Bacteria shown to 'smell' ammonia

Aug 18, 2010 by Lin Edwards report

(PhysOrg.com) -- A new study provides the first evidence that bacteria respond to odors, which according to one of the researchers may be the earliest evolutionary example of olfaction.

Microbiologist Reindert Nijland from the University Medical Centre at Utrecht in the Netherlands, and marine microbiologist Grant Burgess, from the University of Newcastle in the UK, were studying the formation of biofilms by common that live in soils (Bacillus licheniformis), and discovered the were sensitive to the presence of ammonium sulfate, which bacteria metabolize and convert to ammonia, which is a valuable nutrient because it contains nitrogen, which is then used in the production of proteins and . Some ammonia is released to the air in the process.

In the study the researchers used an array consisting of 96 wells and filled one half with a culture medium intended specifically to promote biofilm formation, and the other half with a general, nutrient-rich culture medium. Biofilms were formed in the wells in the biofilm section, but formed best in the central wells closest to the nutrient-rich medium containing ammonium sulfate. Bacteria in these wells were releasing ammonia as they digested the ammonium sulfate.

Nijland and Burgess then experimented with different media and found that media with ammonium sulfate as one of the nutrients produced the greatest volume of biofilms in the central wells. The same pattern was produced if the media was a simple aqueous solution of ammonia, which suggests the bacteria can sense the volatile ammonia and react by growing a biofilm towards its source. This would be an advantage to the bacteria as ammonia indicates the presence of a rich source of nutrients nearby.

Bacteria have previously been shown to respond to gases such as and oxygen, but Nijland said these do not have odors and so the response to them cannot be olfactory. He said it makes no sense to "smell" oxygen as it is always around. "You smell things that give important information," Nijland said. He also countered criticism of the research suggesting the bacteria were responding to changes in pH of the solution as it absorbed ammonia, by saying the effect was observed even when concentrations were too low to have much effect on pH, and the culture medium was also buffered to ensure large pH shifts did not occur.

Nijland said he hoped the results might lead to ways of preventing the formation of biofilms, which are resistant to antibiotics and make bacteria that cause disease more of a threat.

The paper is to be published in the Biotechnology Journal.

Explore further: How a molecular Superman protects the genome from damage

add to favorites email to friend print save as pdf

Related Stories

Bacteria breakthrough is heaven scent

Aug 15, 2010

Bacteria are well-known to be the cause of some of the most repugnant smells on earth, but now scientists have revealed this lowest of life forms actually has a sense of smell of its own.

Genes that make bacteria make up their minds

Mar 30, 2009

Bacteria are single cell organisms with no nervous system or brain. So how do individual bacterial cells living as part of a complex community called a biofilm "decide" between different physiological processes (such as movement ...

Recommended for you

Cell architecture: Finding common ground

Oct 16, 2014

When it comes to cellular architecture, function follows form. Plant cells contain a dynamic cytoskeleton which is responsible for directing cell growth, development, movement, and division. So over time, changes in the cytoskeleton ...

Scientists identify "naïve-like" human stem cell

Oct 16, 2014

Scientists from our university and Berlin have identified a type of human stem cell that appears to be "naïve-like" – able to develop into any type of cell. The discovery of this cell type could potentially ...

Shaping the way to see the world

Oct 16, 2014

The proliferation of cells, in particular the orientation in which they divide, is key in regulating the shapes of tissues. However, the cellular mechanisms that govern cell proliferation and cell division orientation are ...

User comments : 0