Wednesday, 23 Jul, 2008 Science

According to the researchers from the Helmholtz Center for Infection Research, they were able to discover the strategies that biofilm bacteria use.

In most cases biofilm bacteria develop in crowds and squat on areas where they create a community with other bacteria. They can develop on any surface to which bacteria can affix to. It is interesting to note that these biofilms cannot be destroyed by any disinfectants and antibiotics, not even phagocytes and our immune system are able to annihilate the biofilm bacteria.

This is one of the major problems in hospitals if biofilms create a community a catheter or implant, surfaces where bacteria may cause a dangerous infection.

Researchers working at the Helmholtz Centre for Infection Research, located in Braunschweig, claim that they have spotted one of the main mechanisms that biofilms use in order to defend themselves against the attack of phagocytes.

Teamed up with colleagues from Australia, Great Britain and the United States, scientists are now publishing their discoveries in the popular specialist publication PLoS ONE. The finding states that biofilm bacteria apply chemical weapons to protect themselves.

Until recent findings, researchers could not understand the core of the biofilm problem - why phagocytes cannot destroy the biofilm bacteria. Dr. Carsten Matz was the one to start a serious investigation of the problem. The model for his research was the marine bacteria, which face continuous threats in their environment. The threat comes from the amoebae, whose behavior resembles the behavior of phagocytes. The amoebae acts the same way in the sea as the immune cells in human body, namely they look for and feed on the bacteria.

As long as bacteria are free and separated in the water, they turn into an easy target for the attackers. But when they become affixed to a surface and form a community with other bacteria, the amoebae is unable to assault them.

"The surprising thing was that the amoebae attacking the biofilms were de-activated or even killed. The bacteria are clearly not just building a fortress, they are also fighting back," says Carsten Matz.

In order to protect themselves, bacteria use chemical weapons. Marine bacteria, for instance, uses a very effective molecule called pigment violacein. After the protection system is prepared, the biofilm bacteria turn color soft purple. In case the invaders consume only one cell of the biofilm, together with the pigment included, they are instantly paralyzed and the chemical weapon activates their suicide mechanism.

"I feel that these results could offer a change of perspective. Biofilms may no longer be seen just as a problem; they may also be a source of new bioactive agents. When organized in biofilms, bacteria produce highly effective substances which individual bacteria alone cannot produce," says Carsten Matz.

Researchers look forward to apply these molecules in order to deal with a certain group of pathogens: parasites living in human body and causing serious infections, including sleeping illness and malaria. It is worth mentioning that amoeba represent olden relatives of these pathogens, which is why weapons obtained by the biofilm bacteria may offer a great basis for the development of new parasiticidal drugs.

Source: Eurekalert.org.

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