It’s a small world after all

Despite being the oldest type of living organism on earth, it’s only recently that scientists began uncovering the significance of bacteria in the world’s oceans. Mark Blackham looks at NIWA’s exploration into the role of marine bacteria.

Bacteria have been described as the ‘dark matter’ of the biological world – a poorly understood phenomenon that is an unseen force on life on Earth.

It has been estimated that 4 million species of bacteria, most unknown to science, can be found in one metric ton of soil. NIWA’s Wellington Regional Manager, Julie Hall, says that bacteria are just as plentiful in the world’s oceans.

“There are billions upon billions of these guys in the ocean,” Hall says.

“We now know a lot about the critical roles they play in the ocean environment.

“As the technology for studying these microscopic organisms evolves, so does our understanding of who they are and what they do.”

Even though they weigh less than a quadrillionth of a gram each, the total weight of all bacteria in the world is roughly one billion tons. That’s about equal to the weight of all plants on Earth. It means bacteria form half of all biomass in the oceans.

These invisible creatures also pack a powerful punch. Name a chemical element or compound of elements and there are bacteria using it, releasing it, recycling it and transforming it. “This movement of elements through living matter, the atmosphere, oceans and sediments is called cycling and they’re hugely important processes. Without bacteria, life wouldn’t exist.”

In fact, almost any chemical reaction can be done by at least one group of bacteria. Bacterial decomposition, for example, is a core part of nutrient cycling. Another group called cyanobacteria carry out photosynthesis. They take carbon dioxide from the air, turn it into organic parts of their own cells and release oxygen just like plants.

Some can take nitrogen gas from the air and turn it into organic parts of their own cells – they can also perform the reverse. They even affect the weather: some bacteria play a key role in the sulphur cycle, which is linked to cloud formation. Solutions Isolating marine bacteria for further studies.

It's a small world after all

The secret to marine bacteria having such a huge impact on the environment is their adaptability to live pretty much anywhere. Hall calls them Earth’s ‘ultimate survivors’.

“In hydrothermal vents they have to be able to survive at 350 degrees centigrade. Others can be found in the very salty waters of the Dead Sea, sea ice or even places without oxygen.”

They can thrive on a diet of just oil, something only discovered after the 2010 oil spill into the Gulf of Mexico. The oil, although low in nitrogen, provided them with a rich food source, and they were able to compensate for the lack of nitrogen by getting it from the air. The population exploded. Scientists estimated that it took only one day for bacteria to reduce a gallon of oil to a half gallon.

Scientists are now hoping to glean valuable insights into how bacterial technology can be used for cleaning up future oil spills. Hall says there are still many questions that NIWA scientists are looking to find answers to.

“We need to learn more about the community patterns and functions of these necessary organisms, as well as predict how they may respond to environmental changes impacting life on Earth. This information is vital in furthering our scientific endeavours outside of microbial ecology.”

Ocean acidification caused by increasing atmospheric carbon dioxide is a current area of focus for NIWA. A team is studying how ocean acidification affects bacterial processes and what any change to the acidity and temperature of the ocean might mean in the future. “We’re predicting that less carbon from the upper ocean will get into the deep ocean. More and more is being recycled in the upper ocean and at the same time producing more carbon dioxide. When there is less carbon in the deep ocean, it affects the organisms in the deep that rely on the carbon as a food source.

“And with more carbon dioxide in the upper ocean, it adds to the carbon dioxide already absorbed by the ocean and leads to an increase in ocean acidification. Until we make sure the microbial processes are okay, there will be consequences further up the food web.”

Hall says unlocking the secrets of bacteria will play a huge role in developing a better understanding of how the planet works.

“Bacteria have taught us a lot in just a few years. But we know we’re just scratching the surface.”

Isolating marine bacteria for further studies. [Alan Blacklock]
Counting marine bacteria. [Alan Blacklock]