患拟油壶菌病条斑紫菜表面附生菌群分析

拟油壶菌病(Oplidiopsis disease)是海上栽培紫菜(Porphyra sensu lato)的主要病害之一,常引起紫菜大面积病烂并造成严重经济损失。本研究利用拟油壶菌感染海区内不同健康状态下的条斑紫菜(Neopyropia yezoensis)[未发生任何病烂(PyOlpH)、部分紫菜发生病烂(PyOlpM)和发生严重病烂(PyOlpS)],分析其附生菌群多样性、群落结构和主要类群之间的相互作用。结果显示,3种紫菜附生菌群α多样性指数不存在显著差异,但PyOlpM组指数高于其他组。3种紫菜附生菌群共有可操作分类单元(operational taxonomic unit, OTU)数仅占总OTU数的22.7%,菌群之间存在显著差异(置换多元方差分析, R2=0.405, P<0.05)。紫菜感染程度越高,与PyOlpH之间的差异类群数量越多。共注释出23门208属,α-变形菌纲(α-Proteobacteria)、γ-变形菌纲(γ-Proteobacteria)和厚壁菌门(Firmicutes)在所有样品中均占优势,相对丰度前20个属中有16个也位于这3个类群中,且随着感染程度的增加分别出现递增或递减的趋势。其中,贪铜菌属(Cupriavidus)和鞘氨醇单胞菌属(Sphingomonas)是共现网络中连接度最高的细菌类群,二者及其依靠正相互作用连接的细菌类群之间存在负相互作用。本研究可为阐明拟油壶菌致病的微生态机制及寻找生防细菌提供一定的数据支持。     

紫菜养殖对养殖水体中细菌多样性分布及环境因子的影响

采用基于16S rDNA的高通量测序技术对山东长岛紫菜养殖区的细菌多样性分布进行了研究,并与环境因子进行关联分析,以探究紫菜养殖对环境的影响。结果显示,长岛海区水环境细菌多样性较丰富,呈现由近岸区(CDCNS)、养殖区(CDPF)、外海区(CDCOS)递减的趋势。分别基于所有细菌组成以及相对丰度最高的前20个属/种的聚类结果均显示,CDCNS和CDCOS区聚在一起,明显区别于CDPF区。CDPF区的特异优势菌包括鼠尾菌属(Muricauda)、假单胞菌属(Pseudomonas)、盐单胞菌属(Halomonas)、赤杆菌属(Erythrobacter)、海杆菌属(Marinobacter)。3个区域均未检测到河豚毒素假交替单胞菌(Pseudoalteromonas tetraodonis)、柠檬假交替单胞菌(Pseudoalteromonas citrea)等疑似紫菜致病菌。溶解氧(DO)和pH呈现由近岸向外海逐渐降低的趋势,总颗粒悬浮物(TSS)反之。CDPF区氨氮(NH4+-N)含量最低,盐度最高。关联分析发现,环境因子与环境微生物之间具有一定的相关性,如嗜氨菌属(Ammoniphilus)的丰度与NH4+-N 浓度具显著正相关性,CDPF区最低,CDCOS区最高;盐单胞菌属的分布与盐度具显著正相关性,CDPF区盐单胞菌属含量显著高于其他2个海区。研究表明,紫菜养殖海区细菌群落结构特征与环境因子具有关联性,其间的互作机制尚需进一步深入研究。     

微生物制剂对养殖池塘细菌群落影响的PCR-DGGE分析

为了解微生物制剂在水产养殖环境修复中的作用机制,采用聚合酶链式反应—变性梯度凝胶电泳(PCR-DGGE)方法,研究不同微生物制剂对养殖池塘上覆水和沉积物中细菌群落的影响。结果显示,施用微生物制剂前后,试验塘上覆水样品中细菌的DGGE优势条带无明显变化,细菌群落组成没有明显差异,提示微生物制剂对试验塘上覆水中的细菌群落组成影响很小。相对而言,施用过微生物制剂的池塘相对于对照池塘其细菌群落结构发生的变化较大;泼洒EM菌原粉3 000 g/hm2加芽孢杆菌原粉750 g/hm2的试验塘沉积物中细菌群落2 d内发生了较大变化,之后相对稳定,对照池塘和泼洒EM菌原粉3 000 g/hm2加光合细菌原粉1 500 g/hm2的试验塘沉积物中细菌群落组成变化很小。     

