Influence of lactic-acid bacteria feed supplementation on free amino acid levels in serum and feces of rainbow trout (Oncorhynchus mykiss, Walbaum 1792)

IntroductionThe influence of intestinal microbiota, particularly lactic-acid bacteria, on digestion and nutrient metabolic activities has been extensively studied. In this research, we investigated the effects of supplementing the feed of rainbow trout (O. mykiss) with P. acidilactici or L. lactis probiotics. A Control group without probiotic supplementation was also included. The study aimed to evaluate growth, feed conversion indices, free amino acid levels in serum and feces, and the relative gene expression of amino acid solute carrier transporters (SLC).MethodsRainbow trout weighing 73.9±10 g were fed with a basal commercial diet supplemented with mono-strains of P. acidilactici or L. lactis at a dosage of 5 x 108 CFU per gram of feed for 60 days. The trout were reared in 100-liter tanks with independent closed recirculation systems, with a water replacement rate of 80% of the total volume daily and a controlled temperature of 15 ± 0.3 °C. The proximate composition of the basal diet consisted of crude protein (49.8%), fat (32.1%), fiber (1.31%), ash (13%), and moisture (8.3%) on a dry matter basis. The diet was provided at a rate of 2% of bodyweight per day.ResultsNo significant differences (p > 0.05) were observed in growth and feed conversion indices between the experimental groups. However, significant differences in free amino acid levels in feces and serum samples (p ≤ 0.05) were observed. The P. acidilactici group exhibited significantly higher levels of glutamate, lysine, proline, and tyrosine in feces samples, and higher levels of arginine, iso/leucine, phenylalanine, proline, serine, threonine, and valine in serum samples compared to the Control group. Additionally, the supplemented probiotic groups showed significant downregulation (p ≤ 0.05) of theslc6a19 and slc7a9 genes, which encode transporters for neutral and cationic amino acids.DiscussionThe autochthonous rainbow trout strain, P. acidilactici, demonstrated more pronounced effects on amino acid levels in feces and serum compared to the non-autochthonous L. lactis strain. However, the increased amino acid levels, particularly in the serum, resulting from P. acidilactici supplementation, did not lead to improved trout growth or feed conversion. Nonetheless, lactic-acid bacteria supplementation induced measurable metabolic effects, as evidenced by elevated levels of specific amino acids in the serum and feces.Future research should focus on evaluating these probiotic effects using specialized diets and considering the observed metabolic effects in this study

Propuesta para la conformación del Sistema Regional Ambiental - SIRA - en el Caribe colombiano

La política es aquella práctica que se ocupa de gestionar, de resolver los conflictos colectivos y de crear coherencia social, y su resultado son decisiones obligatorias para todos. El origen de los conflictos se sitúa en la existencia de diferencias sociales que se convierten a menudo en desigualdades, puesto que no todos los miembros de la comunidad tienen acceso a los mismos recursos intelectuales, políticos, informaciones y provocan una tensión y unas fracciones sociales que generan sentimientos de incertidumbre, de inferioridad o de peligro en quienes disponen de menos recursos 2 . El Sistema Nacional Ambiental, SINA, como esquema institucional ambiental encierra en sí mismo una gestión política democrática, descentralizada y participativa3 , que también busca dirimir los conflictos propios de la interdependencia institucional, unificar criterios de acción y fortalecer la protección de los activos naturales regionales compartidos. Este enfoque de descentralización estuvo reflejado en la reestructuración y creación de las Corporaciones Autónomas Regionales, hoy por hoy abanderadas de la Gestión Ambiental en el país; esta gestión vista desde cada región natural no alcanza a mostrar el esfuerzo de trabajo a la escala funcional de su desarrollo, solo se han visto los esfuerzos aislados desde las Corporaciones con algunos trabajos regionales que se integran sin los elementos necesarios de Región en el marco de actuación geográfica del Estado como responsable de la administración de los Recursos Naturales Renovables de los cuales es propietaria la Nación.Incluye bibliografía, anexo

Fasting Upregulates npy, agrp, and ghsr Without Increasing Ghrelin Levels in Zebrafish (Danio rerio) Larvae

