Relationships between quality parameters and content of glycerol galactoside and porphyra-334 in dried laver nori <Emphasis Type="Italic">Porphyra yezoensis</Emphasis>

ABSTRACT:   Glycerol galactoside (GG; floridoside + isofloridoside) and porphyra-334 (P-334) are contained in nori (Susabinori Porphyra yezoensis and Asakusanori Porphyra tenera ). Glycerol galactoside has been found to have bifidogenic growth stimulator activity and P-334 is known to have ultraviolet-absorbing activity in the UVA region of sunlight. These substances have, respectively, potential for application to pre-biotic foods and in cosmetics as a sunscreen. In the present study, to investigate the relationships between GG and P-334 contents and the quality of nori, we measured the GG and P-334 contents with other components (total protein, chlorophyll-a, β-carotene and phycobillins) that are related to the quality of nori samples produced from different production areas and with different qualities. We found that the GG content was closely negatively correlated with the contents of other components, whereas P-334 was positively correlated with the other components. From these results, it is suggested that low-quality nori is a potential source of GG, and as a source for P-334, scraps of nori produced during nori processing should be suitable.     

中草药对大菱鲆源哈维氏弧菌的体外抑菌效果

为了解中草药对大菱鲆源哈维氏弧菌的体外抑菌效果,采用琼脂扩散法和二倍稀释法测定了哈维氏弧菌菌株对18种中草药的敏感性。结果显示:五倍子、石榴皮、大黄、乌梅和苏木的抑菌作用最强,最小抑菌浓度(MIC)12.5 mg/m L;黄连、马齿苋、鱼腥草、穿心莲、公丁香和桉树叶的抑菌作用次之,MIC为12.5~25mg/m L;沙棘、黄柏、辣蓼、甘草和薄荷抑菌效果较好,最小抑菌浓度(MIC)为100~500 mg/m L;而陈皮、石菖蒲的抑菌作用不明显,MIC均大于500 mg/m L。结果表明,18种中草药中五倍子、石榴皮、大黄、乌梅和苏木对大菱鲆源哈维氏弧菌有较好的抑菌效果,可为防治大菱鲆哈维氏弧菌病中草药制剂的开发提供参考。     

一株能抑制罗非鱼源无乳链球菌的反硝化芽孢杆菌的筛选鉴定

从尼罗罗非鱼(Oreochromis niloticus)肠道内容物中分离筛选出具有反硝化能力并拮抗无乳链球菌(Streptococcus agalactiae)的芽孢杆菌好氧菌株,并对其中拮抗性最强的1株芽孢杆菌进行形态学、生理生化特性、16S rRNA基因序列鉴定,进一步研究其最适生长条件、水解淀粉和蛋白的能力,并进行菌株药物敏感试验及安全性检测。经鉴定,筛选出的菌株(命名为NY 5)为蜡样芽孢杆菌(Bacillus cereus)。在反硝化性能检测培养基中接种1%的NY5菌液后,对50 mg/L的亚硝酸盐氮12 h去除效率达到100%;对本实验室保存的21株不同来源的无乳链球菌均有拮抗作用,平均抑菌圈直径为(26.67±3.00)mm。NY 5在温度为25~40℃、盐度为0~40、pH为5~9的环境中生长较好。同时NY 5还具有水解酪蛋白和淀粉的功能。NY 5菌株对多数抗生素敏感,对少数检测抗生素(青霉素G、麦迪霉素、头孢唑啉等)耐药。在水体中NY5菌液浓度为2.0×10~7 CFU/mL,以及在注射200μL2.0×10~6 CFU/mL浓度NY 5菌液的条件下,体重为(6.0±1.1)g的罗非鱼均未出现死亡及其他异常现象。综合上述结果,证明筛选出的NY 5菌株为蜡样芽孢杆菌。     

Genetic characterization of a spontaneous green-type pigmentation mutant of Porphyra yezoensis and the significance of using heterozygous conchocelis in nori farming

ABSTRACT: In order to characterize the spontaneous green-type pigmentation mutant of Porphyra yezoensis , growth and contents of photosynthetic pigments were compared with those of the wild type in gametophytic blades. The growth of the green mutant was slower than that of the wild type. The content of phycoerythrin was markedly lower in the green mutant than in the wild type. For genetic analysis, the green mutant was crossed with the wild type. In the cross, the heterozygous conchocelis (the wild-type color) produced many sectored F ₁ gametophytic blades, which were composed of both parental colors. The segregation ratio by counting the wild-type sectors and the green-type sectors of the F ₁ blades was approximately 1 : 1. This suggests that the green mutant is governed by a single recessive gene. All the monospore germlings from the sectored F ₁ gametophytic blades that originated from the heterozygous conchocelis developed into single-colored blades with either the green color or the wild-type color. The advantages of using heterozygous conchocelis (hybrid conchocelis) and monospores from F ₁ gametophytic blades that originated from the heterozygous conchocelis in commercial farming of Porphyra yezoensis are detailed and discussed.     

