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ABSTRACT:   Phytoplankton used in fish hatcheries is mass-cultured in the open air and usually contains large numbers of bacteria. In commercial fish production, the phytoplankton cultures are usually added into the larval rearing tanks; however, the numbers and types of bacteria introduced into the rearing tanks simultaneously are unknown. In this study, the bacterial community structures in Nannochloropsis sp. cultures were analyzed by using fluorescence in situ hybridization (FISH). A direct viable count (DVC)-FISH analysis was also performed as DVC is useful for the detection of actively growing cells. Total numbers of bacteria in Nannochloropsis sp. cultures ranged from 7.72 × 105−2.39 × 106 cells/mL. High proportions of the total bacteria (31.6–53.6%) in the Nannochloropsis sp. cultures showed growth potential. DVC-FISH analysis revealed that α-proteobacteria and the Cytophaga – Flavobacterium cluster were abundant in the bacterial community of actively growing cells. Thus, the high growth potentials of the distinct bacterial communities in Nannochloropsis sp. culture must influence the bacterial communities in larval rearing tanks.  相似文献
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Bacterial community structures were analyzed in water used for rearing fish larvae by fluorescence in situ hybridization. In Experiment 1, red sea bream Pagrus major larvae were reared in two commercial seed production tanks. The survival rate in Tank 1 was higher than in Tank 2, even though phytoplankton, Nannochloropsis sp., was added to both tanks. In Tank 2, γ-proteobacteria became dominant (∼70% of total bacteria) on day 13, there after heavy larval mortalities occurred. In Tank 1, however, α-proteobacteria and the Cytophaga-Flavobacterium cluster were predominant from day − 1 until day 13; no significant mortality was recorded. In Experiment 2, marble goby Oxyeleotris marmoratus larvae were cultured with or without Nannochloropsis sp. At the end of the experiment, larval survival rates in aquaria with Nannochloropsis sp. were significantly (P <0.05) higher than those without. In rearing water without Nannochloropsis sp., γ-proteobacteria increased during rearing. In rearing water with Nannochloropsis sp., α-prote obacteria and the Cytophaga-Flavobacterium cluster were predominant at the beginning of the experiments and the relative abundance of γ-proteobacteria was maintained at a lower level throughout the experiments. The predominance of α-proteobacteria and the Cytophaga-Flavobacterium cluster appears to be a good indicator of successful larval production.  相似文献
