Evaluating the probiotic potential and adhesion characteristics of Bacillus spp. isolated from the intestine of Rhynchocypris lagowskii Dybowski

Probiotics have been widely used in aquaculture worldwide especially in China as antibiotics have been banned in aquaculture. In the present study, 27 potential strains were isolated from Rhynchocypris lagowskii Dybowski intestinal tract towards the assessment of their probiotic potential. Two potential probiotics were finally screened from the 27 candidate strains according to the results of enzyme-producing ability, in vitro against pathogens ability and antibiotic sensitivity test. The 2 potential probiotics were identified and confirmed on the basis of their colony morphology, biochemical characteristics, and 16S rRNA sequencing. The probiotic strains, LSG2-3–2 and LSG3-6, were identified to be Bacillus methylotrophicus and B. tequilensis, respectively. Further studies showed that LSG2-3–2 and LSG3-6 had excellent tolerance to high temperature (80℃), low pH (3–5), bile salts (0.3%), intestinal juice (10%), and gastric juice (0.5%). The adhesion rates of LSG2-3–2 and LSG3-6 in the in vitro intestinal mucosal adhesion model were 17.74% and 24.04%, respectively. Analysis of their bacteria surface adhesive proteins revealed that the lectins on the bacterial surface of LSG2-3–2 and LSG3-6 were mainly protein and glycoprotein properties, respectively. The adhesion receptor components in the mucus proteins of the two strains were all protein properties. The results of the inhibitory adhesion test indicated that LSG3-6 had a higher inhibitory effect on Aeromonas hydrophila and LSG2-3–2 had a better inhibitory effect on A. veronii. The biosafety assay confirmed that the isolates were not pathogenic to the host fish. Based on the presently observed characteristic features, it can be concluded that LSG2-3–2 (B. methylotrophicus) and LSG3-6 (B. tequilensis) retrieved from the digestive tract of R. lagowskii can be used for the healthy breeding and disease prevention of R. lagowskii.

     

地温变化对管道输送5号轻柴油的影响

在地温较低的情况下,成品油管道顺序输送５号轻柴油时,容易出现管壁结蜡现象,使混油量增大,在分析了５号轻柴油质量数据和长输管道各段地温６变化的基础上,提出了“临界点”地温,给出了在“临界点”地温的条件下输送５号轻柴油时应采取的措施,为管道安全经济运行提供了保障。     

黄鳝养殖技术之四:野生黄鳝苗种的筛选方法

人工养殖黄鳝,其苗种主要从市场上购买野生黄鳝苗种,必须严格挑选,最好直接从捕捞者手中选购笼捉或锹刨的黄鳝作为苗种。目前,各地养殖的黄鳝苗种中,深黄大斑鳝体色深黄,身体细长,有褐黑色大斑纹,适应环境能力较强,生长速度较快,个体较大,最适合于人工养殖;浅黄细斑鳝在自然界中数量最多,体色较黄,有细密的褐黑色斑纹,生命力较强,苗种来源广;体色青灰鳝适应环境能力相对较弱,生长速度较慢,个体相对较小,一般不宜选作人工养殖的黄鳝苗种。作为养殖的黄鳝苗种,必须选择规格整齐、体质健壮、色泽光亮、无病无伤、游动活波的鱼体,最好选择当地产…     

Phylogenetic analysis of bacterial communities in the shrimp and sea cucumber aquaculture environment in northern China by culturing and PCR–DGGE

In this study, we investigated the bacterial communities in the shrimp and sea cucumber culture environment, including shrimp ponds (SP), sea cucumber ponds (SCP), mixed-culture ponds (MCP) and the effluent channel (EC) in Qingdao, China. Bacteria cultivation showed that the counts of heterotrophic, nitrate-reducing and sulfate-reducing bacteria in the sediment of SP were higher than that in the sediment of SCP and MCP, varying between 8.7 × 10⁴ and 1.86 × 10⁶, 2.1 × 10⁴ and 1.1 × 10⁵, and 9.3 × 10¹ and 1.1 × 10⁴ CFU g^?1, respectively. In contrast, the counts of ammonium-oxidizing and nitrifying bacteria in the sediment of SP was lower than that in the sediment of SCP and MCP. Denaturing gradient gel electrophoresis (DGGE) of 16S rDNA gene and dendrogram analyses showed that bacterial diversity in the mixed-culture environment was higher than that in the monocultures. The similarity of bacterial community between EC and SCP or MCP was higher than that between EC and SP. These results indicated that sea cucumber culture played a significant role in influencing the environmental bacterial communities that were composed mainly of Flavobacteriaceae (64.3%), Bacteriodetes (21%) and delta proteobacteria (14.7%), including the genera of Croceimarina, Lutibacter, Psychroserpens and so on. The results explained the benefit of sea cucumber culture in shrimp ponds at the level of microbial ecology.     

