Taxonomic and functional profiling of nitrifying biofilms in freshwater, brackish and marine RAS biofilters
Taxonomic and functional profiling of nitrifying biofilms in freshwater, brackish and marine RAS biofilters
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DOI：
10.1016/j.aquaeng.2020.102094
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发表时间：
2020-08-01
影响因子：
4
通讯作者：
Spieck, Eva
中科院分区：
文献类型：
--
作者：
Huepeden, Jennifer;Wemheuer, Bernd;Spieck, Eva
在循环水养殖系统（RAS）中，消除氨和亚硝酸盐等有毒N化合物的关键步骤是通过硝化微生物介导的，并在生物过滤器中进行。在这项研究中，对三种不同RAS的9个移动床生物过滤器的生物载体的微生物定殖分析，发现了淡水、微咸水或海洋工艺水的特定群落。基于illumina的16S rRNA v4区扩增子测序显示，所有生物过滤器中微生物多样性较高，有1000-2500个物种水平的操作分类单位（OTUs），其中微咸水RAS多样性最高。变形菌门、拟杆菌门、植物菌门、氯霉素门和硝基螺旋菌门是最丰富的门。已知的674个属中有76个出现在所有9个生物过滤器中，并被定义为核心分类群，包括硝化细菌（Nitrosomonas和Nitrospira）以及（异养）属plantomyces、Blastopirellula、Nannocystis和Lewinella。硝化群落由不同的、密切相关的、迄今尚未培养的亚硝化单胞菌和硝化螺旋菌组成，这强烈表明RAS生物过滤器中存在几种潜在的新型氨和亚硝酸盐氧化物种。在半盐水生物过滤器中检测到已知的科莫克斯硝化螺旋菌的近缘菌株，其16S rRNA基因序列与Ns的同源性为94- 99%。inopinata。用三种不同RAS的生物过滤器衍生的生物载体进行的耐盐试验显示，在盐度方面具有意想不到的广泛生理灵活性。淡水硝化菌的硝化性能随着盐度的增加而急剧下降，在15 PSU时几乎完全被抑制，而咸淡水和海洋硝化菌表现出较高的抗性，并在很宽的盐浓度范围内保持硝化活性。这些数据有助于在改变工艺水盐度的情况下改善RAS的硝化过程。
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.