In vitro assessment of potential probiotic characteristics of indigenous Lactococcus lactis and Weissella oryzae isolates from rainbow trout (Oncorhynchus mykiss Walbaum).

AIM: The objective of this study was to evaluate the probiotic potential of lactic acid bacteria (LAB) isolated from the intestinal ecosystem of rainbow trout. METHODS AND RESULTS: Among LAB isolates, 10 of them were selected and screened for resistance to acid and bile salts, pancreatin, sodium chloride and temperature, hydrophobicity, growth profile and antimicrobial activity against fish pathogens. Then, biosafety assessments were investigated. Selected LAB tolerated to gastrointestinal physiological conditions, pancreatin and a range of sodium chloride and temperature. They also exhibited hydrophobicity and showed antagonistic activity against Streptococcus iniae and Yersinia ruckeri. Results of 16S rRNA gene sequencing showed that selected LAB belonged to the Lactococcus lactis (n = 5) and Weissella oryzae (n = 5) species. They exhibited no ß-haemolytic activity, while six selected LAB were resistant to some antibiotics. None of them harboured virulence factors. CONCLUSIONS: This study revealed probiotic characteristics of indigenous LAB isolated from the intestinal ecosystem of rainbow trout. However, further studies are required to confirm the effectiveness of these isolates as probiotics in aquaculture. SIGNIFICANCE AND IMPACT OF THE STUDY: To the best of our knowledge, for the first time, the presence of probiotic candidates belonging to W. Oryzae was confirmed in fish intestinal microbiota.

Peroxisome Proliferator-Activated Receptor Alpha (PPARα), a Key Regulator of Lipid Metabolism in Avians.

Dietary fatty acids have various effects on cellular metabolism, and many of these effects are carried out through the alteration of the gene expression. Fatty acids upregulate or downregulate the expression of different genes by acting both as agonists or antagonists for nuclear hormone receptors. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily. To date, three PPAR subtypes, α, ß, and γ, have been recognized. PPARs regulate various target genes with a role in intracellular and extracellular lipid metabolism, mainly those involved in peroxisomal ß-oxidation. PPAR controls several genes involved in lipid metabolism, including Δ-5, Δ-6, and Δ-9 desaturases, acyl-coenzyme A oxidase, and carnitine palmitoyltransferase. The activation of PPARα might thus decrease fat deposits indirectly by raising hepatic fatty acid ß-oxidation. PPARα is likely part of the regulating system of energy metabolism in peripheral tissues such as adipose tissue and skeletal muscles.

Effect of Dietary Fat on Gene Expression in Poultry, A Review.

Traditionally, poultry farmers aimed to produce birds with high body weight and feed conversion ratio. However, in line with current developments, there are other traits that must be taken into account as well. These include producing poultry meat with lower body fat content and improving the nutritional quality of the poultry meat to appeal to consumer requirements. The interrelated importance of human diet and health status is an ancient subject. Human foods as a lifestyle factor is involved in the incidence of many types of diseases, such as cardiovascular diseases and cancer. Recent reports suggest that not only the quantity but also the composition of dietary fat is an important factor to prevent these metabolic diseases in human populations. It has been reported that some dietary fats are able to reduce lipid synthesis and increase fatty acid oxidation and diet-mediated thermogenesis. The outcome of this change is a superior animal product with lower fat content. There is evidence of dissimilar mechanisms of action of n-3 and n-6 fatty acids. Dietary fatty acids have various effects on cellular metabolism, and many of these effects are carried out through the alteration of gene expression. This review will focus on the control of body fat by gene expression in avians.

Ligands and Regulatory Modes of Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) in Avians.

Nutrient and gene interaction is an important aspect of poultry metabolism that determines performance capacity. New technological tools in biochemistry and biotechnology make it possible to explore the molecular base of phenotypic characteristics of poultry production. Fats act as energy deposits in the poultry body and are an essential constituent of animal cell membranes. From a functional standpoint, it has been suggested that ingested lipids change liver fatty acid synthesis and other lipogenic enzymes by regulating mRNA synthesis. Nuclear hormone receptors are ligand-activated transcription factors that control several genes involved in lipid metabolism. The peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of transcription factors. Three separate PPAR genes have been identified; they are known as α, δ, and γ. The most important metabolic effect of PPARγ in chicken is its task in adipogenesis. Reviewing the ligands of chicken PPARγ gene can be useful to a better understanding of PPARγ regulatory functions.