Ion channels from the Bacillus subtilis plasma membrane incorporated into planar lipid bilayers

Fusion of Bacillus subtilis plasma membrane vesicles with planar lipid bilayers induced the appearance of discrete current fluctuations characteristic of ion channels. These channels showed a wide range of conductances and kinetic behaviors. In 300 mM KCl, their conductances ranged from a few hundreds of pS to more than 1 nS, and most of them exhibited several sub-states. The channels poorly discriminated between small univalent anions and cations. Some of them showed voltage dependence and most of them presented a complex gating kinetics. The results are consistent with the hypothesis of the presence in the B. subtilis plasma membrane of pores composed of subunits that function cooperatively.