Biolog GN法对不同地区养殖对虾弧菌区系的比较研究

采用Biolog细菌鉴定技术,分析来自5个国家的4个对虾养殖品种苗期及部分养成期虾体上的185株弧菌(其中24株来自成虾).结果表明:来源、种类不同的养殖对虾苗期的主要弧菌的区系组成相似,溶藻弧菌(Vibrio alginolyticus)和鲨鱼弧菌(V. carchariae)(即哈维氏弧菌V. harveyi)是普遍存在的种类,同一种对虾在不同地区养殖,其区系组成略有差异;哈维氏弧菌多为对虾苗期致病菌,副溶血弧菌(V.parahaemolyticus)主要为成虾致病菌;在健康虾苗和发病虾苗体内都可分离到溶藻弧菌.     

Serotyping of Vibrio anguillarum isolated from diseased freshwater fish in Japan

Abstract. During the period from 1965 to 1980, 263 Vibrio anguillarum strains from ayu, Plecoglossiis altivelis (Temminck & Schlegel), two from rainbow trout. Salmo gairdneri Richardson, and two from eel, Anguilla japonica (Temminck & Schlegel), were collected from fish suffering from vibriosis in various parts of Japan. On the basis of cross-agglutination and cross-absorption tests with thermostable (O) antigens, six distinct serotypes (A, B, C, D, E and F) were established among 12 selected strains of V. anguillarum . 241 strains isolated from ayu and two strains from rainbow trout belonged to serotype A, six strains from ayu and one strain from eel to serotype B, 12 strains from ayu to serotype C, three strains from ayu to serotype D, one strain from ayu to serotype E, and one strain from eel to serotype F. V. anguillarum strains belonging to serotypes D, E and F have not been detected from ayu, rainbow trout and eel since 1973; these serotypes appear to be minor types. V. anguillarum strain NCMB 6 and 1669 belong to our serotype A and V. anguillarum 813 to our serotype C.     

Evaluation of potential probiotics isolated from saline tilapia in shrimp aquaculture

Integration of tilapia to shrimp culture is currently being practiced to minimize the growth of pathogenic luminous bacteria. The microorganisms that are associated in tilapia may contribute to the inhibition of the growth of Vibrio harveyi through the production of secondary metabolites. In this study, two Bacillus strains (MJA1.1, MJA2.1) isolated from mucus of tilapia were evaluated for their possible application in shrimp culture. The inhibitory property of these isolates against V. harveyi was determined in vitro using co-culture assay in a liquid medium. Also qualitative extracellular enzyme assay was conducted to assess whether the bacterial isolates produce extracellular enzymes. Furthermore, the potential use of these isolates as shrimp feed additive was tested. Thereafter, shrimps were exposed to lethal dose of ammonia (140 mg l^?1) to test the effects of the isolates in vivo. The results showed that in vitro co-culture assay after 72 h caused a significant decline in the population of V. harveyi in treatments with potential probiotic isolates. Both isolates showed protease, amylase, and cellulase activities. Although no significant difference was observed in growth, survival was significantly higher in shrimp fed with diets added with either of the isolates. The shrimp exposed to lethal dose of ammonia demonstrated better survival when supplemented with the probionts compared to the control group. Thus, the efficiency of the isolates in inhibiting V. harveyi population and the improvement of survival and resistance of cultured shrimp to ammonia stress indicate their potential as probionts for shrimp culture.     

