When we think of the oceans we rarely consider the microbes found within. The marine microbiome is one of the largest microbiomes on the planet with billions of microbes being found in a single litre of water. These microbes play a crucial role in the generation of energy in the planet and are responsible for half of the primary energy production on earth, either through photosynthesis at the surface of the ocean, or through chemical reactions (chemosynthesis) in the darker ocean depths. Photosynthesis by marine microbes has an important role to play in the removal of carbon dioxide from the earth’s atmosphere as each year these cells can convert approximately 20 billion tonnes of carbon dioxide into organic matter.
The ocean harbours a huge diversity of microbes, however many of these are unable to be grown and studied in the laboratory. In order to overcome these limitations, many studies now try and analyse all the microbial communities in the seawater using a process known as metagenomic sequencing by isolating the DNA of every living cell in a sample, rather than just the small proportion of cells which can be grown in the lab. From this DNA we can unlock the genetic code of all these microbes. This allows us to identify what cells are in the sample and also find out what processes these cells can carry out. Marine microbes are actually an extremely fruitful source of potential new products such as antibiotics and chemotherapy agents. Metagenomic studies have identified a vast amount of genes in the marine microbiome which code for the proteins involved in making new these products. Further studies into these cells could help unlock a number of new treatment strategies for many diseases and illnesses.
Global climate change is having a major effect on all environments in earth, in particular, on marine ecosystems. Ocean acidification and increased temperatures can alter the composition and the productivity of the marine microbiome. These microbes themselves may be an important tool for monitoring climate change. Changes in the composition of the marine microbiome in areas give an indication of the short- and long-term effects of climate change on the marine ecosystem.