凡纳滨对虾(Litopenaeus vannamei)低盐度围隔调控养殖环境微生物研究

在广东省珠海市斗门一个大小为0.3hm2的空白虾池内,设立10个大小为5×5×1.6m(l×b×d)的陆基池塘围隔,对凡纳滨对虾低盐度调控养殖环境微生物进行实验研究,结果低盐度围隔调控养殖系统,水体异养细菌平均为1.33~9.27×104cfu.ml-1,致病性弧菌平均为2.83~7.91×102cfu.ml-1,养殖水体致病性弧菌的数量比异养细菌平均低2个数量级。各围隔水体异养菌在养殖早期都有一个高峰期,中后期低而稳定;围隔异养细菌的数量并未因定期施菌而增高,反而呈下降的趋势。对虾养殖健康的围隔,中后期水体致病性弧菌保持较低的数量,而对虾发病的围隔,致病性弧菌数量高。围隔调控养殖系统,异养细菌的数量相对比较稳定,而致病性弧菌数量呈较大波动。     

杀鱼假交替单胞菌2515的抗弧菌效果及在对虾养殖中的应用

为探讨一株杀鱼假交替单胞菌 2515 Pseudoalteromonas piscicida (简称菌株 2515)在对虾养殖中的抗弧菌效果, 以鳗弧菌(Vibrio anguillarum)为指示菌, 以鳗弧菌的敏感抗生素新霉素为参比, 采用牛津杯打孔法, 比较了菌株 2515 与抗生素抗菌等效关系。设置浓度分别为 10⁴ CFU/mL、10⁵ CFU/mL、10⁶ CFU/mL、10⁷ CFU/mL 的菌株 2515 与鳗弧菌共培养, 评价了该菌对鳗弧菌的拮抗效果。将含量 10³ CFU/g、10⁵ CFU/g、10⁷ CFU/g, 及 10³ CFU/mL、 10⁵ CFU/mL、10⁷ CFU/mL 的菌株 2515 分别添加到对虾饲料和养殖水体中, 养殖凡纳滨对虾(Litopenaeus vannamei), 分析了菌株 2515 对水体和对虾肠道细菌总数、弧菌数及对抗副溶血弧菌效果的影响。结果显示, 相同抗鳗弧菌效果条件下菌株 2515 数量与新霉素质量存在对应关系, 与鳗弧菌混合培养时, 浓度 10⁶ CFU/mL 及 10⁷ CFU/mL 的菌株 2515 对鳗弧菌表现出强的抑菌作用。饲料中添加菌株 2515 浓度 10⁵ CFU/g 及 10⁷ CFU/g 时能够显著降低对虾肠道中的弧菌数量(P < 0.05), 提高对虾养殖的存活率。采用副溶血弧菌(V. parahaemolyticus)攻毒, 显示在饲料中添加菌株 2515 浓度为 10⁵ CFU/g 一组对虾死亡率最低, 为(43.3±5.8)%, 对副溶血弧菌的相对保护率达(53.7±6.2)%。结果表明, 在饲料和养殖水体中添加适宜浓度的菌株 2515 均能够提高凡纳滨对虾抗副溶血弧菌的能力, 降低对虾肠道内的弧菌数量。本研究结果为对虾养殖弧菌病生物防控提供了一种技术支撑。     

