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Ensiling as one of the best methods for utilization of tuna wastes was investigated. docosahexaenoic acid [DHA C22:6(n-3)]- rich products were obtained from the wastes (viscera and dark meat) of four tuna species, namely longtail, skipjack, yellowfin and kawakawa by a procedure involving ensiling in organic acids followed by neutralization. Identification of fatty acids in the samples was performed by comparison with chromatograms of fatty acids standard.
Total lipid content of silages varied from 10.41% in skipjack dark meat silage to 22.01% in kawakawa viscera silage, but all lipids contained high percentages of DHA and EPA [eicosapanteoneic acid C20:5(n-3)]. The highest DHA ratio (15% of total lipids) was found in the lipid of skipjack viscera silage and the highest ratio of EPA (11% of total lipids) belonged to the lipids of kawakawa dark meat silage.
ANOVA test results indicated that DHA ratio was significantly high before silage preparation and linolenic acid [C18:3(n-3)] content significantly differed between the species (p<0.05).

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In the present study bacteriophages isolated from rainbow trout farms and sewage treatment plants were genetically identified and their effectiveness on Yersinia ruckeri isolates from clinical cases of red mouth disease was investigated.  Fish samples suspected to red mouth disease were collected from rainbow trout farms located in west Azerbaijan. Y. ruckeri, the causative agent of red mouth disease was initially identified using biochemical tests. The biotypes of all Y. ruckeri isolates were determined and their identity was confirmed by employing genus specific primers. Antimicrobial resistance of Y. ruckeri isolates were examined using common antibiotics in use in aquaculture. In order to isolating lytic bacteriophages, environmental samples mainly from rainbow trout farms and sewage treatment plants were collected in a period of six months. Isolated bacteriophages were titrated using two-layer agar method and their bactericidal effects were examined. For molecular characterization of bacteriophages, genomic DNA was extracted. Extracted genomic DNA from bacteriophages was digested using MspI endonuclease. The results revealed that 4.48% of examined fish were positive for Y. ruckeri.  Bacteriophages isolated from urban sewage treatment plants were effective on Y. ruckeri isolates. Maragheh and Urmia sewage treatment plants had the maximum and minimum phage titers, respectively. The genomic DNA of all isolated phages were smaller than genomic DNA of Lambda phage and all examined phages showed similar genomic DNA digestion patterns. It was concluded that sewage treatment plants could be an important source for phages effective on Y. ruckeri and maybe other aquaculture bacterial pathogens.  

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Growth and survival of Polychaete, Nereis diversicolor fed on waste water of great sturgeon, Huso huso at different densities were studied. The study aimed to assess the efficacy of feeding of N. diversicolor with waste water derived from different densities of great sturgeon culture as well as to find a balance between fish density and growth of the worm. The worms (0.2-0.3 kg m^-2) with an initial mean weight of 0.05 g were fed for 55 days with waste water of great sturgeon at densities of 2-3, 3-4 and 4-5 kg m^-2 fish. A group of worms fed with fish feed was considered as the control. The obtained results showed that the biomass and average weight of the harvested worms were significantly higher at the density of 3-4 kg m^-2 fish than in the other two treatments (p<0.05). Also, worms fed with fish feed (control group) showed higher survival rate and biomass production than the treatments. Some fatty acids were abundant in worms from the treatments, specifically 14:0, 16:0, C18:1n9c, 20:1, 22:1n-9, 18:3n-3, 20:2, 20:5n-3 (EPA) and 22:6n-3 (DHA), but were significantly lower than the control worms. The results demonstrate that production of N. diversicolor using fish waste water was highly efficient and can offer a sustainable solution to remove organic load in the aquaculture waste waters. Also, production of N. diversicolor via this method as an alternative source of fatty acids and protein for H. huso production could achieve multiple aims such as retention of valuable lipids from the H. huso waste water.

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This study was conducted to remove contaminations from fish farms effluents using iron oxide nanoparticles in a laboratory system. For this purpose, a 5-liter semi-industrial reactor has designed with a mixer blade, a porous plate, and a compressor. The results showed that the levels of nitrate, nitrite, phosphate, ammonium, TDS, TSS, and BOD were 2.78, 3.27, 0.43, 7.46, 2.25, 3.38 and 5.34 mg L^-1 at the entrance to the reactor, respectively. Also, pH and EC were 6.36 and 1362 µmho cm^-1. At the reactor outlet, the levels of nitrate, nitrite, phosphate, ammonium, TDS, TSS and BOD were 1.84, 2.09, 0.27, 3.05, 1.61, 1.78 and  4.96 mg L^-1. Furthermore, pH and EC were 7.22 and 1466 µmho cm^-1. Also, this study has been showed that the system efficiency from the beginning up to 6 hours has been increased, but it has been reduced at the 18^th hour, which has been caused by the sequestration and the formation of an oxide layer on nanoparticles. Therefore, it can be concluded that iron nanoparticles in the reactor fluid space have the potential to reduce the discharge burden of the effluent from fish farms.

