Silver nanoparticles (AgNPs) were produced through an ethanol reduction approach enhanced by ultrasonic agitation to boost dispersion and reaction effectiveness. Tamarind seed polysaccharide (TSP), an eco-friendly and non-toxic polymer, served as the stabilizing agent. Optimal results were obtained using 0.01001 M AgNO3, 800 mg/L TSP at pH 7 or higher, with sonication for 60 min. The nanoparticles produced exhibited a distinctive surface plasmon resonance (SPR) peak within the range of 416-434 nm, validating their synthesis. The deep yellow hue of the colloidal solution suggested the effective reduction of Ag+ to metallic Ag-0. Increased TSP concentrations resulted in enhanced stability of nanoparticles, decreasing aggregation and aligning with earlier research. Antimicrobial assessment demonstrated significant effectiveness against Vibrio natriegens, presenting an average inhibition zone of 1.90 cm, over twice that of the positive control (amoxicillin, 0.90 +/- 0.10 cm, p < 0.05). The estimated minimum inhibitory concentration (MIC) is 1.3 & times; 10(-3) M. This reinforces current evidence regarding the antibacterial properties of AgNPs, probably caused by the disruption of cell membranes and the generation of reactive oxygen species. UV-vis analysis revealed consistent findings, with statistically significant variations in absorbance at the 95% confidence level, emphasizing the method's reliability.
Vibriosis, a bacterial disease, is considered a significant threat to the sustainability and economic viability of shrimp production. The present study evaluated the application of a predatory bacterium to control the population growth of pathogenic Vibrios in Pacific whiteleg shrimp (Penaeus vannamei). The predatory bacterium was identified as Bacteriovorax sp. OP175948.1 based on the 16S rRNA sequence. The Vibrio-inhibitory activity of Bacteriovorax sp. was evaluated using two independent trials with P. vannamei, exposed to two pathogenic Vibrios, including Vibrio parahaemolyticus and Vibrio harveyi. Each trial was conducted in five treatments, including a negative control, a positive control, and a treatment with Bacteriovorax sp. applied at 102, 104, and 106 plaque-forming units mL-1 (PFU mL-1). Results indicated that shrimp infected with V. parahaemolyticus and V. harveyi, and then treated with Bacteriovorax, showed a 6-fold increase in survival for V. parahaemolyticus and a 3-fold increase for V. harveyi, relative to the control. The shrimp treated with 104 to 106 Bacteriovorax sp. improved survival associated with a significant decline in Vibrio spp. counts in the shrimp tissues and rearing water. The Bacteriovorax sp. should be used as a practical strategy to prevent Vibrio-associated mortalities in P. vannamei aquaculture.
Tuna fish solubles (TFS) is a liquid by-product generated from the production of fish meal using tuna processing wastes. In this study, the physico-chemical composition and functional properties of TFS were determined. Proximate analysis showed that it is composed of 41.7 % moisture, 66.0 % protein, 20.1 % ash, and 7.3 % lipid. TFS possessed antioxidant properties as revealed by its radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) at half maximal inhibitory concentrations (IC50) of 4.17 mg·ml-1 and 2.1 mg·ml-1, respectively, and reducing power (6.17–50.40 mmol·kg-1 expressed as ascorbic acid). Its protein solubility in pH 2 to 12 ranged from 38.6 % to 64.4 %. It also exhibited foaming expansion of 5.1 % to 7.7 %, foaming stability of 4.7 % to 7.1 % and an emulsion activity of 1283.09 m2·kg-1 to 1398.58 m2·kg-1. Furthermore, liquid chromatography-mass spectrometry (LC-MS) analysis detected ions whose accurate masses match metabolite classes including alkaloids, glycosides, peptides, and terpenoids, though these require confirmation by further analysis. The findings indicate the potential of TFS as a source of antioxidant compounds and functional ingredients for industrial applications. Recovering valuable products from tuna wastes can promote a more sustainable aquatic food industry.
The Philippines contributes significantly to marine plastic pollution, yet little is known about microplastics (MPs) in its many estuaries. This study was the first to examine how many MPs are present, where they are located, and what types are present in Brgy. Baybay Sur, Miagao, Iloilo. Surface water samples were collected from three sampling sites: sample site 1 (SP1), sample site 2 (SP2), and sample site 3 (SP3) along the estuary, then separated, and MPs were isolated. Visualization of MPs was performed using a microscope and Nile Red Dye, which makes the MPs glow under UV light. The number of MPs ranged from 11 ± 6.02 to 20 ± 13.8 particles per liter. Water movement allows MP deposition near the mouth of the estuary. The morphology of MPs was dominated by fibers (72–85%), suggesting sources such as wastewater and fishing gear. Fragments (15–28%) were also found in the area. The Nile red test showed that the majority of the plastics present were polyester (blue) and polyethylene (yellow). Results showed that the method works well for most plastics (recovering 90.9–100%), but the dye did not work equally for all kinds. These results show that this estuary acts as a collection point for MPs from both land and sea activities. This study sets a starting point for future research and shows that Nile Red can be used to monitor MPs, but it also highlights the need for further testing to accurately identify plastic types in tropical estuaries.
