The effect of dietary fatty acids on lactic acid bacteria associated with the epithelial mucosa and from faecalia of Arctic charr, Salvelinus alpinus (L.)

N-3 Polyunsaturated Fatty Acids and Gut Microbiota

For several decades, studies have reported that n-3 polyunsaturated fatty acids (PUFAs) play a beneficial role in cardiovascular, immune, cognitive, visual, mental and metabolic health. The mammalian intestine is colonized by microbiota, including bacteria, archaea, viruses, protozoans, and fungi. The composition of the gut microbiota is influenced by long-term dietary habits, disease-associated dysbiosis, and the use of antibiotics. Accumulating evidence suggests a relationship between n-3 PUFAs and the gut microbiota. N-3 PUFAs can alter the diversity and abundance of the gut microbiome, and gut microbiota can also affect the metabolism and absorption of n-3 PUFAs. Changes in the populations of certain gut microbiota can lead to negative effects on inflammation, obesity, and metabolic diseases. An imbalanced consumption of n-3/n-6 PUFAs may lead to gut microbial dysbiosis, in particular, a significant increase in the ratio of Firmicutes to Bacteroidetes, which eventually results in being overweight and obesity. N-3 PUFA deficiency disrupts the microbiota community in metabolic disorders. In addition, accumulating evidence indicates that the interplay between n-3 PUFAs, gut microbiota, and immune reactions helps to maintain the integrity of the intestinal wall and interacts with host immune cells. Supplementation with n-3 PUFAs may be an effective therapeutic measure to restore gut microbiota homeostasis and correct metabolic disturbances associated with modern chronic diseases. In particular, marine extracts from seaweed contain a considerable dry weight of lipids, including n-3 PUFAs such as eicosapentaenoic acid (EPA, C20: 5) and docosahexaenoic acid (DHA, C22: 6). This review describes how gut microbiota function in intestinal health, how n-3 PUFAs interact with the gut microbiota, and the potential of n-3 PUFAs to influence the gut-brain axis, acting through gut microbiota composition.

In silico, in vitro and in vivo characterization of host-associated Latilactobacillus curvatus strains for potential probiotic applications in farmed Atlantic salmon (Salmo salar)

Salmon aquaculture is the fastest growing animal protein production system in the world; however, intensive farming leads to poor weight gain, stress, and disease outbreaks. Probiotics offer the potential to enhance growth performance and feed efficiency in Atlantic salmon, as well as immunostimulate fish against common pathogens, benefitting farmers and consumers with more efficient production. Here, we isolated and identified 900 native microbial isolates including 18 Lactobacilli from the farmed salmon intestines. Based on whole-genome sequencing and phylogenetic analysis, the Lactobacillus candidates belonged to Latilactobacillus curvatus (L. curvatus) species and formed two distinct phylogenetic groups. Using bioinformatics and in vitro analyses, we selected two candidates L. curvatus ATCC PTA-127116 and L. curvatus ATCC PTA-127117, which showed desirable safety and probiotic properties. The two L. curvatus candidates were evaluated for safety and efficacy (higher final weight) in Atlantic salmon alongside spore-forming Bacilli isolated from salmon, poultry, and swine. All the tested candidates were safe to salmon with no adverse effects. While we did not see efficacy in any Bacillus supplemented groups, compared to untreated group, the group administered with the two L. curvatus strains consortium in feed for seven weeks in freshwater showed indicators of improvement in final body weight by 4.2%. Similarly, the two L. curvatus candidates were also evaluated for safety and efficacy in Atlantic salmon in saltwater; the group administered with the two L. curvatus strains consortium in feed for 11 weeks showed indicators of improvement in final body weight by 4.7%. Comprehensive metabolomics analyses in the presence of different prebiotics and/or additives identified galactooligosaccharide as a potential prebiotic to enhance the efficacy of two L. curvatus candidates. All together, these data provide comprehensive genomic, phenotypic and metabolomic evidence of safety and desirable probiotic properties as well as indicators of in vivo efficacy of two novel endogenous L. curvatus candidates for potential probiotic applications in Atlantic salmon. The in vivo findings need to be confirmed in larger performance studies, including field trials.

Comparative Analyses of Scylla olivacea Gut Microbiota Composition and Function Suggest the Capacity for Polyunsaturated Fatty Acid Biosynthesis

Although numerous studies in aquatic organisms have linked lipid metabolism with intestinal bacterial structure, the possibility of the gut microbiota participating in the biosynthesis of beneficial long-chain polyunsaturated fatty acid (LC-PUFA) remains vague. We profiled the gut microbiota of the mud crab Scylla olivacea fed with either a LC-PUFA rich (FO) or a LC-PUFA-poor but C18-PUFA substrate-rich (LOCO) diet. Additionally, a diet with a similar profile as LOCO but with the inclusion of an antibiotic, oxolinic acid (LOCOAB), was also used to further demarcate the possibility of LC-PUFA biosynthesis in gut microbiota. Compared to diet FO treatment, crabs fed diet LOCO contained a higher proportion of Proteobacteria, notably two known taxonomy groups with PUFA biosynthesis capacity, Vibrio and Shewanella. Annotation of metagenomic datasets also revealed enrichment in the KEGG pathway of unsaturated fatty acid biosynthesis and polyketide synthase-like system sequences with this diet. Intriguingly, diet LOCOAB impeded the presence of Vibrio and Shewanella and with it, the function of unsaturated fatty acid biosynthesis. However, there was an increase in the function of short-chain fatty acid production, accompanied by a shift towards the abundance of phyla Bacteroidota and Spirochaetota. Collectively, these results exemplified bacterial communities and their corresponding PUFA biosynthesis pathways in the microbiota of an aquatic crustacean species.

Excess DHA Induces Liver Injury via Lipid Peroxidation and Gut Microbiota-Derived Lipopolysaccharide in Zebrafish

Being highly unsaturated, n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) are prone to lipid peroxidation. In this study, zebrafish were fed with low-fat diet (LFD), high-fat diet (HFD), or 2% DHA-supplemented HFD (HFDHA2.0). To study the possible negative effects of the high level of dietary DHA, growth rates, blood chemistry, liver histology, hepatic oxidative stress, apoptosis, and inflammatory processes were assessed. The cell studies were used to quantify the effects of DHA and antioxidant on cellular lipid peroxidation and viability. The possible interaction between gut microbiota and zebrafish host was evaluated in vitro. HFDHA2.0 had no effect on hepatic lipid level but induced liver injury, oxidative stress, and hepatocellular apoptosis, including intrinsic and death receptor-induced apoptosis. Besides, the inclusion of 2% DHA in HFD increased the abundance of Proteobacteria in gut microbiota and serum endotoxin level. In the zebrafish liver cell model, DHA activated intrinsic apoptosis while the antioxidant 4-hydroxy-Tempo (tempo) inhibited the pro-apoptotic negative effects of DHA. The apoptosis induced by lipopolysaccharide (LPS) was unaffected by the addition of tempo. In conclusion, the excess DHA supplementation generates hepatocellular apoptosis-related injury to the liver. The processes might propagate along at least two routes, involving lipid peroxidation and gut microbiota-generated LPS.

Glial-Neuronal Interactions in Pathogenesis and Treatment of Spinal Cord Injury

Traumatic spinal cord injury (SCI) elicits an acute inflammatory response which comprises numerous cell populations. It is driven by the immediate response of macrophages and microglia, which triggers activation of genes responsible for the dysregulated microenvironment within the lesion site and in the spinal cord parenchyma immediately adjacent to the lesion. Recently published data indicate that microglia induces astrocyte activation and determines the fate of astrocytes. Conversely, astrocytes have the potency to trigger microglial activation and control their cellular functions. Here we review current information about the release of diverse signaling molecules (pro-inflammatory vs. anti-inflammatory) in individual cell phenotypes (microglia, astrocytes, blood inflammatory cells) in acute and subacute SCI stages, and how they contribute to delayed neuronal death in the surrounding spinal cord tissue which is spared and functional but reactive. In addition, temporal correlation in progressive degeneration of neurons and astrocytes and their functional interactions after SCI are discussed. Finally, the review highlights the time-dependent transformation of reactive microglia and astrocytes into their neuroprotective phenotypes (M2a, M2c and A2) which are crucial for spontaneous post-SCI locomotor recovery. We also provide suggestions on how to modulate the inflammation and discuss key therapeutic approaches leading to better functional outcome after SCI.

