What have marine microbes ever done for us?

Our lives ultimately depend upon some of the smallest life forms on Earth - the constituents of the ocean microbiome. But what microbes are there in the sea, what are they doing there, and how do they impact us? Katie Haylor spoke to Michael Cunliffe from the University of Plymouth and the Marine Biological Association...

Michael - When you first look at seawater, it’s this translucent liquid. If you're lucky, you might see a fish, you might see a whale. But actually, within that seawater are a huge number of marine microbes. You talk about 10 million viruses and million bacteria or a thousand microbes and eukaryotes that we call protists and that literally is one drop in the ocean.

Katie - These billions of microbes together are known as the ocean microbiome. This is a concept we’re quite familiar with, the microbes both on and inside us make up our own unique human microbiome.

Michael - So particularly, the microbes that are in our gut. They help us to digest food and we wouldn’t really be able to get the same nutritional value from food that we would without those gut microbes. Microbes in the ocean are sort of similar. There's lots of them. They're diverse, and they all have really important functions. It’s those functions that really help the ocean to work.

Katie - What are they actually doing in the water? According to Michael, both the ocean and us would be pretty stuffed without them.

Michael - Collectively, we could consider the marine microbes to be environmental chemists. They're performing all of the chemical reactions that are needed to sustain the chemistry of the ocean and the chemistry of our atmospheres. Microalgae, phytoplankton photosynthesise in the same way that plants and trees are on the dry land, and the scale that this happens is huge. So basically, half of the global photosynthesis is performed by these phytoplankton. So that means, half of the oxygen that we breathe comes from these little unicellular plants that live in surface water. But the other big function that marine microbes have is this base of the marine food chain. All of the larger organisms that live in the sea rely either directly or indirectly on microbes.

Katie - As microbes in the ocean are so fundamental to the life in the seas, understanding the effects that humans might be having on these tiny creatures is big business.

Michael - Thinking about change and the impact that humans have on the marine environment, there's evidence that actually, microbes can respond to that and actually help to mitigate the impact that we have.

Katie - So they're cleaning up our mess essentially.

Michael - Yeah, to a certain extent. There's a really brilliant example of that and that was the Deepwater Horizon oil spill that occurred in the Gulf of Mexico – absolute horrendous environmental disaster. All this oil was produced and had a devastating effect on the ecosystems in the area. But one of the really interesting things that happened was, immediately after the oil spill, microbes increased in abundance. They were specialists in degrading oil. They played a major role in reducing the impact that the oil pollution had.

Katie - What about plastic because plastic seems to be a real problem in the oceans?

Michael - This is a Holy Grail really at the moment to marine microbiology. If you put plastic in seawater, very, very quickly, microbes colonise plastic and work has been done at these different locations around the planet, looking at different types of plastic showing that different sorts of microbes grow on them. So, there's a huge research effort at the moment to try and see if any of these marine microbes are actually able to degrade plastic. If they are, we could maybe look at the enzyme systems that they use and see if we could exploit that to try and deal with this pollution problem.

Katie - There's so much we don’t know about this mysterious environment under the waves. Perhaps ocean microbes could hold the key to a treasure chest of untapped scientific potential and scientists are scouring the seas in search of the next novel compound – a process known as bioprospecting.

Michael - There's a whole area of marine microbiology now where people are looking at the functional roles that microbes have say, “Well actually, can we bring them into the lab? Can we bring them into industry? Can we bring them to biotechnology? Can we actually use them to our advantage?” One of the really exciting areas is basically looking at marine microbes as a source of antimicrobial compounds. So I'm sure everyone is familiar with the major problems that we have at the moment with microorganisms that cause disease, that are resistant to antibiotics, and the problems that people have especially when they're in hospital. There's a real demand now to try and deal with that. Scientists are looking at microbes that live in the ocean and seen if they have any solutions. So, are any of these organisms producing antimicrobial compounds? One of my colleagues at the University of Plymouth is looking at marine sponges and they're trying to identify – are there any antimicrobial-producing microbes in marine sponges?