汕头南澳海域龙须菜栽培系统细菌群落结构特征

为研究养殖规划调整后汕头南澳海域龙须菜(Gracilaria lemaneiformis)栽培系统的细菌群落结构特征, 于 2021 年 4 月，龙须菜生物量最大时, 选择龙须菜栽培区(原为贝藻混合养殖区, 且常年开展牡蛎养殖)和邻近的自然海区(对照区), 调查比较了水体、沉积物、龙须菜藻体及其凋落物的细菌群落结构及环境特征, 并分离鉴定了龙须菜及其凋落物附着可培养优势细菌种类。结果发现, 龙须菜栽培区表层和底层水体细菌总数分别为 3.96× 10⁵ copies/mL 和 4.97×10⁵ copies/mL, 均显著高于对照区(P＜0.05), 沉积物细菌数量差异不显著(P＞0.05), 龙须菜藻体附着细菌数量和可培养细菌数量均显著高于凋落物(P＜0.05)。相对水体和藻体附着细菌, 龙须菜栽培区和对照区沉积物细菌多样性和丰富度最高, 相对于对照区沉积物, 龙须菜栽培区沉积物中拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)相对丰度更高; 两区域水体优势菌群结构类似, 但龙须菜栽培区 Rhodobacteraceae 的相对丰度 (21.1%~29.1%)显著高于对照区(11.9%~12.1%)(P＜0.05)。龙须菜及其凋落物附着优势菌以盖丝藻属(Geitlerinema)、 弧菌属(Vibrio)和假交替单胞菌属(Pseudoalteromonas)为主。可培养优势细菌为溶藻弧菌(Vibrio alginolyticus)、食环芳弧菌(Vibrio cyclitrophicus)和假交替单胞菌(Pseudoalteromonas sp.)等。通过冗余分析(redundancy analysis, RDA) 发现, 水体 pH、溶解氧和盐度是影响水体和藻体附着优势菌群的主导因子, 总磷含量是影响沉积物细菌优势群落组成的主导因子。综上所述, 龙须菜的生长与凋落对区域水体细菌群落结构会产生较大影响, 栽培龙须菜及其凋落物体表能形成独特的微生物区系, 影响龙须菜栽培生态系统的结构和功能。     

低盐度养殖的凡纳滨对虾体长和体重的增长规律

通过池塘陆基围隔实验，研究了凡纳滨对虾在最适水温、溶氧、pH及低盐度(2～6)养殖环境的生长特性及规律。实验结果，低盐度养殖健康对虾体长和体重平均生长率分别为1.398 mm·d^-1和0.169 g·d^-1，对虾前期体长呈线性生长，中后期体重呈加速增长。非线性拟合结果，对虾体长生长为二次曲线，符合Quadratic模型，体重增长为S型曲线，符合Boltzmann模型，生长观测值与模型拟合相关系数R²均达到0.99；凡纳滨对虾低盐度养殖典型体长和体重生长模型为L=7.843+2.297t-0.0105t²和W=16.541+(-0.621-16.541)/(1+e^{(t-54.809)/15.456})。低盐度养殖，对虾体长与体重呈立方关系，符合幂指数模型W=aL^b，a值范围4.9～9.0×10^-6，b值范围2.9495～3.0716，相关系数R²在0.99以上，典型幂指数模型为W=4.9×10^-6L^3.0716。     

三疣梭子蟹池塘综合养殖系统浮游植物群落结构及其与环境因子的关系

在三疣梭子蟹(Portunus trituberculatus)-日本对虾(Penaeus japonicas)混养系统(SC)中, 分别搭养低(SCC₁)、中 (SCC₂)、高(SCC₃)密度的缢蛏(Sinonovacula constricta), 构建 3 种三疣梭子蟹-日本对虾-缢蛏综合养殖系统, 于 2020 年 7 月至 12 月逐月采集养殖系统样品, 分析了养殖期间浮游植物的群落结构特征, 并利用典范对应分析(CCA)和冗余分析(RDA)探讨了浮游植物群落结构变化与环境因子的关系。结果显示: (1)养殖期间共鉴定出浮游植物 6 门 54 属 81 种; 从种的数量上看, 硅藻门(Bacillariophyta)＞甲藻门(Pyrrophyta)＞蓝藻门(Cyanophyta)＞绿藻门(Chlorophyta)＞ 裸藻门(Euglenophyta)＞隐藻门(Cryptophyta); 共包含 30 种优势种, 主要包括小环藻属未定种(Cyclotella sp.)、尖针杆藻(Synedra acus)、双头辐节藻(Stauroneis anceps)、小席藻(Phormidium tenus)、小颤藻(Oscillatoria tenuis)及裸藻属未定种(Euglena sp.); (2)养殖期间浮游植物密度介于 2.23×10⁵ ~28.06×10⁵ cell/L, 生物量为 0.06~21.37 mg/L, Shannon-Wiener 多样性指数范围为 0.90~2.42, Pielou 均匀度指数范围为 0.31~0.78, Margalef 丰富度指数范围为 1.00~2.08, 整体多样性水平高, 群落较为稳定; (3) CCA 与 RDA 结果显示, 水温、透明度和盐度是影响三疣梭子蟹综合养殖系统浮游植物群落结构的主要环境因子。在三疣梭子蟹-日本对虾混养系统中搭配中密度(75.0 kg/hm² )和高密度(112.5 kg/hm² )缢蛏时, 系统浮游植物群落多样性较好, 可实现浮游植物的均衡发展, 增强养殖系统的抗干扰能力, 有利于三疣梭子蟹池塘综合养殖系统的稳定。     