Effects of Inorganic and Organic Fertilization on Physicochemical Parameters,Bacterial Concentrations,and Shrimp Growth in Litopenaeus vannamei Cultures with Zero Water Exchange

To identify ways to improve water quality and shrimp production in closed systems, two parallel experiments (one in tanks and one in ponds) were conducted using Pacific white shrimp, Litopenaeus vannamei, cultures. In both experiments, the effects of inorganic (Nutrilake®) and organic (molasses) fertilization on physicochemical parameters, bacterial concentrations, and shrimp performance under zero water exchange were evaluated. Fertilization with both molasses and Nutrilake enhanced the feed conversion rate, as well as shrimp survival and production. In tanks, the shrimp survival and production rates were highest in the molasses treatment, but this effect was not observed in ponds. In ponds, fertilization with Nutrilake increased nitrogen and phosphorus concentrations more than did the controls and molasses treatments toward the end of the experiment. In tanks, fertilization with molasses reduced ammonia concentrations toward the end of the experiment, but the same effect was not observed in ponds. In ponds, fertilization reduced the proportion of Vibrio spp. bacteria, which most likely reduced the incidence of disease from these potentially pathogenic organisms. In both culture systems, fertilization increased the proportion of Bacillus spp., which most likely enhanced food availability.     

Dynamics of Bacterial Communities in Postharvested Eastern Oyster (Crassostrea virginica) Maintained Under Refrigeration

The selective effect that refrigeration exerts on the autochthonous microbiota of the eastern oyster was investigated using culture-independent methods. Oysters from two different locations along the Gulf Coast of Mexico were analyzed concurrently during 2-week refrigeration. Ribosomal intergenic sequence analysis (RISA) generated complex bacterial community fingerprints that provided a strong association between RISA-defined clusters and sample date. Denaturing gradient gel electrophoresis (DGGE) profiles obtained with universal primers did not reflect any association based on date or geographic origin of the samples. During the storage period, Vibrio parahaemolyticus was replaced, at least in overall abundance, with other nonpathogenic Vibrio species better adapted to cold temperatures. This study shows that refrigeration itself does not limit the growth of the bacterial community nor reduces its richness.     

乙酰甲喹对小新月菱形藻、等鞭金藻3011的毒性效应

通过考察乙酰甲喹对小新月菱形藻(Nitzschia closterium f.minutissima)、等鞭金藻(Isochrysis galbana Parke3011)的生长抑制和对叶绿素a、总超氧岐化酶(T-SOD)活性以及丙二醛(MDA)浓度的影响,研究了乙酰甲喹对2种微藻的毒性效应,为评价兽药乙酰甲喹的使用安全性和保护养殖环境提供基础数据。结果表明,乙酰甲喹对2种微藻的生长抑制作用随质量浓度的增加而增大,乙酰甲喹对小新月菱形藻的24 h-EC50(半数有效浓度)为4.73 mg·L~(-1)、对等鞭金藻3011的24 h-EC50为2.14 mg·L~(-1),乙酰甲喹对2种微藻均属于高毒物质,等鞭金藻3011更敏感。暴露24 h后,随着乙酰甲喹质量浓度的升高,小新月菱形藻叶绿素a浓度下降而等鞭金藻3011叶绿素a浓度基本不受影响;2种微藻的T-SOD活性随着乙酰甲喹质量浓度的升高均显著增加,各实验组MDA浓度也高于对照组,等鞭金藻3011更敏感,说明乙酰甲喹对2种微藻均能造成氧化胁迫,对细胞造成氧化损伤。     

