循环水养殖系统生物滤池细菌群落的PCR-DGGE分析

通过模拟实验对循环水养殖系统中不同初始NH ₄N浓度的生物滤池中生物膜上和水中的细菌数量及群落种类组成进行了研究。对成熟生物膜及水体样品中的异养菌、氨氧化菌、亚硝酸盐氧化菌的培养计数结果表明,随着生物滤池初始氨氮浓度增大,除异养细菌数量逐渐下降外,生物膜上的氨氧化菌和亚硝酸盐氧化菌数量呈逐渐增加趋势,且均高出水样3~4个数量级;同时对上述样品的16S rRNA基因片段的PCR扩增产物进行变性梯度凝胶电泳(DGGE)分析及其序列同源性分析的结果表明,生物膜和水中都有较高的细菌多样性,同一初始氨氮浓度的滤池中生物膜上的细菌多样性高于水中的。生物滤池中的细菌主要由拟杆菌门的黄杆菌纲和变形菌门的α-、β-、γ-变形菌纲的15种细菌组成。生物膜上的优势菌包括奥雷氏菌属、湖饲养者菌属、泥滩杆菌属、沉积杆菌属、雷辛格氏菌属、冷蛇形菌属和亚硝化单胞菌属等;水体中的优势菌则有明显差异,主要有蛋黄色杆菌属、Nautella,玫瑰杆菌属和一种硫氧化菌等。初始氨氮越高的滤池中,亚硝化单胞菌属的细菌在生物膜上所占比例越高,逐渐成为优势菌之一。实验证实,挂膜初期,提高水体中初始氨氮浓度,有利于硝化细菌的富集和固着,提高生物滤池的除氮效率。     

墨瑞鳕循环水养殖系统中不同生物膜反应器水处理效率及微生物群落对比分析

固定床生物膜反应器(fixed-bed biofilm bioreactor, FBBR)和移动床生物膜反应器(moving- bed biofilm reactor, MBBR)在养殖水体氨氮(NH4+-N)和亚硝酸氮(NO2–-N)污染控制中已有较为广泛的研究,然而相关研究大多是在实验室完成的,目前尚缺乏实际生产的循环水养殖系统(recirculating aquaculture system, RAS)中FBBR和MBBR水体净化效能的对比研究。因此,本研究将FBBR (弹性毛刷滤料)和MBBR (PVC多孔环滤料)并联接入实际生产的墨瑞鳕(Macculochella peeli) RAS中,实现二者的同步连续运行(35 d),考察了其出水水质变化和微生物群落结构。出水水质变化表明,FBBR和MBBR中氨氧化能力的形成快于亚硝氮氧化能力,硝化能力渐趋成熟,可以有效控制养殖水体中的NH4+-N和NO2–-N浓度,但会导致养殖水体中硝酸氮(NO3–-N)积累和pH下降;单因素方差分析表明,FBBR出水中NH4+-N、NO2–-N、NO3–-N浓度和pH与MBBR出水无显著差异,两反应器的硝化效率相似。FBBR和MBBR在微生物群落上的相同点在于：优势菌门为变形菌门(Proteobacteria) (相对丰度分别为69.42%和86.92%),优势菌纲为γ-变形菌纲(γ-Proteobacteria) (40.71%和63.36%)和α-变形菌纲(α-Proteobacteria) (26.58%和21.74%),优势菌属为不动杆菌属(Acinetobacter) (27.50%和53.29%);硝化菌由亚硝化单胞菌属(Nitrosomonas)和硝化螺菌属(Nitrospira)构成;硝化螺菌属的相对丰度远高于亚硝化单胞菌属,两反应器中可能存在完全氨氧化菌。两反应器在微生物群落上的不同点在于FBBR微生物群落的丰富度和多样性以及硝化菌的相对丰度均高于MBBR。本研究可以为RAS养殖水体净化提供技术支撑,助推循环水养殖模式的推广应用。     

