Universal Amplicon Sequences (mixed 16S/18S) from GEOTRACES Cruises GA03 and GP13

Dedicated sampling campaigns such as JGOFS, CLIVAR, and GEOTRACES have quantified critical oceanic biogeochemical processes on a global scale. Integrating these measurements with microbial community composition data is highly desirable because it would allow hypotheses about biogeographic distributions to be tested or perhaps lead to the discovery of organisms responsible for a particular biogeochemical process. A promising strategy to generate this microbial community composition data comes from high-throughput sequencing of PCR amplicons generated with the 515Y/926R universal 16S/18S primer set. The two key advantages of the 515Y/926R primers are 1) their comprehensiveness - recovering amplicons from the entire cellular microbial community - and 2) their quantitative nature - recovering gene copy abundances as shown previously with microbial community standards. Compared to metagenomes, amplicons additionally have the advantage of more easily detecting rare community members that may be biogeochemically significant (e.g. diazotrophs). In this study, we applied the 515Y/926R primers to DNA from the recently published bioGEOTRACES metagenomic dataset, and use these results to describe microbial community composition across a longitudinal transect of the southern Pacific Ocean from Australia to Tahiti (GEOTRACES section GP13) and a longitudinal transect of the northern Atlantic from Massachusetts to the Canary Islands (GEOTRACES section GA03). In addition, we conducted intercomparisons with metagenomic taxa abundances and show the two techniques correspond strongly to one another for most samples (average R^2=0.97).

针对海洋生物地球化学关键过程，诸如JGOFS、CLIVAR和GEOTRACES等专项采样活动已在全球范围内进行了量化。将此类测量与微生物群落组成数据相结合，实为一大愿望，因其可验证关于生物地理分布的假设，或许甚至引领至特定生物地球化学过程的负责生物的发现。利用515Y/926R通用16S/18S引物集进行PCR扩增子高通量测序，生成微生物群落组成数据，乃一项颇具前景的策略。515Y/926R引物的两项关键优势在于：1）其全面性——可从整个细胞微生物群落中恢复扩增子；2）其量化特性——恢复基因拷贝丰度，如前所述，与微生物群落标准一致。相较于宏基因组，扩增子还具有易于检测可能具有生物地球化学意义的稀有群落成员（例如硝化细菌）的优势。在本研究中，我们应用515Y/926R引物对近期发表的bioGEOTRACES宏基因组数据集中的DNA进行了测序，并利用这些结果描述了从澳大利亚至塔希提岛（GEOTRACES区域GP13）以及从马萨诸塞州至加那利群岛（GEOTRACES区域GA03）的纵向剖面微生物群落组成。此外，我们还进行了与宏基因组物种丰度的相互比较，并显示出这两种技术在大多数样本中表现出强烈的对应性（平均R²=0.97）。