Aquaculture industry prospective from gut microbiome of fish and shellfish: An overview

The microbiome actually deals with micro-organisms that are associated with indigenous body parts and the entire gut system in all animals, including human beings. These microbes are linked with roles involving hereditary traits, defence against diseases and strengthening overall immunity, which determines the health status of an organism. Considerable efforts have been made to find out the microbiome diversity and their taxonomic identification in finfish and shellfish and its importance has been correlated with various physiological functions and activities. In recent past due to the availability of advanced molecular tools, some efforts have also been made on DNA sequencing of these microbes to understand the environmental impact and other stress factors on their genomic structural profile. There are reports on the use of next-generation sequencing (NGS) technology, including amplicon and shot-gun approaches, and associated bioinformatics tools to count and classify commensal microbiome at the species level. The microbiome present in the whole body, particularly in the gut systems of finfish and shellfish, not only contributes to digestion but also has an impact on nutrition, growth, reproduction, immune system and vulnerability of the host fish to diseases. Therefore, the study of such microbial communities is highly relevant for the development of new and innovative bio-products which will be a vital source to build bio and pharmaceutical industries, including aquaculture. In recent years, attempts have been made to discover the chemical ingredients present in these microbes in the form of biomolecules/bioactive compounds with their functions and usefulness for various health benefits, particularly for the treatment of different types of disorders in animals. Therefore, it has been speculated that microbiomes hold great promise not only as a cure for ailments but also as a preventive measure for the number of infectious diseases. This kind of exploration of new breeds of microbes with their miraculous ingredients will definitely help to accelerate the development of the drugs, pharmaceutical and other biological related industries. Probiotic research and bioinformatics skills will further escalate these opportunities in the sector. In the present review, efforts have been made to collect comprehensive information on the finfish and shellfish microbiome, their diversity and functional properties, relationship with diseases, health status, data on species-specific metagenomics, probiotic research and bioinformatics skills. Further, emphasis has also been made to carry out microbiome research on priority basis not only to keep healthy environment of the fish farming sector but also for the sustainable growth of biological related industries, including aquaculture.

The Application of Lactobacillus reuteri CCM 8617 and Flaxseed Positively Improved the Health of Mice Challenged with Enterotoxigenic E. coli O149:F4

The aim of our study was to monitor the effects of dietary synbiotics on experimentally infected mice. Sixty mice were divided into the following three groups: negative control group C1, positive control group C2 (mice infected with enterotoxigenic Escherichia coli O149:F4_NAL), and experimental group LF (Lactobacillus reuteri CCM 8617_RIF + 10% flaxseed + E. coli O149:F4_NAL). Supplements were administered for 42 days. Microbiological, hematological, and biochemical analyses, electrophoretic analysis of lactate dehydrogenase (LDH) isoenzymes, and analysis of fatty acids using gas chromatography and isotachophoresis were performed. We recorded higher numbers of jejunal and ileal lactic acid bacteria, lower Enterobacteriaceae counts in the feces of the animals, and an increased production of organic acids in the synbiotic-fed group. The supplements applied favored n-3 polyunsaturated fatty acid (PUFA) metabolism and inhibited n-6 PUFA metabolism; thus, they influenced the n-6 to n-3 and eicosapentaenoic to arachidonic acid ratios. Additionally, the incorporation of n-3 PUFAs to the cell membrane decreased the activity of LDH, transaminases, and alkaline phosphatase. Results obtained in our study indicate the positive effect of continuous supplementation of combination of probiotic cheese enriched with L. reuteri CCM 8617_RIF and crushed flaxseed on composition of intestinal microflora and alleviation of the course of infection induced by pathogenic bacterium E. coli O149:F4_NAL.

Oxidative status and intestinal health of gilthead sea bream (Sparus aurata) juveniles fed diets with different ARA/EPA/DHA ratios

The present work assessed the effects of dietary ratios of essential fatty acids, arachidonic (ARA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), on liver and intestine oxidative status, intestinal histomorphology and gut microbiota of gilthead sea bream. Four isoproteic and isolipidic plant-based diets were formulated containing a vegetable oil blend as the main lipid source. Diets were supplemented with ARA/EPA/DHA levels (%DM) equivalent to: 2%:0.2%:0.1% (Diet A); 1.0%:0.4%:0.4% (Diet B); 0%:0.6%:0.6% (Diet C); 0%:0.3%:1.5% (Diet D) and tested in triplicate groups for 56 days. Lipid peroxidation was higher in fish fed diets C and D while no differences were reported between diets regarding total, oxidized, and reduced glutathione, and oxidative stress index. Glutathione reductase was higher in fish fed diet A than diets C and D. No histological alterations were observed in the distal intestine. Lower microbiota diversity was observed in intestinal mucosa of fish fed diet C than A, while diets C and D enabled the proliferation of health-promoting bacteria from Bacteroidetes phylum (Asinibacterium sp.) and the absence of pathogenic species like Edwardsiella tarda. Overall, results suggest that a balance between dietary ARA/EPA + DHA promotes gilthead sea bream juveniles' health however higher dietary content of n-3 LC-PUFA might limited the presence of microbial pathogens in intestinal mucosa.

Isolation, Identification and Investigation of Fermentative Bacteria from Sea Bass (Dicentrarchus labrax): Evaluation of Antifungal Activity of Fermented Fish Meat and By-Products Broths

During fish production processes, great amounts of by-products are generated, representing ≈30–70% of the initial weight. Thus, this research study is investigating 30 lactic acid bacteria (LAB) derived from the sea bass gastrointestinal tract, for anti-fungal activity. It has been previously suggested that LAB showing high proteolitic activity are the most suitable candidates for such an investigation. The isolation was made using a MRS (Man Rogosa Sharpe) broth cultivation medium at 37 ºC under anaerobiosis conditions, while the evaluation of the enzymatic activity was made using the API^® ZYM kit. Taking into account the selected bacteria, a growing research was made fermenting two kinds of broths: (i) by-products (WB), and (ii) meat (MB). Both were fermented at three different times (24, 48 and 72 h). Then, the antifungal activities of both fermented by-products and meat broths were determined qualitatively and quantitatively in solid and liquid medium against two different strains of the genera Penicillium, Aspergillus and Fusarium. After the experiments, a total of 30 colonies were isolated, observing a proteolytic activity in 7 of the isolated strains, which belong to Lactobacillus genus, and the two more active strains were identified by polymerase chain reaction (PCR) as L. plantarum. Several strains evidenced antifungal activity showing an inhibition halo and Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) values between 1–32 g/L and 8–32 g/L, respectively. In conclusion, the isolated bacteria of sea bass had the ability to promote the antifungal activity after the fermentation process, thus being a useful tool to give an added value to fish industry by-products.