凡纳滨对虾(Litopenaeus vannamei)循环水养殖塘挂膜式生物滤器内微生物的多样性

为了解凡纳滨对虾(Litopenaeus vannamei)养殖过程中挂膜式生物滤器内不同位置间微生物群落结构多样性的差异,采集已运行46 d的挂膜式生物滤器内挂膜上部外侧和内侧、下部内侧和外侧及收集盘5个不同位置的微生物,采用分子生物学手段,通过16S rRNA基因高通量测序法对生物滤器内微生物进行多样性分析,并对不同位置间功能性微生物进行对比.结果显示,在门水平上,5个不同位置共鉴定出10个主要类群,其中,变形菌门(Proteobacteria)所占丰度比例较大,为主要优势类群,硝化螺旋菌门(Nitrospirae)在挂膜内外两侧检出比例均较高(平均4.3％),收集盘内则较低(0.33％),存在显著性差异.共鉴定出41种优势属,其中地杆菌属(Pedobacter)为绝对优势种属,短小盒菌属(Parvularcula)为次优势属,二者丰度比例均在10％以上,硝化螺旋菌属(Nitrospira)为第三优势属,挂膜不同位置丰度比例(平均4.31％)显著高于收集盘内比例(0.28％).挂膜上氨氧化细菌(AOB)平均丰度比例为1.70％,硝化细菌(NOB)平均比例为6.99％,是系统中主要去除氨氮和亚硝酸氮的微生物.生物滤器各部位微生物物种多样性丰富,微生态系统稳定,可有效维持循环水系统的水质.生物滤器硝化作用主要在上部进行,下部净化能力较弱,收集盘内基本没有硝化能力.生产中应合理配置挂膜数量,科学设计挂膜长度以提高生物滤器的净化效率.     

对虾海水池塘养殖固形废弃物集污效率以及尾水处理研究

为加快推进水产养殖业绿色发展，解决对虾海水池塘养殖面源污染以及产业发展与生态保护之间矛盾，研究了对虾海水池塘养殖固形废弃物集污效率与尾水生态处理技术。采用自行设计的沉淀塔进行固废收集，三级上向垂直流处理桶利用硝化-反硝化-再硝化处理工艺进行尾水脱氮处理。结果显示，在对虾池塘实际养殖过程中，养殖前期、中期与后期，沉淀塔对固形废弃物集污效率分别为10.6%±1.8%、31.1%±5.7%、52.2%±5.2%;总氮集污效率分别为1.4%±0.2%、3.4%±0.6%、9.1%±0.1%。三级上向垂直流处理桶均装填生物毛刷，自然挂膜60 d后，分别进行溶氧控制30 d,溶氧质量浓度分别为1.11～1.98 mg/L、0.27～0.45 mg/L、4.60～5.82 mg/L。经测定分析，三级处理桶总氮、氨氮去除率可以达到45.5%与93.6%,将处理桶中的毛刷进行高通量测序分析，发现第三级处理桶中硝化细菌丰度最高，主要包括亚硝化单胞菌属(Nitrosomonas)、亚硝化螺菌属(Nitrosospira)、硝化螺菌属(Nitrospira)。本研究构建了“沉淀塔固废集污”+“三级上向垂直流处...     

日本鳗鲡腐皮病病原菌的分离及鉴定

从患腐皮病的日本鳗鲡(Anguilla japonica)体表溃烂处分离到1株病原菌(322A),对其进行了人工感染实验和生理生化分析,测定了该菌株的16S rRNA基因序列和促旋酶(gyrase)B亚单位gyrB基因序列,并分别构建系统发育树。结果显示:感染实验证实菌株322A具有致病性;生理生化分析鉴定该菌株属于气单胞菌属(Aero-monassp.);16S rRNA基因分析显示,该菌株与气单胞菌属细菌的同源性均在99%~100%,构建的系统树显示,菌株322A与嗜水气单胞菌(A.hydrophila(FJ462702))亲缘关系最近;gyrB基因分析表明,该菌株与A.hydrophila种内序列的相似性为96%~98%,种间序列的相似性为94%~95%,构建的系统树结果显示,该菌株与A.hydrophila(FJ608553、FJ608552、AF208259)聚为一个分支。综合上述实验结果,菌株322A可鉴定为嗜水气单胞菌(A.hydrophila)。     

大口黑鲈源维氏气单胞菌的分离鉴定

为查明2020年春季广东省佛山市某养殖场人工养殖大口黑鲈(Micropterus salmoides)鱼苗出现暴发性死亡的病因,该研究对患病大口黑鲈鱼苗肝脏组织中分离的一株细菌GZXR2020进行了分子鉴定,PCR扩增获得该菌株的16S rRNA基因和gyrB基因全长序列,BLAST显示其与维氏气单胞菌(Aeromon...     

