Discovery That Bacterium Is Phosphate Gourmet Key Clue To What Makes It Most Social Of Bacteria

Myxococcus xanthus isamazingly social and co-operative for a bacterium. It "hunts" as apack, it makes a collective decision with other M. xanthus whether togo dormant or not, and it even has methods of policing the behaviour ofindividual bacteria that try to "cheat" in the collective activity ofthe group. Now Dr David Whitworth from the Biological SciencesDepartment of the University of Warwick has also discovered that itappears to seek out and consume phosphate in a "gourmet" manner,providing important evidence as to how such a relatively simpleorganism is able to act in such a social manner.

Dr Whitworthlooked at the signalling pathways used by the bacterium to processinformation to switch actions on or off. Myxococcus xanthus has anunprecedented number (around 150) of the signalling pathways known as"two component switches" which dramatically increases the level ofcomplexity of information that can be processed by the bacterium. DrWhitworth focussed on three previously described signalling pathwaysthat were known to be similar to phosphate utilisation pathways (allorganisms need to consume phosphate to thrive). Until now mostresearchers believed that all bacteria only required one phosphatedependent signalling pathway to find the phosphate needed forconsumption, and so the other two pathways found in M. xanthus simplydid something else. In collaboration with Prof Mitchell Singer of theUniversity of California at Davis, Dr Whitworth found that in fact thebacterium was using all three pathways and part of a further fourthpathway in combination, to detect and utilise phosphates, making it avery sophisticated consumer of phosphates - the bacterial equivalent ofa gourmet diner.

That the 3 pathways act in concert probablyenables the organism to find phosphates in different chemical states orenvironmental conditions, or even to exploit the phosphates found inother M. xanthus cells or those of potential prey organisms. DrWhitworth found that:

* The potential complexity of theinformation on phosphate levels that the bacterium can process issignificantly increased by the findings that there are three phosphatesignalling pathways, with considerable interaction between the threepathways.

* A further additional partial pathway also acts as aphosphate level detector - giving the bacterium even more tools toemploy as a phosphate gourmet.

* Dr Whitworth also has evidencethat the surprising extent of interaction between the three and a halfphosphate signalling pathways is also found among the other 140 plussignalling pathways of the bacterium. If three and half pathways areenough to make it a phosphate gourmet, the level of interactionsbetween up to 150 pathways will easily be enough to give Myxococcusxanthus its precocious social skills.