It is well documented that bacteria can exchange messages by releasing substances into a surrounding liquid culture medium, but this new study is the first to report signaling between physically separated bacterial cells.

Professor Alan Parsons and Dr. Richard Heal of QinetiQ Ltd, Europe's largest science and technology organization, claim to have shown that physically separated colonies of bacteria can transmit signals conferring resistance to commonly used antibiotics.

The discovery is thought to have direct application to the growing problem of resistance of bacteria to antibiotics -- in particular in preventing the growth of biofilms, which often cause infection associated with surgical implants.

Professor Parsons and Dr. Heal conducted their experiments using a Petri dish divided into two compartments connected by a five-millimeter air gap between the top of the wall and the lid.

In one compartment, they placed drops of the bacterium Escherichia coli, together with antibiotics. When the other compartment was empty, the bacteria were killed by the antibiotics.

But when thriving colonies of E.coli were placed in the other compartment, the first colony of bacteria not only survived, but also multiplied. Yet, if the gap between the compartments was sealed, the bacteria in the first compartment died.

Professor Parsons and Dr. Heal concluded that the bacteria must have been responding to some kind of airborne signal from the adjacent culture, probably in the form of a volatile chemical.

Further research is still required to identify the exact nature of the signaling mechanism and to establish whether blocking of the signaling mechanism might prove a valuable weapon in combating the problem of bacterial antibiotic resistance.

The Journal of Applied Microbiology is an international peer-reviewed research journal edited by Dr. Alan Godfree of United Utilities Water plc. It publishes original research and review articles on all aspects of applied microbiology including environmental, food, agricultural, medical, pharmaceutical, veterinary, taxonomy, soil, systematics, water and biodeterioration.

The journal is published by Blackwell Publishing for the UK Society for Applied Microbiology.

(Reference: Heal, R D and Parsons, A T (2002) Novel intercellular communication system in Escherichia coli that confers antibiotic resistance between physically separated populations. Journal of Applied Microbiology 92, 1116-1122.)

[Contact: Dr. Alan Godfree]

29-May-2002