凡纳滨对虾急性肝胰腺坏死病(AHPND)病原分离鉴定及其致病性分析

本研究从患急性肝胰腺坏死病(Acute hepatopancreatic necrosis disease,AHPND)的凡纳滨对虾(Litopenaeus vannamei)肝胰腺中分离到一株优势菌,编号为20160303005-1,通过16S rRNA和分子伴侣蛋白groEL基因序列分析,并结合生理生化特征,将该细菌鉴定为副溶血弧菌(Vibrio parahaemolyticus),其血清型为O1:KUT(K untypeable)。基因分析结果显示,该菌株携带可引起对虾AHPND的相关毒力蛋白基因pirA~(VP)和pirB~(VP),但不携带副溶血弧菌临床菌株毒力基因:耐热直接溶血毒素(Thenmostable direct hemolysin,tdh)和相对耐热直接溶血毒素(TDH-related hemolysin,trh)基因。菌株对凡纳滨对虾具有较强的致病性,浸泡感染的半数致死剂量(LD_(50))为7.96×10~3 CFU/ml。对虾急性感染后,6 h肝胰腺颜色变浅,肠胃变空;9 h肝胰腺呈浅白色,萎缩变小。9 h死亡数过半,24 h全部死亡。组织病理学分析显示,感染后对虾肝胰腺小管崩塌,上皮细胞严重脱落,呈现出典型的AHPND病理症状。药敏实验结果显示,该菌对庆大霉素、环丙沙星和头孢他啶等16种药物敏感,对阿莫西林、替卡西林和头孢噻吩等5种药物表现为耐药。上述研究可为该病原的流行病学及药物防控研究提供基本数据。     

温度对小新月菱形藻叶绿素荧光特性及生长的影响

以小新月菱形藻为试验材料,研究了其在一次性培养过程中,不同温度(5~30℃)对其叶绿素荧光参数[光系统Ⅱ的最大光能转化效率(Fv/Fm)、光系统Ⅱ的潜在活性(Fv/Fo)、光系统Ⅱ的实际光能转化效率(ΦPSⅡ)、相对光合电子传递效率(rETR)、光化学淬灭(qP)和非光化学淬灭(NPQ)]、叶绿素相对含量以及细胞密度的影响。单因子方差分析结果表明,在整个培养周期中,温度对小新月菱形藻各叶绿素荧光参数、细胞密度和叶绿素相对含量均有显著影响(P<0.05)。多重比较结果表明,接种后1~2 d,20℃处理组的主要荧光参数(Fv/Fm、Fv/Fo、rETR、ΦPSⅡ)显著高于其他处理组。30℃的处理组的上述荧光参数从第1 d开始均显著低于其他处理组。20℃处理组的细胞密度和叶绿素相对含量均显著高于其他处理组。在本试验条件下,适宜小新月菱形藻生长的温度为10~25℃,最适温度为20℃。相关性分析结果表明,在整个培养周期中,小新月菱形藻的叶绿素相对含量和细胞密度之间存在显著的正相关。     

应用高通量测序技术分析大菱鲆幼鱼肠道及其养殖环境的微生物群落结构

采用基于Illumina测序平台的高通量测序技术,对大菱鲆(Scophthalmus maximus)幼鱼肠道及其养殖水体、生物饵料中细菌种类及丰度进行研究。测序结果显示,养殖水体、生物饵料和大菱鲆幼鱼肠道等19个样品共获得有效序列547621条,可聚类于3771个可分类操作单元(OTUs),归属于养殖水体、生物饵料、健康幼鱼和发病幼鱼的操作分类单元(OTU)个数分别为3038、1090、87和777,其中,健康幼鱼与生物饵料、健康幼鱼与养殖水体特有的OTU个数分别为57和0,发病幼鱼与生物饵料、发病幼鱼与养殖水体特有的OTU个数分别为481和31。表明幼鱼肠道微生物多样性与生物饵料密切相关。根据细菌注释结果,拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)和变形菌门(Proteobacteria)在大菱鲆幼鱼肠道中占优势地位,其中,健康幼鱼肠道微生物共聚类为8个门,发病幼鱼的肠道微生物可聚类为19个门。与健康幼鱼相比,发病幼鱼肠道门水平上的3种主要优势菌群落结构出现失衡。此外,对各样品中丰度最高的100位OTU分析显示,幼鱼肠道优势菌种类与生物饵料中的优势菌种类密切相关,而每个发病幼鱼肠道优势菌种类具有一定的独立性。本研究旨在为大菱鲆健康养殖和微生态调控提供实验依据。     

