https://japb.guilan.ac.ir/ Aquatic Physiology and Biotechnology en daily 1 Sun, 09 Nov 2025 00:00:00 +0330 Sun, 09 Nov 2025 00:00:00 +0330 https://japb.guilan.ac.ir/article_9190.html Common carp (Cyprinus carpio) is one of the most important warm water cultured fish species in the world. In Development of an sustainable aquaculture system requires year-round fry and fingerlings production of fish. Common carp in tropical and subtropical areas reach maturity at a young age and low weight. In this study, out-of-season common carp fingerligs were used compared to the conventional culture method. 4 ponds of 2 hectares were selected for cultivation.Common carp fingerlings from spring and off-season (autumn) reproductions were used for stocking in the rearing system with conventional density. The beginning of culture period in off-season and spring propagation was done in April and June, respectively. In this study, common carp fingerlings were cultured together with silver carp, big head carp, and rohu species. 6850 fingerling fish were stocked in two hectares. The composition of common carp, silver carp, big head carp, and rohu in off-season carp was 32, 23, 5, and 40%, respectively, with the initial weight of common carp in off-season breeding and spring breedingwas 20 and 6 grams, respectively. Sinking pellet food for common carp with a protein percentage of 26% was used to feed with twice a day. Water parameters were measured during the rearing period. Nutrition and growth parameters including specific growth ratio (SGR), food conversion ratio (FCR), weight gain percentage (WG), survival percentage (SVR), daily growth rate (FI), protein efficiency ratio (PER) were investigated, as well as economic indicators including economic conversion factor and profit index (P) calculated. The results showed that the growth and nutrition indicators did not show significant differences during the culture period. The food conversion rate in off-season carp was lower than the normal culture of spring breeding carp. Economic coefficient and profit index in off-season breeding compared to Spring carp showed a significant difference (P<0.05). The rearing period in common carp outside the season was shorter and they reached the desired weight in September, while in spring breeding carp, the breeding period was longer and they reached market weight at the end of autumn. The obtained results showed that the use of common carp in the off-season can contribute to increasing production and shortening the culture period. https://japb.guilan.ac.ir/article_9232.html In the marine environment, microorganisms colonize all surfaces, including various marine organisms such as macroalgae. These microorganisms associated with marine macroalgae represent a significant source of biologically active metabolites. Biofouling remains a persistent problem in the marine sector, necessitating effective control and cleaning strategies. The search for antifouling bacteria is essential to controlling biofouling, particularly given the environmental pollution associated with the use of toxic chemicals. In this study, four symbiotic bacteria were isolated and purified from Enteromorpha flexuosa macroalgae collected from the Oman Sea. Molecular identification of these bacteria, based on 16S rRNA gene sequence analysis, identified them as Bacillus zhangzhouensis strain Chabahar 1, Virgibacillus dokdonensis strain Chabahar 2, Micrococcus endophyticus strain Chabahar 3, and Bacillus subtilis strain Chabahar 4. These sequences were deposited in GenBank under the accession numbers OL472895, OL514166, OL514165, and OL514183, respectively. A phylogenetic tree was constructed to illustrate the kinship relationships among these bacteria. Ethanol extracts were prepared from these bacteria and screened for activity using the well diffusion method. However, these extracts did not exhibit any growth inhibitory effect. https://japb.guilan.ac.ir/article_9330.html In this research, the probiotic effects of Lactobacillus corvatus bacteria isolated from fish ponds were investigated for