Evaluating Impacts of Different Omega-6 to Omega-3 Fatty Acid Ratios in Corn-Soybean Meal-Based Diet on Growth Performance, Nutrient Digestibility, Blood Profiles, Fecal Microbial, and Gas Emission in Growing Pigs

Simple Summary

There are two major classes of polyunsaturated fatty acids found in the diet, omega-3 and omega-6, these polyunsaturated fatty acids are essential because they cannot be synthesized by humans and animals. Also, they cannot be converted into each other in the body. Supplementation of omega-3 has been reported to improve the performance and health of pigs. However, during the past years, studies had demonstrated that animal performance could be influenced by the dietary level or the ratio of omega-6 and omega-3. A high omega-6: omega-3 ratio in diets promotes the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases. An optimal omega-6: omega-3 ratio could inhibit immune stimulation to ensure the availability of more energy and nutrients for high performance and the homeostatic pathway. The present study investigated the effects of different omega-6: omega-3 ratios (17:1, 15:1, 10:1, 5:1) on growth performance, nutrient digestibility, blood profiles, fecal microflora, and gas emission in growing pigs. The results of this study showed that reducing omega-6: omega-3 ratio from 17:1 to 5:1 by increasing omega-3 in the diet increased body weight, energy digestibility, and reduced the low-density lipoprotein concentrations of blood in growing pigs.

Abstract

This study was conducted to evaluate the effect of different omega-6: omega-3 fatty acid (FA) ratios in a corn–soybean meal-based diet in growing pigs. A total of 140 [Duroc × (Landrace × Yorkshire)] growing pigs with an average body weight (BW) of 24.75 ± 1.43 kg were used in a 6-week trial. Pigs were allocated randomly into one of four treatments according to sex and BW (seven replications with five pigs per pen). The treatment groups consisted of 4 diets with omega-6:omega-3 FA ratios of 17:1, 15:1, 10:1, and 5:1. In the current study, the energy digestibility, BW, and average daily gain (ADG) increased (p < 0.05) in pigs provided with the 5:1 diet compared to pigs fed the 17:1 diet in the sixth week. The low-density lipoprotein (LDL) concentrations of blood were lower (p < 0.05) in pigs fed the 5:1 diet compared to the 17:1 and 15:1 diet. However, the fecal microflora and fecal gas emissions were unaffected (p > 0.05) by the different omega-6: omega-3 FA ratios in diets. In conclusion, reducing omega-6: omega-3 ratio by increasing omega-3 in diet improved BW, ADG, and gross energy digestibility, and reduced the LDL concentrations of blood in growing pigs.

Effects of dietary lipid sources on the intestinal microbiome and health of golden pompano (Trachinotus ovatus)

Replacement of fish oil (FO) with vegetable oils (VO) in diets is economically desirable for the sustainable development of the aquaculture industry. However, inflammation provoked by FO replacement limited its widely application in fish industry. In order to understand the mechanism of VO-induced inflammation, this study investigated the impact of different dietary vegetable oils on the intestinal health and microbiome in carnivorous marine fish golden pompano (Trachinotus ovatus). Three diets supplemented with fish oil (FO, rich in long-chain polyunsaturated fatty acids), soybean oil (SO, rich in 18:2n-6) and linseed oil (LO, rich in 18:3n-3), respectively, were fed on juvenile golden pompano for 8 weeks, and the intestinal histology, digestive enzymes activities, immunity and antioxidant indices as well as intestinal microbiome were determined. The results showed that dietary SO significantly impaired intestinal health, and decreased the number and height of intestinal folds, and muscle thickness, as well as the zonula occludens-1 (zo-1) mRNA expression in intestine. Moreover, the two dietary VO significantly decreased the amylase and lipase activities in intestine, and reduced the trypsin activity in the dietary SO group. Furthermore, the two VO diets increased intestinal acid phosphatase (ACP) activity, while intestinal lysozyme (LZM) activity and serum diamine oxidase (DAO) activity in the SO group were also significantly increased (P < 0.05). Analysis of the intestinal microbiota showed that the two VO diets significantly increased the abundance of intestinal potentially pathogenic bacteria (Mycoplasma and Vibrio) and decreased proportions of intestinal probiotics (Bacillus and Lactococcus), especially in the dietary SO group. These results indicate that complete replacement of FO with VO in diets would induce intestinal inflammation and impair intestinal function, which might be due to changes in intestinal microbiota profiles, and that dietary SO would have a more negative effect compared to dietary LO on intestinal health in T. ovatus.

Effect of fungal gamma-linolenic acid and beta-carotene containing prefermented feed on immunity and gut of broiler chicken

Gamma-linolenic acid (GLA) is a fatty acid from the ω-6 family. It is able to deliver a wide range of health benefits arising from its anti-inflammatory effects. An insufficient supply of GLA from agricultural and animal sources resulted in the development of a fermentation technique using lower filamentous fungi, which have the ability to accumulate high concentrations of GLA and beta-carotene during solid-state fermentation of cereals. The goal of this study was to observe the influence of the addition of prefermented cereal product, containing high amounts of GLA and beta-carotene, into the feed of broiler chickens on their immune status, and also the number of lactic acid bacteria and enterobacteria in gut content, which has never been studied before. Immunostimulation in the GLA group was manifested by a significant increase in the oxidative burst of phagocytes, CD4+CD8- lymphocytes in blood, and the CD4: CD8 ratio. Upregulation of gene expression for IgA in the GLA group indicates that the B-lymphocytes were stimulated at a local gut level. In the caecum, increased mRNA expression for mucin-2 and insulin-like growth factor was observed in the GLA group, which could contribute mainly to the protection of the intestinal mucosa and to better growth and regeneration of skeletal muscles. Improved immune activation and protection of the intestinal mucosa were subsequently reflected in a change of the microbial composition in gut contents; a significant reduction of enterobacteria occurred after GLA administration. We can conclude that prefermented cereals containing fungal GLA and beta-carotene represent a low-cost supplement for broiler diet having a beneficial health effect.

The Gut Microbiota of Marine Fish

The body of work relating to the gut microbiota of fish is dwarfed by that on humans and mammals. However, it is a field that has had historical interest and has grown significantly along with the expansion of the aquaculture industry and developments in microbiome research. Research is now moving quickly in this field. Much recent focus has been on nutritional manipulation and modification of the gut microbiota to meet the needs of fish farming, while trying to maintain host health and welfare. However, the diversity amongst fish means that baseline data from wild fish and a clear understanding of the role that specific gut microbiota play is still lacking. We review here the factors shaping marine fish gut microbiota and highlight gaps in the research.

Effects of different n-6 to n-3 polyunsaturated fatty acids ratio on reproductive performance, fecal microbiota and nutrient digestibility of gestation-lactating sows and suckling piglets

This study was conducted to evaluate the effects of dietary ratios of n-6:n-3 polyunsaturated fatty acids (PUFA) on reproductive performance, fecal microbiota and nutrient digestibility of gestation-lactating sows and suckling piglets. Fifteen primiparous sows (Landrace × Yorkshire) were randomly allotted into three treatments. Fed diets contained different ratios of n-6:n-3 PUFA, including 20:1, 15:1 and 10:1. No differences were detected among the treatments for average daily feed intake (ADFI) of sows and the back fat levels during lactation (P > 0.05). Body weight (BW) loss of sows after farrowing to weanling was greater in the 10:1 treatment compared with 15:1 or 20:1 (P < 0.05). In piglets, a great significant difference for BW was observed at 4 weeks (P < 0.01). Furthermore, average daily gain (ADG) of piglets in the 10:1 treatment was higher (P < 0.05). No difference was observed among treatments in nutrient digestibility of sows (P > 0.05). A great significant difference for fecal microbiota was in the 10:1 treatment compared with 20:1 and 15:1 treatments (P < 0.01). In conclusion, altering the ratio of n-6:n-3 PUFA in gestation-lactating sow diet had no difference on nutrient digestibility in gestation-lactating sows, but it can partially improve reproductive performance.