中国对虾和日本对虾对白斑综合征病毒(WSSV)敏感性的比较

用10⁵拷贝、10⁴拷贝和10³拷贝3个剂量的白斑综合征病毒(WSSV)粗提液分别对中国对虾和日本对虾进行人工注射感染,比较两种对虾对WSSV敏感性的差异,以探讨日本对虾白斑综合征(WSS)低发病率的原因,为对虾的病害防治提供参考。结果显示:用10⁵拷贝、10⁴拷贝和10³拷贝的WSSV粗提液注射后,中国对虾的平均存活时间分别为54.21±0.60 h、71.26±4.26 h和75.04±5.73 h;日本对虾平均存活时间分别为77.61±4.45 h、105.84±6.36 h和168.82±13.15 h。中国对虾和日本对虾的存活时间均随着病毒剂量的降低而延长。同剂量病毒注射下,日本对虾组的存活时间均长于中国对虾组,差异显著(P<0.05)。试验结果表明,日本对虾对WSSV的抵抗力较中国对虾强。     

厦门对虾养殖水域异养细菌和弧菌的研究

本文对厦门三个主要对虾养殖区水体中异养细菌和弧菌的数量进行了研究。结果表明，在对虾养殖水环境中，异养细菌和弧菌的数量与水温、盐度、氨氮、化学耗氧量的水体营养指数密切相关，弧菌可作为高温季节有机污染的一个指标，弧菌的数量与对虾对病有一定的关系。     

一株引起坛紫菜绿斑病病原的分离鉴定及致病性研究

为了明确引起坛紫菜绿斑病的病原,对2012年发生在福建省莆田养殖海区坛紫菜叶状体绿斑病开展了病原的分离鉴定和致病性研究。利用2216E海水培养基平板,从患病藻体分离得到一株优势细菌X5;在实验室条件下将X5进行回接感染实验,在显微镜下观察到坛紫菜叶状体发生组织病理变化,出现绿斑病症状:感染初期出现黄绿色小斑点,病斑逐渐扩大出现空洞,最后导致紫菜叶片流失;用浓度为10⁴~10⁸ cfu/mL的X5感染坛紫菜时,在7 d内引起紫菜出现10%~100%病斑面积,这些结果表明X5为坛紫菜绿斑病的病原。利用生理生化和多基因序列分析方法对X5进行鉴定,结果显示该菌为革兰氏阴性菌,大小为0.6 μm×0.4 μm~1.0 μm×0.4 μm,无鞭毛,在温度4~42℃、盐度50~150、pH6~10范围内生长,最适生长温度为16℃,最适生长盐度为50,最适pH为7,对甲硝唑、林可霉素和青霉素耐药,对25种抗生素敏感,Biolog和API ID-32E细菌鉴定系统的结果显示X5为弧菌属细菌(Vibriosp.);基于多基因序列(16S rRNA,rpoA,recA,pyrH)构建的系统进化树分析显示,X5与V.casei、V.litoralis、V.rumoiensis聚为一支,进化距离为0.095~0.108,这些结果说明X5为弧菌属的一个新种或是V.casei、V.litoralis、V.rumoiensis之一的一个新亚种。本研究报道了弧菌X5能够引起坛紫菜绿斑病,为紫菜流行病学及疾病防治提供了理论支撑。     