Food intake in fish and mammals is orchestrated by hypothalamic crosstalk between orexigenic (food intake stimulation) and anorexigenic (food intake inhibition) signals. Some of these signals are released by peripheral tissues that are associated with energy homeostasis or nutrient availability. During the fish larva stage, orexigenic stimulation plays a critical role in individual viability. The goal of this study was to assess the mRNA levels of the main neuropeptides involved in food intake regulation (npy, agrp, carppt, and pomc), in concert with the mRNA levels and peptide levels of ghrelin, under a fasting intervention at the larval stage in zebrafish (Danio rerio). Prior to the fasting intervention, the zebrafish larva cohort was reared for 20 days post fertilization (dpf) and then randomly divided into two groups of 20 individuals. One group was subjected to a fasting intervention for 5 days (fasted group), and the other group was fed normally (fed group); this experimental protocol was performed twice independently. At the end of the fasting period, individuals from each experimental group were divided into different analysis groups, for evaluations such as relative gene expression, immunohistochemistry, and liquid chromatography coupled to nano high-resolution mass spectrometry (nLC-HRMS) analyses. The relative expression levels of the following genes were assessed: neuropeptide Y (npy), agouti-related peptide (agrp), proopiomelanocortin (pomc), cocaine and amphetamine-regulated transcript (cartpt), ghrelin (ghrl), ghrelin O-acyltransferase (mboat4), growth hormone secretagogue receptor (ghsr), and glucokinase (gck). In the fasted group, significant upregulation of orexigenic peptides (npy – agrp) and ghsr was observed, which was associated with significant downregulation of gck. The anorexigenic peptides (pomc and cartpt) did not show any significant modulation between the groups, similar to mboat4. Contrary to what was expected, the relative mRNA upregulation of the orexigenic peptides observed in the fasted experimental group could not be associated with significant ghrelin modulation as assessed by three different approaches: qPCR (relative gene expression of ghrelin), nLC-HRMS (des-acyl-ghrelin levels), and immunohistochemistry (integrated optical density of prepropeptides in intestinal and hepatopancreas tissues). Our results demonstrate that zebrafish larvae at 25 dpf exhibit suitable modulation of the relative mRNA levels of orexigenic peptides (npy and agrp) in response to fasting intervention; nevertheless, ghrelin was not coregulated by fasting. Therefore, it can be suggested that ghrelin is not an essential peptide for an increase in appetite in the zebrafish larva stage. These results give rise to new questions about food intake regulation factors in the early stages of fish

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

Comparison of gene expression patterns of key growth genes between different rate growths in zebrafish (Danio rerio) siblings

Variable individual growth rate is a phenomenon observed in fish cohorts that influences the aquaculture performance and fish cohort ecological viability. Our aim was to compare gene expression patterns of key growth genes in zebrafish larvae with different growth rate. The body length of sibling zebrafish larvae at 6 days post hatching (dph) was measured. The larvae were reared to 20 dph and measured again. Two body-length groups were clearly observed: 4 mm (small larvae) and 5-6 mm (large larvae). Total RNA was isolated from both groups. Growth hormone (gh), growth hormone receptor (ghr), insulin-like growth factor 1 (igf-1), insulin-like growth factor receptor (igf-1r a/b), insulin-like growth factor binding protein 1 (igfbp-1), thyroglobulin (tg), cholecystokinin (cck), and ghrelin were evaluated by quantitative polymerase chain reaction (qPCR). Glucokinase (gck) and igfbp-1 were included as a gene expression marker of larvae nutritional status. Two genes showed significant differences between the body length groups, igfbp-1 (P = 0.01) and igf-1r (P = 0.02). The igfbp-1 suggests than growth rate variability was associated with the larvae nutritional status and this condition affect the gene expression pattern of igf-1r. Therefore these genes are interesting genes markers for growth rate variabilities studies.FONDE CYT Post-Doctorado Nº3130518 from CONICYT-Chile / Concurso Nacional de Inserción de Capital Humano Avanzado en la Academia Nº79110002 from CONICYT-Chile

Reduction of Soybean Meal Non-Starch Polysaccharides and α-Galactosides by Solid-State Fermentation Using Cellulolytic Bacteria Obtained from Different Environments

Soybean meal (SBM) is an important protein source in animal feed. However, the levels of SBM inclusion are restricted in some animal species by the presence of antinutritional factors (ANFs), including non-starch polysaccharides (NSPs) and α-galactosides (GOSs). The aim of this study was to reduce the soybean meal NSPs and GOSs by solid-state fermentation (SSF) using a combination of cellulolytic bacteria isolated from different environments (termites, earthworms, corn silage and bovine ruminal content). To analyse the key enzymatic activities, the isolates were grown in minimal media containing NSPs extracted from SBM. The selected bacterial strains belonged to the genera Streptomyces, Cohnella and Cellulosimicrobium. SSF resulted in a reduction of nearly 24% in the total NSPs, 83% of stachyose and 69% of raffinose and an increase in the protein content. These results suggest that cellulolytic bacteria-based SSF processing facilitates SBM nutritional improvement. In addition, the us

Effect of Dietary Carbohydrate-to-Protein Ratio on Gut Microbiota in Atlantic Salmon (Salmo salar)