Effect of a dietary probiotic, Lactobacillus johnsonii BS15, on growth performance, quality traits, antioxidant ability, and nutritional and flavour substances of chicken meat

To determine whether Lactobacillus johnsonii BS15 supplementation improves the growth performance and meat quality of broilers, 450 1-day-old male chicks (Cobb 500) were randomly divided into three groups: control group (basal corn-soybean diet), L-BS15 group (basal diet + 1 × 105 colony-forming unit BS15/g as feed), and H-BS15 group (basal diet + 1 × 106 colony-forming unit BS15/g as feed). These diets were fed for 42 days. Abdominal fat decreased (P < 0.05) as the concentration of BS15 increased. BS15 supplementation significantly increased the pH at 24 h after sacrifice and decreased drip loss and shearing force (P < 0.05), although meat colour and pH at 40 min after sacrifice remained unchanged. Antioxidant capacity and total protein and intramuscular fat levels were unchanged by the treatments, but BS15 supplementation significantly increased inosine monophosphate level and decreased total cholesterol and triglyceride levels (P < 0.05). The levels of proline, total amino acids, and flavour-related amino acids were increased (P < 0.05) by BS15 supplementation, but the levels of other amino acids did not change significantly. BS15 supplementation significantly decreased (P < 0.05) C16:0, C22:4n-6, and n-6 :  n-3 ratio and increased (P < 0.05) C18:3n-3, C20:5n-3,C22:6n-3, total polyunsaturated fatty acid (PUFA), n-3 PUFA and PUFA : saturated fatty acid ratio. These findings suggest that L. johnsonii BS15 supplementation improves the meat quality of broilers by increasing the shelf life and flavour and nutritional substances. In addition, BS15 supplementation can induce changes in fat deposits and fatty acid composition.

The highly variable microbiota associated to intestinal mucosa correlates with growth and hypoxia resistance of sea bass, Dicentrarchus labrax, submitted to different nutritional histories

Background

The better understanding of how intestinal microbiota interacts with fish health is one of the key to sustainable aquaculture development. The present experiment aimed at correlating active microbiota associated to intestinal mucosa with Specific Growth Rate (SGR) and Hypoxia Resistance Time (HRT) in European sea bass individuals submitted to different nutritional histories: the fish were fed either standard or unbalanced diets at first feeding, and then mixed before repeating the dietary challenge in a common garden approach at the juvenile stage.

Results

A diet deficient in essential fatty acids (LH) lowered both SGR and HRT in sea bass, especially when the deficiency was already applied at first feeding. A protein-deficient diet with high starch supply (HG) reduced SGR to a lesser extent than LH, but it did not affect HRT. In overall average, 94 % of pyrosequencing reads corresponded to Proteobacteria, and the differences in Operational Taxonomy Units (OTUs) composition were mildly significant between experimental groups, mainly due to high individual variability. The highest and the lowest Bray-Curtis indices of intra-group similarity were observed in the two groups fed standard starter diet, and then mixed before the final dietary challenge with fish already exposed to the nutritional deficiency at first feeding (0.60 and 0.42 with diets HG and LH, respectively). Most noticeably, the median percentage of Escherichia-Shigella OTU_1 was less in the group LH with standard starter diet. Disregarding the nutritional history of each individual, strong correlation appeared between (1) OTU richness and SGR, and (2) dominance index and HRT. The two physiological traits correlated also with the relative abundance of distinct OTUs (positive correlations: Pseudomonas sp. OTU_3 and Herbaspirillum sp. OTU_10 with SGR, Paracoccus sp. OTU_4 and Vibrio sp. OTU_7 with HRT; negative correlation: Rhizobium sp. OTU_9 with HRT).

Conclusions

In sea bass, gut microbiota characteristics and physiological traits of individuals are linked together, interfering with nutritional history, and resulting in high variability among individual microbiota. Many samples and tank replicates seem necessary to further investigate the effect of experimental treatments on gut microbiota composition, and to test the hypothesis whether microbiotypes may be delineated in fish.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0885-2) contains supplementary material, which is available to authorized users.

Influence of Flaxseed Oil on Fecal Microbiota, Egg Quality and Fatty Acid Composition of Egg Yolks in Laying Hens

Although there have been many attempts to produce ω-3 fatty acid-rich eggs using alpha-linolenic acid (ALA) that is a popular fatty acid in the poultry feed industry, only limited knowledge about the effects of ALA-enriched diets on chicken fecal microbiota is currently available. Herein we examined the changes in the fecal microbiota composition, egg quality traits and fatty acid composition of the egg yolks of laying hens fed ALA-rich flaxseed oil for 8 weeks. The animals fed the experimental diets that contained 0 % (group C), 0.5 % (group T1), and 1.0 % (group T2) of flaxseed oil, respectively, and eggs and feces were obtained for the analyses. ω-3 fatty acids, including ALA, were increased in T1 and T2 compared with C. Furthermore, the freshness of eggs was improved with no side effects on the eggs. The diet also changed the fecal microbiota; Firmicutes was increased in T1 and T2 (48.6 to 83 and 79.6 %) and Bacteroidetes was decreased (40.2 to 8.8 and 4.2 %). Principal coordinate analysis revealed that Lactobacillus, among the 56 examined genera, was the most influenced bacterial group in terms of the fecal microbial community shifts. These results indicate that ALA-rich diets influenced both the egg and fecal microbiota in beneficial manners in laying hens although the association between the fatty acid composition of the egg yolk and the fecal microbiota was not clear. This study is a first step to understand the effect of flaxseed oil as well as intestinal microbiota of laying hens.

Evolution of probiotics in aquatic world: Potential effects, the current status in Egypt and recent prospectives

The increase in the human population in addition to the massive demand for protein of animal origin forced the authorities to seek for additional sources of feed supplies. Aquaculture is the world worth coming expansion to compensate the shortage in animal protein. Feed in aquaculture plays an important role in the production cycle and exert threshold on both practical and economic aspects. Feed additive sectors are expanding day after day to achieve better growth and health for fish and shrimp and to meet the potential requirements of the culturists. Probiotic proved its successes in human and animal feeding practices and recently gained attention in aquaculture; it has beneficial effects in diseases control and competes with various environmental stressors as well as to promote the growth of the cultured organisms. Probiotics have the privilege to manipulate the non-specific innate immunity among fishes, hence help them into resist many pathogenic agents and are actively used worldwide. The present review is an informative compilation of the probiotics, their mode of action and their useful effects on fishes. The review also highlights the status of probiotics in aquaculture of Egypt, probiotic recent prospective for the possible role of probiotics in fish external and internal environment.

Flax-seed oil and Lactobacillus plantarum supplementation modulate TLR and NF-κB gene expression in enterotoxigenic Escherichia coli challenged gnotobiotic pigs

The present study analyses the effect of flax-seed oil rich in n-3 polyunsaturated fatty acids (PUFAs), the probiotic strain Lactobacillus plantarum - Biocenol™ LP96 and their combination on the expression level of selected Toll-like receptor (TLR) genes (TLR2, TLR4, TLR5, TLR9) and their downstream molecules (myeloid differentiation factor 88, MyD88; nuclear factor-κB, NF-κB) in the jejunum of gnotobiotic pigs challenged with enterotoxigenic Escherichia coli (ETEC). The results show that both immunomodulators are able to modulate the RNA level of at least one of the target molecules and thus regulate pathogeninduced inflammation. We confirmed that not only probiotic lactobacilli or flaxseed oil alone but also their synergistic action has great potential in the prevention and treatment of porcine colibacillosis. The results give an insight into one of the possible mechanisms by which natural agents, such as probiotic lactobacilli and flax-seed oil, exert their immunoregulatory properties during pathogen-induced inflammation.

Bacteriophages and dairy fermentations

This review highlights the main strategies available to control phage infection during large-scale milk fermentation by lactic acid bacteria. The topics that are emphasized include the factors influencing bacterial activities, the sources of phage contamination, the methods available to detect and quantify phages, as well as practical solutions to limit phage dispersion through an adapted factory design, the control of air flow, the use of adequate sanitizers, the restricted used of recycled products, and the selection and growth of bacterial cultures.