Qualitative and Quantitative Analysis of Campylobacter jejuni and Campylobacter coli in Fresh Blue Crab (Callinectes sapidus) Meat

Samples of fresh picked crabmeat from twelve different blue crab processing facilities were analyzed for general microbial quality and the presence of Campylobacter jejuni and Campylobacter coli. Twenty samples from each plant were analyzed for a total of 240 samples. Aerobic plate counts ranged from 7.4 x 10³ to 4.6 x 10⁸. Coliform and fecal coliform counts ranged from <0.3 to 32.8 MPN/g and <0.3 to 2.26 MPN/g, respectively. Eshcherichia coli counts ranged from <0.3 to 0.77 MPN/g. Campylobacter jejuni was isolated from 36 (15%) samples and Campylobacter coli was isolated from 14 (5.8%). There was no statistical correlation between general microbial quality, plant size or inspection score (sanitation) and the presence of Campylobacter species.     

小球藻和亚心扁藻的超低温保存

实验采用两步法冷冻技术低温保存小球藻和亚心扁藻,通过冻存后再培养的生长情况的研究,检验两步法冷冻技术低温保存藻种的可行性。实验利用两种不同的抗冻剂对各藻类分别进行预处理、冷冻保存、解冻、再培养,测定相应波段的吸光光度值,以计算叶绿素a的含量,反映各藻类的生长情况。实验结果显示,各藻类经冻存后均有成活,但不同藻在经过不同抗冻剂处理后的生长速度有所不同。     

近红外光谱技术在鱼糜定性和定量上的应用

以海水鱼糜(包括狭鳕、带鱼、鲷和混合鱼糜)以及淡水鱼糜(包括鲢和草鱼鱼糜)为研究对象,应用傅立叶近红外光谱技术结合化学计量学对鱼糜进行定性和定量分析。用聚类分析和线性判别的方法建立海水和淡水鱼糜的定性鉴别模型,并应用偏最小二乘法(PLS)分别建立海水鱼糜水分含量和蛋白质含量的近红外定量分析模型。结果表明,海水和淡水鱼糜的定性鉴别模型预测率达100%;建立的近红外定量分析模型中,海水鱼糜的水分和蛋白质的模型的相关系数分别达0.98和0.96以上,模型能较为准确、快速地预测定海水鱼糜中水分和蛋白质含量,有很大的潜力可应用于实际生产。     

铜绿微囊藻和小球藻室内竞争实验研究

对铜绿微囊藻和小球藻进行藻类竞争实验,并通过模拟计算,分别得到铜绿微囊藻和小球藻纯培养和竞争条件下的生长模式,并计算了2种藻之间的相互竞争抑制强度。纯培养时铜绿微囊藻和小球藻的增长速率r分别为0.451/d和0.419/d,最大环境容量K分别为1414×104个/mL和812×104个/mL;混合培养时铜绿微囊藻对小球藻的种间竞争强度为1.44,小球藻对铜绿微囊藻的种间竞争强度为0.9。     