盐度和溶解氧对刺参非特异性免疫酶活性的影响

测定了不同盐度(20、25、30、35、40)和不同溶氧水平(充空气,DO 7~9mg/L)充纯氧,DO15~20mg/L;不充气,DO 2~5mg/L)对刺参体腔液中酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、溶菌酶(LZM)和超氧化物歧化酶(SOD)活性变化的影响。盐度试验结果表明,盐度急性变化会引起刺参体腔液ACP、AKP、LZM活性的升高和SOD活性降低,其中第10天时盐度对酶活性的影响最大。溶氧试验显示,过饱和溶氧(DO 15~20mg/L)可使刺参体腔液ACP、AKP、LZM、SOD活性维持在较高水平,不充气组(DO 2~5mg/L)刺参体腔液中ACP、AKP、LZM活性出现短暂升高。恢复性试验中,盐度20、25组对AKP活性和盐度20、40组对SOD活性的影响未恢复到初始水平,其余实验组均能恢复至初始水平,说明低盐对刺参免疫力的影响较大。充纯氧组刺参的AKP活性显著高于充空气组,表明高溶解氧水平在一定程度上提高了刺参免疫力。     

草鱼单养和混养池塘的水质与生物组成特征

为比较单养、混养草鱼(Ctenopharyngodon idella)养殖池塘的水质与生物组成特点，采取水质分析、环境DNA与传统鉴别方法对草鱼单养、混养(80:20)两类池塘的水质变化、浮游生物、底栖生物、菌群结构进行了分析。结果表明，混养池塘的水质优于单养池塘，混养池塘水体中总氮(TN)、硝态氮(NO_3^--N)、氨氮(NH_4⁺-N)、亚硝态氮(NO_2^--N)的浓度比单养池塘分别低10.15%、3.78%、5.07%、80.18%，总磷(TP)和活性磷(SRP)的浓度分别低27.14%和56.26%；两类池塘中浮游植物均以绿藻门(Chlorophyta)、蓝藻门(Cyanophyta)、隐藻门(Cryptophyta)为优势种，但单养池塘中的藻类密度为30×10^₆cells/L，低于混养池塘104×10^₆cells/L；两类池塘中的浮游动物均以轮虫和原生动物为优势种，枝角类和桡足类生物数量较少，单养池塘中浮游动物密度高于混养池塘；在底栖动物方面，单养池塘存在螺类、水蚯蚓和摇蚊幼虫，而混养池塘仅有螺类和摇蚊幼虫。在菌群组成方面，单养池塘水体中以厚壁菌门(Firmicutes)为优势类群，混养池塘水体中以变形菌门(Proteobacteria)为优势类群；但在两类池塘底泥中，均以变形菌门为优势类群。以上结果表明，草鱼混养有利于改善养殖池塘水质，增加浮游植物丰富度，改变养殖水体菌群的结构。本研究为优化草鱼池塘养殖结构，改善水质，构建高效池塘养殖模式提供了依据。     

Bacterial Change in the Gut and Hepatopancreas of Tiger Shrimp Reared in Bioaugmented System

The study was conducted in nine 150‐L capacity glass aquaria for 192 h to determine the changes in the microflora in the gut and hepatopancreas of tiger shrimp, Penaeus monodon, after bioaugmenting (water treatment and probiotics). Results showed that luminous bacterial counts were significantly lower in bioaugmented than in nonbioaugmented systems (range 0–5.9 × 10³ cfu/g and 0–3.2 × 10³ cfu/g in gut and hepatopancreas, respectively). Biochemical tests of isolates showed that the bioaugmented systems were dominated by Gram‐positive Bacillus and Streptococcus and the Gram‐negative Vibrio dominated the control. In water‐treated and probiotics‐fed bioaugmented system, the change in bacterial dominance to Bacillus became evident 2 h in the gut and 24 h in the hepatopancreas. Bacterial dominance shifted to Vibrio species after 120 h. Shrimp in the control were observed to become lethargic after 72 h as Vibrio species significantly increased in number. Dissolved oxygen and unionized ammonia levels were significantly lower in bioaugmented system compared with the control.     

