Seaweed Protein Hydrolysates and Bioactive Peptides: Extraction,Purification, and Applications

Seaweeds are industrially exploited for obtaining pigments, polysaccharides, or phenolic compounds with application in diverse fields. Nevertheless, their rich composition in fiber, minerals, and proteins, has pointed them as a useful source of these components. Seaweed proteins are nutritionally valuable and include several specific enzymes, glycoproteins, cell wall-attached proteins, phycobiliproteins, lectins, or peptides. Extraction of seaweed proteins requires the application of disruptive methods due to the heterogeneous cell wall composition of each macroalgae group. Hence, non-protein molecules like phenolics or polysaccharides may also be co-extracted, affecting the extraction yield. Therefore, depending on the macroalgae and target protein characteristics, the sample pretreatment, extraction and purification techniques must be carefully chosen. Traditional methods like solid–liquid or enzyme-assisted extraction (SLE or EAE) have proven successful. However, alternative techniques as ultrasound- or microwave-assisted extraction (UAE or MAE) can be more efficient. To obtain protein hydrolysates, these proteins are subjected to hydrolyzation reactions, whether with proteases or physical or chemical treatments that disrupt the proteins native folding. These hydrolysates and derived peptides are accounted for bioactive properties, like antioxidant, anti-inflammatory, antimicrobial, or antihypertensive activities, which can be applied to different sectors. In this work, current methods and challenges for protein extraction and purification from seaweeds are addressed, focusing on their potential industrial applications in the food, cosmetic, and pharmaceutical industries.     

Incidental captures of sea turtles by swordfish and albacore longlines in the Ionian sea

ABSTRACT:   Incidental catches in pelagic longline fishing pose a serious threat to sea turtle populations throughout the world's seas and oceans. In this work, carried out in the framework of the EC-DG-Fisheries 98/008 project, information on sea turtle catch rates from swordfish and albacore longline fishing activities observed in Italian waters off the Ionian Sea during 1999 and 2000, are reported. In addition, biometric data, health status, and tagging return rate of sea turtles captured are provided. A total of 200 sea turtles were caught (198 loggerhead turtles and 2 green turtles), comprising 0.5–15.7% of the total catch in number of individuals. The estimates of the sea turtles caught by the total fishing effort of both longlines in the whole study area were 1084 specimens in 1999 (95% CI = 667–1502) and 4447 specimens in 2000 (95% CI = 3189–5705). Although all sea turtles were released alive, nearly half of them had hooks that could not be removed and remained deeply embedded in the digestive tract.     

Performance and food behaviour of Brycon orbignyanus larvae submitted under food restriction

This study was carried out to evaluate the effects of feed restriction on the performance and feeding behaviour of Brycon orbignyanus. Ten‐day larvae (72.84 ± 8.61 mg) were distributed in 36 aquariums (density of 15 larvae/L) in a completely randomized design consisting of six treatments and six replicates. The treatments were determined according to the number of feed restriction days: 0, 2, 4, 6, 8 and 10 days (F0, F2, F4, F6, F8 and F10, respectively), totalling 10 days. The results for final weight, weight gain and specific growth rate were significant (p < .05), and F2 and F0 presented the highest values among all experimental groups. The adopted feeding strategies did not influence final survival (p > .05), and no cannibalism behaviour was observed in any of the treatments. F2 and F0 treatments also displayed higher swimming speed (p < .05) among the assessed groups. The time spent searching for and capturing prey was significantly lower in the F0 treatment. Muscular atrophy for the F10 group was observed, and F2 animals presented no significant difference (p > .05) in muscle fibre diameter when compared to F0. Thus, dietary restrictions can be applied as a strategy for B. orbignyanus reared in intensive laboratory systems for 2 days without compromising performance, muscle growth and feeding behaviour.     

Ontogenetic variation of food intake and gut evacuation rate in larvae of the doncella Pseudoplatystoma punctifer,as measured using a non‐destructive method

Food intake (FI) and gut evacuation (Rg) were measured in larvae of Pseudoplatystoma punctifer (4.5–18.4 mm SL) fed Artemia nauplii, taking advantage of the translucence of their abdominal region to achieve this in a non‐destructive way, using digital photographs and mathematical reconstruction of gut volume content (ellipsoidal and cylindrical models for stomach and intestine respectively). The inaccuracy of the method, with reference to counts of nauplii following fish dissection, was low (2.9 ± 1.5%) and independent of fish size (P = 0.6153). Pigmentation hampered measurement in fish >18–19 mm SL. Anaesthesia was needed in fish >9.5 mm SL, thereby preventing the measurement of Rg in individual fish. The FI increased rapidly during the ontogeny, passing from <7% M at 0.6 mg, to 14% M at 1 mg and 21% M at 15–40 mg, and then decreased slightly in larger fish. At 28.5°C, Rg (% M h^?1) was modelled as Rg = ?8.22 + 12.11 log FI + 6.30 log M – 12.67 (log M)² (R² = 0.904, d.f. = 27, with FI in% M and M in mg). Extrapolations of Rg over 24 h gave estimates of daily food rations that fit well with those measured in cannibalistic P. punctifer.     