Morphological, structural, and functional characterization of the haemocytes of the scallop, Argopecten irradians

Argopecten irradians is one of the most important commercial species of Pectinidae family in China. The internal defense system of mollusks consists of circulating haemocytes. In order to characterize the haemocytes of the scallop A. irradians, light and electron microscopical studies were carried out. Four types of haemocytes were recognized: type I small hyalinocytes (2.38 ± 0.08 μm, 30-35%), type II large hyalinocytes (4.41 ± 0.33 μm, 15-20%), type III small granulocytes (4.15 ± 0.26 μm, 20-25%), and type IV large granulocytes (8.26 ± 0.52 μm, 25-30%). Granulocyte types showed smaller N/C ratios than hyalinocytes. The mean haemocyte concentration was about (3.75 ± 0.65) × 10⁷ cells ml^− 1 of haemolymph. Among haemocytes, 44.7% are granular and 55.3% are agranular. These gave a relatively systematic classification scheme for haemocytes of A. irradians. Three types of granules were identified: type I, with high electron-density; type II, with low electron-density; and type III, with a middle level of electron-density, based on TEM studies. Different haemocyte types were not separated with DDGC of Percoll in this study. Both granulocytes and hyalinocytes showed a phagocytic response to the two strains of bacteria, Escherichia coli and RLOs. The phagocytic ability of granulocyte was significantly higher (41-48%) than that of hyalinocyte (9.2-11.2%).     

南美白对虾养殖技术之三:黄河下游盐碱地池塘大面积养殖南美白对虾高产技术

为了探索黄河下游地区盐碱地池塘无公害养殖南美白对虾的经验,山东省博兴县水产局于2004年进行了"北方盐碱地池塘无公害养殖南美白对虾高产高效技术研究"试验项目,取得良好的经济效益和社会效益.     

野生动物利用态度调查及分析

采用问卷调查法及访谈,对部分来自于黑龙江省东北林业大学的在读本科生、在读研究生、本科入学新生以及新生家长共300人进行了调查.对当前人们普遍关注的野生动物利用热点问题进行了提问,调查结果表明影响野生动物利用态度形成的深层次原因为受教育程度、生活经验、媒体宣传、国家政策了解程度、某些非政府组织(NGO)的误导,并根据分析结果提出了促进野生动物可持续发展与利用的几点可行性建议.     

Annexin V法检测盐胁迫下烟草原生质体的早期凋亡

将膜联蛋白V( Annexin V)法与碘化丙啶(PI)染色法相结合检测烟草(Nicotiana tabacum L.)原生质体的早期凋亡,结果表明:在中性盐胁迫下,能够很好地区分早期凋亡的原生质体和死亡的原生质体.200 mmol·L-1 NaC1对烟草原生质体胁迫5h,凋亡率能达到7.57％;但在200 mmol·L-1 NaHCO3碱性盐胁迫下,质膜透性发生了改变,不易区分早期凋亡的原生质体和死亡的原生质体,同时,随着碱性的增加,原生质体破碎率显著升高.碱性的NaHCO3和Na2CO3表现出对细胞膜的破坏作用.     

贵州省大鲵养殖产业化的发展前景

贵州省曾是大鲵的广泛分布地,一段时间以来,由于栖息地的生态遭到破坏,野生大鲵资源量锐减。进行产业化的养殖,扩大大鲵种群数量,才能有效地保护和开发这一资源。陕西省是目前国内大鲵增殖保护走在前列的省份,取得了较大的成效。通过对贵州与陕西两省大鲵主要分布区的地理地貌、温度、降水量及无霜期等条件的对比,比较大鲵生长的生态条件,探讨贵州省大鲵养殖产业化发展的前景。     

Haematological and blood biochemical characteristics of <Emphasis Type="Italic">Glyptosternum maculatum</Emphasis> (Siluriformes: Sisoridae) in Xizang (Tibet)

This study investigated the haematological and blood biochemical characteristics of Glyptosternum maculatum. The haematological and biochemical parameters were measured in 30 adult fish collected from Nyingchi Reach of Yarlung Zangbo River in Tibet. The red blood cell count (RBC), haemoglobin concentration (Hb), haematocrit (Hct), erythrocyte osmotic fragility (maxEof and minEof), the erythrocyte sedimentation rate, mean cell volume (MCV), mean cellular haemoglobin content (MCH), and mean cell haemoglobin concentration (MCHC) were determined. Compared with other Siluriformes fishes, G. maculatum showed similar mean values for Hct, Hb, MCH, and MCHC and had slightly lower RBC and higher MCV. The biochemical parameters were assayed including alanine aminotransferase, aspartate aminotransferase (AST), alkaline phosphatase, total protein, albumin, globulin, albumin/globulin ratio, total bilirubin, direct bilirubin, urea, creatinine, glucose, total cholesterol, and triglyceride. The result showed that the value of AST in G. maculatum was obviously higher than that in Rhamdia quelen as well as in Silurus merdionalis.