histopathological studies. For this purpose, white fish fry with an approximate weight of 8.05 ± 1.58 grams were randomly divided into six groups. The control group, the group with only Lactobacillus curvatus (10 8 Cfu/g), the group exposed to lead (12 mg), the group exposed to cadmium (4 mg), the group + Lactobacillus corvatus (10 8 Cfu/g with lead) and the cadmium group + Lactobacillus curvatus (10 8 Cfu/g with cadmium). Each treatment was done in three replicates. After adapting to the environmental conditions for 14 days, the treatments were kept for 56 days. After the mentioned period, the anesthetized fishes, the intestines and livers of the fishes were isolated, stored in Boen's solution and transferred to a specialized laboratory for histopathology tests. The results of microscopic tests showed that in the treatment containing lead and cadmium, hyperemia (low), the presence of blood cells in the lamina propria (lp), necrosis of enterocyte cells and microvilli and cell vacuoles were observed in the intestines of juvenile fish. Histopathological examination of liver tissue showed hyperemia and bleeding (high), cell necrosis (high) and cell vacuolation (low). After examining the liver and intestinal tissues of fishes exposed to heavy metals lead and cadmium compared to the treatments containing probiotics, the amount of tissue repair was observed in the treatment containing probiotics. Therefore, according to the results, a favorable effect on the liver tissue was observed at this stage. https://japb.guilan.ac.ir/article_9541.html Phycobiliproteins, a class of natural bioactive compounds derived from various organisms such as red algae and cyanobacteria, have gained significant attention due to their diverse biological activities. This study investigated the structures of two pigments, phycocyanin and phycoerythrin, their optical spectral characteristics, ability to scavenge free radicals, exert antioxidant and antimicrobial properties. These pigments were extracted from Spirulina platensis and Gracilaria gracilis. The extraction process involved freeze-thaw cycles followed by ammonium sulfate precipitation and dialysis for partial purification. Spectroscopic analysis revealed maximum absorption for phycocyanin at 620nm and for phycoerythrin at 495 and 545nm. The SDS-PAGE band pattern confirmed the presence of α and β subunits (18–20kDa) and the γ subunit (31kDa). FTIR spectra also indicated the presence of biological functional groups, including amide I at 1644cm-1 and tetrapyrrole structures. The DPPH assay confirmed the antioxidant activity of both pigments. The free radical scavenging percentages were reported as 59% for phycoerythrin and 42% for phycocyanin. The disc diffusion assay demonstrated that both pigments possessed antimicrobial effects against Staphylococcus aureus and Escherichia coli. The highest activity against the Gram-positive bacterium, S. aureus, was observed with phycoerythrin, while phycocyanin showed the highest inhibitory effect against the Gram-negative bacterium, E. coli. These results demonstrate the high potential of these pigments for pharmaceutical, industrial and food applications. https://japb.guilan.ac.ir/article_9684.html In this study, density, growth and cellular morphology in green algae Scenedesmus quadricauda (Chlorophyceae) population were investigated at pH of 6, 6.5, 7, and 8 in the experimental conditions. The experiment was carried out as completely randomized design (CRD) for a 21-day period. Results showed that increment of population density of S. qaudricauda cultured on pH levels of 7 and 8 were higher than pH levels of 6 and 6.5 during experiment. The highest cellular density (442.7×103 cell/mL), maximum specific growth rate (0.098 /day) and minimum population doubling time (7 days) were obtained at pH 8. Cellular morphology (based on cells per colony) of S. quadricauda population was considerably changed during experiment. At pH of 6 and 6.5 dominated by only 1 cell/colony while the cell composition at pH of 7 and 8 were tendency to more than 1 cell/colony. The findings