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1.
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2.
Outbreak of luminescent disease was reported from Litopenaeus vannamei shrimp farms in Zhangpu County, Southern China during May–July 2011. The clinical signs included fluorescent, less food consumption and high mortality. Bacteria were isolated from the infected shrimps. The pathogen, a luminescent bacterium named VH1 was identified as Vibrio campbellii based on MLSA analysis (16S rDNA, rpoD and toxR). The haemolysin (hly) gene specific in V. campbellii was detected in strain VH1. Pathogenicity test using immersion infection confirmed that strain VH1 was virulent to L. vannamei postlarvae and juveniles, and the LC50 value was 1.55 × 106 CFU mL?1 and 1.7 × 106 CFU mL?1 respectively.  相似文献   

3.
The bioflocs technology (BFT) for shrimp production has been proposed as a sustainable practice capable of reducing environmental impacts and preventing pathogen introduction. The microbial community associated with BFT not only detoxifies nutrients, but also can improve feed utilization and animal growth. Biofloc system contains abundant number of bacteria of which cell wall consists of various components such as bacterial lipopolysaccharide, peptidoglycan and β‐1, 3‐glucans, and is known as stimulating nonspecific immune activity of shrimp. Bioflocs, therefore, are assumed to enhance shrimp immunity because they consume the bioflocs as additional food source. Although there are benefits for having an in situ microbial community in BFT systems, better understanding on these microorganisms, in particular molecular level, is needed. A fourteen‐day culture trial was conducted with postlarvae of Litopenaeus vannamei in the presence and absence of bioflocs. To determine mRNA expression levels of shrimp, we selected six genes (prophenoloxidase1, prophenoloxidase2, prophenoloxidase activation enzyme, serine proteinase1, masquerade‐like proteinase, and ras‐related nuclear protein) which are involved in a series of responses known as the prophenoloxidase (proPO) cascade, one of the major innate immune responses in crustaceans. Significant differences in shrimp survival and final body weights were found between the clear water and in the biofloc treatments. mRNA expression levels were significantly higher in the biofloc treatment than the clear water control. These results suggest that the presence of bioflocs in the culture medium gives positive effect on growth and immune‐related genes expression in L.vannamei postlarvae.  相似文献   

4.
This study aimed to evaluate the contribution of three diatom species on the lipid content of bioflocs, their permanence on the bioflocs and influence on the growth performance of juvenile shrimps. Juveniles of Litopenaeus vannamei were reared (30 days; three replicates per treatment) in biofloc systems inoculated with diatoms Amphora coffeaeformis (A), Cylindrotheca closterium (C), Conticribra weissflogii (W), or biofloc only (BF, chlorophycean rich). Water quality parameters were monitored daily and the microbiota on days 1, 10, 20 and 30. The lipid content and fatty acid profiles of bioflocs were analyzed at the end of the experiment. Shrimp survival rate (99%) at treatment A was significantly higher than at BF. The bioflocs in A treatment presented the highest lipid content, differing significantly from BF and W. The content of EPA (20:5) (n‐3) was significantly higher in A and lower in BF, while linoleic acid (18:2) (n‐6) was significantly higher in BF. The results indicate that high cell density of diatoms can be successfully maintained with silicate addition in biofloc systems and that the pennate A. coffeaeformis and the centric C. weissflogii are potentially better suited than the pennate C. closterium as food supplements for shrimp diets in biofloc nurseries system.  相似文献   

5.
In a 30‐day experiment, Farfantepenaeus brasiliensis PL25 (25 ± 10 mg; 17.9 ± 1.6 mm) were raised in nine circular floating cages with a stocking density of 1000 shrimp m?3. Three treatments were evaluated: (1) culture in BFT system plus a commercial feed supply (BFT+CF); (2) culture in BFT system without feed supply (BFT) and (3) culture in clear water with feed supply (control). Post‐larvae (PL) final weight (218.9, 236.5 and 176.0 mg, for BFT+CF, BFT and control respectively), final biomass (17.9, 15.7 and 8.2 g) and weight gain (193.9, 211.5 and 151.0 mg) were similar in the BFT regardless of whether they were fed a commercial diet (P>0.05), but were both significantly higher than the control (P<0.05). Survival (81.5%, 67.0% and 84.8% respectively) and final length did not differ between treatments (P>0.05). The biofloc analysis identified five main microorganism groups: protozoa (ciliate and flagellate), rotifers, cyanobacteria (filamentous and unicellular) and pennate diatoms. Free living bacteria and attached bacteria in bulk were 25.73 ± 8.63 and 0.86 ± 3.17 × 106 mL?1 respectively. Proximate analysis in the biofloc indicated high levels of crude protein (30.4%). Results confirmed favourable nutritional quality of biofloc, and enhanced growth and production of F. brasiliensis PL in biofloc systems.  相似文献   