健康和患病凡纳滨对虾幼虾消化道菌群结构的比较

凡纳滨对虾养殖过程中,早期阶段是病害易感阶段,而消化道菌群结构与对虾健康关系密切。因此,探讨幼虾的消化道菌群尤其是弧菌类细菌与对虾发病的关系对病害有效防治具有重要意义。本实验采用Illumina测序研究了凡纳滨对虾健康和患病幼虾的消化道细菌群落结构,并基于纯培养和16S r DNA,rec A和pyr H基因序列比对,分析了幼虾消化道中弧菌的主要种类组成。结果发现,健康幼虾消化道中α-变形菌纲和厚壁菌门丰度较高,而患病幼虾中γ-变形菌纲、拟杆菌门、放线菌门和β-变形菌纲较高,其中放线菌门丰度差异显著。基于科水平的响应比分析,发现患病幼虾消化道中动性球菌科和噬菌弧菌科的丰度显著降低,而弧菌科的丰度显著升高。相似度分析发现,驱动群落变异的OTU主要来源于弧菌属、海洋杆状菌属、冷杆菌属、假交替单胞菌属以及未分类至属的红杆菌科和微杆菌科。健康幼虾消化道弧菌组成以锡那罗亚州弧菌为主,而患病幼虾消化道弧菌组成以坎氏弧菌为主。尽管健康和患病幼虾消化道内细菌群落结构整体差异不显著,但一些重要类群丰度变化显著,其特征与已知的生态功能一致。     

Use of molasses as a carbon source during the nursery rearing of Farfantepenaeus brasiliensis (Latreille, 1817) in a Biofloc technology system

The present work evaluated the use of molasses as a carbon source during the nursery rearing of Farfantepenaeus brasiliensis in a Biofloc technology system. During a 30 days trial, three replicate tanks were randomly assigned to the following treatments: 1.) molasses (with molasses addition) and 2.) control (without molasses addition). Bacteriological analysis was used to quantify the abundance of presumptive Vibrio spp. between control and molasses treatment. The concentration of this microorganism was lower in molasses compared with control. For the immunological analysis, shrimp haemolymph was collected to determine the total haemocyte count and the total protein concentration. The immunological results were not different between treatments. The performance results of shrimp reared with molasses addition showed that the survival rate (88.87 ± 6.36), the mean final weight (1.22 ± 0.38) and the specific growth rate (0.0309 ± 1.06) were significantly higher compared with control (80.5 ± 2.42; 1.03 ± 0.13; 0.0256 ± 0.97 respectively). Moreover, the addition of molasses contributed to the maintenance of water quality and lower concentration of presumptive Vibrio spp. The control presented an unstable variation of Vibrio spp. reaching values of 80 × 10² CFU/ml, while the highest result of molasses was 20 × 10² CFU/ml, confirming the beneficial effects of molasses addition.     

The use of probiotics during the nursery rearing of the pink shrimp Farfantepenaeus brasiliensis (Latreille, 1817) in a zero exchange system

The present work evaluated the use of probiotics during the nursery rearing of the pink shrimp Farfantepenaeus brasiliensis, in a zero exchange aerobic heterotrophic culture system during 30 days. Three replicate tanks were randomly assigned to the following treatments: (1) Bacillus spp. mixture (Sanolife Pro‐‐W^®), (2) Bacillus sp., Enterococcus sp., Lactobacillus spp. mixture (Biomin Start‐grow^®), (3) Bacillus cereus var. toyoi and (4) control treatment (without probiotic addition). Bacteriological analysis monitored the abundance of presumptive Vibrio spp. in the water of experimental tanks. For the immunological analysis, shrimp haemolymph was collected to determine the granular haemocyte count and total protein concentration. Results showed that mean final weight and specific growth rate of shrimp in the probiotic treatments were significantly higher. Furthermore, shrimp reared in the probiotic treatments showed higher levels of total protein and granular haemocyte. The bacteriological analysis showed that the concentration of Vibrio spp. measured in probiotic treatment tanks was lower than that recorded in the control tanks.     