Atlantic salmon (Salmo salar) is a carnivorous fish species whose productive performance tends to be suboptimal when fed low-cost carbohydrate rich meals. It is of interest to study the dynamics of gut microbiota communities in salmonids fed high carbohydrate diets since gut microbes are referred to as key players that influence the metabolism and physiology of the host. A study was conducted to determine the effect of feeding a high carbohydrate diet to Atlantic salmon in gut microbiota communities. A medium carbohydrate (15% wheat starch)/medium protein (MC/MP) diet or a high carbohydrate (30% wheat starch)/low protein (HC/LP) diet was fed to triplicate tanks (28 fish each) during four weeks. We conducted an in-depth characterization of the distal intestine digesta microbiota using high-throughput sequencing of the V4 region of the 16S rRNA gene. Firmicutes, Actinobacteria and Proteobacteria were the major phyla determined in either experimental group. Phylum Planctomycetes, class Planctomycetia, order Planctomycetales and genus Lactococcus were significantly more abundant in fish fed the HC/LP diet compared with fish fed the MC/MP diet. Our study suggests feeding a carbohydrate rich meal to salmon exerts a low impact on the structure of gut microbial communities, affecting mostly low-abundance bacteria capable of metabolizing anaerobically carbohydrates as a major energy-yielding substrate

Effect of Dietary Carbohydrate-to-Protein Ratio on Gut Microbiota in Atlantic Salmon (Salmo salar)

Atlantic salmon (Salmo salar) is a carnivorous fish species whose productive performance tends to be suboptimal when fed low-cost carbohydrate rich meals. It is of interest to study the dynamics of gut microbiota communities in salmonids fed high carbohydrate diets since gut microbes are referred to as key players that influence the metabolism and physiology of the host. A study was conducted to determine the effect of feeding a high carbohydrate diet to Atlantic salmon in gut microbiota communities. A medium carbohydrate (15% wheat starch)/medium protein (MC/MP) diet or a high carbohydrate (30% wheat starch)/low protein (HC/LP) diet was fed to triplicate tanks (28 fish each) during four weeks. We conducted an in-depth characterization of the distal intestine digesta microbiota using high-throughput sequencing of the V4 region of the 16S rRNA gene. Firmicutes, Actinobacteria and Proteobacteria were the major phyla determined in either experimental group. Phylum Planctomycetes, class Planctomycetia, order Planctomycetales and genus Lactococcus were significantly more abundant in fish fed the HC/LP diet compared with fish fed the MC/MP diet. Our study suggests feeding a carbohydrate rich meal to salmon exerts a low impact on the structure of gut microbial communities, affecting mostly low-abundance bacteria capable of metabolizing anaerobically carbohydrates as a major energy-yielding substrate

Characterization of the intestinal microbiota of wild-caught and farmed fine flounder (Paralichthys adspersus)

A comparative analysis of the cultivable intestinal microbiota of farmed (AF) and wild-caught (WF) Paralichthys adspersus was performed. The 16S rRNA gene was used for taxa identification, and the ITS region for strain differentiation. We detected the presence of Vibrio, Bacillus, Photobacterium, Staphylococcus and Carnobacterium in AF, and Exiguobacterium, Klebsiella, Arthrobacter, Raoultella, Kluyvera, Myroides, Streptococcus, Vagococcus, Staphylococcus, Acinetobacter, Psychrobacter, Lactobacillus, Weissella and Lactococcus in WF. The microbial community was more diverse in WF than in AF. Some bacterial groups were only found in wild-caught fish and may be studied as potential beneficial agents for improving production traits in farmed fish. As the first study of microbiota of P. adspersus, it provides significant information that can potentially help improve farming practices by using strains as species-specific probiotics.CONICYT-Chile / Fondecyt 1140734/1171129 / Corfo, Centro Aquapacifico 15PCTI-4628

Characterization of the intestinal microbiota of wild-caught and farmed fine flounder (Paralichthys adspersus)

A comparative analysis of the cultivable intestinal microbiota of farmed (AF) and wild-caught (WF) Paralichthys adspersus was performed. The 16S rRNA gene was used for taxa identification, and the ITS region for strain differentiation. We detected the presence of Vibrio, Bacillus, Photobacterium, Staphylococcus and Carnobacterium in AF, and Exiguobacterium, Klebsiella, Arthrobacter, Raoultella, Kluyvera, Myroides, Streptococcus, Vagococcus, Staphylococcus, Acinetobacter, Psychrobacter, Lactobacillus, Weissella and Lactococcus in WF. The microbial community was more diverse in WF than in AF. Some bacterial groups were only found in wild-caught fish and may be studied as potential beneficial agents for improving production traits in farmed fish. As the first study of microbiota of P. adspersus, it provides significant information that can potentially help improve farming practices by using strains as species-specific probiotics.CONICYT-Chile / Fondecyt 1140734/1171129 / Corfo, Centro Aquapacifico 15PCTI-4628