Enrichment of conjugated linoleic acid (CLA) in hen eggs and broiler chickens meat by lactic acid bacteria

1. The aim of this work was to compare conjugated linoleic acid (CLA) concentrations in chickens supplemented with 4 American Tissue Culture Collection (ATCC) bacterial strains, Lactobacillus plantarum, Lactobacillus lactis, Lactobacillus casei and Lactobacillus fermentum, and 4 isolates of Lactobacillus reuteri from camel, cattle, sheep and goat rumen extracts. 2. Micro-organisms were grown anaerobically in MRS broth, and 10(6) CFU/ml of bacteria were administered orally to mixed-sex, 1-d-old broiler chickens weekly for 4 weeks and to 23-week-old layer hens weekly for 6 weeks. 3. The 4 strains were evaluated for their effects on synthesis of CLA in hen eggs and broiler meat cuts. 4. Administration of pure Lactobacillus and isolated L. reuteri strains from camel, cattle, goat and sheep led to significantly increased CLA concentrations of 0.2-1.2 mg/g of fat in eggs and 0.3-1.88 mg/g of fat in broiler chicken flesh homogenates of leg, thigh and breast. 5. These data demonstrate that lactic acid bacteria of animal origin (L. reuteri) significantly enhanced CLA synthesis in both eggs and broiler meat cuts.

Polyunsaturated fatty acids modify expression of TGF-β in a co-culture model ultilising human colorectal cells and human peripheral blood mononuclear cells exposed to Lactobacillus gasseri, Escherichia coli and Staphylococcus aureus

Commensal bacteria and polyunsaturated fatty acids (PUFAs) have both been shown independently to modulate immune responses. This study tested the hypothesis that the different colonic immunomodulatory responses to commensal (Lactobacillus gasseri) and pathogenic bacteria (Escherichia coli and Staphylococcus aureus) may be modified by PUFAs. Experiments used a Transwell system combining the colorectal cell line HT29, or its mucous secreting sub-clone HT29-MTX, with peripheral blood mononuclear cells to analyse immunomodulatory signalling in response to bacteria, with and without prior treatment with arachidonic acid, eicosapentaenoic acid or docosahexaenoic acid. L. gasseri increased transforming growth factor β1 (TGF-β1) mRNA and protein secretion in colonic cell lines when compared with controls, an effect that was enhanced by pre-treatment with eicosapentaenoic acid. In contrast, the Gram-negative pathogen E. coli LF82 had no significant effect on TGF-β1 protein. L. gasseri also increased IL-8 mRNA but not protein while E. coli increased both; although differences between PUFA treatments were detected, none were significantly different to controls. Colonic epithelial cells show different immunomodulatory signalling patterns in response to the commensal L. gasseri compared to E. coli and S. aureus and pre-treatment of these cells with PUFAs can modify responses. Practical applications: We have demonstrated an interaction between dietary PUFAs and epithelial cell response to both commensal and pathogenic bacteria found in the gastrointestinal tract by utilising in vitro co-culture models. The data suggest that n-3 PUFAs may provide some protection against the potentially damaging effects of pathogens. Furthermore, the beneficial effects of combining n-3 PUFAs and the commensal bacteria, and potential probiotic, L. gasseri are illustrated by the increased expression of immunoregulatory TGF-β1.

Changes in gut microbiota due to supplemented fatty acids in diet-induced obese mice

Consumption of a high-fat diet (HFD), which is associated with chronic 'low-grade' systemic inflammation, alters the gut microbiota (GM). The aim of the present study was to investigate the ability of an oleic acid-derived compound (S1) and a combination of n-3 fatty acids (EPA and DHA, S2) to modulate both body weight and the GM in HFD-induced obese mice. A total of eighty mice were fed either a control diet or a HFD, non-supplemented or supplemented with S1 or S2. At week 19, faeces were collected in order to analyse the GM. Group-specific primers for accurate quantification of several major bacterial groups from faecal samples were assayed using quantitative PCR. The HFD induced an increase in body weight, which was reduced by supplementation with S1. Furthermore, S1 supplementation markedly increased total bacterial density and restored the proportions of bacteria that were increased (i.e. clostridial cluster XIVa and Enterobacteriales) or decreased (i.e. Bifidobacterium spp.) during HFD feeding. S2 supplementation significantly increased the quantities of Firmicutes (especially the Lactobacillus group). Correlation analysis revealed that body weight correlated positively with the phylum Firmicutes and clostridial cluster XIVa, and negatively with the phylum Bacteroidetes. In conclusion, the consumption of a HFD induced changes in the faecal microbiota, which were associated with the appearance of an obese phenotype. Supplementation of the HFD with S1 counteracted HFD-induced gut dysbiosis, together with an improvement in body weight. These data support a role for certain fatty acids as interesting nutrients related to obesity prevention.

PCR-TTGE analysis of 16S rRNA from rainbow trout (Oncorhynchus mykiss) gut microbiota reveals host-specific communities of active bacteria

This study assessed the relative contributions of host genetics and diet in shaping the gut microbiota of rainbow trout. Full sibling fish from four unrelated families, each consisting of individuals derived from the mating of one male and one female belonging to a breeding program, were fed diets containing either vegetable proteins or vegetable oils for two months in comparison to a control diet consisting of only fish protein and fish oil. Two parallel approaches were applied on the same samples: transcriptionally active bacterial populations were examined based on RNA analysis and were compared with bacterial populations obtained from DNA analysis. Comparison of temporal temperature gradient gel electrophoresis (TTGE) profiles from DNA and RNA showed important differences, indicating that active bacterial populations were better described by RNA analysis. Results showed that some bacterial groups were significantly (P<0.05) associated with specific families, indicating that microbiota composition may be influenced by the host. In addition, the effect of diet on microbiota composition was dependent on the trout family.

Dietary long-chain n-3 PUFA, gut microbiota and fat mass in early postnatal piglet development--exploring a potential interplay

Dietary n-3PUFA and gut bacteria, particularly Bacteroidetes, have been suggested to be related to adiposity. We investigated if n-3PUFA affected fat storage and cecal bacteria in piglets. Twenty-four 4-day-old piglets were allocated to formula rich in n-3PUFA (∼3E%) from fish oil (FO) or n-6PUFA from sunflower oil (SO) for 14 days. We assessed body weight, fat accumulation by dual-energy X-ray absorptiometry and microbial molecular fingerprints. Dietary PUFA-composition was reflected in higher erythrocyte n-3PUFA in the FO- than the SO-group (P<0.001). Principal component analysis revealed group differences in the overall microbiotic composition, which involved a larger Bacteroides community in the SO-group (P=0.02). There was no significant difference in body fat percentage and no relationship between fat accumulation and gut Bacteroides. Hence, this study does not support an impact of n-3PUFA or microbiota on fat accumulation during the postnatal maturation period. The impact of dietary PUFA on the gut Bacteroides warrants further investigation.

Effects of dietary lipids and Clostridium butyricum on the performance and the digestive tract of broiler chickens

The effects of two sources of dietary lipids and supplementation of Clostridium butyricum on performance and intestinal metabolism of broilers were investigated. In a 2 x 2 factorial arrangement, 168 one-day-old broiler chicks were divided into four treatment groups, and fed four diets with two lipid sources (soya bean oil or fish oil, at 25 g/kg and 30 g/kg in starter and grower diets respectively), and without or with supplementation of C. butyricum (1 x 10(9) colony forming units per kg diet). C. butyricum had no effect on broiler performance. At 20 and 40 d of age, the pH of caecal digesta and the relative length of caecum were decreased after supplementation of C. butyricum (p < 0.05). After this treatment, the activity of alkaline phosphatase was increased in jejunal mucosa at 40 d of age (p < 0.01). Furthermore, there were increases in populations of lactic acid bacteria and the concentrations of acetic acid, n-butyric acid, n-valeric acid and total short chain fatty acids in caecal digesta of birds fed C. butyricum (p < 0.05). A significant interaction between lipid source and C. butyricum was found in the pH of caecal digesta at 20 d of age (p < 0.01). The results of the present study indicated that dietary supplementation of C. butyricum maybe a benefit for gut health of broiler chickens.