双斑东方鲀循环水养殖水体细菌群落结构分析

利用16S rRNA高通量基因测序技术研究了双斑东方鲀(Fugu bimaculatus)循环水养殖系统养殖水体细菌种群结构特征,并比较养殖患病(溃疡症)的双斑东方鲀的水体细菌群落结构与健康的之间的差异,探讨细菌群落结构与双斑东方鲀细菌性病害发生的相关性。研究结果表明,双斑东方鲀循环水养殖水体细菌群落的优势细菌门为变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes),优势细菌纲为γ-变形菌纲(Gammaproteobacteria)、黄杆菌纲(Flavobacteriia)、α-变形菌纲(Alphaproteobacteria),优势细菌目为黄杆菌目(Flavobacteriales)、硫发菌目(Thiotrichales)、红细菌目(Rhodobacterales)、交替单胞菌目(Alteromonadales)、弧菌目(Vibrionales),优势细菌科为黄杆菌科(Flavobacteriaceae)、硫发菌科(Thiotrichaceae)、红细菌科(Rhodobacteraceae)、弧菌科(Vibrionaceae)、交替假单胞菌科(Pseudoalteromonadaceae)。患病的和健康的循环水养殖水体细菌群落种类组成相似度高,细菌群落多样性指数无较大差异,在同一分类水平上各细菌群落丰度占比差异显著;二者核心微生物(属)的差异明显,健康的循环水养殖水体核心细菌群落以Polaribacter属为主;患病的循环水养殖水体核心细菌群落以弧菌科的发光杆菌属(Photobacterium)和弧菌属(Vibrio)为主,而发光杆菌属和弧菌属的多数种类属于病原菌或条件致病菌。双斑东方鲀患病(溃疡症)与养殖水体细菌群落的弧菌属丰度占比高有关。该研究结果对双斑东方鲀循环水养殖细菌性病害的监测、预警、诊断及管理控制具有重要的意义。     

海南三亚斑节对虾野生种群mtDNA 16S rRNA基因和控制区序列的多态性

采用聚合酶链式反应(PCR)技术对海南三亚野生斑节对虾(Penaeus monodon)20个个体的mtDNA 16S rRNA基因和控制区序列进行扩增,PCR产物经纯化后进行测序,得到16S rRNA基因的495 bp的核苷酸序列和控制区序列470 bp的核苷酸片段.用Clustal X软件对16S rRNA和控制区序列进行了比对,通过ARLEQUIN 2000软件对所得线粒体16S rRNA基因片段和控制区序列进行了比较分析.16S rRNA序列检测出17个多态位点,8种单倍型;控制区序列检测出100个多态位点,17种单倍型.该种群16S rRNA序列基因多样度(H)和碱基多样度(π)分别为0.700和0.0045;控制区序列的H和π分别为0.984和0.0480.研究结果表明16S rRNA序列不适应斑节对虾的种群遗传多样性分析;控制区序列适应斑节对虾种群遗传多样性研究.     

