Amany M. Diab

The purpose of this research was to determine whether or not supplementing a diet with ethanolic roselle calyces extract (ER) had any effect on the rate of growth, intestinal morphometry, total carotene in skin and muscle, blood profile, immunity status, and the expression response of red tilapia. The ER was added to four experimental diets at 0% (0 g kg⁻¹), 0.5% (5 g kg⁻¹), 1% (10 g kg⁻¹), and 2% (20 g kg⁻¹), which were designated as ER0 (control group), ER0.5, ER1, and ER2, respectively. The results show that ER1 induced higher weights (final weight, weight gain, specific growth rate, and weight gain rate) and all ER groups had considerably (p < 0.05) decreased feed conversion rates (FCR) compared with the control diet. Histomorphometric examination of the intestinal villi absorptive capacity showed fish given ER, specifically ER1, had increased villus length, width, and goblet cells (p < 0.05). The best hematological and biochemical parameters (the antioxidant enzyme activity of superoxide dismutase and catalase, lysozyme activity, and WBCs count) were observed for 5 g kg⁻¹ ER. In addition, diets supplemented with different levels of ER stimulated phagocytic activity (p < 0.05). Additionally, the highest total carotene content in skin and muscle was observed in ER0.5. The 0.5, 1, and 2% roselle extract diets induced upregulation of IGF-1, GHr, SOD, TNF-α, and LPL, whereas MSTN, HSP 70, and FAS were downregulated. In conclusion, dietary ER supplementations are advantageous for red tilapia because they improve immunological and growth-related parameters.

Astaxanthin (AX) is one of the commonly used feed supplements to enhance the growth performance and provide antioxidant and immune functions of several aquatic animals. In the current study, juveniles of white-leg shrimp (Litopenaeus vannamei) with mean initial weight of 0.340 ± 0.041 g were fed with diets supplemented with 0 (control), 25, 50, 100, and 200 mg/kg feed for 8 weeks. At the end of the feeding trial, shrimps were exposed to Vibrio harveyi, and their mortality rates were observed for additional 10 days. The growth indices in the AX-fed groups were significantly (P < 0.05) higher than what were observed in shrimps in the control group. Dietary AX stimulated the final weight, weight gain, and specific growth rate and optimum growth levels were achieved at 100–200 mg AX/kg feed. Furthermore, the AX-enriched diets significantly enhanced feed intake more than the control diet, and the amount of AX had no effects on feed conversion ratios. In comparison to the control group, the AX-fed animals had significantly (P < 0.05) higher villi length, villi width, and absorption area and their optimum values were observed at 100–200 mg AX/kg feed treatments. Moreover, the intestinal morphometry especially villi and its crypt, both internal and external tunica muscularis, and submucosal tissues did not show any inflammatory and/or degenerative changes in AX-fed shrimp. Furthermore, the dietary AX at escalating levels linearly and quadratically enhanced (P < 0.05) the activities of serum superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and increased levels of total antioxidant capacity and reduced glutathione. In addition, malondialdehyde levels decreased significantly in AX-fed animals, and the highest levels were observed in the control group (without AX). The expression levels of cMn-SOD, CAT, and GPx genes were significantly upregulated in the hepatopancreas of L. vannamei fed with AX-enriched diets (especially in the 200-mg/kg feed treatment) as compared with the control diet. The immunity indices of the AX treatments (hematocyte count, total protein, lysozyme, phagocytic activity, and phenoloxidase) of L. vannamei were linearly (P < 0.05) and quadratically (P < 0.05) increased. This study revealed the antibacterial activity of AX against V. harveyi abundance. After the bacterial challenge, feeding L. vannamei with dietary AX significantly increased (P < 0.05) the relative percentage of survival, especially in the treatment of 200-mg/kg diet (82.7%). The findings of the current study demonstrate that dietary AX (100–200 mg/kg feed) was effective in enhancing the growth, antioxidant status, immune response, and increasing the resistance of L. vannamei against V. harveyi infection.

