最新一期Science上发表了文章《Metagenomic Analysis of the Human Distal Gut Microbiome》，文章采样两个健康人体排泄物内的细菌，进行了相当于environmental环境测序的研究。如下面引用，他们一共获取了接近140,000(十四万)高质量测序读取结果，获取了接近80,000,000bp(八千万碱基对)的序列，平均每个read有570bp。相当于仅仅是高质量的测序反应，就有至少十四万个。如果一次测序成本为3美元，单就测序反应成本就有四十多万美元以上，如果有一半的反应是低质量的测序结果，成本随即提高一倍。
A total of 65,059 and 74,462 high-quality sequence reads were generated from random DNA libraries created with fecal specimens of two healthy humans (subjects 7 and 8). These two subjects, ages 28 and 37, female and male, respectively, had not used antibiotics or any other medications during the year before specimen collection (11). The combined sequenced distal gut “microbiome” of subjects 7 and 8 consisted of 17,668 contigs that assembled into 14,572 scaffolds, totaling 33,753,108 bp. The scaffolds ranged in size from 1000 to 57,894 bp and the contigs from 92 to 44,747 bp. The average depth of sequence coverage in contigs was 2.13-fold. Forty percent of the reads (56,292 total) could not be assembled into contigs, most likely because of a combination of low depth of coverage and low abundance of some organisms within the specimens. Together, these singletons accounted for an additional 45,078,063 bp of DNA.
文章最后说，需要进行更多的研究，采样更多的微生物种类，不同年龄、饮食、疾病状态、不同环境，以及间隔不同的时间。这片文章基本上也就采了两个样，花掉了很多钱。如果采样要如此丰富，需要多少钱呢？不过文章表示，这项研究很有意义，基本上对于人类健康有方方面面的好处，这也是为什么只要和人有关的研究，经费总是比较容易拿的：
The results should provide a broader view of human biology, including new biomarkers for defining our health; new ways for optimizing our personal nutrition; new ways for predicting the bioavailability of orally administered drugs; and new ways to forecast our individual and societal predispositions to disorders such as infections with pathogens, obesity, and misdirected or maladapted host immune responses of the gut.