凡纳滨对虾(Litopenaeus vannamei)循环水养殖塘挂膜式生物滤器内微生物的多样性

为了解凡纳滨对虾(Litopenaeus vannamei)养殖过程中挂膜式生物滤器内不同位置间微生物群落结构多样性的差异,采集已运行46 d的挂膜式生物滤器内挂膜上部外侧和内侧、下部内侧和外侧及收集盘5个不同位置的微生物,采用分子生物学手段,通过16S r RNA基因高通量测序法对生物滤器内微生物进行多样性分析,并对不同位置间功能性微生物进行对比。结果显示,在门水平上,5个不同位置共鉴定出10个主要类群,其中,变形菌门(Proteobacteria)所占丰度比例较大,为主要优势类群,硝化螺旋菌门(Nitrospirae)在挂膜内外两侧检出比例均较高(平均4.3%),收集盘内则较低(0.33%),存在显著性差异。共鉴定出41种优势属,其中地杆菌属(Pedobacter)为绝对优势种属,短小盒菌属(Parvularcula)为次优势属,二者丰度比例均在10%以上,硝化螺旋菌属(Nitrospira)为第三优势属,挂膜不同位置丰度比例(平均4.31%)显著高于收集盘内比例(0.28%)。挂膜上氨氧化细菌(AOB)平均丰度比例为1.70%,硝化细菌(NOB)平均比例为6.99%,是系统中主要去除氨氮和亚硝酸氮的微生物。生物滤器各部位微生物物种多样性丰富,微生态系统稳定,可有效维持循环水系统的水质。生物滤器硝化作用主要在上部进行,下部净化能力较弱,收集盘内基本没有硝化能力。生产中应合理配置挂膜数量,科学设计挂膜长度以提高生物滤器的净化效率。     

海南三亚斑节对虾野生种群mtDNA 16S rRNA基因和控制区序列的多态性

采用聚合酶链式反应(PCR)技术对海南三亚野生斑节对虾(Penaeus monodon)20个个体的mtDNA 16S rRNA基因和控制区序列进行扩增,PCR产物经纯化后进行测序,得到16S rRNA基因的495 bp的核苷酸序列和控制区序列470 bp的核苷酸片段。用Clustal X软件对16S rRNA和控制区序列进行了比对,通过ARLEQUIN 2000软件对所得线粒体16S rRNA基因片段和控制区序列进行了比较分析。16S rRNA序列检测出17个多态位点,8种单倍型；控制区序列检测出100个多态位点,17种单倍型。该种群16S rRNA序列基因多样度(H)和碱基多样度(π)分别为0．700和0．0045；控制区序列的H和π分别为0．984和0．0480。研究结果表明：16S rRNA序列不适应斑节对虾的种群遗传多样性分析；控制区序列适应斑节对虾种群遗传多样性研究。     

Variability of the nitrifying bacteria in the biofilm and water column of a recirculating aquaculture system for tilapia (Oreochromis niloticus) production

The aim of this study was to evaluate variability of nitrifying bacterial community in the biofilm and in the water of a recirculating aquaculture systems (RAS) in a tilapia farming in order to determine if nitrification process is dependent, or not, of nitrifying bacteria abundance. Biofilm and water samples were collected periodically for 30 days and analysed with the fluorescent in situ hybridization (FISH) technique, used to quantify ammonia‐oxidizing bacteria (AOB) and nitrite‐oxidizing bacteria (NOB). Ammonia presented the peak in the first week, while the nitrite's maximum was recorded in the second week. Nitrate increased steadily, indicating nitrification activity. Total bacterial abundance in biofilm increased continuously, while in water, it did not change significantly. In the biofilm, number of AOB was high at beginning, decreased after few days and increased again following augment of ammonia. Number of NOB also showed an increase in abundance in biofilm following the increment of nitrite and nitrate. In water, AOB and NOB did not show major variability. Relative abundance of nitrifying bacteria represented more than 30% of total bacteria in biofilm at beginning of the experiment. Their contribution decreased to >3% in last days. It indicates that nitrifying bacteria are biofilm colonizers, and that their activity seems to be directly related to the concentration of nitrogen compounds. However, contribution of nitrifying bacteria did not vary much along the time. We may conclude that the biofilm‐nitrifying bacteria plays major role in nitrification process in RAS and that the activity of these organisms is dependent of their abundance in response to the concentration of nitrogen compounds.     

Impact of ozonation and residual ozone-produced oxidants on the nitrification performance of moving-bed biofilters from marine recirculating aquaculture systems

