Robson Matheus Marreiro Gomes

The study analysed the effects of dietary resveratrol supplementation, either alone or in combination, with fumaric acid on the zootechnical performance and bioenergetics parameters of juvenile Litopenaeus vannamei. A dose–response trial was conducted with 0, 10, 60, 110, and 160 mg·kg⁻¹ of resveratrol. Subsequently, a second experiment was performed with shrimp from the control group and the best-performing resveratrol group. The treatments were control (C), fumaric acid 8.47 g·kg⁻¹ (F), resveratrol (R) and R + F (RF). Growth performance (final weight gain (g), specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER)) and the concentration of energy-yielding molecules evaluated. Shrimp fed with 60 mg·kg⁻¹ of resveratrol showed higher weight gain, SGR, protein and glucose concentrations in the muscle, increased PER, and lower FCR (ANOVA and Tukey HSD post hoc test (p < 0.05). Combined supplementation (RF) further enhanced growth performance and protein, glucose, and glycogen concentrations (p < 0.05) (ANCOVA test; p < 0.05). The zootechnical responses were also improved, where in 14 days the animals gained almost three grams of weight, with an FCR of 1.14 ± 0.03 and SGR of 6.99 ± 0.17% per day (p < 0.05). Overall, the combined supplementation of resveratrol and fumaric acid acted as an effective metabolic modulator, improving metabolic status of L. vannamei.

Silver nanoparticles (AgNPs) are known for their antimicrobial properties, and can be synthesized through various routes. We used both chemical synthesis and green synthesis from the biomass of black soldier larvae (Hermetia illucens). To test the antimicrobial potential of these nanoparticles, we employed an in vitro test, with CFU counting, and also used the worm Caenorhabditis elegans as an in vivo model. C. elegans were infected with Pseudomonas aeruginosa and treated with AgNPs from both syntheses. These AgNPs exhibited absorption spectrum peaks around 400 nm and sizes of 8 ± 3.5 (chemical) and 11 ± 4.7 nm (green). P. aeruginosa-infected worms, without treatment with AgNPs, achieved 100% mortality within 3 days, while AgNPs-treated worms survived until the end of the experiment, with no statistical differences compared to the non-infected worms of the control group. The results demonstrate that nanoparticles produced from H. illucens biomass have antimicrobial capacity, reducing bacterial growth in vitro and being able to protect C. elegans from infection by P. aeruginosa, similar to those produced by chemical synthesis. However, AgNPs from green synthesis are less harmful to the environment while maintaining their antimicrobial potential.

The present research aims to valorize biofloc waste by extracting polyphenols via alkaline hydrolysis, utilizing them as reducing and stabilizing agents in the optimization of green synthesis of silver nanoparticles (BIOAgNPs). For the alkaline extractions, potassium hydroxide (KOH) concentrations of 0 to 4 M were used in combination with ultrasound. Total polyphenol content and antioxidant activity were evaluated. BIOAgNPs synthesis was optimized using the response surface methodology and central composite design. The parameters time, temperature, AgNO₃ concentration, and the percentage of the biofloc extract (2 M KOH), with measurements taken for the area under the curve (AUC) (400–500 nm) and the mean hydrodynamic diameter (DLS), were evaluated. Antibacterial activity was determined for Gram-negative and Gram-positive bacteria. Higher polyphenol content and antioxidant activity were observed using 2 M KOH. The optimized model for DLS and the AUC was obtained in 4 h, at 40 °C, using 2.4 mM AgNO₃ and obtaining 2.5% of extract. Optimized BIOAgNPs had a diameter of 22.4 nm, hydrodynamic diameter of 106.5 nm, zeta potential of −28 mV, and polydispersity index of 0.26. BIOAgNPs demonstrated bactericidal activities. This study enhanced the valorization of aquaculture residues through improved polyphenol extraction techniques and developed an effective methodology for synthesizing silver nanoparticles with antimicrobial activity.

A 60-day feeding trial was conducted to evaluate the effects of including pumpkin seeds and pomace in the diets of Pacific white shrimp Penaeus vannamei, and the effects of these supplements on growth performance, body composition, and total polyphenol, flavonoid and carotenoid contents, as well as on total antioxidant activity, and body color parameters. Five diets were evaluated: pumpkin seeds (PS) at 50 and 100 g·kg⁻¹, pumpkin pomace (PP) at 50 and 100 g·kg⁻¹, and a control treatment. Pacific white shrimp (P. vannamei) juveniles (0.60 ± 0.01 g) were stocked in 15 tanks (310 L), containing 30 shrimps per tank, and the treatments were randomly distributed in triplicate. At the end of the experiment, shrimps were euthanized, weighed, and dissected for further analyses. The inclusion of PS in the diets impaired growth performance, reduced the total flavonoid content and had a pro-oxidative effect on muscle. The inclusion of PP in the diets did not affect growth performance, improved the feed conversion ratio, increased the total flavonoid content in the diets and hepatopancreas, and improved the antioxidant activity of the feeds and shrimp muscle. The total carotenoid content of the feeds increased with the inclusion of PS or PP in the diets; however, the total carotenoid content of shrimp increased only in those fed PP diets. Shrimp fed with PS diets showed a yellowish color and higher saturation when fresh and a reddish color and yellow hue angle after cooking. Shrimp fed PP diets turned reddish and yellowish, both when fresh and after cooking. The inclusion of PS in P. vannamei diets is not recommended; however, PP can be included at 100 g·kg⁻¹ without affecting the growth parameters. Further studies evaluating the inclusion of higher PP levels in shrimp diets are recommended.