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Fungal assist microalgal cultivation is getting substantial considerations due to the highly efficiency of bioflocculation process without demanded of using chemicals and little bit energy input. Therefore, Fungi pelletization-assisted microalgal cultivation were applied for improving algal harvesting process and nutrient recovery as step wise for wastewater treatment. Two strains of marine microalgae (Nannochloropsis salina and Chlorella salina) and three species of marine fungi (Penicillium chrysogenum, Aspergillus niger and Aspergillus fumigatus) were implied to investigate the effect of fungi-algae pelletization process on wastewater recovery. After 48 hour of cultivation, the highest flocculation efficiency (98.9%) was recorded by A. fumigatus assist C. salina, while the lowest percentage (85.9%) recorded by A. niger assist N. Salina. The highest nutrient removal percentage was for nitrite by A. niger assist C. salina /tap water (98.4%) followed by phosphate A. fumigates assist N. salina/sea and tap water (90.9%), then ammonia by A. fumigates assist N. salina/seawater (89.5%). The bioflocculation process is a promising for algal harvesting techniques and wastewater nutrient recovery.

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In this study, the effects of diets (D_1-3) including fish meal (FM), hazelnut meal (HM), soybean meal (SM), and phytase enzyme [- (0),+(1000 FTU)]  in varying rates (D_1-, D₁₊; D_2-, D₂₊; D_3-, D₃₊)  were examined on nitrogen and phosphorus discharge based on the nutrition of rainbow trout (Oncorhynchus mykiss) juveniles. The study was conducted in tanks with 3 replicates for each group. In this trial, it was found that the differences among total-particle nitrogen, particle phosphorus, and total solid waste values released from the rainbow trout groups were insignificant; however, the differences between the values of total-dissolved phosphorus and dissolved nitrogen released were found significant (p<0.05).The interactions among the factors were determined as insignificant (p>0.05). Moreover, although there were increases in the total and dissolved phosphorus and dissolved nitrogen discharge in all groups fed with diets including phytase, the particle phosphorus discharge decreased (p<0.05). Based on the decrease in the amounts of hazelnut meal and soybean meal used in the diets, it was determined that there was a decrease in the amount of dissolved phosphorus released to the environment; besides, it was determined that it led to an increase in the amount of released dissolved phosphorus in all groups fed with diets containing phytase enzyme (p<0.05).   

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The study aimed to evaluate and compare the nutrient cycling efficiencies of bacterial biofilms of a moving-bed filter and three aquatic plants (Lemna minor, Hygroryza aristata and Phyllanthus fluitans) as biological filters in recirculating aquaculture systems (RASs). The nutrient cycling capacities were tested in 12 independent RASs used for culturing common carp (Cyprinus carpio L.) in greenhouse conditions. The efficiencies were determined by comparing fish survival and growth performance, water quality parameters and removal rates of NH₄-N, NO₂-N, NO₃-N, PO₄³-P and TP among biofilters. All biofilter types were efficient in maintaining water quality parameters, removing nutrients and providing an acceptable environment for fish growth and survival. However, the bacterial biofilm filter had the highest removal efficiencies of NH₄-N and NO₂-N than those of the other filters; while H. aristata and L. minor filters had higher removal efficiencies of NO₃-N and PO₄³-P than those of P. fluitans and bacterial biofilm filters. The bacterial biofilm filter had a higher ability to deal with higher concentrations of NH₄-N and NO₂-N; whereas plant based filters were more effective in maintaining NO₃-N concentrations. Nutrient uptake capacities of selected plants differ and are strongly influenced by the growth rate of plants. The present study suggests that plant based filters in this filtration technique could be beneficial in removing nutrient overload in RASs, adding harvestable product and reducing the overall cost of RASs; whereas bacterial biofilm filter is a superior filter in maintaining ammonium and nitrite concentrations in RASs.
 

