Bioencapsulation and Colonization Characteristics of Lactococcus lactis subsp. lactis CF4MRS in Artemia franciscana: a Biological Approach for the Control of Edwardsiellosis in Larviculture

Predominance of beneficial bacteria helps to establish a healthy microbiota in fish gastrointestinal system and thus to reduce emerging pathogen. In this study, the colonization efficacy of Lactococcus lactis subsp. lactis CF4MRS in Artemia franciscana and its potential as a probiotic in suppressing Edwardsiella sp. infection were investigated in vivo. The colonization extent of the bioencapsulated L. lactis was established through visualization of gfp gene-transformed L. lactis in A. franciscana. Here, we demonstrate that when A. franciscana is administrated with L. lactis at 108 CFU mL−1 for 8 h, the highest relative percentage of survival (RPS = 50.0) is observed after inoculation with Edwardsiella sp. The total counts of L. lactis entrapped in Artemia were the highest (ranged from 3.2 to 5.1 × 108 CFU mL−1), when 108–109 CFU mL−1 of L. lactis was used as starting inoculum, with the bioencapsulation performed within 8–24 h. Fluorescent microscopy showed gfp-transformed L. lactis colonized the external trunk surfaces, mid-gut and locomotion antennules of the A. franciscana nauplii. These illustrations elucidate the efficiency of colonization of L. lactis in the gastrointestinal tract and on the body surfaces of Artemia. In conclusion, L. lactis subsp. lactis CF4MRS shows a good efficacy of colonization in Artemia and has the potential for biocontrol/probiotic activity against Edwardsiella sp. infection

Poly-β-hydroxybutyrate administration during early life: effects on performance, immunity and microbial community of European sea bass yolk-sac larvae

The reliable production of marine fish larvae is one of the major bottlenecks in aquaculture due to high mortalities mainly caused by infectious diseases. To evaluate if the compound poly-β-hydroxybutyrate (PHB) might be a suitable immunoprophylactic measure in fish larviculture, its capacity to improve immunity and performance in European sea bass (Dicentrarchus labrax) yolk-sac larvae was explored. PHB was applied from mouth opening onwards to stimulate the developing larval immune system at the earliest possible point in time. Larval survival, growth, microbiota composition, gene expression profiles and disease resistance were assessed. PHB administration improved larval survival and, furthermore, altered the larva-associated microbiota composition. The bacterial challenge test using pathogenic Vibrio anguillarum revealed that the larval disease resistance was not influenced by PHB. The expression profiles of 26 genes involved e.g. in the immune response showed that PHB affected the expression of the antimicrobial peptides ferritin (fer) and dicentracin (dic), however, the response to PHB was inconsistent and weaker than previously demonstrated for sea bass post-larvae. Hence, the present study highlights the need for more research focusing on the immunostimulation of different early developmental stages for gaining a more comprehensive picture and advancing a sustainable production of high quality fry

MicroRNA antagonist therapy during normothermic machine perfusion of donor kidneys<strong> </strong>

Normothermic machine perfusion (NMP) is a novel clinical approach to overcome the limitations of traditional hypothermic organ preservation. NMP can be used to assess and recondition organs prior to transplant and is the subject of clinical trials in solid organ transplantation. In addition, NMP provides an opportunity to deliver therapeutic agents directly to the organ thus avoiding many limitations associated with systemic treatment of the recipient. We report the delivery of oligonucleotide-based therapy to human kidneys during NMP, in this case to target microRNA function (antagomir). An antagomir targeting mir-24-3p localised to the endothelium and proximal tubular epithelium. Endosomal uptake during NMP conditions facilitated antagomir co-localisation with proteins involved in the RNA-induced silencing complex (RISC) and demonstrated engagement of the miRNA target. This pattern of uptake was not seen during cold perfusion. Targeting mir-24-3p action increased expression of genes controlled by this microRNA, including heme oxygenase-1 and sphingosine-1-phosphate receptor 1. The expression of genes not under the control of mir-24-3p was unchanged, indicating specificity of the antagomir effect. In summary, this is the first report of ex-vivo gymnotic delivery of oligonucleotide to the human kidney and demonstrates that NMP provides the platform to bind and block detrimental microRNAs in donor kidneys prior to transplantation

Poly-beta-hydroxybutyrate (PHB) and infection reduction in farmed aquatic animals

There is a continuous effort in finding effective and sustainable strategies to control diseases in farmed animals, and in recent years, the application of the bacterial storage compound poly-β-hydroxybutyrate (PHB) was identified as a new disease control agent for aquaculture. The idea of using PHB as a biocontrol agent was conceived based on the knowledge that this biopolymer can be degraded into short-chain fatty acids (SCFAs), and SCFAs are known compounds with antimicrobial properties. At the beginning of this chapter, an overview about the PHB granule, its detection, quantification, production, and recovery in microorganisms is presented. The main topic focuses on the application and beneficial effects of PHB in farmed aquatic animals. The mechanisms by which PHB provides beneficial effects to the host are discussed