Delivery of HUFA, probionts and biomedicine through bioencapsulated Artemia as a means to enhance the growth and survival and reduce the pathogenesity in shrimp Penaeus monodon postlarvae

One of the major problems in the shrimp culture industry is the difficulty in producing high-quality shrimp larvae. In larviculture, quality feeds containing a high content of highly unsaturated fatty acids (HUFA) and ingredients that stimulate stress and disease resistance are essential to produce healthy shrimp larvae. In the present study, Penaeus monodon postlarvae (PL15) were fed for 25 days on an unenriched Artemia diet (control; A) or on a diet of Artemia enriched with either HUFA-rich liver oil of the trash fish Odonus niger (B), probionts [Lactobacillus acidophilus (C1) or yeast-Saccharomyces cerevisiae (C2)] or biomedicinal herbal products (D) that have anti-stress, growth-promoting and anti-microbial characteristics. P. monodon postlarvae fed unenriched Artemia exhibited the lowest weight gain (227.9 ± 8.30 mg) and specific growth rate (9.95 ± 0.05%), while those fed the HUFA-enriched Artemia (B) exhibited the highest weight gain and specific growth rate (362.34 ± 12.56 mg and 11.77 ± 0.08%, respectively). At the end of the 25-day rearing experiment, the shrimp postlarvae (PL40) were subjected to a salinity stress study. At both low and high (0 and 50‰) salinities, the group fed the control diet (A) experienced the highest cumulative mortality indices (CMI) 935.7 ± 2.1 and 1270.7 ± 3.1, respectively. Those fed diet D showed the lowest stress-induced mortality, and CMI were reduced by 31.1 and 32.3% under conditions of low and high salinity stress, respectively. A 10-day disease challenge test was conducted with the P. monodon postlarvae (PL40–PL50) by inoculating the shrimp with the pathogen Vibrio harveyi at the rate of 10⁵–10⁷ CFU/ml in all rearing tanks. P. monodon postlarvae fed probiont-encapsulated Artemia diets (C1 and C2) exhibited the highest survival (94.3 and 82.3%, respectively) and lowest pathogen load (V. harveyi) in hepatopancreas (5.2 × 10² ± 9.0 × 10 and 4.6 × 10² ± 9.0 × 10 CFU g⁻¹, respectively) and muscle (2.0 × 10² ± 6 × 10 and 1.7 × 10² ± 8.6 × 10 CFU g⁻¹, respectively) tissues. The shrimp that were fed the unenriched Artemia (Control; A) showed the lowest survival (26.33%) and highest bacterial load in the hepatopancreas (1.0 × 10⁵ ± 5 × 10³ CFU g⁻¹) and muscle (3.6 × 10⁴ ± 6 × 10² CFU g⁻¹). The shrimp fed the herbal product (D)-enriched Artemia also exhibited enhanced survival and reduced V. harveyi load in the tissues tested compared to the control diet (A) group. The results are discussed in terms of developing a quality larval feed to produce healthy shrimp larvae.     

A novel research on isolation and characterization of Photobacterium damselae subsp. damselae from Pacific white shrimp,Penaeus vannamei,displaying black gill disease cultured in China

In June 2019, massive mortalities of cultured Penaeus vannamei occurred in a local farm in Hainan Province, China. The diseased shrimp displayed evident black gills. Three bacterial strains 20190611001, 20190611007 and 20190611022 were isolated from hepatopancreas and gills of the diseased shrimp and identified as Photobacterium damselae subsp. damselae based on the sequence analysis of 16S rRNA and toxR genes. These three isolates showed haemolytic activities. Of them, strain 20190611022 isolated from hepatopancreas was selected and processed for pathogenic analysis. The calculated median lethal dose (LD₅₀) was 9.75 ± 4.29 × 10⁵CFU/g (body weight) by challenging P. vannameivia reverse gavage. The diseased shrimp displayed enlarged hepatopancreatic tubules and sloughing of epithelial cells in tubular lumens. The strain 20190611022 was also characterized by the testing of API 20NE systems and antibiotic susceptibility. The results of disc diffusion test showed that strain 20190611022 was sensitive to chloramphenicol, compound sulfamethoxazole, cefoperazone, ceftriaxone, ceftazidime and cefuroxime. To our knowledge, this is the first report of isolation and characterization of Photobacterium damselae subsp. damselae from natural diseased P. vannamei. Our findings can serve as a basis for further studies of its pathogenicity and provide technological support for disease controlling in shrimp aquaculture.     