6.
The experiment was conducted with three biofloc treatments and one control in triplicate in 500 L capacity indoor tanks. Biofloc tanks, filled with 350 L of water, were fed with sugarcane molasses (BFTS), tapioca flour (BFTT), wheat flour (BFTW) and clean water as control without biofloc and allowed to stand for 30 days. The postlarvae of Litopenaeus vannamei (Boone, 1931) with an Average body weight of 0.15 ± 0.02 g were stocked at the rate of 130 PL m?2 and cultured for a period of 60 days fed with pelleted feed at the rate of 1.5% of biomass. The total suspended solids (TSS) level was maintained at around 500 mg L?1 in BFT tanks. The addition of carbohydrate significantly reduced the total ammonia‐N (TAN), nitrite‐N and nitrate‐N in water and it significantly increased the total heterotrophic bacteria (THB) population in the biofloc treatments. There was a significant difference in the final average body weight (8.49 ± 0.09 g) in the wheat flour treatment (BFTW) than those treatment and control group of the shrimp. Survival of the shrimps was not affected by the treatments and ranged between 82.02% and 90.3%. The proximate and chemical composition of biofloc and proximate composition of the shrimp was significantly different between the biofloc treatments and control. Tintinids, ciliates, copepods, cyanobacteria and nematodes were identified in all the biofloc treatments, nematodes being the most dominant group of organisms in the biofloc. It could be concluded that the use of wheat flour (BFTW) effectively enhanced the biofloc production and contributed towards better water quality which resulted in higher production of shrimp.  相似文献   

7.
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8.
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9.
A 45‐day trial was performed to evaluate the effect of biofloc technology (BFT) with or without fresh food (FF) supplementation during pre‐maturation period on Farfantepenaeus duorarum spawning performance, biochemical composition and fatty acid profile of eggs as compared with conventional clear‐water system (CW+FF). Females raised in biofloc and that received FF supplementation (FLOC+FF) achieved better spawning performance in terms of number of eggs per spawn (49 × 103), number of eggs per spawn per g of spawner's body weight (2.1 × 103) and egg size (~275 μm) as compared with CW+FF (23 × 103, 1.1 × 103 and 263 μm respectively), but both treatments did not vary from FLOC (P > 0.05). High spawning activity was also observed in biofloc system as compared with clear‐water system as shown in number of spawns per ablated female (2.2–3.0 versus 0.6) and percentage of females that spawn at least once (80–82 versus 25%). Biochemical composition of eggs presented no significant differences among treatments. FA profile of eggs indicated that high spawning activity performed by females in FLOC+FF treatment was reflected in lower mean levels of EPA, DHA and sum of polyunsaturated fatty acids (n‐3) and (n‐6). The better reproductive performance demonstrated by females raised in biofloc justified the application of this technology in F. duorarum broodstock.  相似文献   

10.
A 60‐day indoor experiment was conducted to study the effect of dietary supplementation of biofloc on metabolic enzyme activities and immune responses in Penaeus monodon juveniles. Biofloc developed in indoor fibreglass‐reinforced plastic (FRP) tanks (1000 L) was used as dietary supplement in P. monodon (2.90 ± 0.10 g) reared in 1000‐L FRP tanks. Graded level of dried biofloc was included in shrimp basal diets, 0% (control, B0), 4% (B4), 8% (B8) and 12% (B12). The level of metabolic enzymes like malate dehydrogenase (MDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was not significantly different with control up to 8% dietary supplementation. A higher level of total haemocyte count (THC) was noticed in B8 (22.16 ± 2.17 × 106 cells mL?1) and B4 (21.11 ± 0.56 × 106 cells mL?1) compared with control, C (14.61 ± 2.74 × 106 cells mL?1). Biofloc‐supplemented groups recorded significantly higher (P < 0.05) serum SOD and catalase activity (P < 0.01) in comparison with control. The groups fed with 4% dietary biofloc supplement recorded highest relative percentage survival (RPS), 45% after challenge with Vibrio harveyi followed by 36% and 27% RPS in B8 and B12 groups. Based on these results, it can be concluded that supplementation of biofloc even at 4% level in the feed improves immune responses and metabolic activities in black tiger shrimp juveniles.  相似文献   