Zinc is an essential element for metabolism of Nile tilapia (Oreochromis niloticus). Nanomaterials have important benefits in aquaculture. The present study evaluated the effects of green-synthesized zinc oxide nanoparticles (ZnO-NPs) using Ulva fasciata extract as an anti-fungal agent against Candida albicans (C. albicans) in vitro and in vivo in O. niloticus. A total of 252 apparent healthy O. niloticus (20 ± 0.457 g/fish) were randomly allocated into six groups: The 1^st group fed on basal diet contaminated with C. albicans 15 × l0⁶ CFU/g diet, the 2^nd group fed basal diet only, the 3^rd and 5^th groups fed the basal diet supplemented with 40 or 60 mg/kg ZnO-NPs, respectively, and the 4^th and 6^th groups fed the basal diet contaminated with C. albicans 15 × l0⁶ CFU/g and concomitantly supplemented with 40 or 60 mg/kg ZnO-NPs, respectively. The experiment lasted for 8 weeks. The phyco-synthesized ZnO-NPs were characterized by XRD, UV-V, FTIR, TEM, and zeta potential. The anti-fungal activities of ZnO-NPs and the morphological changes to C. albicans cell due to ZnO-NPs were detected. The results revealed that dietary supplementation with the green-synthesized ZnO-NPs significantly improved the growth performance, survival, serum lysozyme activity, phagocytic activity, phagocytic index, respiratory burst activity, expression of immune-related genes (IL-1β, TGF, TNF-α), digestive enzyme activity, and histopathological finding in C. albicans-infected group, with a relative superiority to 40 mg/kg feed ZnO-NPs. It could be concluded that supplementing diets with 40 mg/kg of phyco-synthesized ZnO-NPs could be considered a better choice for controlling candidiasis in Nile tilapia.

Fish-borne zoonotic bacteria can endanger the health of human and aquatic organisms; the nanobiotechnology applications can help. Curcumin nanoparticles (NC) were synthesized using gum Arabic (GA) and the resulted NC was innovatively employed for mediating selenium nanoparticles (NSe), then each compound/composite was evaluated as candidates for inhibiting fish-borne pathogens ( Aeromonas hydrophila , Escherichia coli , Salmonella typhimurium , and Staphylococcus aureus ). The nanomaterials’ characterizations revealed the successfulness of their synthesis and conjugation. Promisingly, the NSe had particles’ diameter in the range of 2.4–15.8 nm and mean diameter of 6.1 nm, whereas the NC/NSe particles’ diameter was in the range of 15.4–92.3 nm and their mean diameter was 50.7 nm. The antibacterial activity of biosynthesized NC, NSe, and NC/NSe was validated quantitatively/qualitatively toward all examined bacteria; their powers were sorted as NC < NSe < NC/NSe. A. hydrophila was the most sensitive strain and S. aureus was the most resistant. The scan image of A. hydrophila cells exposed to NC/NSe indicated the high capability of nanocomposite to distort bacterial cells and lead them to death within 10 h of exposure. The biosynthesized NC, NSe, and NC/NSe are substantially advocated as natural biocides for controlling fish-borne zoonotic pathogens.

Bioactive nanocomposites were constructed, containing chitosan (Cht), extracted from shrimps wastes, and transformed into nanoparticles (NPs) using ionic-gelation. Selenium NPs (Se-NPs) were phytosynthesized using cinnamon (Cinnamomum zeylanicum) bark extract (CIE), characterized and evaluated with Cht-NPs as antimicrobial composites against bacterial food-borne pathogens Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes and as potential edible coating (EC) basements. The CIE-phytosynthesized Se-NPs had well-distributed and spherical shapes with 23.2nm mean diameter. The CIE, CIE/Se-NPs, and innovative CIE/Se/Cht-NP composites exhibited distinguished antibacterial actions toward the entire screened pathogens; CIE/Se/Cht-NP composite was significantly the most potent. The formulated ECs from CIE/Se/Cht-NP nanocomposites had matching antibacterial manner, which was strengthened with CIE/Se-NP percentage increments. Scanning micrographs indicated the attachment of CIE/Se-NPs to bacterial cells to cause their complete lysis and death after 10h of exposure. CIE/Se/Cht-NP composites are proposed as effectual control agents toward food-borne pathogens using efficient biological carriers and eco-friendly phytosynthesis protocol.