Organizational learning through participatory research: CIP and CARE in Peru

Participatory research (PR) has been analyzed and documented from different points of view, with emphasis on the benefits generated for farmers. The effect of PR on organizational learning has, however, received little attention. This paper analyzes the interaction between a research and a development institution, the International Potato Center (CIP) and CARE in Peru, respectively, and makes the case that PR can contribute to creating a collaborative learning environment among organizations. The paper describes the evolution of the inter-institutional collaborative environment between the two institutions for more than a decade, including an information-transfer period (1993–1996), an action-learning period (1997–2002), and a social-learning period (2003–2007). Several lessons learned from each period are described, as are changes in institutional contexts and stakeholders’ perceptions. The case shows that research and development-oriented organizations can interact fruitfully using PR as a mechanism to promote learning, flexibility in interactions, and innovation. Interactions foster the diffusion of information and the sharing of tacit knowledge within and between organizations, which in turn influences behavior. However, the paper also argues that long-term inter-organizational interactions are needed to facilitate learning, which can be used to influence the way organizations implement their interventions in a constantly changing environment.     

Probiotic bacteria may prevent haemorrhagic septicaemia by maturing intestinal host defences in Brazilian native surubins

The farming of hybrid surubins in Brazil has been affected by bacterial diseases. To avoid this problem, the development of prophylactics such as probiotics has proved to be a promising tool against bacterial outbreaks. This study evaluated the dietary supplementation with lactic acid bacterium Weissella cibaria and its probiotic action in the intestinal tract focusing the hemato‐immunological parameters, histology and electron microscopy. A total of 96 fish were maintained in a recirculation system and divided into 12 tanks, two treatments (supplemented and unsupplemented fish) and six replicates. Fish were fed supplemented commercial diet with W. cibaria for a period of 45 days, and the unsupplemented fish were with commercial feed without probiotic. The numbers of red blood cells, thrombocytes and lymphocytes were higher in supplemented fish after 45 days (P < 0.05). The percentage of phagocytosis, the agglutination titre and the total immunoglobulin concentration were higher in fish fed probiotic. Fish fed supplemented diet presented increased length and width of the intestinal villi, the number of goblet cells and villi's perimeter. The probiotic W. cibaria was capable of colonizing and benefitting the surubins' gastrointestinal tracts, improving intestinal health and the hemato‐immunological parameters of fish.     

Evaluation of carbohydrate/lipid ratios on growth and metabolic response in tropical gar (Atractosteus tropicus) juvenile

Five experimental diets with different carbohydrates/lipid ratio (CHO:L, 0.75, 1.28, 2.10, 2.52, 4.63) were formulated. Fish were randomly assigned by triplicate (10 fish per tank, 0.50 ± 0.01 g). Growth was registered every 15 days until end of the experiment (45 days). Samples were taken for analysis of chemical carcass composition, blood chemistry, glycogen and lipid liver content, digestive and metabolic enzyme activities. Results showed that survival, growth performance parameters and plasma glucose were not affected by treatments (p > 0.05). Lipids of carcass and liver, as well as triglycerides and plasma cholesterol increase significantly as CHO:L ratio decreased. While an inversely proportional tendency was observed for carcass protein and liver glycogen (p < 0.05). Digestive enzymes did not show significant differences among treatments (p > 0.05). Finally, Hexokinase (HK), glucokinase (GK), phosphoenol pyruvate carboxykinase (PEPCK) and fructose‐1,6‐biphosphase (FBPase) showed high regulation by carbohydrates up to the CHO:L ratio of 2.10 (p < 0.05), while pyruvate kinase (PK) activity was not significantly affected by the CHO:L ratio. By the other side, glucose‐6‐phosphate dehydrogenase (G6PD) tends to significantly increase as the CHO:L ratio increases. We conclude that A. tropicus fry have a high capacity to utilize carbohydrates substituting lipids as energy source in balanced diets.     

Total Mercury Bioaccumulation in Tissues of Carnivorous Fish (Micropogonias furnieri and Cynoscion acoupa) and Oysters (Crassostrea brasiliana) from Sepetiba Bay,Brazil

Total mercury (Hg) levels were determined by cold vapor atomic absorption spectrophotometry (CVAAS) in tissues of two species of carnivorous fishes and in the soft tissue of oysters caught in Sepetiba Bay, Brazil. Hg was distributed unevenly in the organs and tissues of the fish; the mean Hg content was highest in the kidneys (0.048 μg/g wet weight) and lowest in the gills (0.004 μg/g w.w.). Mean Hg levels were higher in the oysters (0.052 μg/g w.w.) than in the fish (0.022 μg/g w.w). The total Hg concentration did not exceed the maximum concentration for food allowed by Brazilian legislation in any of the fish and oyster samples analyzed. Moreover, the Hg concentrations observed were all within the maximum level for fish recommended by the Food and Agriculture Organization (FAO; 0.5 μg/g w.w.).     

Optimal Immobilization of Acidic Proteases from Monterey Sardine (Sardinops sagax caeurelea) on Partially Deacetylated Chitin from Shrimp Head Waste

ABSTRACT

Response surface methodology was employed to optimize the immobilization yield of acidic proteases from Monterey sardine (Sardinops sagax caeurelea) using partially deacetylated chitin as immobilization support. A rotatable central composite design was applied to evaluate the effects of immobilization conditions such as enzyme loading (X₁), immobilization pH (X₂), and tripolyphosphate concentration (X₃) on the immobilization yield. The analysis of variance revealed that the established model was significant (p < 0.05), and the adjustment of the quadratic model with the experimental data was satisfactory. Under optimal conditions (X₁ = 0.05 mg/mL, X₂ = 3.16, and X₃ = 0.75%), an immobilization yield of 79.1% was achieved; a value that was in accordance with the predicted one.