) soil physicochemical properties, soil enzyme activities, and the biomass (through analysis of microbial fatty acids) and diversity (through 16S rRNA gene and ITS2 amplicon sequencing) of the soil microbial community, and ii) the nutrient content, physiology, yield, and fruit quality of tomato plants. Overall, the soil physicochemical properties were slightly affected by the treatments applied, showing some differences between continuous and intermittent irrigation with ozonated water. Only the soil pH was significantly reduced by continuous irrigation with ozonated water at the end of the assay. Biochemical parameters (enzymatic activities) showed no significant differences between the treatments studied. The biomasses of Gram- bacteria and fungi were decreased by intermittent and continuous irrigation with ozonated water, respectively. However, the diversity, structure, and composition of the soil microbial community were not affected by the ozone treatments. Changes in soil properties slightly affected tomato plant physiology but did not affect yield or fruit quality. The stomatal conductance was reduced and the intrinsic water use efficiency was increased by continuous irrigation with ozonated water. Our results suggest that soil health and fertility were not compromised, however ozonated water treatments should be tailored to individual crop conditions to avoid adverse effects.

The Role of Dietary and Microbial Fatty Acids in the Control of Inflammation in Neonatal Piglets.

Simple SummaryThe maturation of the gut is a specific and very dynamic process in new-born piglets. Consequently, piglet’s gut is very susceptible to disturbances, especially in stressful periods of life, such as weaning, when the gut lining often becomes inflamed and leaky. Dietary fatty acids (FA) do not only serve as source of energy and essential FA, but they are important precursors for bioactive lipid mediators, which modulate inflammatory signalling in the body. The current review summarizes results on dietary sources of FA for piglets, the signalling cascades, bioactivities, the necessity to consider the autoxidation potential of polyunsaturated FA and the area of microbially produced long-chain FA. That said, porcine milk is high in fat, whereby the milk FA composition partly depends on the dietary FA composition of the sow. Therefore, manipulation of the sow diet is an efficient tool to increase the piglet’s intake of specific FA, e.g., n-3 polyunsaturated FA which show anti-inflammatory activity and may support intestinal integrity and functioning in the growing animal.Excessive inflammation and a reduced gut mucosal barrier are major causes for gut dysfunction in piglets. The fatty acid (FA) composition of the membrane lipids is crucial for mediating inflammatory signalling and is largely determined by their dietary intake. Porcine colostrum and milk are the major sources of fat in neonatal piglets. Both are rich in fat, demonstrating the dependence of the young metabolism from fat and providing the young organism with the optimum profile of lipids for growth and development. The manipulation of sow’s dietary polyunsaturated FA (PUFA) intake has been shown to be an efficient strategy to increase the transfer of specific FAs to the piglet for incorporation in enteric tissues and cell membranes. n-3 PUFAs, especially seems to be beneficial for the immune response and gut epithelial barrier function, supporting the piglet’s enteric defences in situations of increased stress such as weaning. Little is known about microbial lipid mediators and their role in gut barrier function and inhibition of inflammation in neonatal piglets. The present review summarizes the current knowledge of lipid nutrition in new-born piglets, comparing the FA ingestion from milk and plant-based lipid sources and touching the areas of host lipid signalling, inflammatory signalling and microbially derived FAs.

Microbial fatty acid transport proteins and their biotechnological potential.

Fatty acid metabolism has been widely studied in various organisms. However, fatty acid transport has received less attention, even though it plays vital physiological roles, such as export of toxic free fatty acids or uptake of exogenous fatty acids. Hence, there are important knowledge gaps in how fatty acids cross biological membranes, and many mechanisms and proteins involved in these processes still need to be determined. The lack of information is more predominant in microorganisms, even though the identification of fatty acids transporters in these cells could lead to establishing new drug targets or improvements in microbial cell factories. This review provides a thorough analysis of the current information on fatty acid transporters in microorganisms, including bacteria, yeasts and microalgae species. Most available information relates to the model organisms Escherichia coli and Saccharomyces cerevisiae, but transport systems of other species are also discussed. Intracellular trafficking of fatty acids and their transport through organelle membranes in eukaryotic organisms is described as well. Finally, applied studies and engineering efforts using fatty acids transporters are presented to show the applied potential of these transporters and to stress the need for further identification of new transporters and their engineering.

