It is well known that most bacteria possess two distinct life styles, including 1) planktonic style in which single cells can swim freely in the medium, the growth and replication of each cell is somehow independent of others (here, we neglect the communication among cells); 2) surface association (eventually those cells would form biofilms) style in which single cells would form communities, the behaviors of each cell spatially and temporally depend on others. People have known that cells would spontaneously switch their phenotype from the planktonic to the surface association style when planktonic cells grown on a surface. This fact actually pose a challenging fundamental question - How bacteria switch (select) their own life style? This question can also be asked in other ways: Can bacteria sense a contact (surface)? In other words, are there physical or chemical signals that trigger the cells switching their phenotype after they contact to a surface? If yes, Can we blocking these signals to lock cells at the phenotype of planktonic?
In our studies, we focused on two clues that may relate to the surface sensing mechanisms, including 1) c-di-GMP signaling pathway; 2) membrane voltage. To test these ideas, by using some protein sensors to in vivo monitor the concentration of c-di-GMP or the membrane voltage, we investigated whether surface contact can alter the concentration of c-di-GMP or the membrane voltage, thereby triggering the phenotype switch.
c-di-GMP signaling pathways in Pseudomonas aeruginosa