Probiotic bacteria effects on growth and bacterial composition of black tiger shrimp (Penaeus monodon)

The effects of Bacillus probiotic forms on growth performance and microbiota were examined in black tiger shrimp (Penaeus monodon). Shrimp were fed for 120 days with one of three diets; a control diet alone or supplemented with either probiotics consisting of live‐sprayed Bacillus (LS) or freeze‐dried Bacillus (FD). Culturable bacteria counts in the hepatopancreas, intestine and culture water of the three treatments were relatively constant during the experiment. Bacillus numbers in the hepatopancreas and intestines of probiotic‐treated groups increased significantly (P < 0.05) after 30 treatment days and remained relatively constant afterwards while no appreciable changes occurred in the control. Shrimp supplemented with LS and FD contained significantly lower concentrations of Vibrio (P < 0.05) in the hepatopancreas, intestine and culture water, compared to those in the control group. Shrimp treated with LS and FD probiotic bacteria showed a significant improvement (P < 0.05) in specific growth rate (SGR) and feed efficiency (FE), compared to those of control group. Probiotic bacteria have the potential to enhance shrimp culture by reducing Vibrio and improving growth performance.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.     

脊尾白虾“僵尸病”的初探

为确定2018年冬季以来江苏省沿海地区养殖脊尾白虾患“僵尸病”的病原及流行病学特点，实验采用LB培养基和PDA培养基从病虾血淋巴中分离得到直径为1~3 mm、边缘整齐、米黄色隆起菌落；人工回感实验结果显示，回感后的脊尾白虾表现出与自然患病脊尾白虾相同的症状，并在回感脊尾白虾体内也分离出了相同的菌株，符合科赫氏法则。对该菌株进行形态观察结合18S rRNA序列对比及系统发育分析，发现分离菌株MQ2101具有酵母的典型形态，且与二尖梅奇酵母相似度达99.82%，结果表明菌株MQ2101为二尖梅奇酵母。致病性结果初步分析显示，MQ2101对脊尾白虾的半致死浓度 (LD₅₀)为1.39×10⁷ CFU/尾。病理学观察发现，患病脊尾白虾鳃、肌肉和肝胰腺均发生不同程度的病变，其中肝胰腺病变最为严重，肝小管呈现空泡化，管腔体积变大；在鳃和肝胰腺组织中均存在大量定殖的菌体。流行病学调查结果显示，每年2—5月发病迅速，发病率为5%~30%，死亡率为3%~10%。本研究确定了二尖梅奇酵母为江苏沿海地区脊尾白虾“僵尸病”的病原，其对脊尾白虾具有较强致病性，主要侵染组织为肝胰腺和鳃。以上研究结果为脊尾白虾“僵尸病”的防控提供了相关科学依据。     

Vibrio spp. isolated from salmonids with shallow skin lesions and reared at low temperature

In Iceland the rearing temperature of salmonid fish, mostly Atlantic salmon, is generally below 10°C. Infections most often characterized by shallow skin lesions that may cause considerable mortality have been endemic in the country since rearing in salt water started. A variety of Vibrio spp. has been isolated from the diseased fish. In the present study, a total of 58 strains isolated from salmonid fish and 21 reference strains were subjected to a numerical taxonomy study. The results show that two phena are most common in the diseased fish; one of them includes V. marinus, whereas the other does not include a reference strain but has similarities to V. logei. Challenge tests showed that a representative strain of the phenon that included V. marinus is pathogenic for Atlantic salmon with an LD₅₀ lower than 3.5 × 10³.