The climate changing gas dimethyl sulphide (DMS) is being made by microbes at the rate of more than 200 million tonnes a year in the worlds seas, scientists heard today (Tuesday 1 April 2008) at the Society for General Microbiologys 162nd meeting being held this week at the Edinburgh International Conference Centre.
This gas has many different effects, says Dr Andrew Curson from the University of East Anglia in Norwich, UK. It triggers clouds to form over the oceans and clouds are amongst the worlds most potent climate cooling factors; it attracts birds by alerting them to a food supply; and it smells that typical seaside smell.
The source of the dimethyl sulphide gas is another sulphur compound made by many seaweeds and marine plankton as an anti-stress protection. Some marine bacteria can break down this compound to release chemical energy, and dimethyl sulphide is given off as a by-product, with about 10% finding its way up into the atmosphere.
Using genetic analysis, we showed for the first time that different types of bacteria could degrade the sulphurous compound made by phytoplankton in different ways. We even found some species of bacteria that could use multiple methods to break down and release dimethyl sulphide, says Dr Curson.
The research identified the genes needed to make DMS, and the scientists had three surprises. The first was that different bacteria use completely different biochemical mechanisms to break down compounds from phytoplankton. Secondly, the mechanisms that scientists predicted bacteria would use were generally not the ones observed during the investigation. Finally, the scientists were surprised when they identified some terrestrial microbes that had never even been suspected of making dimethyl sulphide gas, which have significant ecological and evolutionary consequences.
These multiple-use genes, which we were particularly interested in, are rampantly transferred between microbes th
|Contact: Lucy Goodchild|
Society for General Microbiology