Stimulation of glycerol kinase in grass carp preadipocytes by EPA

This study was conducted to assess the effect of eicosapentaenoic acid (EPA) on grass carp preadipocyte glycerol kinase (GyK) expression, as well as to explore the mechanism. Here, we cloned partial sequence of grass carp GyK gene and analyzed its tissue distribution. The result showed that GyK gene expressed most in the liver, followed by adipose tissue and the kidney. Besides, 400 μM oleic acid (18:1n-9, OA) was used to establish a hypertrophic preadipocyte model. GyK gene expression and enzyme activity were significantly enhanced after model cells were treated with 100 μM eicosapentaenoic acid (20:5n-3, EPA) for 6, 12, and 24 h. Meanwhile, peroxisome proliferative-activated receptor (PPAR)γ, adipose triglyceride lipase (ATGL), and the two isoforms of grass carp HSL gene were first identified by Sun et al (2016), and they defined the two isoforms as HSLa and HSLb. Therefore, maybe HSLa and HSLb are appropriate.. The content of triglyceride was dramatically increased by EPA treatment for 24 h. Further, a competitive ATGL antagonist, HY-15859, attenuated the increase in GyK induced by EPA at 12 h. Surprisingly, the enhanced lipolysis and PPARγ gene expression induced by serum deprivation were paralleled by an increase in GyK gene expression, whereas a stabilization in GyK enzyme activity. Other fatty acids, including docosahexaenoic acid, alpha-linolenic acid, linoleic acid, and OA also promoted GyK gene expression. Moreover, an irreversible PPARγ antagonist, GW9662, was used to investigate the role of PPARγ in GyK induction. Data showed that GW9662 abolished the induction of GyK by EPA at 12 h. Together, these data suggested that EPA elevated grass carp preadipocytes GyK expression. ATGL and PPARγ contributed to the induction of GyK. PPARγ may be a key regulator in response to GyK expression induced by EPA.     

In vitro survival and the effect of water chemistry and oxidative chemical treatments on isolated gill amoebae from AGD-affected Atlantic salmon

Amoebic gill disease (AGD) of cultured salmonids in Tasmania is caused by the amphizoic parasitic amoeba Neoparamoeba pemaquidensis. The freshwater tolerance of amoebae isolated from the gills of AGD-affected salmon (predominantly N. pemaquidensis) was tested in vitro using a trypan blue exclusion assay. Amoebae exposed to water containing high concentrations of Ca²⁺ or Mg²⁺ (200 mg l⁻¹) showed high levels of survival up to 3 h of exposure. Exposure to water containing elevated Na⁺, choline chloride or water at different pH all had no significant survival of amoebae. Exposure of amoebae to different concentrations of chlorine dioxide, chloramine-T or hydrogen peroxide in artificially hard water demonstrated that chloramine-T and hydrogen peroxide were the most efficacious at killing amoebae in vitro. This work suggests that the hardness of freshwater may be an important factor for the survival of marine amoebae (predominantly N. pemaquidensis) on the gills of AGD-affected salmon and have significant implications with regard to the efficacy of freshwater bathing practices for the control of AGD on farms. Additionally, chloramine-T and hydrogen peroxide appear to be efficacious at killing marine gill amoebae in vitro and may be useful for the control of AGD in farmed Atlantic salmon.     

Characteristics of marine vibrios isolated from fish farm tanks

Twenty-five cultures of organisms (grouped into presumptive V. parahaemolyticus and V. alginolyticus strains) isolated from tank water used to farm marine fish were subjected to a series of preliminary tests for the identification of V. parahaemoliticus. None were positively identified as this organism. Consequently the isolates, following their characterization as Gram-negative, motile, oxidase-positive rods which were fermentative without the production of gas, together with ten named Vibrio spp., were subjected to various tests and the results were subjected to computer analysis.They were sorted into clusters and it was found that both the presumptive V. parahaemolyticus and V. alginolyticus groups were largely homogeneous. The analysis also showed that the presumptive V. parahaemolyticus strains and one presumptive V. alginolyticus strain were best classified as V. parahaemolyticus and that all but one of the presumptive V. alginolyticus strains would have been best classified as V. anguillarum. The named V. alginolyticus strains proved to be a heterogeneous group and were not closely related to any other group of organisms. The significance of the occurrence of Vibrio spp. in tank water used to farm marine fish, especially when this water is heated power station effluent, is discussed.     

Malachite-green-removing properties of a bacterial strain isolated from fish ponds in Thailand

Malachite green (MG) has been focused on as a biotreatment target and its biological properties have also been an issue in food fish aquaculture. An MG-removing bacterium was isolated from aquaculture fish pond sediment samples in Thailand. The isolate, strain T-5-2, is a Gram-negative, aerobic rod-shaped bacterium, and has been identified as a member of the Pseudomonas putida group. Proton nuclear magnetic resonance spectroscopy (¹H-NMR) analysis of a broth culture medium containing MG showed that the concentration of MG decreased markedly and that other molecules, including leucomalachite green (LMG), were generated. Moreover, liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis showed that the MG concentration in the broth culture medium continuously decreased. This analysis also demonstrated that the concentration of LMG initially increased and then gradually decreased. Furthermore, gas chromatography–mass spectrometry (GC–MS) analysis showed 4-(dimethylamino)benzophenone (4DABP) as a degradation component of MG, which was confirmed by ¹H-NMR and LC–MS/MS analysis. These findings suggest that this bacterial strain can remove MG in broth culture and degrade it to certain metabolites, including LMG and 4DABP. This study is the first detailed evaluation by the combination of LC–MS/MS, GC–MS, and ¹H-NMR analyses of an MG-removing bacterium isolated from Thai aquaculture fish ponds.     