不同光照条件对小新月菱形藻和等鞭金藻8701生长及生化成分的影响

研究了小新月菱形藻(Nitzschiaclosteriumf.minutissima)(MACC/B228)和等鞭金藻8701(IsochrysisgalbanaParke8701)(MACC/H060)在4种光照条件下的生长情况,以及不同光强下、不同时期收获的藻细胞中总脂和碳水化合物含量的变化。结果表明,小新月菱形藻在光强70μmol·s-1·m-2时细胞分裂频率(μ)最大,最适光强70～140μmol·s-1·m-2;260μmol·s-1·m-2光强能导致细胞分裂频率变慢,指数期缩短。等鞭金藻8701在光强140μmol·s-1·m-2时μ值最大,260μmol·s-1·m-2下略有降低。2种藻均在低光下脂肪含量多,小新月和等鞭金藻脂肪含量分别占干重的25.5%～35.3%和28.3%～37.5%;而碳水化合物含量少,分别占干重的5.5%～18.2%、3.9%～11.4%;在高光强下相反。不考虑光照条件的影响,2种藻细胞内碳水化合物的含量均在静止期达到最大,分别占干重的18.98%和23.32%。小新月菱形藻在70μmol·s-1·m-2光强下的指数期细胞有最大的脂肪含量,等鞭金藻的最高脂肪含量出现于光强20μmol·s-1·m-2下指数末期的细胞中。二者在光强140μmol·s-1·m-2下生长且进入静止期时均可获得较大生物量,同时细胞的脂肪和碳水化合物的含量也处于较高水平。     

A Qualitative and Quantitative Approach to Determine the Optimum Combination of Feeding Stimulants for Striped Bass Morone saxatilis Using an Agar Gel Carrier

A series of experiments was conducted to determine the optimum combination of previously identified feeding stimulants (FS), namely L-alanine (Ala), L-serine (Ser), inosine-5'-monophosphate (IMP), and betaine (Bet), for striped bass Morone saxatilis . Three experiments were conducted to determine the optimum combination of FS using an agar gel matrix as a carrier. In the first experiment a 2⁴ factorial experiment was conducted to test all possible combinations of the four FS at two levels, 0 and 0.1 M. Significant interactions between the FS were found, suggesting the complexity of gustatory stimulation and palatability. In the second experiment a 4 × 6 factorial design was employed to test each FS alone and at concentrations ranging from 0 to 8% in order to determine the minimum level at which maximal stimulation is achieved. The results suggest that there is no significant improvement in feed intake beyond the 1 % level of supplementation for all the FS. In addition, Ala produced a significantly greater response compared to all other FS. In the last experiment, a modified single factor method was used to estimate the optimum levels for each FS in a mixture. The range of the concentrations tested was 0–1% of the agar gel for each FS. Combining all four compounds yielded maximal stimulation. The levels of each compound in the final optimum combination of FS were: Ala, 0.4; Ser, 0.6; Bet, 0.4; and IMP, 0.3% of the agar gel.     

济兴牌强力消毒剂防治细菌性鱼病试验

用济兴牌强力消毒剂进行室内和鱼塘防治细菌性鱼病试验。室温２５℃，用０．４×１０－６消毒剂２４ｈ即能全部杀灭赤皮、烂鳃、肠炎病原菌；轻病鱼塘用０．５×１０－６，重病鱼塘用０．８×１０－６消毒剂全池泼洒，２天１次，２～３次即愈。     

Qualitative modelling and indicators of exploited ecosystems

Implementing ecosystem-based fisheries management requires indicators and models that address the impacts of fishing across entire ecological communities. However, the complexity of many ecosystems presents a challenge to analysis, especially if reliant on quantification because of the onerous task of precisely measuring or estimating numerous parameters. We present qualitative modelling as a complementary approach to quantitative methods. Qualitative modelling clarifies how community structure alone affects dynamics, here of exploited populations. We build an array of models that describe different ecosystems with different harvesting practices, and analyse them to predict responses to various perturbations. This approach demonstrates the utility of qualitative modelling as a means to identify and interpret community-level indicators for systems that are at or near equilibrium, and for those that are frequently perturbed away from equilibrium. Examining the interaction of ecological and socio-economic variables associated with commercial fisheries provides an understanding of the main feedbacks that drive and regulate exploited ecosystems. The method is particularly useful for systems where the basic relationships between variables are understood but where precise or detailed data are lacking.