Molecular fingerprints of the human fecal microbiota from 9 to 18 months old and the effect of fish oil supplementation

OBJECTIVES

The aim of this study was to monitor changes in the fecal microbiota from 9 to 18 months and to investigate the effect of increasing dietary n-3 polyunsaturated fatty acids on the fecal microbiota.

PATIENTS AND METHODS

In a double-blind controlled trial with random allocation to daily supplementation with 5 mL of fish oil (FO) or sunflower oil (SO) from 9 to 18 months of age, stool samples were collected from 132 healthy Danish infants. Molecular fingerprints of the bacterial DNA were obtained by terminal restriction fragment length polymorphism (T-RFLP).

RESULTS

The T-RFLP profiles indicated that a few T-RFs became dominant with age (bp100 and 102, both presumed to be Bacteroidetes) concomitantly with an overall increase in the microbial diversity (P = 0.04). Breast-feeding influenced both the T-RFLP profiles at 9 months and the changes from 9 to 18 months, and breast-feeding cessation during the trial modified the response to the dietary oils. In the FO group, the increase in bp102 was significantly reduced among children weaned before compared with those weaned during the trial (P = 0.027), whereas the increase in bp100 was reduced in the preweaned children of the SO group relative to those weaned during the trial (P = 0.004). This was supported by intervention group differences in the changes in bp102 and bp100 among the earlier weaned children (P = 0.06 and P = 0.09, respectively).

CONCLUSIONS

Cessation of breast-feeding played a dominant role relative to developmental changes in the fecal microbiota from 9 to 18 months. FO compared with SO supplementation affected changes in large bacterial groups, but only among children who had stopped breast-feeding before 9 months of age.

Involvement of gut microbial fermentation in the metabolic alterations occurring in n-3 polyunsaturated fatty acids-depleted mice

Backround

Western diet is characterized by an insufficient n-3 polyunsaturated fatty acid (PUFA) consumption which is known to promote the pathogenesis of several diseases. We have previously observed that mice fed with a diet poor in n-3 PUFA for two generations exhibit hepatic steatosis together with a decrease in body weight. The gut microbiota contributes to the regulation of host energy metabolism, due to symbiotic relationship with fermentable nutrients provided in the diet. In this study, we have tested the hypothesis that perturbations of the gut microbiota contribute to the metabolic alterations occurring in mice fed a diet poor in n-3 PUFA for two generations (n-3/- mice).

Methods

C57Bl/6J mice fed with a control or an n-3 PUFA depleted diet for two generations were supplemented with prebiotic (inulin-type Fructooligosaccharides, FOS, 0.20 g/day/mice) during 24 days.

Results

n-3/-mice exhibited a marked drop in caecum weight, a decrease in lactobacilli and an increase in bifidobacteria in the caecal content as compared to control mice (n-3/+ mice). Dietary supplementation with FOS for 24 days was sufficient to increase caecal weight and bifidobacteria count in both n-3/+ and n-3/-mice. Moreover, FOS increased lactobacilli content in n-3/-mice, whereas it decreased their level in n-3/+ mice. Interestingly, FOS treatment promoted body weight gain in n-3/-mice by increasing energy efficiency. In addition, FOS treatment decreased fasting glycemia and lowered the higher expression of key factors involved in the fatty acid catabolism observed in the liver of n-3/-mice, without lessening steatosis.

Conclusions

the changes in the gut microbiota composition induced by FOS are different depending on the type of diet. We show that FOS may promote lactobacilli and counteract the catabolic status induced by n-3 PUFA depletion in mice, thereby contributing to restore efficient fat storage.

Effects of dietary lipids and Clostridium butyricum on fat deposition and meat quality of broiler chickens

The effects of dietary lipids and Clostridium butyricum on carcass quality, fat deposition, meat quality, and fatty acid contents of breast meat in broiler chickens were investigated. One hundred sixty one-day-old broiler chicks (Arbor Acres) were divided into 4 treatment groups in a 2x2 factorial arrangement and fed 4 diets with 2 lipid sources (soybean oil or fish oil) and 2 levels of C. butyricum (0 or 5 g/kg of diets) were used. Abdominal fat was significantly reduced when chicks were fed the fish oil diet compared with the soybean oil diet (P<0.01). Fish oil diets increased drip losses of the breast and thigh muscles, thawing losses of breast muscle, and boiling losses of thigh muscle (P<0.05). Moreover, the C. butyricum diet profoundly reduced shear force of muscle (P<0.05). The supplementation of C. butyricum increased i.m. fat, the contents of C20:5n-3 (P<0.05), and total n-3 polyunsaturated fatty acids (P<0.05) in breast muscle. Additionally, there were significant interactions between lipids and C. butyricum for drip losses of breast muscle (P<0.01) and boiling losses of thigh muscle (P<0.05) and for the contents of C20:5n-3 (P<0.05) and n-3 polyunsaturated fatty acids (P<0.05) of breast muscle. The results of this study indicate that dietary inclusion of C. butyricum improves meat quality and fatty acid profiles of breast meat in male broilers, particularly interacting with a fish oil diet.

Effect of prebiotic xylooligosaccharides on growth performances and digestive enzyme activities of allogynogenetic crucian carp (Carassius auratus gibelio)

The effect of prebiotic xylooligosaccharides (XOS) on the growth performance and digestive enzyme activities of the allogynogenetic crucian carp, Carassius auratus gibelio, was investigated. XOS was added to fish basal semi-purified diets at three concentrations by dry feed weight: diet 1, 50 mg kg(-1); diet 2, 100 mg kg(-1); diet 3, 200 mg kg(-1), respectively. Twelve aquaria (n = 20) with three replicates for each treatment group (diets 1-3) and control treated without XOS were used. Weights of all collected carp from each aquarium were determined at the initial phase and at the end of the experiment, and the carp survival was also determined by counting the individuals in each aquarium. After 45 days, there were significant differences (P < 0.05) in the relative gain rate (RGR), and daily weight gain (DWG) of diets 1-3 were compared with the control. However, the survival rate was not affected (P > 0.05) by the dietary treatments. For enzymatic analysis, dissection produced a crude mixture of intestine and hepatopancreas of each segment to measure. The protease activity in the intestine and hepatopancreas content of fish in diet 2 (487.37 +/- 20.58 U g(-1) and 20.52 +/- 1.93 U g(-1)) were significantly different (P < 0.05) from that in the control (428.13 +/- 23.26 U g(-1) and 12.81 +/- 1.52 U g(-1)) and diet 3 (428.00 +/- 23.78 U g(-1) and 14.04 +/- 1.59 U g(-1)). Amylase activity in the intestine was significantly higher for diet 2 compared to diet 1 and the control. As for amylase in the hepatopancreas, assays showed higher activity in diet 2 (P < 0.05) compared to the rest.

A preliminary in vitro assessment of GroBiotic-A, brewer's yeast and fructooligosaccharide as prebiotics for the red drum Sciaenops ocellatus

This study examined the effects of brewers yeast, fructooligosaccharide (FOS), and GroBiotic-A, a mixture of partially autolyzed brewers yeast, dairy components and dried fermentation products, on the intestinal microbial community of red drum, Sciaenops ocellatus. Gastrointestinal (GI) tracts were aseptically removed from three sub-adult red drum previously maintained on a commercial diet and placed in an anaerobic chamber. Intestinal contents were removed, diluted and incubated in vitro in one of four liquid media: normal diet alone, diet + 2% (w/w) GroBiotic-A, diet + 2% brewers yeast, and diet + 2% FOS. After 24 and 48 h of incubation at 25 degrees C, supernatants were removed for volatile fatty acid (VFA) analysis and DNA was extracted for denaturing gradient gel electrophoresis (DGGE) analysis. Polymerase chain reaction (PCR) was performed on a highly conserved region of M 16S rDNA and the amplicons were subjected to DGGE. The microbial community (MC) fingerprint was used to distinguish microbial populations. The intestinal contents incubated with GroBiotic-A had significantly (P<0.05) higher acetate and total VFA concentrations at 48 h compared to the other treatments. DGGE analysis demonstrated that the microbial community was significantly altered by Grobiotic-A and brewers yeast.

