微生物絮凝剂在水产养殖水环境改良中的应用前景

综述了微生物絮凝剂的种类、絮凝特性、絮凝机理以及微生物絮凝剂在水质改良中的应用现状,并分析了它作为水质改良剂在水产养殖中的应用前景。     

一株产絮凝剂芽孢杆菌的分离鉴定及絮凝剂特性分析

从山东及河北沿海分离到一株产絮凝剂细菌(编号200903091102,简称1102),分别用细菌全脂肪酸气相色谱法和16S rDNA序列分析比对法对该菌进行鉴定,两种方法的鉴定结果均显示细菌1102为一种芽孢杆菌(Bacillus sp.)。系统发育分析显示,细菌1102与枯草芽孢杆菌(B.subtilis)、特基拉芽孢杆菌(B.tequilensis)等亲缘关系最近。应用高氏1号培养基培养细菌1102,提取其絮凝剂进行絮凝力测定,结果显示,该菌所产絮凝剂的絮凝率达到80.19%。发酵72 h时,絮凝剂得率最高达19.5 g/L;分别采用凝胶渗透色谱法、苯酚-硫酸法及氨基酸自动分析仪对所得絮凝剂的相对分子质量、多糖含量及氨基酸含量进行分析,结果显示絮凝剂的重均相对分子质量为7 063 D,多糖质量分数占58.58%,氨基酸质量分数占2.49%。提示该菌在海水养殖中将具有较高的开发价值。本研究旨在为海水养殖废水的生物净化提供科学依据。     

生物絮团的研究进展

生物絮团是养殖水体中以好氧微生物为主体的有机体和无机物,经生物絮凝形成的团聚物,由细菌、浮游动植物、有机碎屑和一些无机物质相互絮凝组成。通过对生物絮团研究的发展过程、絮团的结构特征、絮凝机理、影响絮团的形成因素以及生物絮团技术在水产养殖应用中存在的问题进行了综述,为生物絮团技术在水产领域中的进一步研究和应用具有一定的指导意义。     

微生态制剂及其在水产养殖中的应用问题(三)

五、微生态制剂在水产养殖中的应用目前,我国在水产养殖过程中使用微生物活菌制剂品种和生产厂家多,产品功能各异,养殖业者对其效果也难以作出准确的判断。市售的微生物活菌制剂大概可分下面几大类:从微生物种属上分类,有光合细菌、芽孢杆菌属、硝化细     

初探生物絮团技术在北方盐碱高原池塘中的应用

<正>生物絮团是养殖水体中以好氧微生物为主体的有机体和无机物,经生物絮凝形成的团聚物,由细菌、浮游动植物、有机碎屑和一些无机物质相互絮凝组成。生物絮团技术最早由以色列养殖专家在1999年系统提出,并于2005年在印度尼西亚试验成功,它是指通过操控水体营养结构,向水体中添加有机碳物质,调节水体中的C/N比,促进水体中异养细菌的繁殖,利用微生物同化无机氮,将水体中的氨氮等养殖代谢产物转化成细菌自身成分,并且通过细菌絮凝     

水产用微生物菌剂衰亡过程的初步研究

近年来,微生物菌剂在水产养殖中的应用越来越广泛。微生物不仅可以改善养殖环境,提高动物的免疫力,抑制病原微生物的生长,而且可以改善动物肠道环境,促进其对营养的吸收转化。菌剂中的活菌数越高（细菌分泌物越多）,对养殖个体和环境的作用越大。本试验分别以水产养殖用芽孢杆菌、乳酸杆菌、酿酒酵母为主要菌种,研究其在不同水质、恒温条件下的衰亡过程,为指导养殖户用好微生物菌剂提供技术参考。     

渔用微生物絮凝剂产生菌的筛选及培养条件研究

本实验以筛选出能用于养殖水体净化的菌株为目的,通过稀释涂板法和划线法,从河道污泥、花园土壤、鲈肠道内分离筛选到6株产絮凝剂的细菌,经过复筛得到1株高效絮凝剂产生菌DK—1。     

噬菌蛭弧菌及其微生物生态制剂在水生动物养殖上的应用

近几年,随着水产品健康养殖理念的不断深入人心,健康养殖技术的逐步推广以及政府有关部门对渔药使用监管力度的日益增大,抗生素及其它化学合成药物在水产养殖中的使用已经受到并将进一步受到严格禁止或限制。与此同时,与水域生态环境相对友好的微生物生态制剂因其具有改善养殖水体的水质和底质、提高养殖水生动物对疾病的抵抗能力、减少药物的使用量和残留等特点,在水生动物养殖中得到越来越广泛的应用。其中有一个发展迅速、异军突起的微生物生态制剂,那就是噬菌蛭弧菌微生物生态制剂。跟其它微生物生态制剂相比,噬菌蛭弧菌具有“寄生”和“溶解”细菌的特性,噬菌蛭弧菌微生物生态制剂的生产工艺特殊,但它对生产的工艺技术和应用等都有较高的要求,如果生产或应用不当,效果往往会适得其反。为此,本刊特约长期从事噬菌蛭弧菌及其微生态制剂研究,原中国医学细菌保藏管理中心弧菌噬菌体专业研究室主任秦生巨研究员就噬菌蛭弧菌的基本特性、研究概况、作用机制以及生态制品的应用等内容进行系统、详尽的论述,并以连载的方式刊出,期望能对广大读者比较全面、系统地了解和正确应用噬菌蛭弧菌及其微生物生态制剂有所帮助。     

几种活菌生物制剂在罗氏沼虾育苗生产中应用试验

近年来，随着应用生物技术的发展，活菌生物制剂的水产养殖中得到的广泛应用，效果显。但有关于活菌生物制剂的应用报道多集中在土池养殖方面，而在水泥池养殖特别是在罗氏沼虾育苗生产中的可行性以及其应用效果，2001年5月5日-6月2日我们在本所的罗氏沼虾苗场进行了养殖保、利生素、西菲利等三种活菌微生物制剂的罗氏沼虾育苗生产应用试验。     

发酵饲料对水产动物的作用及其影响因素

正发酵饲料是一种新型环保型饲料,特点是利用微生物新陈代谢进行发酵,分解饲料中的大分子物质和抗营养因子,产生有机酸、小肽类氨基酸等营养物质,便于动物吸收及利用。相比于普通饲料,发酵饲料成本更低、效果更好,应用前景十分广泛。一、发酵饲料在水产养殖中的应用1.促进营养吸收,提高生长性能一方面,发酵饲料可促进水产养殖动物对营养的吸收,提高其生长性能。菌种在发酵的过程中会产生大量的活菌,在     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.