11.
This is the first study to isolate, identify and characterize Streptococcus iniae as the causative disease agent in two tilapia (Oreochromis aureus) populations. The populations were geographically isolated, of distinct origins, and did not share water sources. Affected fish showed various external (e.g., exophthalmia and cachexia, among others) and internal (e.g., granulomatous septicaemia and interstitial nephritis, among others) signs. All internal organ samples produced pure cultures, two of which (one from each farm, termed S‐1 and S‐2) were subjected to biochemical, PCR and 16S rRNA sequencing (99.5% similarity) analyses, confirming S. iniae identification. The two isolates presented genetic homogeneity regardless of technique (i.e., RAPD, REP‐PCR and ERIC‐PCR analyses). Pathogenic potentials were assessed through intraperitoneal injection challenges in rainbow trout (Oncorhynchus mykiss) and zebrafish (Danio rerio). Rainbow trout mortalities were respectively 40% and 70% at 104 and 106 CFU per fish with the S‐1 isolate, while 100% mortality rates were recorded in zebrafish at 102 and 104 CFU per fish with the S‐2 isolate. The obtained data clearly indicate a relationship between intensified aquaculture activities in Mexico and new disease appearances. Future studies should establish clinical significances for the tilapia industry.  相似文献   

12.
The objective of the study was to examine the effects of biofloc technology on the muscle proteome of Litopenaeus vannamei. Two biofloc treatments and one control were compared: biofloc‐based tanks under zero‐water exchange fed with 150 g/kg crude protein (BF15), or with 250 g/kg crude protein (BF25) diets, and clear water tanks with 50% of daily water exchange stocked with shrimp fed with similar amount of a 250 g/kg crude protein diet, referred to as control. The shrimp (5.28 ± 0.42 g) were divided into the 300‐L fibreglass tanks (water volume of 200 L) at a density of 35 shrimp per tank and were cultured for 35 days. The biofloc groups displayed better growth and survival compared to the control. The muscle tissue from the control and BF25 groups was subjected to proteomic analysis. Lactate dehydrogenase, enolase, arginine kinase, mitochondrial ATP synthase subunit alpha, mitochondrial ATPase inhibitor factor 1 precursor, serpin 3 and myeloid differentiation factor 88 had an increased abundance in the BF25 group, while myosin heavy chain type 1 and myosin heavy chain type 2 showed a decreased abundance. The results indicate that biofloc technology could alter the expression of proteins involved in structure, metabolism and immune status of cultured shrimp.  相似文献   

13.
This work compared the effects of different densities of Mugil curema integrated in the rearing of Litopenaeus vannamei in a biofloc system on the yield and ecological performance of the system. For that, an experiment lasting 55 days was conducted. Four groups were evaluated as follows: (a) T0: shrimp reared without mullet, (b) T10: shrimp reared with 22 fish per tank, (c) T20: shrimp reared with 43 fish per tank, and (d) T30: shrimp reared with 65 fish per tank, each treatment with four replicates. The sludge:biomass ratio was higher in the T0 treatment, while the T10–T20 treatments were more efficient, producing more biomass and less sludge. The use of water was 17% more efficient in all treatments with mullet. Mullet survival was higher in the T10 and T20 treatments (mean: 84 ± 8%) than in the T30 (61 ± 5%) treatment. The fish final biomass and yield limits of the system were 0.37 kg and 3.7 kg/m3 respectively. Finally, there was no increase in the total nitrogen output of the system up to the T10 density. In conclusion, it is possible to integrate mullet up to 3.7 kg/m3, increasing the yield in 20% and decreasing water use.  相似文献   

14.
Vibrio harveyi is a causative agent of the Vibriosis or luminescent bacterial disease in worldwide aquaculture industry. A reliable assay for identification of V. harveyi infection is important to prevent the bacterial spread. In this study, biotinylated loop‐mediated isothermal amplification (LAMP) amplicons were produced by a set of four designed primers that recognized specifically the V. harveyi vhhP2 gene, encoding a putative outer membrane protein with unknown function, followed by hybridization with an fluorescein isothiocyanate (FITC)‐labelled probe and lateral flow dipstick (LFD) detection. A novel set of PCR primer was also designed specifically to vhhP2 gene and appear to be a species‐specific tool for V. harveyi detection. The optimized time and temperature conditions for the LAMP assay were 90 min at 65°C. The LAMP‐LFD and PCR methods accurately identified 22 isolates of V. harveyi but did not detect 16 non‐harveyi Vibrio isolates, and 34 non‐Vibrio bacterial isolates. The sensitivity of LAMP‐LFD for V. harveyi detection in pure culture was 1.1 × 102 CFU mL?1 or equivalent to 0.6 CFU per reaction, while that of PCR was 6 CFU per reaction. For spiked shrimp sample, the sensitivity of LAMP was 1.8 × 103 CFU g?1 or equivalent to 5 CFU per reaction, while that of PCR was 50 CFU per reaction. In conclusion, the established LAMP‐LFD methods provided a valuable tool for rapid identification of V. harveyi and can be used to distinguish V. harveyi from V. campbellii.  相似文献   