of this experiment also showed that the percentage of four-cell colonies in the population grown at pH 8 was higher than at other pH levels. Overall, the response of S. quadricauda to increased pH resulted in a decrease in the number of single-cell individuals and an increase in the formation of multicellular colonies (mainly four-cell colonies). https://japb.guilan.ac.ir/article_9685.html This study was conducted to screen water and sediments bacterial flora of silver carp broodstock including Bacillus subtilis, Escherichia coli, Corynebacterium ammoniagenes, Staphylococcus aureus, Pseudomonas aeruginosa, Micrococcus luteus, Aeromonas hydrophila, and Unidentified as probiotics. Antibacterial activities were conducted by using disc diffusion, well diffusion and cross streak methods under the influence of different pH, salt, temperature and time duration. The 96h effectiveness of a suspension of three probiotic candidate species and the pathogenic bacterium A. hydrophila was investigated on the mortality rate of silver carp larvae with different concentrations of candidate bacteria (105 and 107 cells/mL) and a control without bacteria in a flask (1L). Also, effectiveness of selected bacteria was investigated on the water quality and survival rate of silver carp fry in the treatment and control groups during 28 days. The three probiotics candidates Bacillus, Corynebacterium and Micrococcus were shown to have antibacterial activity against pathogenic bacteria. The optimal growth and antibacterial bio-components production of selected B. subtilis with inhibitory and lethal effectiveness characteristics against A. hydrophila were found at pH 8 and temperature 30 and 37°C. There were significant differences between treatments and control groups in larva mortality rates during 96h exposure to different concentrations of candidate bacteria (P<0.05). There were significant differences in water quality and growth indices between treatments and control groups during 28 days exposure to selected B. subtilis in aquaria (P<0.05). From this, we can conclude that the candidate B. subtilis can be used to improve water quality and growth of silver carp culture. https://japb.guilan.ac.ir/article_9442.html This study aimed to investigate the effects of feeding zebrafish (Danio rerio) larvae with Artemia nauplii enriched with different levels of prebiotic Prodi 450, containing mannan-oligosaccharide and β-glucan, on growth performance and innate immune parameters. The experiment was conducted in two phases, including Artemia nauplii enrichment and zebrafish larval feeding for 14 days. Artemia nauplii were enriched with four levels of prebiotic including zero (P0), 50 (P50), 100 (P100), and 200 (P200) mg L⁻¹. Larvae with an initial mean weight of 46.08 ± 0.58 mg were reared under controlled conditions. Growth parameters including weight gain, body weight increase, specific growth rate, daily growth rate, feed efficiency, and survival rate were measured, and innate immune parameters including total protein, total immunoglobulin, and alkaline phosphatase activity were evaluated. The results showed that feeding larvae with prebiotic-enriched Artemia nauplii had no significant effect on final weight or survival rate (p>0.05); however, weight gain, daily growth rate, and feed efficiency in the P200 group were significantly higher than in P50 (p<0.05), although not significantly different from the other treatments (p>0.05). Specific growth rate and body weight increase were significantly higher in P0 and P200 compared to P50 (p<0.05), while innate immune parameters showed no significant differences among treatments (p>0.05). These findings suggest that prebiotics may enhance larval growth performance, possibly through regulation of gut microbiota and improving nutrient absorption, even within a short feeding period, whereas their effects on immune indices remain limited at the larval stage. Partial retention of prebiotics within Artemia tissues, as well as enrichment dose and duration, may influence final bioavailability. The nonlinear growth