In marine recirculating aquaculture systems (RAS) ozone is often used in combination with biofiltration for the improvement of process water quality. Especially for disinfection purposes ozone residuals are required, that lead to a fast formation of secondary oxidants in seawater, summed up as ozone-produced oxidants (OPO). We studied the impact of OPO on nitrifying biofilter bacteria in a series of laboratory batch experiments by exposing (i) cell suspensions of the ammonia-oxidizing bacteria (AOB) Nitrosomonas marina strain 22 and the nitrite-oxidizing bacteria (NOB) Nitrospira strain Ecomares 2.1, (ii) a pure culture of the NOB Nitrospira strain immobilized on biocarriers, as well as (iii) a heterogeneous biofilm culture settled on biocarriers from a marine RAS for 1 h to different OPO concentrations up to 0.6 mg/l chlorine equivalent. Subsequent activity tests detected a negative linear correlation between OPO concentration and nitrifying activity of suspended pure cultures. Immobilization on biocarriers increased the tolerance of AOB and NOB dramatically, suggesting the biofilm matrix to be highly protective against OPO. Furthermore, we investigated the chronic effect of moderate ozonation at OPO concentrations of 0, 0.05, 0.10 and 0.15 mg/l chlorine equivalent on biofilter performance in a 21 d exposure experiment using 12 experimental RAS, stocked with tilapia (Oreochromis niloticus). Chronic exposure experiments could not reveal any harmful impact on biofilter performance for OPO concentrations up to 0.15 mg/l, even at continuous exposure. Surprisingly, nitrifying activity was enhanced at all OPO concentrations compared to the control without ozonation, suggesting moderate ozonation to promote biological nitrification. It can be concluded that rather health, welfare and performance of most cultivated fish species are the limiting factors for ozone dosage than nitrification performance of biofilters. The results may further have practical implications in relation to design and operational strategy of water treatment processes in RAS and might thus contribute to the optimization of an effective and safe treatment combination of biofiltration and ozonation.     

Effects of formaldehyde on nitrification in biofilters of small‐scale recirculating systems

Florfenicol (Aquaflor®) is the only U.S. Food and Drug Administration (FDA) approved drug for treating diseased fish reared in recirculating aquaculture systems (RAS). Treating diseased fish in RAS is challenging because of the potential to damage nitrifying bacteria in the biofilters. Impaired nitrification can lead to concentrations of ammonia and nitrite that compromise fish welfare. The objective of this study was to determine the effects of a FDA‐approved parasiticide and fungicide, Parasite‐S^® (formalin), on biofilter nitrification. Stable biofilters were exposed once to 0, 9.25, 18.5, 37, or 55.5 mg/L formaldehyde. Total ammonia nitrogen (TAN) and nitrite nitrogen were monitored daily before and throughout the study to quantify biofilter function. Formaldehyde concentrations ≥37 mg/L increased TAN and nitrite nitrogen concentrations, and nitrification did not recover to pre‐exposure concentrations up to 8 day postexposure. On the basis of those results, a second trial was conducted. Stable biofilters were exposed once or on four consecutive days to 9.25 or 18.5 mg/L formaldehyde. Biofilters repeatedly exposed to formaldehyde showed signs of impairment and had variable recovery relative to single exposures. Results of this study may help identify formaldehyde concentrations that can be safely applied to RAS when treating diseased fish.     

Use of an internal fibrous biofilter for intermittent nitrification and denitrification treatments in a zero-discharge shrimp culture tank

To achieve water reuse in recirculating aquaculture systems, intermittent nitrification and denitrification processes using internal fibrous media was proposed. A pre-acclimated Biocord biofilter, with an initial nitrification rate of 17.1 ± 12.4 mg total ammonia nitrogen-N/m²/d was applied in a marine whiteleg shrimp (Litopenaeus vannamei) culture tank. Throughout the experiment, the aerobic nitrification activity of the biofilter was sufficient to control the ammonia and nitrite levels below 0.2 mg-N/L with an accumulation of nitrate up to 50 mg-N/L. The remaining nitrate was successfully removed after shrimp harvest with the same biofilter through anoxic denitrification in conjunction with a methanol supplement at a chemical oxygen demand: nitrate-N ratio of 5:1. With complete nitrogen removal, the water was re-aerated and the next crop of shrimp culture was initiated. In this study, a two-crop shrimp cultivation was performed in sequence in the same tank without water exchange. The microbial diversity was monitored using high-throughput sequencing on Illumina MiSeq, which demonstrated that Proteobacteria (45.3 %), Chloroflexi (18.4 %), and Bacteroidetes (17.1 %) were the most abundant phyla. With an emphasis on nitrogen removal, the family Nitrosomonadaceae and Nitrospiraceae were the dominant nitrifying bacteria during the aerobic nitrification, while a high relative abundance of the Methylophaga and Methylotenera genera was observed under the anoxic condition.     