Carnobacterium: positive and negative effects in the environment and in foods

The genus Carnobacterium contains nine species, but only C. divergens and C. maltaromaticum are frequently isolated from natural environments and foods. They are tolerant to freezing/thawing and high pressure and able to grow at low temperatures, anaerobically and with increased CO₂ concentrations. They metabolize arginine and various carbohydrates, including chitin, and this may improve their survival in the environment. Carnobacterium divergens and C. maltaromaticum have been extensively studied as protective cultures in order to inhibit growth of Listeria monocytogenes in fish and meat products. Several carnobacterial bacteriocins are known, and parameters that affect their production have been described. Currently, however, no isolates are commercially applied as protective cultures. Carnobacteria can spoil chilled foods, but spoilage activity shows intraspecies and interspecies variation. The responsible spoilage metabolites are not well characterized, but branched alcohols and aldehydes play a partial role. Their production of tyramine in foods is critical for susceptible individuals, but carnobacteria are not otherwise human pathogens. Carnobacterium maltaromaticum can be a fish pathogen, although carnobacteria are also suggested as probiotic cultures for use in aquaculture. Representative genome sequences are not yet available, but would be valuable to answer questions associated with fundamental and applied aspects of this important genus.

Probiotics in marine larviculture

Owing to the problem of antibiotic resistance and subsequent reluctance of using antibiotics, the use of probiotics in larviculture is becoming increasingly popular. During the early stages of development, manipulation of the larval digestive system seems possible through the addition of probiotics either through the culture water or via the livefood. Well-studied probiotics used in human medicine and terrestrial agriculture have proved to be successful in aquaculture and therefore reduce the need for extensive biosafety trials. The selection of probiotics requires various in vitro screening experiments, which assay for the production of antagonist compounds, their growth in and attachment to fish intestinal mucus, and the production of other beneficial compounds such as vitamins, fatty acids and digestive enzymes. Further information regarding probiont suitability can be obtained from its identification, interaction with livefood and host pathogenicity. Finally, pilot-scale in vivo tests need be performed, after which a production cost-benefit analysis to determine its economic viability needs to be undertaken.

The potential interactions between polyunsaturated fatty acids and colonic inflammatory processes

n-3 Polyunsaturated fatty acids (PUFAs) are recognized as having an anti-inflammatory effect, which is initiated and propagated via a number of mechanisms involving the cells of the immune system. These include: eicosanoid profiles, membrane fluidity and lipid rafts, signal transduction, gene expression and antigen presentation. The wide-range of mechanisms of action of n-3 PUFAs offer a number of potential therapeutic tools with which to treat inflammatory diseases. In this review we discuss the molecular, animal model and clinical evidence for manipulation of the immune profile by n-3 PUFAs with respect to inflammatory bowel disease. In addition to providing a potential therapy for inflammatory bowel disease there is also recent evidence that abnormalities in fatty acid profiles, both in the plasma phospholipid membrane and in perinodal adipose tissue, may be a key component in the multi-factorial aetiology of inflammatory bowel disease. Such abnormalities are likely to be the result of a genetic susceptibility to the changing ratios of n-3 : n-6 fatty acids in the western diet. Evidence that the fatty acid components of perinodal adipose are fuelling the pro- or anti-inflammatory bias of the immune response is also reviewed.

Major depressive disorder: probiotics may be an adjuvant therapy

Major depressive disorder (MDD) is an extremely complex and heterogeneous condition. Emerging research suggests that nutritional influences on MDD are currently underestimated. MDD patients have been shown to have elevated levels of pro-inflammatory cytokines, increased oxidative stress, altered gastrointestinal (GI) function, and lowered micronutrient and omega-3 fatty acid status. Small intestinal bacterial overgrowth (SIBO) is likely contributing to the limited nutrient absorption in MDD. Stress, a significant factor in MDD, is known to alter GI microflora, lowering levels of lactobacilli and bifidobacterium. Research suggests that bacteria in the GI tract can communicate with the central nervous system, even in the absence of an immune response. Probiotics have the potential to lower systemic inflammatory cytokines, decrease oxidative stress, improve nutritional status, and correct SIBO. The effect of probiotics on systemic inflammatory cytokines and oxidative stress may ultimately lead to increased brain derived neurotrophic factor (BDNF). It is our contention that probiotics may be an adjuvant to standard care in MDD.

Carnobacterium divergens and Carnobacterium maltaromaticum as spoilers or protective cultures in meat and seafood: phenotypic and genotypic characterization

Carnobacterium, a genus of lactic acid bacteria, frequently dominate the microflora of chilled vacuum- or modified atmosphere-packed meat and seafood. In this study Carnobacterium isolates were characterized by phenotypic and molecular methods in order to investigate the association of species and intra-species groups with distinct kinds of meat and seafood. Of 120 test strains, 50 originated from meat (beef and pork products, including 44 strains isolated during this study and 6 strains obtained from culture collections) and 52 from seafoods (cod, halibut, salmon, shrimps and roe products). In addition, 9 reference strains of Carnobacterium spp from other sources than meat and fish and 9 reference strains of lactic acid bacteria belonging to other genera than Carnobacterium were included. Numerical taxonomy relying on classical biochemical reactions, carbohydrate fermentation and inhibition tests (temperature, salt, pH, chemical preservatives, antibiotics, bacteriocins), SDS-PAGE electrophoresis of whole cell proteins, plasmid profiling, intergenic spacer region (ISR) analysis and examination of amplified-fragment length polymorphism (AFLP) were employed to characterize the strains. The numerical taxonomic approach divided the carnobacteria strains into 24 groups that shared less than 89% similarity. These groups were identified as Carnobacterium divergens with one major cluster (40 strains) and 7 branches of one to four strains, Carnobacterium maltaromaticum (previous C. piscicola) with one major cluster (37 strains) and 9 branches of one to four strains and Carnobacterium mobile (three branches consisting in total of 4 strains). Branches consisting of references strains of the remaining Carnobacterium spp. were separated from clusters and branches of C. divergens, C. maltaromaticum and C. mobile. Isolates from the main clusters of C. divergens and C. maltaromaticum were found both in fresh and lightly preserved meat and seafood products. High phenotypic intra-species variability was observed for C. divergens and C. maltaromaticum but despite this heterogeneity in phenotypic traits a reliable identification to species levels was obtained by SDS-PAGE electrophoresis of whole cell proteins and by ISR based on 16S-23S rDNA intergenic spacer region polymorphism. With AFLP, two distinct clusters were observed for C. divergens but only one for C. maltaromaticum. The two C. divergens clusters were not identical to any of the clusters observed by numerical taxonomy. A limited number of C. divergens and C. maltaromaticum isolates possessed a biopreservative potential due to their production of bacteriocins with a wide inhibition spectrum. This study serves as a base-line for further investigations on the potential role of species of Carnobacterium in foods where they predominate the spoilage microflora.

