Isolation and characterization of two lytic bacteriophages, ΦSt2 and ΦGrn1; phage therapy application for biological control of <i>Vibrio alginolyticus</i> in aquaculture live feeds

Bacterial infections are a serious problem in aquaculture since they can result in massive mortalities in farmed fish and invertebrates. Vibriosis is one of the most common diseases in marine aquaculture hatcheries and its causative agents are bacteria of the genus Vibrio mostly entering larval rearing water through live feeds, such as Artemia and rotifers. The pathogenic Vibrio alginolyticus strain V1, isolated during a vibriosis outbreak in cultured seabream, Sparus aurata, was used as host to isolate and characterize the two novel bacteriophages φSt2 and φGrn1 for phage therapy application. In vitro cell lysis experiments were performed against the bacterial host V. alginolyticus strain V1 but also against 12 presumptive Vibrio strains originating from live prey Artemia salina cultures indicating the strong lytic efficacy of the 2 phages. In vivo administration of the phage cocktail, φSt2 and φGrn1, at MOI = 100 directly on live prey A. salina cultures, led to a 93% decrease of presumptive Vibrio population after 4 h of treatment. Current study suggests that administration of φSt2 and φGrn1 to live preys could selectively reduce Vibrio load in fish hatcheries. Innovative and environmental friendly solutions against bacterial diseases are more than necessary and phage therapy is one of them

Bacteriophages in the control of pathogenic vibrios

Vibrios are common inhabitants of marine and estuarine environments. Some of them can be pathogenic to humans and/or marine animals using a broad repertory of virulence factors. Lately, several reports have indicated that the incidence of Vibrio infections in humans is rising and also in animals constitute a continuing threat for aquaculture. Moreover, the continuous use of antibiotics has been accompanied by an emergence of antibiotic resistance in Vibrio species, implying a necessity for efficient treatments. One promising alternative that emerges is the use of lytic bacteriophages; however, there are some drawbacks that should be overcome to make phage therapy a widely accepted method. In this work, we discuss about the major pathogenic Vibrio species and the progress, benefits and disadvantages that have been detected during the experimental use of bacteriophages to their control.Fondecyt 11140412 11140257 Proyecto PUCV DI Investigacion Innovadora Interdisciplinaria 039.461/201

Surplus of dietary micronutrients promotes antioxidant defense and improves fin erosions in European seabass (Dicentrarchus labrax) fry

Dietary micronutrient supplementation can serve as skin health promotor to prevent from natural infections and can be applied to decrease the use of antibacterial agents and their impact on the environment. Such supplementation has indicated anti-inflammatory and antioxidant properties in farmed fish. In this study, dietary supplementation of zinc, selenium, ascorbic acid and niacin, at levels 2 to 3-fold higher than recommended, was evaluated as a measure to promote skin health and antioxidant defense in European seabass, Dicentrarchus labrax, fry. For this purpose, fish survival, growth performance, fin and skin erosions as well as whole-fish antioxidant enzyme activity (catalase, selenium (Se)-independent and dependent glutathione peroxidase) were assessed. Moreover, bacterial load in the rearing water and skin mucus were evaluated to assess the potential of the dietary micronutrient mixture as a preventive from natural infections. A group fed with a diet including these micronutrients at recommended levels served as a control. Surplus of these micronutrients significantly reduced the percentage of fish with eroded fins, while also induced the activity of catalase and Se-dependent glutathione peroxidase. Fish growth and bacterial loads in the water and fish skin mucus were not affected, whereas no skin lesions were observed. Overall, a mineral- and vitamin-supplemented diet at levels higher than recommended seems to act as a promotor of skin health and prevent from fin erosions, potentially through an increase in the antioxidant defense system.</p

Bioaccessibility of phenolic compounds in fresh and dehydrated blueberries (Vaccinium corymbosum L.)

Blueberries (Vaccinium corymbosum L.) contain compounds with antioxidant properties that are beneficial to health. The effects of fruit preservation (freeze-drying, osmotic dehydration, and convection drying) on antioxidant capacity (DPPH and ORAC), total polyphenols and total anthocyanins were studied. Convection drying best preserved the total polyphenol contents and antioxidant capacity. While, freeze-drying and convection drying showed no significant differences in total anthocyanins. To determine the effects of the preservation techniques on the phenolic compounds/antioxidant capacity, their bioaccessibility was determined by a static model of in vitro gastrointestinal digestion. The results of the intestinal stage (ileum) showed that convection drying improved the preservation of antioxidant properties (DPPH), reaching values of 91.6% bioaccessibility (29.1 mmol Trolox equivalents (TE)/g DW) and 48.7% (9.4 mmol TE/g DW) for the freeze-dried berries. Meanwhile, osmotically dehydrated berries exhibited the lowest percentage of bioaccessibility of the antioxidant compounds at 27.6% (4.0 mmol TE/g DW). It was concluded that total polyphenols, total anthocyanins and antioxidant capacity are better preserved by convection drying, followed by freeze-drying and osmotic dehydration

Teosinte (Dioon mejiae) Flour: Nutritional and Physicochemical Characterization of the Seed Flour of the Living Fossil in Honduras

Teosinte (Dioon mejiae) is a dioecious tree native to Honduras, whose seeds are used to make flour for the preparation of traditional foods and beverages. The objective was to evaluate the nutritional and physicochemical composition of teosinte flour for the first time. Using diverse techniques, teosinte flour was found to be a high-calorie food rich in total carbohydrates and mainly composed of starch, with an amylopectin:amylose ratio of 2:1 and a concentration of resistant starch greater than 50%. Its proteins were similar to other cereals in which the essential amino acids glutamic acid, leucine, and especially lysine were the most important. Some 75% of its total dietary fiber was insoluble. The fatty acid profile was characterized by a high unsaturated fatty acid content in which oleic acid (C18:1) and linoleic acid (C18:2) predominated. As for minerals, teosinte flour had higher iron content, lower sodium concentration, and similar zinc, calcium, and phosphorus content to other cereal flours. We highlight that teosinte flour has nutrients and qualities that convert it into flour with excellent nutritional abilities and health benefits; it is also a very good industrial and technological alternative to be mixed mainly with types of flour from other sources

ECOPHAGE: Combating Antimicrobial Resistance Using Bacteriophages for Eco-Sustainable Agriculture and Food Systems

The focus of this meeting was to discuss the suitability of using bacteriophages as alternative antimicrobials in the agrifood sector. Following a One Health approach, the workshop explored the possibilities of implementing phage application strategies in the agriculture, animal husbandry, aquaculture, and food production sectors. Therefore, the meeting had gathered phage researchers, representatives of the agrifood industry, and policymakers to debate the advantages and potential shortcomings of using bacteriophages as alternatives to traditional antimicrobials and chemical pesticides. Industry delegates showed the latest objectives and demands from consumers. Representatives of regulatory agencies (European Medicines Agency (EMA) and Spanish Agency of Medicines and Health Products (AEMPS)) presented an update of new regulatory aspects that will impact and support the approval and implementation of phage application strategies across the different sectors