Maximization of saturated fatty acids through the production of P450BM3 monooxygenase in the engineered Escherichia coli

The microbial fatty acid biosynthesis, which can be utilized as precursors for diverse chemical production has recently attracted important attention. Saturated fatty acids (SFAs) occur rarely in nature but are more significant due to their higher industrial applications. They can be improved by engineered Escherichia coli; although, the previous production was low. In this work, improvements of both the strain and cultivation conditions were used to augment extracellular SFAs production by engineered E. coli. In addition, engineering with P450BM3 monooxygenase was applied to regulate SFAs production in E. coli. Three fatty acids (Lauric, LA, Myristic, MA, and Decanoic, DA) from engineered E. coli were first determined by HPLC. The expression of P450BM3 monooxygenase plasmid gene revealed higher yields of SFAs. Furthermore, optimization of SFAs production using diverse concentrations of glycerol (0.4%, 0.8% and 1.6%), iron (0.12 and 0.24 g/L) and trace element volumes (4 and 8 mL) was carried out in batch flasks and bioreactor to obtain the highest content of such FAs in E. coli. This study exhibited an improved yield of SFAs in E. coli reached to almost 35-fold higher for DA and 3-times for LA and MA, but in prior studies these FAs levels were not reported. Moreover, the produced SFAs were mainly secreted into the cultivation medium helped to favor its recovery. Therefore, the synthetic biotechnology can provide effective techniques for economic, high value and viable production of FAs in engineered E. coli.

Combined ozonation and solarization for the removal of pesticides from soil: Effects on soil microbial communities

Pesticides have been used extensively in agriculture to control pests and soil-borne diseases. Most of these pesticides can persist in soil in harmful concentrations due to their intrinsic characteristics and their interactions with soil. Soil solarization has been demonstrated to enhance pesticide degradation under field conditions. Recently, ozonation has been suggested as a feasible method for reducing the pesticide load in agricultural fields. However, the effects of ozonation in the soil microbial community have not been studied so far. Here, we evaluate the combined effects of solarization and ozonation on the microbial community of a Mediterranean soil. For this purpose, soil physico-chemical characteristics and enzyme activities and the biomass (through analysis of microbial fatty acids) and diversity (through 16S rRNA and ITS amplicon sequencing) of soil microbial communities were analyzed in a 50-day greenhouse experiment. The degradation of the pesticides was increased by 20%, 28%, and 33% in solarized soil (S), solarized soil with surface ozonation (SOS), and solarized soil with deep ozonation (SOD), respectively, in comparison to control (untreated) soil. Solarization and its combination with ozonation (SOS and SOD) increased the ammonium content as well as the electrical conductivity, while enzyme activities and soil microbial biomass were negatively affected. Despite the biocidal character of ozone, several microbial populations with demonstrated pesticide-degradation capacity showed increases in their relative abundance. Overall, the combination of solarization plus ozone did not exacerbate the effects of solarization on the soil chemistry and microbial communities, but did improve pesticide degradation.

Effect of various salt concentrations on the ruminal parameters of goats

The objective of this study was to evaluate the effects of various concentrations of sodium chloride (NaCl), magnesium chloride (MgCl2), and calcium chloride (CaCl2) on the growth and in vitro fermentation of cellulolytic, glycolytic, and amylolytic microorganisms from the rumen of a goat. Six concentrations of each salt were tested separately, namely 0 mg/dL, 100 mg/dL, 200 mg/dL, 400 mg/dL, 800 mg/dL, and 1600 mg/dL in the culture medium. The experiments were conducted in a completely randomized design, in a 6 x 3 factorial arrangement of salt concentration and substrate (starch, cellulose, and glucose) with three replications of each treatment combination. Concentrations of microbial protein, ammonia (NH3-N), and volatile fatty acids (acetate, propionate, and butyrate) were measured. A quadratic effect of CaCl2 concentration on the production of microbial protein was observed in the cellulose medium. The effect of MgCl2 on NH3-N production in the cellulose medium decreased linearly. Propionate concentration decreased linearly with increasing levels of NaCl and MgCl2 in the media containing starch. There was a decreasing linear effect of MgCl2 on the concentration of butyrate in the media containing glucose. In conclusion, concentrations of NaCl and CaCl2 up to 1,600 mg/dL did not affect the microbial activity of starch, cellulose, and glucose-fermenting organisms. However, the microbial activity of starch-fermenting microbes was inhibited at salt concentrations above 800 mg/dL. Thus, brackish water could be used by goats in semiarid regions, but its use should be managed carefully so that it does not have a negative impact on rumen microbial populations.Keywords: cellulose, glucose, saline water, starch, ruminants