Zinc oxide nanoparticles (ZnONPs) were the targets of numerous biological syntheses to attain their precious values in various biomedical fields. The phycosynthesis of ZnONPs were innovatively investigated using cell-free extract of the macroalgae, Ulva fasciata Delile. The phycosynthesized U. fasciata-zinc oxide nanoparticles (UFD-ZnONPs) had 77.81 nm mean size, with flower and sphere shapes and positive zeta potential. The UFD-ZnONPs infra-red analysis indicated their basic components’ cross-linkage. The antibacterial potentialities of UFD-ZnONPs were confirmed, qualitatively and quantitatively, against foodborne microorganisms (Escherichia coli plus Staphylococcus aureus); the bactericidal action was higher for UFD-ZnONPs than the annealed phycosynthesized ZnONPs. The scanning micrographs of S. aureus and E. coli cells treated with UFD-ZnONPs indicated the severe action of nanoparticles to destroy bacterial cells in time-dependent manners. Peeled shrimps (Fenneropenaeus indicus) were biopreservated through refrigerated storage (4 °C) with UFD-ZnONPs based solution for six days. The microbial examination of UFD-ZnONPs -treated shrimps displayed decrease in microbial loads throughout the storage days. Moreover, the UFD-ZnONPs-treated shrimps showed acceptable sensorial attributes (appearance, odor, color and texture) compared to untreated shrimps. UFD-ZnONPs nanocomposite concentration of 3% and 5% could be remarkably suggested as efficient procedure for shrimps’ biopreservation during refrigerated storage regarding sensorial quality and microbial profile of product.

The biopreservation, flavoring, and coloration of foodstuffs, e.g., seafoods, with natural plant derivatives are major demands for consumers and overseers. Different colored plant parts, i.e., Hibiscus sabdariffa calyces, Curcuma longa rhizomes, and Rhus coriaria fruits, were extracted and evaluated as biopreservatives, antimicrobial and colorant agents for fish surimi from Oreochromis niloticus. All colorant plant extracts (CPEs) exhibited strong antibacterial activities against screened pathogens, Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Pseudomonas aeruginosa. H. sabdariffa extract (HCE) was the most effectual antimicrobial CPEs. S. aureus was the most sensitive strain to CPEs, whereas S. typhimurium and P. aeruginosa were the most resistant strains. The exterior coloration of tilapia surimi with CPEs resulted in great bacterial count reduction in colored products; stored CPEs-colored surimi had enhanced sensorial attributes. HCE-exposed S. aureus indicated bacterial cell lyses in time-dependent manner. CPEs application as colorants and antibacterial and quality enhancing agents is recommended for seafoods biopreservation.

Shrimps are highly valuable and perishable foodstuff that could be rapidly spoiled. Chitosan (Cht) was extracted and transformed into nanoparticles (NPs) via ionic gelation and fortified with cloves (Syzygium aromaticum) buds extract (CLE) for usage as antimicrobial composites against food-borne bacterial pathogens (Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus) and as edible coating (EC) for shrimp (Fenneropenaeus indicus) biopreservation throughout refrigerated storage. The synthesized CLE/Cht-NPs were electrostatically cross-linked and appeared with spherical shapes and homogenized distribution, with 159.4nm mean size diameter and positive charge of 17.4mV. The entire agents (Cht-NPs, CLE, and CLE/Cht-NPs) exhibited remarkable antibacterial activities toward all food-borne pathogens; CLE/Cht-NPs were significantly the most forceful. The scanning micrographs of treated S. typhimurium with CLE/Cht-NPs displayed NPs ability to attach and destroy bacterial cells. The ECs-treated shrimps exhibited sharp decrease in microbial groups load (aerobic microorganisms, E. coli, Enterobacteriaceae, and staphylococci) during refrigerated storage (41C) for 10 days. Additionally, the sensorial attributes (appearance, odor, color, and texture) of EC-treated samples preserved their elevated qualities for storage duration. The most effective EC blend contained 1.5 from Cht/NPs and 1.0 from CLE. The CLE/Cht-NPs could be impressively recommended as effectual natural composites for shrimps biopreservation during cold storage.