15.
The bioflocs technology proved to be a sustainable technique used in zero‐water exchange shrimp culture systems. However, the pH and alkalinity may decrease due to the biofloc formation process and Nitrification. A 48‐day experiment was performed to investigate the effects of different pH (7.1–7.6; 7.6–8.1) conditions on water quality, the growth and the health status of shrimp in biofloc technology (BFT) through using sodium bicarbonate to adjust pH respectively. Two pH treatments and one control were compared: T0 — control, T1 — pH 7.6 — NaHCO3, T2 — pH 8.1 — NaHCO3, each treatment consisted of three replicate tanks (90 L water volume) and each replicate stocked with 30 shrimp (equivalent to 333 shrimp m?3). Significant physical, chemical and biological differences (P < 0.05) were detected among treatments. At the end of the experiment, water quality, the growth and the immune response of shrimp in control were significantly lower (P < 0.05) than the other treatments. Moreover, the T2 treatment had a better performance in these three aspects. The results indicated that it was necessary to adjust the pH and alkalinity in the BFT, and a higher pH as well as alkalinity for shrimp growth and the stability of the BFT were more favourable.  相似文献   

16.
Closed recirculating aquaculture systems (RAS) offer advantages over traditional culture methods including enhanced biosecurity, the possibility of indoor, inland culture of marine species year‐round and potential marketing opportunities for fresh, never‐frozen seafood. Questions still remain regarding what type of aquaculture system may be best suited for the closed‐system culture of marine shrimp. In this study, shrimp (Litopenaeus vannamei) were grown in clear‐water RAS and in biofloc‐based systems. Comparisons were made between the system types with respect to water quality, shrimp production and stable isotope dynamics used to determine the biofloc contribution to shrimp nutrition. Ammonia and nitrite concentrations were higher, and shrimp survival was lower in the biofloc systems. Although stable isotope levels indicated that biofloc material may have contributed 28% of the carbon and 59% of the nitrogen in shrimp tissues, this did not correspond with improved shrimp production. Overall, the water column microbial communities in biofloc systems may be more difficult to manage than clear‐water RAS which have external filters to control water quality. Biofloc does seem to offer some nutritional contributions, but exactly how to take advantage of that and ensure improved production remains unclear.  相似文献   

17.
In a Biofloc Technology System (BFT), there is constant biofloc formation and suspended solids accumulation, leading to effects on water quality parameters that may affect the growth performance of cultured shrimp. This study aimed to analyse during biofloc formation the effect of different total suspended solids (TSS) levels on water quality and the growth performance of Litopenaeus vannamei shrimp in a BFT system. A 42‐day trial was conducted with treatments of three ranges of TSS: 100–300 mg L?1 as low (TL), 300–600 as medium (TM) and 600–1000 as high (TH). The initial concentrations of 100 (TL), 300 (TM) and 600 mg L?1 (TH) were achieved by fertilization before starting the experiment. Litopenaeus  vannamei juveniles with an average weight of 4.54 ± 1.19 g were stocked at a density of 372 shrimp m?3. Physical and chemical water parameters and shrimp growth performance were analysed. After 6 weeks, TSS mean concentrations were 306.37, 532.43 and 745.2 mg L?1 for, respectively, TL, TM and TH treatments. Significant differences (P < 0.05) were observed in TSS, settleable solids, pH, alkalinity and nitrite, especially between the TL and TH treatments. Similarly, differences (P < 0.05) were observed in the growth performance parameters, specifically final weight, survival, feed conversion and productivity. The water quality parameters at lower range of total suspended solids concentration (TL) treatment resulted in a better performance of L. vannamei in the BFT system. The maintenance at range of 100–300 mg L?1 TSS is thus important to the success of shrimp culture.  相似文献   