response may reflect complex metabolic and microbial interactions, suggesting the need for further research in this field. https://japb.guilan.ac.ir/article_9707.html In the past decade, there has been a significant increase in the resistance of pathogenic bacteria to antibacterial agents, which has direct consequences on human pathogenicity and mortality. This study aimed to comparatively examine the antibacterial effects of the aqueous extract of a premix of brown macroalgae (Sargassum ilicifolium, Nizimuddinia zanardini, Cystoseira indica, and Padina australis) and antibiotics (oxytetracycline, cephalexin, erythromycin, and nitrofurantoin) against pathogenic bacteria (Vibrio parahemolyticus, V. harveyi, V. alginolyticus, and Acute hepatopancreatic necrosis disease (AHPND+) and the probiotic bacterium Lactobacillus plantarum in marine aquaculture. After sampling and transferring the samples to the laboratory, the brown macroalgae samples (S. ilicifolium, N. zanardini, C. indica, and P. australis) were washed, dried, mixed in equal proportions (1:1:1:1), and ground. An aqueous solvent was used for extraction. To investigate the antibacterial effect of the aqueous extract of the macroalgae premix on 4 species of gram-negative bacteria (V. parahemolyticus, V. harveyi, V. alginolyticus, and AHPND+) and the probiotic bacterium L. plantarum, the agar disk diffusion test was employed. The results showed that the aqueous extract of the brown macroalgae premix had an inhibitory effect on the growth of gram-negative bacteria (V. parahemolyticus, V. harveyi, V. alginolyticus, and AHPND+). Among the mentioned gram-negative bacteria, the inhibitory effect of the aqueous extract of the brown macroalgae premix on the growth of V. parahemolyticus, V. harveyi, and AHPND+ bacteria was significantly greater than on V. alginolyticus (P > 0.05). The extract of the brown macroalgae premix showed no inhibitory effect on the growth of the Gram-positive bacterium L. plantarum, and no zone of inhibition was observed. However, the bacterium V. alginolyticus exhibited greater sensitivity to the brown macroalgae premix extract, with a zone of inhibition measuring 8.43 ± 0.06 mm, compared to cephalexin, which showed no zone of inhibition (P > 0.05). Overall, although according to the results, the antibacterial property of the aqueous extract of the brown macroalgae premix studied was found to be lower than that of standard antibiotics, the brown macroalgae premix extract can be introduced as a potential source of new natural antimicrobial compounds and, given their abundance, can be utilized for pharmaceutical applications and dietary supplements. https://japb.guilan.ac.ir/article_9735.html این مطالعه با هدف بررسی اثر آب مغناطیسی‌شده بر زنده‌مانی، رشد، الگوی متیلاسیون DNA و بیان ژن‌های مرتبط با متیلاسیون و رشد در مراحل تخم چشم‌زده و لارو ماهی قزل‌آلای رنگین‌کمان (Oncorhynchus mykiss) انجام شد. برای این منظور، تخم‌های چشم‌زده در معرض چهار تیمار شامل شاهد، آب مغناطیسی‌شده با شدت‌های 2/0، 5/0 و 2/1 تسلا قرار گرفتند. تغییرات الگوی متیلاسیون DNA با استفاده از تکنیک MSAP و بیان نسبی ژن‌های dnmt1 و gh1 با روش Real-time PCR ارزیابی شد. نتایج نشان داد که تیمارهای مختلف آب مغناطیسی موجب تغییرات معنی‌دار در الگوهای متیلاسیون DNA شدند. در مرحله تخم چشم‌زده، تیمار 5/0 تسلا بیشترین میزان متیلاسیون کل و متیلاسیون کامل را نشان داد، در حالی که در تیمار 2/1 تسلا افزایش جایگاه‌های غیرمتیله و شبه‌متیله مشاهده شد. در مرحله لاروی نیز تفاوت‌های معنی‌داری در توزیع انواع متیلاسیون بین تیمارها مشاهده گردید. نتایج بیان ژن نشان داد که بیان dnmt1 و gh1 در شدت‌های بالاتر میدان مغناطیسی افزایش یافت، به‌طوری‌که بیشترین میزان بیان dnmt1 در تیمار 2/1 تسلا در مرحله لاروی و بیشترین بیان gh1 در تیمار 5/0 تسلا در مرحله تخم چشم‌زده ثبت شد. تحلیل مؤلفه‌های اصلی (PCA) نیز جدایش مشخص تیمارها را بر اساس الگوهای متیلاسیون تأیید کرد. به‌طور کلی، نتایج این مطالعه نشان داد که آب مغناطیسی‌شده می‌تواند از طریق تغییر در الگوهای اپی‌ژنتیکی و تنظیم بیان ژن‌های مرتبط با رشد، بر فرایندهای زیستی اولیه در قزل‌آلای رنگین‌کمان اثرگذار باشد و به‌عنوان یک ابزار مدیریتی بالقوه در آبزی‌پروری مورد توجه قرار گیرد.