The objective of this was to evaluate the ability of bioflocs to assimilate and transfer antioxidant compounds present in açaí Euterpe oleracea to juvenile Penaeus vannamei shrimp grown in a biofloc system. Juvenile shrimp were distributed into four treatment groups (control, 5, 20, and 80 mg açaí L⁻¹), containing 31 shrimps/tank (90 L), and cultivated for 30 days. Every 24 h throughout the experimental period, the respective açaí concentrations were added directly to the cultivation water. The bioflocs and hepatopancreas lost their antioxidant capacity with increasing concentrations of açaí; however, lipid damage was mitigated after treatment with 20 mg of açaí L⁻¹ (p < 0.05). The application of 20 mg açaí L⁻¹ increased the mean height and area of the middle intestinal microvilli (p < 0.05). Mortality and protein and lipid damage in shrimp muscle increased with daily administration of 80 mg açaí L⁻¹ (p < 0.05). It is concluded that the bioflocs were able to assimilate the antioxidants present in açaí and transfer them to the shrimp, and the administration of 20 mg açaí L⁻¹ presented the best performance, demonstrating the possibility of its application in the cultivation of P. vannamei in a biofloc system.

Lipoic acid (LA) is a mitochondrial coenzyme that, depending on the concentration and exposure time, can behave as an antioxidant or pro-oxidant agent and has a proven ability to modulate metabolism by promoting lipid and glucose oxidation for energy production. To assess the effects of LA on energy metabolism and redox balance over time, Artemia sp. nauplii was used as an animal model. The administered concentrations of the antioxidant were 0.05, 0.1, 0.5, 1.0, 5.0, and 10.0 µM. Therefore, possible differences in protein, triglyceride, glucose, and lactate concentrations in the artemia samples and total ammoniacal nitrogen (TAN) in the culture water were evaluated. We also measured the effects of LA on in vivo activity of the electron transport system (ETS), antioxidant capacity, and production of reactive oxygen species (ROS) at 6, 12, 18, and 24 h post-hatching. There was a decrease in glucose concentration in the LA-treated animals, and a decrease in ammonia production was observed in the 0.5 µM LA treatment. ETS activity was positively regulated by the addition of LA, with the most significant effects at concentrations of 5.0 and 10.0 µM at 12 and 24 h. For ETS activity, treatments with LA presented the highest values at 24 h, a period when ROS production decreased significantly, for the treatment with 10.0 µM. LA showed positive regulation of energy metabolism together with a decrease in ROS and TAN excretion.

The chemoprotection of "buriti” Mauritia flexuosa (inclusion in diet: 0-control group; 1.25; 2.50; 5.00; and 10.00% W/W) to Litopenaeus vannamei postlarvae (PL) exposed to ammonia or nitrite was investigated. Analyzed variables include antioxidant (ACAP) and oxidative damage (TBARS) responses and levels of total carotenoids. The results indicated that there was no significant difference (p >0.05) in zootechnical variables between diets. The PL carotenoid content (R2 = 0.86), ACAP (R2 = 0.78), and TBARS (R2 = 0.91) showed a dose-dependent relationship with the inclusion levels of "buriti” (p <0.05). After 43 days, juvenile shrimps were exposed for 96 h to ammonia (0.48 mg NH3-N L-1) or nitrite (40 mg NO3 L-1). Higher scavenging activity against peroxyl radicals was observed in PL fed with 2.50 and 5.00% of "buriti” (ammonia exposure), or 5.00 and 10.00% (nitrite exposure) of "buriti” inclusion. Content of reduced glutathione was higher in shrimps exposed to ammonia and fed with 10.00% of "buriti”. Lipid peroxidation levels were lower in shrimps exposed to ammonia or nitrite and previously fed with inclusion higher than 2.50% of "buriti”. The increased scavenging activity and lower lipid peroxidation in ammonia or nitrite-exposed organisms and previously supplemented with "buriti” point to a hormetic response that increases the resilience of L. vannamei to cope with nitrogenous compounds, pointing to the use of this fruit as a chemoprotectant agent.