18.
In the present study, the effects of Artemia supplemented with 2‐β‐mercapto‐ethanol (β‐ME) treated yeast cell, Saccharomyces cerevisiae, on growth and reproductive performance, lysozyme activity, and disease resistance to Aeromonas hydrophila of freshwater ornamental species, Poecilia latipinna, were investigated. Within 60 days, molly fish were fed with three treatments including commercial food (T1), un‐supplemented Artemia (T2), and Artemia supplemented with β‐ME‐treated yeast cell (at concentration of 4 × 107 CFU/L of water) (T3). After the feeding period, the fish were exposed to 100 μl of a suspension (1.1 × 107 cells/ml) of A. hydrophila (BCCM5/LMG3279) and the cumulative mortality rates were recorded for 12 days. No significant difference was found between survival rate and growth performance of P. latipinna except for weight gain that was higher in fish fed through Artemia supplemented with β‐ME‐treated yeast cell compared to control group. Fecundity rate was significantly improved in fish fed using T3 with the maximum amount of 49.5 ± 2.29 per female (p < 0.05). Besides, lysozyme activity was significantly increased in group 3 (p < 0.05). Moreover, lowest fish mortality was significantly observed in this treatment (p < 0.05). In addition, the number of colonies formed by yeast cell in T3 (634 × 103 CFU/g intestine) showed significant difference with other treatments (p < 0.05). In sum, Artemia enriched with β‐ME‐treated yeast improved reproductive indices, immune responses, and resistance against A. hydrophila of P. latipinna.  相似文献   

19.
Effect of different carbon sources on nursery performance of Pacific white shrimp (Litopenaeus vannamei) cultivated in biofloc system was investigated. Shrimp postlarvae (98.47 ± 8.6 mg) were fed for 32 days in tanks with water volume of 130 L and density of 1 individual L?1. One control treatment and four biofloc treatments (BFT1, BFT2, BFT3 and BFT4) with adding different carbon sources including molasses, starch, wheat flour and mixture of them, respectively, were considered at equal weight ratios. According to the results, salinity, dissolved oxygen and pH were not significantly different among the biofloc treatments (P > 0.05). Maximum pH (8.27) and maximum dissolved oxygen (6.35 mg L?1) were recorded in the control. Maximum (0.43 mg L?1) and minimum (0.09 mg L?1) ammonia were recorded in the control and BFT2, respectively (P < 0.05). Using simple carbohydrates (molasses and starch) lowered the ammonia concentration significantly. The highest increase in body weight (1640.43 ± 231.28 mg), growth rate, specific growth rate (8.97 ± 0.42% per day) and biomass (190.29 ± 26.83 mg) were found in BFT1 and the highest survival (90 ± 0.77%) was found in BFT4. The highest feed conversion (1.52 ± 0.23) and the lowest feed efficiency (66.81 ± 7.95) were observed in the control (P < 0.05). The proximate composition analysis revealed an increase in lipid and ash in biofloc treatments. Results indicated that using biofloc technology with zero‐water exchange system and adding carbon sources could help to recycle waste and improve the water quality. Moreover, the type of carbonaceous organic matter as a substrate for heterotrophic bacteria would be effective in degradation and metabolization of ammonia and nitrite.  相似文献   

20.
Shrimp farming is a fast‐expanding activity that has supported the growth in the supply of these crustaceans to consumers around the world. However, the end product is vulnerable to contamination at all stages of the process, including the rearing tanks, where current practices prioritize to raise stocking densities and the minimization of water renewal. It is thus important to evaluate the potential of these systems for the proliferation of undesirable microorganisms, which may render the product unfit for human consumption. In the present study, the presence of coagulase‐positive Staphylococcus, Salmonella spp., Vibrio spp., and total and thermotolerant coliforms was verified in biofloc tank and conventional pond systems used for the rearing of Litopenaeus vannamei in Pernambuco, Brazil, and the results were compared with the legislation regulating the marketing of fresh shrimp. Samples were collected from two biofloc tanks with a density of 375 shrimp m?2, and two conventional ponds with 12 shrimp m?2. None of the samples tested positive for either Salmonella spp. or coagulase‐positive Staphylococcus, which is consistent with the legislation. While no standards are defined legally for Vibrio spp. or coliforms, very low concentrations were recorded in both systems, in comparison with other studies. While some variation in bacterial contamination was observed over the rearing process, the end product of both systems was fit for human consumption. The results of the study indicate that, while the water is not renewed in the biofloc system, the development of undesirable microorganisms can be controlled, with no adverse effects for the end product.  相似文献   

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