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采用PCR-DGGE分子指纹图谱技术研究了2007年夏季桑沟湾不同养殖区水体微生物群落结构特征。DGGE指纹图谱分析表明, 不同站位之间既存在共同图谱, 又具有各自的特征谱带, 总体上可分为4个区, 湾外区、湾口区, 湾中区和湾底区, 分别与非养殖区、海带养殖区、综合养殖区、贝类单养与网箱养殖区行相对应; 扇贝养殖区和牡蛎养殖区微生物相似性最高为94%, 贝类单养与网箱养殖区和非养殖区相似性最低为41%, 仅在网箱区发现对含氮污染物有去除作用的玫瑰杆菌属(Roseobacter)17个站位表层水样共获得30个优势菌群, 选择比较明显的12条带进行回收、扩增和测序, GenBank中已经登录的细菌种群的同源性进行比较(相似性92%~98%), 结果表明, 12条序列所代表的细菌分属于变形菌亚门(α-proteobacteriaγ-proteobacteria)、放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)。研究结果说明贝类单养和网箱养殖对环境的改变较大, 海带养殖对环境的改变较小, 综合养殖能减少贝类和网箱养殖对环境的污染程度, 是一种值得大力推广的养殖模式。

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为研究添加芽孢杆菌对池塘水体理化因子和细菌群落结构的影响,采用高通量测序技术分析了实验组(添加芽孢杆菌池塘)与对照组(普通池塘)水体和底泥细菌群落结构,同时分析了两种池塘水体和底泥的理化指标。结果显示,8、9月实验组池塘水体中TN、${\rm{NH}}_4^ + $-N和${\rm{NO}}_3^ - $-N含量显著低于对照组,底泥中的${\rm{NO}}_3^ - $-N、${\rm{NH}}_4^ + $-N、TN和TP含量显著高于对照组。实验组池塘水体中发酵单胞菌属(Zymomonas)、玫瑰单胞菌(Roseomonas)、脱氯单胞菌(Dechloromonas)和噬几丁质菌属(Chitinophaga)细菌丰度显著高于对照组。在这些细菌群落中,脱氯单胞菌、噬几丁质菌属有去除硝酸盐的作用,发酵单胞菌属、玫瑰单胞菌具有脱氮的功能。实验组池塘水体Chao1指数和Shannon指数显著高于对照组。水体中优势细菌群落中的噬氢菌属(Hydrogenophaga)、GeothermobacterHaliscomenobacter与硝酸盐、总磷呈负相关性,与氨氮、总氮呈正相关性。研究表明,通过向池塘添加芽孢杆菌,可以改变水体中细菌群落的结构,从而实现对池塘理化因素的调节。研究结果为降低水产养殖尾水对水域环境的污染具有一定的借鉴意义。  相似文献
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为提高对虾养殖系统水质净化能力,改善对虾养殖水环境,利用3种微生态制剂(枯草芽孢杆菌、硝化细菌、光合细菌)和2种生物膜载体(陶粒、纤维毛球)建立4个南美白对虾(Penaeus vannamei)养殖系统,比较不同养殖系统硝化功能的建立过程及对氨氮和亚硝酸盐氮的净化能力,采用高通量测序方法分析细菌群落结构。结果表明,各系统硝化功能建立后,24 h氨氮去除率较初期分别提高12.47%、13.95%、17.25%和17.65%。以纤维毛球为载体,投加硝化细菌、枯草芽孢杆菌和光合细菌系统的氨氧化能力和亚硝酸盐氧化能力强于陶粒系统,24 h氨氮去除率分别高9.03%和9.06%。投放虾苗后,在30 d养殖周期内各系统氨氮和亚硝酸盐氮含量分别维持在0.20 mg/L和0.15 mg/L以下,硝酸盐氮含量呈缓慢上升趋势。细菌群落结构分析表明养殖系统生物膜中优势菌门均为变形菌门,占比超40%;优势菌纲为α-变形菌纲、β-变形菌纲、γ-变形菌纲,系统中存在Nitrosomonas、Nitrospira和Nitrococcus等多种参与水体净化以及Algisphaera、Gemmatimonas和Paucibacter等参与有机质分解与对虾益生作用的类群。本研究可为减少养殖水体废物排放及降低水生环境污染风险提供参考。  相似文献
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采用16S rDNA-PCR 菌群分离鉴定的方法, 对循环水养殖条件下云纹石斑鱼(Epinehelus moara)幼鱼的胃、幽门盲囊、前肠、中肠和后肠的菌群结构进行了鉴定, 用产酶菌筛选培养法对产消化酶的菌株进行了分离鉴定, 并测试了各菌株消化酶的活力。研究发现, 云纹石斑鱼幼鱼消化道内可培养的主要菌群为假单胞菌属(Pseudomonas)、微小杆菌属(Exiguobacterium) 、不动杆菌属(Acinetobacter) 、寡养单胞菌属(Stenotrophomonas) 和葡萄球菌属(Staphylococcus), 其中产消化酶的菌株占可培养菌的55.6%。在产酶菌中, 同一株菌产3 种酶的有5 ; 2 种酶的有9 ; 中肠和后肠的菌株数最为丰富, 胃次之, 幽门盲囊和前肠菌群种类较少; 产脂肪酶的菌株都集中在中肠。产消化酶的菌株主要以产蛋白酶和淀粉酶为主, 且产酶量丰富, 产蛋白酶活力最高达(87.732±1.134) U/mL; 淀粉酶活力为(77.176±0.599)~(73.458±0.574) U/mL; 产纤维素酶的菌仅一株, 且酶活力较低。分析得知, 消化道的菌群结构直接影响了外源性消化酶的种类与活性。本研究为工厂化循环水养殖条件下产酶有益菌的筛选提供了理论依据。

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16S rDNA为分子标记, 通过构建克隆文库、限制性片段长度多态性(Restriction Fragment Length Polymorphism, RFLP)分析等技术手段, 研究大黄鱼(Larimichthys crocea)网箱养殖水体中细菌的群落结构。样品采自福建省宁德市三都湾富发养殖基地。随机选取5个不同养殖网箱水样混合, 3 L混合水样过滤富集细菌后提取总DNA, 用细菌通用引物27F1 492R扩增其16S rRNA基因, 构建克隆文库。从文库中随机挑选154个克隆子进行分析, 得到137个阳性克隆, 92RFLP带型。对部分代表性克隆子进行测序的结果表明, 大黄鱼养殖水体中细菌多样性非常丰富。序列分析结果显示, γ-变形菌纲的假交替单胞菌属(Pseudoalteromonas)细菌为最优势菌(γ-变形菌纲克隆子数的31.2%), 海源菌属(Idiomarina)次之(γ-变形菌纲克隆子数的15.1%)。此外还存在6.6%的厚壁菌门(Firmicutes)5.9%的拟杆菌门(Bacteroidetes)、各0.7%的浮霉状菌门(Planctomycetes)、绿屈挠菌门(Chloroflexi)、绿菌门(Chlorobi)细菌和OP11类群。本研究结果阐明了网箱养殖大黄鱼水体细菌的群落结构, 为大黄鱼养殖区病害防治、环境监测以及探讨大黄鱼健康养殖与养殖水体细菌间的关系奠定了基础。  相似文献
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