Through research at the University of Warwick it has been
discovered that phototrophic and heterotrophic bacteria, two of the most
abundant microorganisms in the ocean, work together in many of the nutrient
cycles. This challenges the common belief that phototrophs and heterotrophs are
in competition for nutrients that are scarce in the marine environment.
The interaction between these organisms balances the
nutrient levels in the ocean, thus provides a base for a healthy marine
ecosystem. Phototrophic bacteria fixes carbon dioxide from the air using light.
This then converts to organic matter which heterotrophs consume and then
release nutrients back into the ecosystem. This interaction was observed by the
researchers through nutrient and molecular analyses, after growing cultures of
each bacteria and putting them in natural seawater. Both microorganisms reached
a stable state where both bacteria began to mutually benefit each other. This
system works like an economy with nutrients acting as currency. If one of the
partners takes too much and does not give back, they will suffer the
consequences in the long term.
As half of the world’s primary production and oxygen we
breathe relies on the interaction in this system to be efficient. The rate at
which our oceans will continue to buffer against carbon dioxide in our
atmosphere is determined by the speed at which nutrients are cycled through
this process. These essential processes need to be understood more deeply, which
will allow us to understand how to improve and conserve our waters. Through
this predictions as to how the oceans will react to climate change can be made.
Referenced paper: Joseph A. Christie-Oleza, Despoina
Sousoni, Matthew Lloyd, Jean Armengaud, David J. Scanlan. Nutrient recycling
facilitates long-term stability of marine microbial phototroph–heterotroph
interactions. Nature Microbiology, 2017; 2: 17100 DOI: 10.1038/nmicrobiol.2017.100
Hi Zoe,
ReplyDeleteThank you for your summary, this was an interesting read. I was wondering if you could clarify what you meant with this statement: "This challenges the common belief that phototrophs and heterotrophs are in competition for nutrients that are scarce in the marine environment". Are you referring to nutrients such as vitamins or trace elements?
On a separate note, I was wondering if the authors acknowledged the fact that mixotrophy is a prevalent trophic mode in the plankton (Stoecker et al., 2017). Did they attempt to theorise about how including a mixotroph in the experimental design could affect the equilibrium that was reached in their two species co-culture?
Thank you,
Alessandro
Stoecker, D. K., Hansen, P. J., Caron, D. A. & Mitra, A. (2017) "Mixotrophy in the Marine Plankton". Annual Review of Marine Science, 9(1), pp 311-335