Genetic and phenotypic comparison of Nocardia seriolae isolated from fish in Japan

The phenotypic and genetic characterizations of 58 isolates of the fish pathogen Nocardia seriolae , from amberjack, Seriolae dumerili , yellowtail, Seriola quinqueradiata , Japanese flounder, Paralichthys olivaceus , and chub mackerel, Scomber japonicus, in Japan from 1970–2005, were examined to investigate the epidemiological relationship between isolates. The phenotypic and genetic characterizations were determined by α-glucosidase activity and biased sinusoidal field gel electrophoresis (BSFGE) analysis, respectively. There was no α-glucosidase activity in strains isolated from 2000–05 ( n  = 50) with a few exceptions ( n  = 3), while all strains isolated from 1970–90 ( n  = 8) were positive. In BSFGE analysis, digestions with restriction enzymes Xba  I and Ase  I produced 15 and 16 restriction patterns, respectively. All restriction patterns obtained from 50 strains isolated during 2000–05 were unrelated to those obtained from eight strains isolated during 1970–90, with the exception of two strains isolated during recent outbreaks. Based on the phenotypic and genetic characterizations, recent outbreaks of nocardiosis in Japan are suggested to be epidemiologically unrelated to earlier outbreaks in Japan. Although a low genetic relationship was observed in the restriction pattern between recent and earlier isolates, identity was confirmed between these groups of isolates because five representative strains showed 99.9% homology with N. seriolae ATCC43993^T in the 16S rRNA sequence.     

Preparation and characterization of fermented seaweed sauce manufactured from low-quality nori (dried and fresh fronds of <Emphasis Type="Italic">Pyropia yezoensis</Emphasis>)

The present study tested processes to manufacture fermented sauce from low-quality nori (dried and fresh fronds of Pyropia yezoensis). The nori sauce was prepared using three tanks with fresh or dried nori cultured in different conditions. In the present study enzymes were not added for the promotion of the degradation of nori, while in a previous study they were. The supernatants of culture mashes obtained from the three tanks were combined, and this low-quality nori sauce (LNS) was characterized and compared with sauces manufactured from high-quality nori, soy, and fish. The LNS showed low concentrations of total nitrogen compounds (0.20 g/100 ml) and free amino acids, and its taste showed a high sourness score as evaluated by a taste-sensing system. On the other hand, the LNS was rich in polysaccharides, which were observed to be readily degraded to lower molecular weight size sugars by heat treatment. The LNS showed little risk for heavy metal or allergen contamination. The obtained sauce product is expected to be commercially utilized as a component of low allergen-risk sauce products after blending with other seasonings without wheat or soy elements.     

Prebiotic,probiotic, and synbiotic in the diet of Nile tilapia post-larvae during the sex reversal phase

This study evaluated the use of the prebiotic Active-MOS® (mannanoligosaccharides—Biorigin®) and two probiotics: PAS-TR® (Bacillus subtilis and Bacillus cereus var. toyoi—Imeve®) and Bioplus 2BC® (1.6 × 10¹⁰ UFC g^?1 de Bacillus subtilis and 1.6 × 10¹⁰ UFC g^?1 Bacillus licheniformis—Christian Hansen®) tested separately and together, in the diet of Nile tilapia post-larvae during the sex reversal phase. The experiment was conducted in two stages: (i) a total of 2160 3-day-old post-larvae (PL) (10.39 ± 0.85 mm and 12.28 ± 3.15 mg) were used and distributed in 24 tanks of 40 L each (3.0 PL L^?1). Growth performance, chemical analysis of carcass, bacterial recovery, and histomorphometry of intestinal villi were evaluated; (ii) 240 tilapia (4.28 ± 0.19 cm and 1.19 ± 0.09 g) from the previous experiment were used and stocked at 10 PL per aquarium. The parameters evaluated were survival and relative protection level after bacterial challenge against Aeromonas hydrophila. Six treatments with four replications in a completely randomized design were used for both experimental stages. Additives in the diet of tilapia post-larvae did not determine significant differences in growth, survival, microbiological, or histomorphometric parameters in this study. Nevertheless, after the experimental infection, advantages on the use of the additives were observed in terms of higher relative protection levels (38.10%) and relative percent survival in fish receiving Active-MOS® + Bioplus 2BC®. Therefore, we recommend the use of synbiotic (Active-MOS® + Bioplus 2BC®) in the farming of Nile tilapia PL with recurrent outbreaks of bacterial diseases during the sex reversal phase.     