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Vibriosis is one of the major diseases which cause problems in the aquaculture industry. The disease is a bacterial infection responsible for the mortality of breeding shrimp around the world. This study aimed to isolate and identify V. alginolyticus contaminated shrimp samples in Bushehr city, Southwest Iran. Shrimp samples were collected from Persian Gulf waste water. Identification of bacterial isolates was performed by phenotypic and biochemical and molecular tests (PCR and sequencing) by using forward primer (5-GAGTTTGATCCTGGCTCAG-3) and reverese primer (5-ACGGGCGGTG+GTRC-3). Antibiotic susceptibility profile of isolates was detected. isolate of V. alginolyticus was detected with resistance to ampicillin, but susceptible to cefotaxime, ceftazidime, chloramphenicol, ciprofloxacin, gentamicin, and imipenem and tetracycline disks.  V. alginolyticus is participated in shrimp contamination which lead to food destroy and also human impairments. Key words: Vibrio alginolyticus, primer, Vibriosis, 16srRNA sequencing

 

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Nowadays, the need to simultaneously achieve the valorization and recovery of fishing waste is critical for addressing environmental challenges and promoting resource sustainability. Fishing waste hosts enzymes that hold the potential for extraction and utilization in various industries. In this sense, the aim of this work was to extract and purify enzymes from the gastrointestinal tract of Myliobatis goodei using low-cost processes. The proteolytic and lipolytic activities of the extracted enzymes were also investigated. In addition, the detergent compatibility of the purified enzyme extract was evaluated to determine its potential application as an additive in laundry soaps. The crude extract was obtained by homogenization of 100g gastrointestinal tract in buffer Tris-HCl (pH=8.0). Then, it was precipitated with ammonium sulfate and purified by filtration. Finally, it was subjected to centrifugation at 10,000 ×g for 30 min at 4°C in an ultrafilters membrane with a 100 kDa cut-off. This purification protocol showed good performance for proteases and lipases as their activity was recovered at each step. The proteolytic activity was assayed using azocasein as substrate at pH 8.0 and 40°C, while trypsin activity was analyzed against the specific substrate benzoyl-arginine-p-nitroanilide. The lipolytic activity was carried out by p-nitrophenol production through the reaction of p-nitrophenylacetate dissolved in 2-propanol at pH 7.0 and 37°C. The compatibility of the enzyme activity with some commercial detergents was evaluated. Additionally, proteolytic and lipolytic activities were tested on spiruline and soybean oil stains and showed a strong ability to remove them from cotton fabrics. Due to its promising properties, the purified enzymes isolated from the gastrointestinal tract of M. goodei may be considered as a potential effective active ingredient for its use in the detergents industry.

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A biological filter (biofilter) is a technique that aims to degrade nutrients that are wasted in water bodies by utilizing living organisms such as plants and shellfish. The study aims to determine the potential of duckweeds (Lemna minor)-freshwater mussel (Anodonta cygnea) integrated biofilters in utilizing nutrients from wastewater from rearing rainbow trout (Oncorhynchus mykiss) juveniles. This study used the initial weight of 25±2.0g of rainbow trout juveniles, freshwater mussels (A. cygnea) with an initial weight of 58±2.0 g, and duckweeds (L. minor) with two different biomass weights (treatment 1: 270 g and treatment 2: 360 g) were used in the flow-through system. The water temperature was around 13-14^oC during the experimental periods. Using duckweeds as a biofilter with two different stocking densities significantly affected (p<0.05) the pH, DO, nitrate, and total phosphorus values in the treatment tanks. This study's results also revealed that using duckweed-freshwater mussels integrated biofilters could minimize the concentration of ammonium and total phosphorus in wastewater from rainbow trout juvenile rearing tanks.

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Proteases are the most important industrial enzymes and widespread in nature. In the present work, sardine waste (viscera) was used to optimize the protease production by newly isolated Streptomyces sp. strain. A comparative study of proteolytic activity was first carried out on a synthetic medium, sardine waste broth (in submerged fermentation), and powder of the same waste (in solid-state fermentation). The enzyme production media were optimized according to statistical methods, while using two plans of experiences. The first corresponded to the Plackett-Burman matrices and the second was the Box-Wilson central composite design. The protease characteristics study showed an optimum temperature of 40°C and an optimum pH of 7, which is a typical characteristic of neutral proteases. The results of protease production optimization showed maximum activity on the following fermentation medium: sardine viscera broth (25%), NaCl (7.99 g/L), and gelatin (9.82 g/L). All these results confirmed the high biotechnological potential of this strain for neutral protease production on sardine viscera, which provides an interesting and promising strategy for large-scale enzyme production on fish waste