A case study of biofilter activation and microbial nitrification in a marine recirculation aquaculture system for rearing Atlantic salmon (Salmo salar L.)

Marine recirculation aquaculture system (RAS) is a prominent technology within fish farming. However, the nitrifying bacteria in the biofilter have low growth rates, which can make the biofilter activation a long and delicate process with periods of low nitrification rates and variations in water quality. More knowledge on the microbial development in biofilters is therefore needed in order to understand the rearing conditions that favour optimal activation of the biofilters. In this case study, we investigated the activation of two biofilters in a marine RAS for Atlantic salmon post‐smolt associated with either high or low stocking densities of fish by monitoring the microbial communities and chemical composition. The results showed that the microbial communities in both biofilters were similar during the first rearing cycle, despite variations in the water quality. Nitrifying bacteria were established in both biofilters; however, the biofilter associated with low stocking density had the highest relative abundance of ammonia‐oxidizing Nitrosococcus (1.0%) and nitrite‐oxidizing Nitrospira (2.1%) at the end of the first rearing cycle, while the relative abundance of ammonia‐oxidizing Nitrosomonas (2.3%–2.9%) was similar in both biofilters. Our study showed that low fish stocking density during the first rearing cycle provided low and steady concentrations of ammonium, nitrite and organic load, which can stimulate rapid development of a nitrifying population in new marine RAS biofilters.     

Taxonomic and functional profiling of nitrifying biofilms in freshwater,brackish and marine RAS biofilters

In recirculating aquaculture systems (RAS), the crucial step of eliminating toxic N compounds like ammonia and nitrite is mediated via nitrifying microorganisms and takes place in biofilters. In this study, analyses of microorganisms colonizing biocarriers of nine moving-bed biofilters of three different RAS operated with freshwater, brackish or marine process water uncovered site specific communities. Illumina-based amplicon sequencing of the V4-region of the 16S rRNA gene revealed a high microbial diversity with 1000–2500 species-level operational taxonomic units (OTUs) in all biofilters with the highest diversity in the brackish RAS. Proteobacteria, Bacteriodetes, Plantomycetes, Chloroflexi and Nitrospirae represented the most abundant phyla. 76 out of 674 known genera occurred in all nine biofilters and were defined as core-taxa, including nitrifying bacteria (Nitrosomonas and Nitrospira) as well as members of the (heterotrophic) genera Planctomyces, Blastopirellula, Nannocystis and Lewinella. Nitrifying communities composed of different, closely related and so far uncultured members of Nitrosomonas and Nitrospira were identified, strongly indicating that several potentially novel ammonia and nitrite oxidizing species are present in RAS biofilters. Relatives of known comammox Nitrospira were detected in the brackish biofilters, revealing 94–99 % identity of the 16S rRNA gene sequence to Ns. inopinata. Salinity tolerance tests with biocarriers derived from biofilters of the three distinct RAS showed an unexpected broad physiological flexibility with regard to salinity. Nitrification performance of freshwater nitrifiers was drastically reduced with increasing salinity and nearly completely inhibited at 15 PSU, while the brackish and marine nitrifiers showed a high resistance and maintained nitrification activity in a broad range of salt concentrations. This data can help to improve the nitrification process in RAS with changing salinity of the process water.     

Effect of particulate organic carbon on heterotrophic bacterial populations and nitrification efficiency in biological filters

Competition between heterotrophic and nitrifying bacteria is of major practical importance in aquaculture biofilter design and operation. This competition must be understood to minimize the negative impact of heterotrophic bacteria on an aquaculture system. On the other hand, the heterotrophic population is suspected of having a positive effect against pathogenic bacteria. Little information is available on the bacterial communities present within aquaculture systems, except for nitrifying bacteria, but a combination of traditional aquacultural engineering research methods and novel microbiological techniques offers new opportunities for the study of these communities.

