Microbes dominate the planet, especially the ocean, and help support the entire marine food web. In a recent report published in Nature Microbiology, SOEST oceanography professor Ed DeLong and his team report the largest single-site microbiome gene catalog constructed to date. With this new information, the team discovered nutrient limitation is a central driver in the evolution of ocean microbe genomes.
Water samples were collected over two years, and modern genome sequencing technologies were used to decode the genes and genomes of the most abundant microbial species in the upper 3,000 feet of water at the Hawaiʻi Ocean Time-series (HOT) Program open ocean field site, Station ALOHA.
Just below the depth of sunlit layer, the team observed a sharp transition in the microbial communities present. They reported that the fundamental building blocks of microbes, their genomes and proteins, changed drastically between depths of about 250-650 feet.
“In surface waters, microbial genomes are much smaller, and their proteins contain less nitrogen—a logical adaptation in this nitrogen-starved environment,” said Daniel Mende, post-doctoral researcher in SOEST and lead author on the paper. “In deeper waters, between 400–650 feet, microbial genomes become much larger, and their proteins contain more nitrogen, in tandem with increasing nitrogen availability with depth.”
“These results suggest that the availability of nutrients in the environment may actually shape how microbial genomes and proteins evolve in the wild,” said DeLong.