Lactobacillus growth and membrane composition in the presence of linoleic or conjugated linoleic acid

Five Lactobacillus strains of intestinal and food origins were grown in MRS broth or milk containing various concentrations of linoleic acid or conjugated linoleic acid (CLA). The fatty acids had bacteriostatic, bacteriocidal, or no effect depending on bacterial strain, fatty acid concentration, fatty acid type, and growth medium. Both fatty acids displayed dose-dependent inhibition. All strains were inhibited to a greater extent by the fatty acids in broth than in milk. The CLA isomer mixture was less inhibitory than linoleic acid. Lactobacillus reuteri ATCC 55739, a strain capable of isomerizing linoleic acid to CLA, was the most inhibited strain by the presence of linoleic acid in broth or milk. In contrast, a member of the same species, L. reuteri ATCC 23272, was the least inhibited strain by linoleic acid and CLA. All strains increased membrane linoleic acid or CLA levels when grown with exogenous fatty acid. Lactobacillus reuteri ATCC 55739 had substantial CLA in the membrane when the growth medium was supplemented with linoleic acid. No association between level of fatty acid incorporation into the membrane and inhibition by that fatty acid was observed.

Evaluation of immunomodulatory effects of lactic acid bacteria in turbot (Scophthalmus maximus)

In the present work, the effects of several lactic acid bacteria on the immune response of turbot (Scophthalmus maximus) macrophages have been studied both in vitro and in vivo. Out of six lactic acid bacterial strains tested, only heat-killed Lactococcus lactis significantly increased the turbot head kidney macrophage chemiluminescent (CL) response after 24 h of incubation. Nitric oxide (NO) was also significantly enhanced by this bacterium after 72 h of incubation with either viable (10(3) and 10(6) cells/ml) or heat-killed (10(6) cells/ml) bacteria. Viable Leuconostoc mesenteroides (10(6) cells/ml) was also capable of significantly increasing NO production. Since L. lactis proved to be the strain with more effects on the host immune function, further in vivo and in vitro experiments were conducted with this bacterium. The in vitro capacity of L. lactis to adhere to turbot intestinal mucus was positively confirmed. When orally administered, L. lactis significantly increased the macrophage CL response and the serum NO concentration after 7 days of daily administration. The antibacterial effect of the extracellular products from the six LAB strains against the fish-pathogenic bacterium Vibrio anguillarum was also demonstrated in vitro.

Improvement of the probiotic effect of micro-organisms by their combination with maltodextrins, fructo-oligosaccharides and polyunsaturated fatty acids

Probiotics could represent an effective alternative to the use of synthetic substances in nutrition and medicine. The data concerning the efficacy of probiotics are often contradictory. This paper focuses on the enhancement of the efficacy of probiotics by their combination with synergistically acting components of natural origin. Maltodextrins can be obtained by enzymatic hydrolysis of starch and are suitable for consumption. Administration of Lactobacillus paracasei together with maltodextrin decreased the number of Escherichia coli colonising the jejunal mucosa of gnotobiotic piglets by 1 logarithm compared to the control group. Fructo-oligosaccharides (FOS) are naturally occurring oligosaccharides, mainly of plant origin. L. paracasei administered in combination with FOS significantly increased counts of Lactobacillus spp., Bifidobacterium spp., total anaerobes and total aerobes compared to the control group as well as the L. paracasei group. It also significantly decreased Clostridium and Enterobacterium counts in the faeces of the weanling piglets compared with the control group. Dietary lipids influence the gastrointestinal microbiota and specifically the population of lactic acid bacteria. In gnotobiotic piglets the oral administration of an oil containing polyunsaturated fatty acids (PUFA) significantly increased the number of L. paracasei adhering to jejunal mucosa compared to the control group. Our results showed that maltodextrin KMS X-70 and PUFA can be used to enhance the effect of probiotic micro-organisms in the small intestine, and similarly FOS enhance the effect of probiotic micro-organisms in the large intestine.

Influence of probiotic supplemented infant formula on composition of plasma lipids in atopic infants

Probiotic therapy is a new, successful approach to alleviating allergic symptoms. In this study, our aim was to investigate whether the positive results obtained with probiotic therapy would be associated with the differential absorption and utilization of dietary PUFA. 15 infants referred to a pediatric clinic on the basis of atopic eczema were weaned to Bifidobacterium Bb-12 or Lactobacillus GG supplemented infant formula, or to the same formula without probiotics (randomized, placebo-controlled, double blind study design). In plasma neutral lipids, alpha-linolenic acid (18:3 n-3) proportions were reduced by the probiotic supplementation. In phospholipids, Lactobacillus GG supplemented formula did not influence alpha-linolenic acid proportions, while Bifidobacterium Bb-12 supplemented formula increased the proportion of alpha-linolenic acid; from 0.13 +/- 0.03 to 0.24 +/- 0.03 (mean +/- SEM) (P = 0.002). These results show that some physiological effects of probiotics may be associated with physiological interactions between probiotics and dietary PUFA.

Characterization of Carnobacterium divergens strain 6251 isolated from intestine of Arctic charr (Salvelinus alpinus L.)

An atypical strain of Carnobacterium divergens, strain 6251, was isolated from the small intestine of Arctic charr (Salvelinus alpinus L.), fed high dietary carbohydrate. This strain showed marked growth inhibitory effects in vitro against the fish pathogens Aeromonas salmonicida subsp. salmonicida (furunculosis), Vibrio anguillarum (vibriosis) and Vibrio viscocus (winter ulcer). The strain is a non-motile Gram-positive psychrotrophic rod that lacks both catalase and oxidase, grows at pH 9.1 (CTAS agar), but not on acetate containing media (pH < or = 5.4), on TCBS or at < or =6% sodium chloride content. Strain 6251 is facultatively anaerobic and utilises tryptone as a sole source of nutrient. Further characterisation showed the most abundant cellular fatty acid of strain 6251 to be oleic acid (18:1) (n-9) (36.0%). Sequencing of a 16S rDNA region of 578 nucleotides and AFLP microbial fingerprinting suggested that strain 6251 is not closely related to any carnobacteria known, however, DNA-DNA similarity determinations showed high similarity (96.2%) with the type strain of Carnobacterium divergens. The unique phenotypic attributes of this strain represent new information on the biodiversity and ecology of carnobacteria and especially of the species C. divergens.

The intestinal mucosa as a target for dietary polyunsaturated fatty acids

Several studies have reported beneficial effects of dietary polyunsaturated fatty acids (PUFA) on various aspects of both human and animal health, and particular reference has been made to their effects on systemic immune responses. Both immune stimulation and immune suppression have been reported, with the outcome dependent on the type of PUFA, the target cell, as well as the immune competence of the cells before exposure. The systemic and the mucosal immune systems are discrete entities, which have evolved specific approaches in the defense of the host. The latter comprises several interconnected tissues, which communicate with one another through the action of soluble mediators and the trafficking of cellular components. After the oral mucosa, the intestinal epithelium and its associated gut-associated lymphoid tissue are the primary targets of dietary components. Absorption of dietary PUFA and its incorporation into intestinal tissues has been well studied, but the consequences of these events in relation to local immune responses have received little attention. This article describes some of the immune mechanisms operating at this barrier and, where possible, pinpoints areas for which a modulatory role for PUFA has already been demonstrated. Although not an exhaustive treatise of the subject, it is hoped that this review will foster research into the specific interaction between dietary PUFA and cell populations comprising the intestinal barrier.

Identification and characterization of Carnobacteria isolated from fish intestine

Eleven bacterial strains were isolated from the gastrointestinal tract of four fish species, Atlantic salmon (Salmo salar L.), Arctic charr (Salvelinus alpinus L.), Atlantic cod (Gadus morhua L.) and wolffish (Anarhichas lupus L.). All the strains were Gram-positive rods, non-sporing, catalase and oxidase-negative, able to grow at pH 9.0 but not on acetate containing media (pH < or = 5.4), and were fermentative. They had a high content of oleic acid (18:1 n-9) in cellular lipid, and were found to belong to the genus Carnobacterium by phenotypic criteria. The eleven carnobacteria strains were further identified on the basis of 16S rDNA sequence analysis and AFLP(TM) fingerprinting.