The heterotrophic bacterial population activity and the nitrification efficiency of a submerged biological filter were studied for an influent TAN concentration of 2 mg/l and varying C/N ratios. The TAN removal rate was found to be 30% lower at a C/N ratio of 0.5 than at a C/N ratio of 0. For higher C/N ratios the reduction in nitrification efficiency was 50% while the attached bacterial abundance was doubled. Moreover, results confirm that abundance of sheared and attached bacteria are correlated. It is not known to what extent biofilter configuration might influence the relationship between heterotrophic and nitrifying bacteria, and further work will be carried out with moving bed and fluidized filters. A better understanding of the role of the heterotrophic bacteria in RAS will help to optimize any positive “biocontrol” effect and to minimize the microbial degradation of rearing water and the reduction of nitrification rates.     

生物强化移动床生物膜反应器处理水产养殖循环水初步研究

利用自制的硝化细菌菌剂促进移动床生物膜反应器(Moving bed biofilm reactor,MBBR)的挂膜启动,分析不同载体氨氮负荷、碳氮比条件下反应器运行状况,并进一步进行了实验室模拟循环水养殖草金鱼实验。结果显示,利用自制硝化菌剂能够完成整个移动床反应器的启动过程,在接种15 d后使循环出水氨氮稳定在1 mg/L以下。单位体积载体氨氮负荷实验表明,MBBR能够在100 mg TAN/(L填料·d)条件下,使出水满足一般水产养殖水质要求(氨氮0.5 mg/L,亚硝氮0.1 mg/L)。进水碳氮比在1以内时MBBR能够稳定高效运行。在实验室模拟循环水养殖过程中,经菌剂强化的MBBR能维持循环出水氨氮低于0.5 mg/L,亚硝氮低于0.05 mg/L。     

A quantitative method for detecting ammonia‐oxidizing bacteria in coastal aquaculture systems

There is a need to quantify autotrophic nitrifiers in coastal aquaculture systems for evolving a bioremediation strategy. Autotrophic nitrifiers are extremely slow‐growing organisms, which cannot be detected by traditional methods as they are notoriously difficult to culture. Molecular techniques based on functional genes could be deployed for the detection of nitrifiers. Ammonia monooxygenase (amoA), that catalyses the oxidation of ammonia to hydroxylamine in the rate‐determining step of nitrification is largely unique to ammonia‐oxidizing bacteria (AOB). In the present study, a quantitative real‐time polymerase chain reaction assay targeting amoA was developed to estimate AOB population size in coastal soil, ammonia‐removing bioaugmentors and the solid matrix. To achieve this objective, different set of primers and a dual labelled probe have been designed for SYBR Green and TaqMan real‐time assays. The abundance of AOB ranged from 10⁴ to 10⁶ order of magnitude in the samples. In the present study, biofilm formation of the consortium of nitrifying bacteria onto bagasse has also been quantified. The results demonstrate that the developed method is a rapid and sensitive tool for the quantitative detection of nitrifying bacteria in aquatic and related environment. This helps in making the bioremediation approach for ammonia removal by immobilization of nitrifying bacteria onto the natural substrate.     

不同浓度臭氧对循环水养殖系统生物膜活性及其净化效能的影响

本文通过在循环水养殖系统中添加不同浓度的臭氧,研究其对循环水养殖系统生物膜活性及其净化效能的影响.结果显示,当氧化还原电位(ORP)小于450 mV时,氨氮的去除率随着臭氧浓度升高而升高,最高去除率达39.9％,亚硝酸盐氮的平均去除率为28.2％,生物膜菌群的平均存活率为88.1％,生物膜对养殖水体氨氮和亚硝酸盐氮的处理效果良好;当氧化还原电位为500 mV时,经过臭氧24 h处理,氨氮和亚硝酸盐氮的去除率分别由36.5％、28.1％降到12.2％、8.4％,而臭氧4h处理后,生物膜对氨氮和亚硝酸盐氮的去除率分别由47.5％、32.1％降到5.0％、3.3％,水处理效果明显下降,生物膜菌群存活率由88.1％降到31.5％.由此可见臭氧添加浓度对生物膜及净化效能有重大影响.综合试验结果和分析评估,建议封闭循环水养殖系统的臭氧添加量以控制生物滤池内的氧化还原电位低于400 mV为宜,可保证循环水系统的安全性和经济性.