Arachidonic acid metabolism in gill homogenate and isolated gill cells from rainbow trout,Oncorhynchus mykiss: the effect of osmolality,electrolytes and prolactin

An assay method based on thin layer chromatography to study the arachidonic acid (AA) metabolism in gill tissues was optimized and the effect of osmotically different incubation mediums on AA metabolism was evaluated. Rainbow trout gill tissues metabolize AA into PGE₂ in highest concentration followed by PGD₂, PGF₂ and 6-keto-PGF₁ (the stable metabolite of PGI₂) among the prostanoids tested. Approximately 40% of PGE₂ is synthesized within the first minute of incubation and is directly dependent on the substrate concentration (AA). As in mammalian tissues, PGE₂ synthesis in fish gills is inhibited by the cyclooxygenase inhibitor indomethacin. PGE₂ synthesis in gill homogenate and isolated gill cells incubated in trout Ringer was 0.45 and 1.9 ng/mg protein, respectively, and increased to 8.9 and 4.3 ng/mg protein, respectively, when incubated in KPO₄ buffer, due to a ten-fold increase in the free AA. The hydroxy acid synthesis of the gill homogenate was higher (13%), and that of the isolated gill cells incubated in KPO₄ buffer was lower (44%) compared to gill homogenate and cells incubated in trout Ringer. Gill homogenate incubated in 50 mM phosphate buffer with increasing sodium or potassium concentrations (up to 250 mM) exhibited a concentration-dependent increase in PGE₂ synthesis (220% and 72%, respectively). Prolactin stimulated the PGE₂ synthesis up to 30% while PGD₂, PGF₂ and 6-keto-PGF₁ synthesis was not affected. This effect of prolactin was maximal when PGE₂ synthesis was estimated 30 minutes after prolactin addition and diminished after two hours. These results suggest that rainbow trout gills possess the ability to metabolize AA through the cyclooxygenase and lipoxygenase pathways. PGE₂ synthesis may be under the influence of ion balance and prolactin availability, indicating the probable involvement of AA metabolites in the regulation of ion balances across the gill membrane.     

鱼鳞营养成分的分析及对高脂饲料大鼠血脂水平的影响

报道了我国几种淡水鱼鱼鳞基本化学组成,并考察了鱼鳞对高脂饲料大鼠甘油三酸酯（ＴＧ）和总胆固醇（ＴＣ）的影响。结果表明,鱼鳞粗蛋白质含量为４０％～８０％,糖、脂肪含量极低;氨基酸组成中,甘氨酸含量极高,并含有较多的天冬氨酸、谷氨酸、丙氨酸、精氨酸、脯氨酸、羟脯氨酸。矿物元素以钙、鳞含量较高。鱼鳞可有效防止大鼠实验性高胆固醇血症,并可降低进食高胆固醇饲料大鼠血清ＴＣ和ＴＧ含量。     

养殖鳗鲡致病性气单胞菌对抗生素药物的敏感性

以30种抗生素药物（包括12大类）研究32株鳗鲡致病性气单胞菌（包括嗜水、维氏、豚鼠和简达气单胞菌4种）对药物的敏感性.结果表明,多数致病性气单胞菌对庆大霉素、阿米卡星、头孢他啶、头孢噻肟、卡那霉素、洛美沙星、呋喃妥因、哌拉西林、左氧氟沙星、壮观霉素、链霉素、阿奇霉素、氟哌酸、头孢曲松、强力霉素和头孢呋辛等16种药物敏感;而多数菌株对新生霉素、头孢克罗、头孢拉定、头孢唑林、头孢噻吩、利福平、复方新诺明、氨苄西林、乙酰螺旋霉素、羧苄青霉素和青霉素等11种药物耐药.32株菌对β-内酰胺类、氨基糖苷类、氟喹诺酮类、喹诺酮类、四环素类和硝基呋喃等6类药物敏感,而对安沙霉素类、磺胺类和香豆素等3类药物耐药;除哌拉西林外,所有菌株对另外3种青霉素类药物耐药;致病菌株普遍对其中的1种大环内酯类（阿奇霉素）和4种头孢类（头孢呋辛、头孢曲松、头孢噻肟、头孢他啶）药物敏感,而对其它大环内酯类和头孢类产生了耐药性.研究发现仅维氏气单胞菌对头孢克罗、头孢拉定、头孢噻吩和头孢唑林敏感,而其余3种菌均耐药.