Bacteria shown to 'smell' ammonia

August 18, 2010 by Lin Edwards report

( -- 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: Major biofilm dispersion finding announced

Related Stories

Genes that make bacteria make up their minds

March 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 ...

Bacteria breakthrough is heaven scent

August 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.

Recommended for you

Study finds 'rudimentary' empathy in macaques

December 1, 2015

(—A pair of researchers with Centre National de la Recherche Scientifique and Université Lyon, in France has conducted a study that has shown that macaques have at least some degree of empathy towards their fellow ...

Scientists overcome key CRISPR-Cas9 genome editing hurdle

December 1, 2015

Researchers at the Broad Institute of MIT and Harvard and the McGovern Institute for Brain Research at MIT have engineered changes to the revolutionary CRISPR-Cas9 genome editing system that significantly cut down on "off-target" ...

Which came first—the sponge or the comb jelly?

December 1, 2015

Bristol study reaffirms classical view of early animal evolution. Whether sponges or comb jellies (also known as sea gooseberries) represent the oldest extant animal phylum is of crucial importance to our understanding of ...

Trap-jaw ants exhibit previously unseen jumping behavior

December 1, 2015

A species of trap-jaw ant has been found to exhibit a previously unseen jumping behavior, using its legs rather than its powerful jaws. The discovery makes this species, Odontomachus rixosus, the only species of ant that ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.